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Plant systematics is a science that includes and encompasses traditional taxonomy; however,
its primary goal is to reconstruct the evolutionary history of plant life. It divides plants into
taxonomic groups, using morphological, anatomical, embryological, chromosomal and
chemical data. However, the science differs from straight taxonomy in that it expects the
plants to evolve, and documents that evolution. Determining phylogeny - the evolutionary
history of a particular group - is the primary goal of systematics.
Classification Systems for Plant Systematics
Approaches to classifying plants include cladistics, phenetics, and phyletics.
 Cladistics: Cladistics relies on the evolutionary history behind a plant to classify it into a
taxonomic group. Cladograms, or "family trees", are used to represent the evolutionary
pattern of descent. The map will note a common ancestor in the past, and outline which
species have developed from the common one over time. A synapomorphy is a trait that
is shared by two or more taxa and was present in their most recent common ancestor
but not in earlier generations. If a cladogram uses an absolute time scale, it is called a
phylogram.
 Phenetics: Phenetics does not use evolutionary data but rather an overall similarity to
characterize plants. Physical characteristics or traits are relied upon, although the similar
physicality can reflect evolutionary background as well. Taxonomy, as brought forth by
Linnaeus, is an example of phenetics.
 Phyletics: Phyletics is difficult to compare directly with the other two approaches, but it
may be considered as the most natural approach, as it assumes new species
arise gradually. Phyletics is closely linked to cladistics, though, as it does clarify ancestors
and descendants.
How does a plant systematicist study a plant taxon?
Plant scientists can select a taxon to be analyzed, and call it the study group or ingroup. The
individual unit taxa are often called Operational Taxonomic Units, or OTUs.
How do they go about creating the "tree of life"? Is it better to use morphology (physical
appearance and traits) or genotyping (DNA analysis)? There are benefits and disadvantages to
each. The use of morphology may need to take into account that unrelated species in similar
ecosystems may grow to resemble one another in order to adapt to their environment (and
vice versa; as related species living in different ecosystems may grow to appear differently).
It is more likely that an accurate identification can be done with molecular data, and these
days, performing DNA analyses is not as cost prohibitive as it was in the past. However,
morphology should be considered.
There are several plant parts which are particularly useful for identifying and segmenting plant
taxa. For example, pollen (either via the pollen record or pollen fossils) are excellent for
identification. Pollen preserves well over time and is often diagnostic to specific plant groups.
Leaves and flowers are often used as well.
History of Plant Systematic Studies
Early botanists such as Theophrastus, Pedanius Dioscorides, and Pliny the Elder may very well
have unwittingly started the science of plant systematics, as each of them classified many

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plant species in their books. It was Charles Darwin, however, who was the main influence on
the science, with the publication of The Origin of Species. He may have been the first to use
phylogeny, and called the rapid development of all the higher plants within recent geological
time "an abominable mystery".

INTERNATIONAL CODE OF BOTANICAL NOMENCLATURE (ICBN)
Name is the means of reference to all living and non-living things. Any object known to human
being is given a name to describe and communicate ideas about it. The name may be different
in different languages and at different places. The art of naming the object is known as
Nomenclature. And when it comes to naming of plants it is called Botanical nomenclature.
The process of naming plants based on international rules proposed by botanists to ensure a
stable and universal uniform system is called Botanical nomenclature.
Common name is the same of the plant in a particularly area or locality given by the people of
that particular area. Such names vary from place to place and language to language. It is
vulnerable. In India the name changes even with the dilect.
To overcome the problems of common names, scientists suggested name in such a way that it
is accepted in the world and is used internationally. But again, the problem remains the same,
i.e., the language which is not universal. So the botanists agreed to lay down certain rules and
conditions. The main suggestion was that the language of the name should be Latin.
It is because:
(a) The language is not a national language of any country at present.
(b) European languages derived from Latin only.
(c) Past European scholars learnt their subjects in Latin. A lot of previous botanical
literature is written in Latin only.
During 1600 to 1850 AD Europe, particularly Greece, had dominated the world of science. The
language was Latin but the script was Roman.
History of ICBN
Before the middle of the 18
th
century, plant names were usually polynomials i.e. made up of
several words in a series. It was superseded by the binomial system, which was first applied for
the plant kingdom by Linnaeus in his Species Planetarium. It was Linnaeus who proposed the
elementary rules of naming plants first in 1737 in his Critica botanica and then in 1751 in
Philosophia Botanica.
Elementary rules were framed to serve as a guide to botanists. Later in 1813, A.P. de Candolle
in his Theories elementary de la botanique gave a detailed set of rules regarding plant
nomenclature.
However discovery of new plants from later explorations caused concern over procedures for
naming these species. Thus, with the passage of time, the need for an international system
and rule for naming plants became increasing apparent.

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It was then that Alphonse de Candolle, son of A.P. de Candolle convened an assembly of
botanists of several countries to present a new set of rules. Candolle convened the First
International Botanical Congress held at Paris in 1867.
Subsequent meetings of the International Botanical Congress were held in 1892 (Rochester
Code), 1905 (Vienna Code), 1907 (American Code) and 1910, but a general agreement
regarding the internationally acceptable rules of plant nomenclature was reached in 1930 at
the IBC meeting at Cambridge where for the first time in botanical history, a code of
nomenclature came into being that was international in function as well as in name.
This code is called the International Code of Botanical Nomenclature (ICBN). The modifications
or amendments as suggested by the International Botanical Congress at the subsequent
meetings have been incorporated in the ICBN on a regular basis.
Binomial Nomenclature
Linnaeus for the first time proposed that every living being has bionomial name, i.e., a name
with two epithets. One is generic and the other is specific epithet. If an organism has a variety
also, then the name becomes trinomial.
Linnaeus proposed some rules for generic names of plants in Fundamental Botanica (1736)
and Critica Botanica (1737). A.P.de Candolle for the first time proposed rules for nomenclature
of plants which are passed by International Botanical Congress at Paris (1867).
For the first time it was a Swedish Naturalist Carolus Linnaeus who started naming plants in
1753 as Binomial names. It was published in his book “Species plantarum”.
The generic name is always a noun showing colour, name or adjective, e.g., Sarracenia named
after a scientist Michel Sarracin. Species is always an adjective, e.g., for white flower, it is alba.,
for edible one it is sativa, black colour-nigrum etc.
These names are not used always. Species may be a Pronoun, e.g., americana, indica,
benghalensis, etc. It may be shape of a leaf (character of plant), e.g., sagittifolia, name of other
scientist to whom the plant is dedicated, e.g., Sahnii etc.
Before the middle of 18
th
century, plant names were generally polynomial consisting of several
words in a series. Linnaeus proposed the elementary rules in Philosophia Botanica in 1751.
In 1813 A.P.de Candolle proposed details of the rules regarding plant nomenclature in Theorie
elementaire de la botanique. Alphonse de Candolle son of A.P.de Candolle after a long time
convened an assembly of botanists of the world to present a new set of rules. Candolle
convened the first International Botanical Congress at Paris in 1867.
Linneaus to Tourneforte to A.P.de Candolle made Laws of Botanical Nomenclature. In 1867 it
was put before Paris Botanical Congress with principles of priority as Basic code with no
exception.
Earlier to this in 1787 Tourneforte laid 7 laws:
i. Plants of one genus must have same generic name.
ii. Plants of different genera must have different generic name.
iii. If two plants have same name then it should be banished from one place.
iv. He who establishes a new genus should give a name.
v. Polynomials are invalid.

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vi. Generic name based on plant character should be encouraged.
vii. Technical term in place of generic name is invalid.
(A) Paris Code (1867)
The First International Botanical Congress was held at Paris in August, 1867, and was aimed at
the standardization and legislation of proper nomenclature practices. About 150 American and
European botanists were invited to attend the congress.
It was resolved that the Laws, as adopted by the Assembly, shall be recommended as the best
Guide for Nomenclature in the Vegetable Kingdom. These Laws were called the Paris Code, as
they were adopted at the French capital, or de Candolle rules, as they were prepared by
Alphonse de Candolle. According to the Paris Code, the starting-point for all nomenclature was
fixed with Linnaeus.
However no date or any work was specified. The rule of priority was considered as basic with
no provisions for exceptions. It was very important that the publication be valid and attention
was given to author citation and terms applied to categories of plants. Although the Paris Code
guided taxonomic activity in most countries to a considerable degree, but their application
showed many inherent defects.
As time went on, American and British botanists deviated from the rules and they started
practicing the unwritten law named Kew Rule according to which if a species was transferred
to another genus, the specific epithet need not be transferred to the new genus but the
author was free to use a new epithet in the new combination.
(B) Rochester Code (1892)
N.L. Brittan headed the Botanical Congress at Rochester, New York, USA in 1892. The Paris
code was modified and with new recommendations, it was called as Rochester Code.
Some important recommendations were:
(i) Strict adherence to Principles of Priority.
(ii) Name and date of publication for interpretation of priority.
(iii) Acceptance of alternate binomials from employment of the principles of priority
even in case of tautonyms.
(iv) Establishment of the type concept to ascertain the correct application of names.
(C) Vienna Code (1905)
The third International Botanical Congress was held at Vienna in June 1905. In this congress, it
was established that Linnaeus Species Plantarum (1753) is the starting point for naming
vascular plants. Nomina genera conservenda by which generic names having a wide use would
be conserved over earlier but less well known names. Tautonyms are banned and the names
of new taxa be accompanied by Latin diagnosis.
(D) American Code (1907)
The botanist proposed Rochester Code were dissatisfied with Vienna Code and refused to
accept it in 1907. They modified the Rochester code to American Code. American code does
not subscribe to the principle of Nomina generica conservenda or the requirement of Latin
diagnosis. It accepts type concept. In American Code, a binomial cannot be used again for a
plant in any way if it has been employed previously for another plant.

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(E) Brussels Code (1912)
Fourth International Botanical Congress was held at Brussels in 1910. This code accepts
different starting points for priority of names of non-vascular plants. It recognises the type
concept and classification of Pharseology of the Vienna rules.
(F) Cambridge Code (1935)
The difference between Vienna code and American code was removed at the fifth Botanical
Congress held at Cambridge (1930).
The provisions suggested in this code are as follows:
(i) Type concept should be persued.
(ii) A list of Nomina generica conservenda should be provided.
(iii) Tautonyms should be discarded.
(iv) Latin diagnosis of plants is necessary after January 1, 1932.
(G) Amsterdam Code (1947)
Sixth International Botanical Congress was held at Amsterdam in 1935. In this a major change
in the rules was made, i.e., from January 1, 1935, names of new groups of recent plants,
(except Bacteria) are to be considered as validity published only when they have a Latin
diagnosis.
(H) Stockholm Code (1952)
The 7
th
International Botanical Congress was held at Stockholm in 1952. For the first time word
“Taxon” was introduced to designate any taxonomic group or entity.
(I) Paris Code (1956)
8
th
International Botanical Congress was again held in Paris in July 1954. Here, the rule of
compulsion of Latin diagnosis was scraped out and it was decided that it should be published
in English, French and German languages. Preamble and Principles of the code were separated
from the Rules and Recommendations. Nomina Generica Conservenda et rejecienda was
amended and supplemented.
(J) Montreal Code (1961)
9
th
International Botanical Congress met at Montreal in August 1959, where a committee was
appointed to study the question of conservation of family names. Nomina familiarum
conservanda for Angiospermae was introduced. The code also asserted the naming of fossil
plants should also follow the same lines as those of recent ones.
(K) Edinburgh Code (1966)
In the 10
th
Botanical Congress held at Edinburgh in August 1964, the report of committee was
presented. According to it, for family names the starting point should be A.L.de Jussieu’s
Genera Plantarum (1789).
Some of the spelling of a few families were changed, (e.g., Capparaceae for Capparidaceae and
Cannabaceae for Cannabinaceae) in the list of Nomina familiarum Conservenda. A new
committee was formed to work upon the preparation of Glossary of technical terms which was
called An Annotated Glossary of Botanical Nomenclature.
(L) Seattle Code (1972)

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11
th
International Botanical Congress met at Seattle in August 1969. The code was published in
1972 by F.A. Stafleu. Seattle Code includes the tautonymous designations of taxa between
genus and species and below it. Code introduced a new word Autonym, i.e., automatically
established names.
(M) Leningrad Code (1978)
The Twelfth International Botanical Congress was held in July, 1975 at Leningrad, Russia and its
recommendations came out in 1978.
This Code indicates only small differences from the Seattle Code and includes the following
changes:
(a) The concept of organ genera is eliminated for fossil plants.
(b) The Code does not apply to names of organisms treated as bacteria and does apply to
all other organisms treated as plants.
(c) The principle of automatic typification is extended to those names of taxa above the
family rank that are ultimately based on generic names and the application of the
priority principle is recommended while selecting among names thus typified.
(d) A name or combination published before 1953 without indicating the rank is considered
validly published but imperative in questions of priority except for homonymy and
certain names to be accepted at the varietal rank.
(e) Art. 69 of the previous Code is modified on the basis of type method and Art. 70-71
dealing with discordant elements and monstrosities were deleted, but the Art numbers
are retained to facilitate the use of the Code.
(f) The section on orthography is thoroughly rewritten.
(g) Individual paragraphs on all Articles and Recommendations are numbered in a decimal-
like system, some being rearranged.
(N) Sydney Code (1983)
13
th
Botanical Congress was held at Sydney in August 1981 and the outcomes were published
in 1983.
(O) Berlin Code (1988)
14
th
International Botanical Congress was held at Berlin 1986 and the outcomes were
published in 1988. Nomina Specifica Conservenda was introduced in the congress. Articles 66
and 67 were removed. In this two species names Triticum aestivum Linn, and Lycopersicon
esculentum P. Miller were conserved against the rules of priority as these names were used
widely and it was thought that if the names were changed confusion might arise.
(P) Tokyo Code (1994)
15
th
International Botanical Congress met at Yokohama in Japan in 1993. The code was
translated into Chinese, French, German, Italian, Japanese, Russian and Slovak.
(Q) St. Louis Code (1999)
16
th
International Botanical Congress was held at St. Louis, Missouri in 1999. This code is also
available in many languages. The code is divided into Rules, Articles, and Recommendations.
Rules are set up to put the nomenclature of the past into order and to provide space for the
future.

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Recommendations deal with subsidiary points. According to it in future the names not
following the recommended ones be rejected. Rules and Recommendations apply for all living
and fossil organisms and fungi but do not include Bacteria. For Bacteria International Code of
Nomenclature of Bacteria (ICNB) was proposed separately.
Presently, the rules and recommendations of St. Louis code which were proposed by Greuter
in 1999 are in practice.
The seventeenth International Botanical Congress met at Vienna in 2005 but its code is not
published as yet.
Principles of International Code of Botanical Nomenclature, (ICBN):
I. Botanical nomenclature is independent of zoological nomenclature. The code applies
equally to names of taxonomic groups treated as plants whether or not these groups
were originally so treated (Plants do not include Bacteria).
II. Application of names of taxonomic groups is determined by means of nomenclature
types.
III. The nomenclature of a taxonomic group is based upon priority of publication.
IV. Each taxonomic group with a particular circumscription, position, and route can bear
only one correct name, the earliest that is in accordance with the rules, except in
specific cases.
V. Scientific names of taxonomic groups are treated as Latin regardless of their
derivation.
VI. The rules of nomenclature are retroactive unless expressly limited.
The Principles were laid down in 1983.
Preamble of ICBN 1983:
1. Botany requires a precise and simple system of nomenclature used by Botanists in all
countries, dealing, on the one hand, with the terms which denote the ranks of
taxonomic groups or units, and on the other hand with the scientific names which are
applied to the individual taxonomic groups of plants.
The purpose of giving a name to a taxonomic group is not to indicate its character or
history, but to supply a means of referring it and to indicate its taxonomic rank. The
code aims at the provision of a stable method of naming taxonomic groups, avoiding
and rejecting the use of names which may cause error or ambiguity or throw science
into confusion. It avoids the useless creation of names.
2. The Principles form the basis of the system of Botanical Nomenclature.
3. The detailed provisions are divided into Rules and Recommendations. Examples are
added to the rules and the recommendations to illustrate them.
4. The object of the Rules is to put the nomenclature of the past into order and to provide
for that of the future, names contrary to a rule cannot be maintained.
5. The Recommendations deal with subsidiary points, their object being to bring about
greater uniformity and clearness, especially in future nomenclature, names contrary to a
recommendation cannot, on that account, be rejected, but they are not examples to be
followed.
6. The provisions regulating the modification of this code from its last decisions.

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7. The Rules and Recommendations apply to all organisms treated as plants (except
Bacteria), whether fossil or non-fossil. Nomenclature of Bacteria is governed by the
ICNB. Special provisions are needed for certain groups of plants. The International Code
of Nomenclature of cultivated plants (1980) was adopted by the International
Commission for the Nomenclature of Cultivated Plants; provisions for the names of
hybrids appear in Appendix I.
8. The only proper reason for changing a name is either a more profound knowledge of the
facts resulting from adequate taxonomic study or the necessity of giving up
nomenclature that is contrary to the rules.
9. In the absence of a relevant rule or where the consequences of rules are doubtful,
established custom is followed.
10. This edition of the code supersedes all previous editions.
Division III. Governance of the Code:
1. The code may be modified only by action of a plenary session of an International
Botanical Congress on resolution moved by the nomenclature section of the congress.
2. Permanent Nomenclature Committees are established under the auspices of the
International Association for Plant Taxonomy. Members are elected by an International
Botanical Congress. The Committees have power to co-opt and to establish sub-
committees.
3. The Bureau of Nomenclature of International Botanical Congress its officers are:
(a) The president,
(b) The recorder,
(c) The rapporteur-general, and
(d) The vice-rapporteur.
4. The voting on nomenclature proposals is of two kinds:
(a) Preliminary guiding mail vote
(b) Final and binding vote at the nomenclature section of the International Botanical
Congress.
Some Important Rules and Recommendations:
1. All those plants which belong to one genus must be designed by the source generic
name (Rule 213).
2. All those plants which belong to different genera must be designated by different
generic names (Rule 214)
3. He who establishes a new genus should give it a name (Rule 218).
4. Those generic names are best which show essential characters of plants or its
appearance (Rule 240).
5. Generic names one and a half foot long or difficult to pronounce or unpleasant are to be
avoided (Rule 249).
6. The specific name must distinguish a plant from all its relatives (Rule 257).
7. Size does not distinguish species (Rule 260).
8. The original place of plant does not give specific difference (Rule 264).
9. A generic name must be applied to each species (Rule 284).

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10. The specific name should always follow the generic name (Rule 285).
In accordance with the ICBN some traditional names of the families are changed to their
alternate names as:
Compositae is now known as Asterceae.
Gramineae is now known as Poaceae.
Labiatae is now called as Lamiaceae.
Palmae is now called as Arecaceae.
Umbelliferae is now known as Apiaceae.
A unique exception to article 52 of the code is that the name Leguminosae is sanctioned only
as long as it includes all three subfamilies Papilionoideae, Caesalpinoideae and Mimosoideae.
If the subsfamilies are upgraded to family status the Papilionaceae shall be called Fabaceae.
Author Citation
A name cannot be complete without an author’s name. The author’s name is abbreviated, e.g.,
Linneaus is abbreviated as Linn or L, Benthm as Benth; Hooker as Hook, Roxburgh as Roxb,
Lamark as Lamk etc.
According to Article 46 the indications of name of a taxon are to be accurate and complete. It
is necessary to cite the name of the author who first validly published the name. If the author’s
name is too long it should be abbreviated. e.g., Hibisus L., Indigofera grandulosa var. Syskessi
Baker, Solarium nigrum Linn etc.
According to Article 49 when a genus or taxon of a lower rank is altered in upper rank but
retains its name or epithet, the author who first published this as a legitimate name or epithet
must be cited in parentheses; followed by the name of the author was effected the alternation
e.g., Citrus auranium var. grandis L; when raised to rank of species it become Citrus grandis (L)
Obseck. Here L is the first author and Osbeck altered it.
Similarly, when a subdivision of a genus or a species is transferred to another genus or
placed under another generic name (Article 54 and 55), it will be written as:
(i) Saponaria section vaccaria DC when transferred to Gypsophila, it becju.es Gypsophila
sec. vaccaria (DC) Godr.
(ii) Limonia aurantifolia Christm, when transferred to Citrus it becomes Citrus aurantifolia
(Christm) Swingle.
In case of infraspecific changes it is, Alysicapus nummularifolius DC when reduced to variety it
becomes Alysicarpus viginalis var. nummularifolius (DC) Baker.
The names of two authors are linked by ex. when the first author proposed a name but was
validly published only by second author, the first author failing to satisfy all requirements of
the code, e.g.,
Cerasus cornuta Wall ex. Royle. When two or more authors publish a new species their names
are linked by et, e.g., Delphinium viscosum Hook.F. et Thomson. When the first author
publishes a new species or name in a publication of another author, in is used, e.g., Carex
kashmirensis Clarke in Hook. F, it means Clarke published the new species in Hooker’s Flora of
British India.

12. SECTION 1: PLANT SYSTEMATICS MCQs

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1. The level of taxonomic study related to
biological aspects of taxa, inclusive of
intraspecific populations, speciation,
evolutionary trends and rates is
(a) theta taxonomy
(b) alpha taxonomy
(c) beta taxonomy
(d) gamma taxonomy
Answer: (d)
2. The process wherein the labellum in
Orchidaceae surfaces at the anterior side
via the twisting of the ovary through 180
degree
(a) Articulation
(b) Adnation
(c) Attenuation
(d) Resupination
Answer: (d)
3. The organization of taxonomic
information in logical classification is known
as
(a) Phenetic
(b) Systematics
(c) Dendogram
(d) Phylogenetic
Answer: (b)
4. One of these is not a plant fossil
(a) Rhynia
(b) Lepidocarpon
(c) Lepidodendron
(d) Archaeopteryx
Answer: (d)
5. The primary advantage of Bentham and
Hookers classification is
(a) It is a system whose basis is on
evolutionary concepts
(b) It is a natural system of classification of
all plant groups
(c) Deemed to be the phylogenetic aspect
as well
(d) The taxa description is based on the
actual examination of the specimens
Answer: (d)
6. Α taxonomy pertains to
(a) Chemotaxonomy
(b) Phylogeny
(c) Classical taxonomy
(d) Experimental taxonomy
Answer: (c)
7. To comprehend general plant
relationships, this is one of the best
methods
(a) Experimental Taxonomy
(b) Numerical Taxonomy
(c) Cytotaxonomy
(d) Chemotaxonomy
Answer: (d)
8. The condition of Polyadelphous can be
found in
(a) Rutaceae
(b) Leguminosae
(c) Compositae
(d) Liliaceae
Answer: (a)
9. Linnaeus is credited with the following
(a) Law of Limiting factor
(b) Binomial nomenclature
(c) Concept of inheritance
(d) Theory of heredity
Answer: (b)
10. The reason why the system of plant
classification proposed by Carolus
Linnaeus was artificial is
(a) Because it considered the physiological
facts along with the morphological traits
(b) Because it was based on the similarities
and differences in floral and other
morphological characters only
(c) Because it was on the basis of
evolutionary relationships of plants
(d) None of these
Answer: (b)
11. Which of these is the most advanced
phylogenetically among the dicotyledonous
families?

13. SECTION 1: PLANT SYSTEMATICS MCQs

DIWAKAR EDUCATION HUB Page 3
(a) Scrophulariaceae
(b) Acanthaceae
(c) Umbelliferae
(d) Compositae
Answer: (d)
12. The substitute for the newly collected
specimen when the original type material is
missing in a herbarium is entitled as
(a) Holotype
(b) Neotype
(c) Lectotype
(d) Isotype
Answer: (b)
13. If all the puddles and ponds are
destroyed, the entities likely to be
destroyed are
(a) Plasmodium
(b) Ascaris
(c) Leishmania
(d) Trypanosoma
Answer: (a)
14. In the five-kingdom system of
classification, into which kingdom would
you classify nitrogen-fixing organisms and
archaea?
(a) Fungi
(b) Plantae
(c) Protista
(d) Monera
Answer: (d)
15. This is considered as a demerit of the
‘Engler and Prantl’ in the system of
classification
(a) Gymnosperms are placed between
monocotyledons and dicotyledons
(b) Dicotyledons are placed after
monocotyledons
(c) Dicotyledons are placed before
monocotyledons
(d) Gymnosperms are placed among
Dicotyledons
Answer: (b)
16. Phenetic classification is based on
(a) Observable characteristics of existing
entities
(b) The ancestral lineage of existing
organisms
(c) Dendrograms based on DNA
characteristics
(d) Sexual characteristics
Answer: (a)
17. Difference between the natural system
of plant classification and artificial system
of classification is
(a) Considers only one vegetative character
(b) Considers all the similarities between
plants
(c) Considers only one floral character
(d) All of the above
Answer: (b)
18. This system of classification was used
by Linnaeus
(a) Phylogenetic system
(b) Natural system
(c) Artificial system
(d) Asexual system
Answer: (c)
19. Pick the right sequence of taxonomic
categories
(a) division-class-family-tribe-order-genus-
species
(b) division-class-family-order-tribe-genus-
species
(c) division-class-order-family-tribe-genus-
species
(d) division-order-class-family-genus-tribe-
species
Answer: (c)
20. ‘New Systematics’ term was coined by
(a) Linnaeus
(b) Bentham and Hooker
(c) A.P. de Candolle
(d) Juliane Huxley
Answer: (d)
21. Which among the following is the
correct order of classification?

14. SECTION 1: PLANT SYSTEMATICS MCQs

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A. Kingdom, Phylum, Genus, Division,
Order, Class, Species, Family.
B. Phylum, Division, Class, Order,
Genus, Species, Family, Kingdom.
C. Kingdown, Division, Class, Order,
Family, Genus, Species.
D. Division, Genus, Family, Species,
Class, Order, Kingdom, Phylum.
Answer: C (Kingdown, Division, Class,
Order, Family, Genus, Species)
22. Out of the following options, which is
the correct Class of a Banana?
A. Plantae.
B. Liliopsida
C. Musa acuminata
D. Musaceae
Answer: B (Liliopsida)
23. Which among the below systems does
not exist?
A. Phylogenetic system
B. Artificial system
C. Natural system
D. None of the Above
Answer: D (None of the Above)
24. Choose the right answer for the
common characteristic in Plant taxonomy.
A. Morphology
B. Palynology
C. All of the Above
D. Anatomy
Answer: C (All of the Above)
25. Which year was the beginning phase of
modern biological nomenclature?
A. 1856
B. 1758
C. 1747
D. 1857
Answer: B (1758)
26. The document that includes all the
information related to a particular genus or
plant family is termed as:
A. Monograph
B. Record
C. Revision
D. Plant Module
Answer: A (Monograph)
27. Systematic Biology is the term used to
refer:
A. Phenetics + Plant Taxonomy
B. Phylogenetic + Biology
C. Systematics + Plant Taxonomy
D. Dendrogram + Biology
Answer: C (Systematics + Plant Taxonomy)
28. Who was the first-ever philosopher to
classify living organisms?
A. Whittaker
B. Aristotle
C. Linnaeus
D. Charles Darwin
Answer: B (Aristotle)
29. Taxon is-
a) A taxonomic unit
b) A species
c) A taxonomic group of any rank
d) A genus
Answer: c
30. Phylogeny is the study of
a) Evolution of plants
b) Origin and development of plants
c) Origin and development of man
d) Physiology of plants
Answer: a
31. Liliopsida is divided in to 5 sub-classes
& 19 orders by
a) Takhtajan
b) Dehlgren
c) Cronquist
d) Thorne
Answer: c
32. System of classification based on a
number of characters is referred as
a) Phylogenetic system
b) Artificial system
c) Natural system

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d) All of the above
Answer: c
33. The National Botanical Research
Institute is located at
a) Dehradun
b) Delhi
c) Gangtok
d) Lucknow
Answer: d
34. Which year marked birth of modern
system of biological nomenclature?
a)1753
b)1857
c)1757
d)1854
Answer: a
35. Level of taxonomic study concerned
with the biological aspects of taxa,
including intraspecific populations,
speciation, evolutionary rates and trends
a) alpha taxonomy
b) beta taxonomy
c) gamma taxonomy
d) theta taxonomy
Answer: c
36. Labellum in Orchidaceae comes to
anterior side by the twisting of the ovary
th180degree. This process is called
a) adnation
b) articulation
c) resupination
d) attenuatio
Answer: c
37. The Commelinaceae family is
commonly known as the
a) spiderwort family
b) aster family
c) grass family
d) lily family
Answer: a
38. Foeniculum vulgare belongs to the
family
a) Rutaceae
b) Meliaceae
c) Apiaceae
d) Brassicaceae
Answer: c
39. When two or more authors publish a
new species or propose a new name, their
names are linked using the epithet?
a) In
b) ex
c) et
d) emend
Answer: c
40. Binomials with identical genus name
and specific epithet are called
a) Homonym
b) Tautonym
c) Basionym
d) Synonym
Answer: b
41. A document containing a
comprehensive account of a specific
taxonomic group, generally a genus or
family is
a) Manual
b) Flora
c) Monograph
d) Revision
Answer: c
42. Which among the following is
considered a demerit of the ‘Engler and
Prantl’ system of classification?
a) Gymnosperms are placed between
Monocotyledons and Dicotyledons
b) Gymnosperms are placed among
Dicotyledons
c) Dicotyledons are placed before
Monocotyledons
d) Dicotyledons are placed after
Monocotyledons
Answer: d
43. The principles of Numerical taxonomy
were developed by

16. SECTION 2: PLANT ANATOMY
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17. SECTION 2: PLANT ANATOMY
DIWAKAR EDUCATION HUB Page 2
Plant anatomy is the study of the shape, structure, and size of plants. As a part of botany (the
study of plants), plant anatomy focuses on the structural or body parts and systems that make
up a plant. A typical plant body consists of three major vegetative organs: the root, the stem,
and the leaf, as well as a set of reproductive parts that include flowers, fruits, and seeds.
Plant anatomy or phytotomy is the general term f or the study of the
internal structure of plants. Originally it included plant morphology, the description of the
physical form and external structure of plants, but since the mid-20th century plant anatomy
has been considered a separate field referring only to internal plant structure. Plant anatomy
is now frequently investigated at the cellular level, and often involves the sectioning
of tissues and microscopy.
As a living thing, all of a plant's parts are made up of cells. Although plant cells have a flexible
membrane like animal cells, a plant cell also has a strong wall made of cellulose that gives it a
rigid shape. Unlike animal cells, plant cells also have chloroplasts that capture the Sun's light
energy and convert it into food for itself. Like any complex living thing, a plant organizes a
group of specialized cells into what are called tissues that perform a specific function. For
example, plants therefore have epidermal tissue that forms a protective layer on its surface.
They also have parenchyma tissue usually used to store energy. The "veins" or pipeline of a
plant are made up of vascular tissue that distribute water, minerals, and nutrients throughout
the plant. Combined tissues form organs that play an even more complex role.
The study of various external features of the plant is known as plant morphology.
The Angiosperm is characterized by the presence of roots, stems, leaves, flowers and fruits.
The main characteristics of angiosperm are:
1. The Root
2. The Stem
3. The Leaf
4. The Flower
5. The Fruit

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19. SECTION 2: PLANT ANATOMY
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ROOT
The plants that we see today is the result of billions of years of evolution. Today, plants cover
almost 30 per cent of the total landmass and account for the 50 per cent of the plant’s
productivity (generation of biomass). Plants fulfil many roles in the ecosystem. They are a
source of food, nutrition, shelter, maintain the integrity of soil (by preventing erosion) and
most importantly, they are the main source for balancing the oxygen level in the atmosphere.
Anatomically, plants are very complex organisms and are classified into various types based on
certain defining characteristics. Roots are very important structures that provide a variety of
functions, but contrary to popular belief, all plants do not have roots. Roots are absent in
plants like mosses and liverworts.
A plant's roots, like the foundation of a skyscraper, help it to stay upright. They also absorb
water and dissolved minerals from the ground and give the plant what it needs to make its
own food. Most roots grow underground and move downward because of the influence of
gravity, although the roots of some water plants float. Other root systems, like that of the
English ivy, actually attach themselves to a vertical surface and allow the plant to climb. There
are two main types of root systems: taproot and fibrous. Plants that have taproots grow a
single, long root that penetrates straight down and firmly anchors the plant. Trees and
dandelions have taproots that serve this function. Fibrous roots are shorter and more shallow
and form a branching network. Grass has a fibrous root system that grows at a shallow level
and in all directions. Inside a root are pipelines or veins that carry water and minerals to the
rest of the plant. These pipes are concentrated in the center of the root, like the lead in the
center of a pencil. At the end of each root is a cap that protects it as it pushes farther into the
soil. Extending from the sides of the root, but further back from the root cap are root hairs.
These hairs are the main water and oxygen absorbing parts of a plant. Materials enter and
leave roots by two main processes: diffusion and osmosis. When molecules are distributed
unequally, nature always seeks a balance and molecules will move from an area of high
concentration to one of low concentration. When the cells of a root hair have little oxygen and
the soil around the root hair has a lot, oxygen will move from the soil to the root automatically
without the plant having to expend any energy. Osmosis is a similar situation (from high to low
concentration), but it occurs when molecules, like those of water, move across a membrane
that will not allow other materials to pass. Like diffusion, osmosis does not require the plant to
use any energy.
Definition
Roots are the important underground part of all vascular plants. This part of the plant is mainly
responsible for anchoring it down into the ground and absorbing the essential mineral
elements, nutrients, and water from the soil. It is also used to store food.
However, not all plants have their roots underground, some plants have their roots growing
above the ground. These are called aerial roots. Alike underground roots, these aerial roots
are also responsible for absorbing nutrients, anchoring and affixing the plant by supporting
them to the structures such as nearby walls, rocks, trellises, etc.
Few examples of plants with the aerial roots are–Bonsai, Banyan Tree, Mangroves, etc.

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Roots Name Examples
Tap Root – Originates from radicle Dandelion, Turnip, and Carrots
Fibrous Root – Originates from the base of the state Wheat and Paddy.
Adventitious Root – Originates from the part of the
plant other than radica
Banyan Tree (Prop Roots) Maize
(stilt roots).
Characteristics of Root
1. Root is the descending or underground part of the plant axis.
2. Root is usually positively geotropic (i.e. grows downward into the soil) and positively
hydrotropic (i.e. grows towards the source of water) but negatively phototropic (i.e.
grows away from sunlight).
3. Root is usually cylindrical and non-green (i.e. lack chlorophylls), but sometimes green as
in Trapa and Taeniophylum.
4. Root does not bear nodes, internodes, leaves or buds (exceptions are sweet potato,
wood apple etc.)
5. The growing point of root tip is sub-terminal and protected by a root cap or calyptra.
6. Unicellular root hairs present just behind the root caps which increase the absorptive
surface area of roots,
7. Lateral roots are endogenous in origin i.e. arise from pericycle of the main root.
Rootless Plants
Many plants growing in aquatic habitats do not possess roots because there is little
requirement for absorption of water and mineral salts, e.g., Wolffia, Utricularia, Myriophyllum,

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Ceratophyllum. In other aquatic plants, roots develop only for balancing (e.g., Lemna, Pistia)
and fixation (e.g., Hydrilla).
Types of Roots
On the basis of their origin, roots are of two types – tap root and adventitious root.
(a) Tap root: On germination of a seed, the radicle elongates into primary root or true root
or tap root. In dicot plants, the tap root is persistent and produces lateral roots such as
secondary’ roots, tertiary roots etc. All lateral roots arise in acropetal succession i.e.
younger roots towards apex and older roots towards base. The tap root and its branches
constitute the tap root system.
(b) Adventitious root: These are the roots that grow from any part of the plant other than
radicle. In monocot plants, the tap root is short lived and soon replaced by adventitious
roots. A group of adventitious roots and their branches constitute adventitious root
system.
On the basis of their origin, the adventitious roots are of following three types:
i. Fibrous roots: These are a cluster of equally prominent thread-like roots that
develop either from the base of stem (e.g., rice, wheat, maize, onion etc.) or
from the nodes of horizontal stem (e.g., grass, wood sorrel etc.)
ii. Foliar roots: They arise from petiole (e.g., Pogostemon, rubber plant etc.) or
veins of leaf due to some injury. These can also be induced by application of
hormones. Some foliar buds can produce foliar roots, e.g., Bryophyllum,
Begonia etc.
iii. True adventitious roots: They arise from the nodes and internodes of the
stem, e.g., Prop roots of banyan, stilt roots of sugarcane, clasping roots of
money plant and roots from the stem cuttings.
Foot Structure
A typical root can be differentiated into five regions. From apex to base they are:
(a) Root Cap (Calyptra): It is a cap like protective structure of the growing root tip. In
Pandanus (screwpine) multiple root caps present while in aquatic plants (Pistia,
Eichhornia, Lemna) root pockets present instead of root cap.
Function:
(i) Protects root meristem,
(ii) Secrete mucilage that help tender root to penetrate the hard soil,
(iii) Helps in perception of gravity (Darwin, 1880),
(iv) Root packet s functions as balances.
(b) Growing point or Meristematic Zone: It is about 0.25-1.0 mm long, lies just behind the
root cap and thus sub-terminal in position. Its shape is like an inverted concave dome
of cells. The central rarely dividing cells are called quiescent centre.
Function: Root meristem adds cells to root cap and the basal region of the root.
(c) Zone of elongation: It is about 1-10 mm long and lies just behind the meristematic
zone. As the name implies, it is the site of rapid and extensive cell elongation. This zone

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increases length of the root. The external cells can absorb water and minerals from the
soil.

(d) Root hair Zone or Zone of differentiation: It is about 1 -6 cm long. It is the zone where
cell differentiate to form epiblema, cortex, endodermis, pericycle, xylem and phloem.
Many cells of epiblema elongate to form unicellular root hairs. As the root grows, new
root hairs develop and older one shrivel and sloughed off.
Function: Root hairs increase the absorptive surface area of root.
(e) Zone of maturation: In constitute the major portion of the root. The cells attain
maturity when they reach this zone.
Function:
(i) Lateral roots may emerge from pericycle
(ii) Radial differentiation of tissues causes’ secondary growth in dicots.
Functions of Roots
Roots perform two kinds of functions — Primary and Secondary. The primary functions are
performed by all kinds of roots, and they are structurally adapted to per-form these functions.
The secondary functions are specialized one and are performed only by those roots which are
modified accordingly.

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(A) The primary functions of roots are:
1. Anchorage: The roots anchor or fix the plant to the substratum or soil and provide
mechanical support to the aerial part of the plant.
2. Absorption: Roots perform very important function of absorption of water and minerals
from the soil in almost all the terrestrial plants. Since these functions are not critical in
submerged aquatics, the roots are poorly developed or totally absent in them (e.g.
Ceratophyllum, Utriculciria, etc.)
3. Conduction of water and minerals: Upward movement of absorbed water and minerals
is done by roots. Root pressure also plays an important role in this process.
4. Translocation of organic nutrients. Roots are non – green: They lack chlorophyll and
they are incapable of photosynthesis. Sugar, produced in the leaves by photosynthesis,
is transported downward to the tissues of the root where it is metabolised.
(B) The Secondary Functions of root are:
1. Food storage. It occurs mainly by fleshy roots. Examples – Carrot, Radish, Beet, Sweet
potato, Turnip, Asparagus, Dahlia, Curcuma, etc.
2. Additional mechanical support: In some plants, roots are modified to provide additional
mechanical support. Examples – prop roots (e.g., Banyan, Rhizophora), stilt roots (e.g.,
Maize, Sugar-cane, Pandanus. etc.), buttress roots (e.g., Bomb ax), etc.
3. Haustorial roots: Roots of some parasitic plants act as haustoria e.g., Cuscuta). They
penetrate upto phloem of host and absorb nourishment.
4. Assimilation: Roots of some plants are photosvnthetic. e.g., Trapa, Taeniophyllum,
Tinospora, Podostemum.
5. Aeration: Roots of some plants help in exchange of gases, e.g., Rhizophora, Sonneratia,
Heritiera.
6. Symbiotic nitrogen fixation: Roots of leguminous plants have nodules containing
nitrogen fixing bacteria.
7. Floating and balancing: Roots of some aquatic plants store air and help in floating and
balancing, e.g.,Jussiaea (= Ludwigia), Pistia, Eich – homia, etc.
8. Hygroscopic roots: Aerial roots absorb moisture from the air e.g., epiphytic plants,
Orchids, young prop roots of Banyan, etc.
9. Reproduction: Some modified roots possess adventitious buds which grow to produce
new plants and help in vegetative propagation, e.g.. Sweet potato, Dalbergia, etc.
10.Climbing: Some weak stemmed plants develop climbing roots which help the plant to
climb up the support, e.g., Betal, Money plant, Tecomct, etc.
Modifications of Root
 Roots are modified for storage, nitrogen fixation, aeration and support.
 The taproot of carrot, turnip, and adventitious root of sweet potato get swollen to store
food.

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 The Prop root of Banyan and Stilt root of maize and sugarcane have supporting roots
coming out from the lower node of stems.
 In Rhizophora, Pneumatophores are present which help to get oxygen for respiration as
it grows in swampy areas.

(A) Tap Root Modifications:

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1. Fusiform root: When root is thickened in the middle and tapering at the ends, e.g.,
Raphanus sativus (radish).
2. Napiform root: When root is almost spherical at one end and tapering sharply at the
other end, e.g., Brassica rapa (turnip).
3. Conical root: Root which appears like a cone, i.e., broad at the base and tapering
gradually into a pointed end, e.g., Daucas carota (carrot or Gazar).
4. Tubercular root: When root is thick, fleshy and of irregular shape. It may be a
modification of tap root, e.g., Mirabilis jalapa (Four O’clock plant), or of adventitious
root, e.g., Ipomoea batatas (sweet potato).
(B) Adventitious and Fibrous Root Modifications:

26. SECTION 2: PLANT ANATOMY MCQs

27. SECTION 2: PLANT ANATOMY MCQs
DIWAKAR EDUCATION HUB Page 2
1. What type of meristem is responsible for
the production of shoots and leaves?
A. Axillary Meristem
B. Shoot Apical Meristem
C. Lateral Meristem
D. Root Apical Meristem
Answer: B
Explanation: An axillary bud is the site of
leaf growth, and is found on the lateral
parts of the shoot apical meristem. The
lateral meristem is responsible for lateral
growth. The root apical meristem is
responsible for root growth.
2. What kind of tissue is not found in the
apical meristem?
A. Protoderm
B. Ground meristem
C. Procambium
D. Cork cambium
Answer: D
Explanation: The cork cambium is found in
the lateral meristem and contributes to
secondary growth rather than primary
growth.
3. What is apical dominance?
A. When the presence of apical meristem
prevents growth from the lateral meristem.
B. When the presence of an apical bud
prevents growth from the lateral meristem.
C. When the presence of an apical bud
prevents growth from the lateral bud.
D. When the presence of an apical
meristem prevents growth from the lateral
bud.
Answer: C
Explanation: Apical dominance is defined as
dormancy at the lateral buds because of
inhibiting factors received from the apical
bud. The lateral meristem contributes to
secondary growth and is not relevant in
apical dominance.
4. What is the difference between an apical
meristem and an intercalary meristem?
A. No difference
B. The apical meristem is at the tip
C. Intercalary meristems can be apical
Answer: B
Explanation: The term apical simply means
at the tip. A meristem is simply a portion of
the organism with stem cells. Intercalary
describes the space between apical
meristems, in which smaller branches form.
5. How can the apical meristem be
manipulated to increase the harvest of a
crop?
A. They can be cut to create a bushy plant
B. More meristems means more fruit
C. They can’t be manipulated
Answer: B
Explanation: While it might also create a
bushy plant, most fruits and vegetables are
the product of a fertilized flower. Flowers
typically form at a meristem. Therefore, if
clipping the apical meristem means more
meristems, more flowers can be created.
6. How is the apical meristem similar to
stem cells in a human fetus?
A. Both have the ability to differentiate
B. They are completely different
C. They divide in the same way
Answer: A
Explanation: Both sets of cells
are totipotent, in that they can differentiate
into an entire organism. While the apical
meristem may stay totipotent, the stem
cells in humans typically reduce the stem
cells to multipotent, able to only transform
into a handful of related cell types. This is
one reason it is much harder to clone a
human.
7. The morphological nature of the edible
part of a coconut is
a. 1. Cotyledon

28. SECTION 2: PLANT ANATOMY MCQs
DIWAKAR EDUCATION HUB Page 3
b. 2. Perisperm
c. 3. Pericarp
d. 4. Endosperm
Answer: d
8. ______ are the non-essential parts of a
flower
a. Androecium and gynoecium
b. Sepals and carpels
c. Sepals and petals
d. Sepals and gynoecium
Answer: c
9. Four long and two short stamens are
found in
a. Asteraceae
b. Brassicaceae
c. Liliaceae
d. Solanaceae
Answer: b
10. A fruit developed from a condensed
inflorescence is
a. Composite fruit
b. Simple fruit
c. Aggregate fruit
d. Etaerio
Answer: a
11. Radial symmetry is found in the flowers
of
a. Cassia
b. Pisum
c. Trifolium
d. Brassica
Answer: d
12. The stem modified into flat, green
organs performing the function of leaves
a. Phyllodes
b. Cladodes
c. Phylloclades
d. Scales
Answer: c
13. Leaves become modified into spines in
a. Opuntia
b. Onion
c. Silk cotton
d. Pea
Answer: a
14. Geocarpic fruits are formed in
a. Onion
b. Carrot
c. Groundnut
d. Watermelon
Answer: c
15. Testa of seed develops from
a. Hilum
b. Funicle
c. Ovary wall
d. Outer integument
Answer: d
16. Replum is found in the ovary of
a. Brassicaceae
b. Malvaceae
c. Liliaceae
d. Asteraceae
Answer: a
17. One seeded winged fruit is
a. Nut
b. Samara
c. Cypsela
d. Achene
Answer: b
18. Veins of the leaves are useful for
a. Mechanical support
b. Transport of water and minerals
c. Transport of organic nutrients
d. All of the above
Answer: d

29. SECTION 2: PLANT ANATOMY MCQs
DIWAKAR EDUCATION HUB Page 4
19. Placenta and pericarp are edible
portions in
a. Potato
b. Banana
c. Tomato
d. Apple
Answer: c
20. ———- is an edible underground stem
a. Potato
b. Groundnut
c. Sweet potato
d. Carrot
Answer: a
21. Vexillum is found in
a. Cruciferae
b. Rosaceae
c. Solanaceae
d. Papilionaceae
Answer: d
22. Water is absorbed by
a. Root cap
b. Root apex
c. Root hairs
d. Root
Answer: c
23. Roots that develop from plant parts
other than the radicle are
a. Epicaulous
b. Fibrous
c. Adventitious
d. Epiphyllous
Answer: c
24. Pneumatophores occur in plants of
a. Marshy soil
b. Saline soil
c. Water
d. Sandy soil
Answer: a
25. Food present in bulbil occurs in
a. Root
b. Petiole
c. Leaf base
d. Stem
Answer: c
26. Sweet potato is a modification of
a. Leaf
b. Primary root
c. Adventitious root
d. Underground root
Answer: c
27. Phyllotaxy is
a. Folding leaf in the bud
b. Arrangement of leaves on the stem
c. Both (1) and (2)
d. None
Answer: b
28. Winged petiole is found in
a. Acacia
b. Peepal
c. Citrus
d. Radish
Answer: c
29. ————– is the characteristic of
monocot plants
a. Stilt roots
b. Taproots
c. Fibrous roots
d. Annulated roots
Answer: c
30. Which root modification does not store
food?
a. Stilt
b. Conical
c. Napiform

30. SECTION 2: PLANT ANATOMY MCQs
DIWAKAR EDUCATION HUB Page 5
d. Tuberous
Answer: a
31. Bulbils participate in
a. Vegetative reproduction
b. Sexual reproduction
c. Respiration
d. Transpiration
Answer: a
32. Nodulated roots enrich the plant with
a. Proteins
b. Fats
c. Carbohydrates
d. Food
Answer: a
33. ——— is the edible part of a banana
a. Epicarp and mesocarp
b. Epicarp
c. Mesocarp and less developed
endocarp
d. Endocarp and less developed
mesocarp
Answer: c
34. Which plant has all roots?
a. Podostemon
b. Utricularia
c. Lemna
d. Wolffia
Answer: a
35. Velamen takes part in
a. Exchange of gases
b. Transpiration
c. Absorption of moisture from the air
d. Absorption of water from the soil
Answer: c
36. Leaves are attached to the stem at
a. Internode
b. Nodes
c. Apical meristem
d. Axillary meristem
Answer: b
37. ———– plants have root pockets
a. Opuntia
b. Capparis
c. Banyan
d. Eichhornia
Answer: d
38. Turmeric is a stem because
a. It grows parallel to the soil surface
b. It stores food material
c. It has chlorophyll
d. It has nodes and internodes
Answer: d
39. Vivipary is the characteristic of
a. Mesophytes
b. Xerophytes
c. Hydrophytes
d. Halophytes
Answer: d
40. The outer covering of the epiphytic root
is
a. Rhizophore
b. Osmophore
c. Pneumatophore
d. Velamen
Answer: d
41. A root hair does not contain
a. Vacuole
b. Chloroplast
c. Cell wall
d. Nucleus
Answer: b
42. The waxy substance associated with the
wall of the cork cell is
a. Lignin

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PLANTS GROWTH AND DEVELOPMENT
Growth can be defined as an irreversible permanent increase in size of an organ or its parts or
even of an individual cell. Generally, growth is accompanied by metabolic processes.
The root apical meristem and the shoot apical meristem provide the primary growth of the
plants and also help to the elongation of the plants along their axis. The lateral meristems,
vascular cambium and cork-cambium appear later m life in dicotyledonous plants and
gymnosperms; these ar7e the Meristems cause the increase in the girth of the organs in which
they are active. This is a secondary growth of the plant as shown in Fig. 15.2.

Locations of root apical meristem, shoot apical meristem and vascular cambium. Arrows
exhibit the direction of growth of cells and organ. The period of growth has three phases,
meristematic, elongation and maturation as shown in Fig. 15.2.
The constantly dividing cells, both at the root apex and the shoot apex, represent the
meristematic phase of growth. This region cells are rich in protoplasm, possess large
conspicuous nuclei. Their cell walls are primary in nature, thin and cellulosic with abundant
plasmodesmatal connections. The cells being proximal to the meristematic zone are the phase
of elongation.
The growth rate shows an increase which may be arithmetic or geometrical, during stages
embryo development show geometric and arithmetic phases as shown in Fig. 15.3.

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Figure shows the simplest expression of arithmetic growth is exemplified by a root elongating
at a constant rate. If the length of the organ against time is plotted a linear curve is obtained.
Initial by growth is slow and it increases rapidly thereafter- at an exponential rate. Here, both
the progeny cells following mitotic cell division retain the ability to divide and continue to do
so.
The growth slows down leading to a stationary phase due to limited nutrient supply. A typical
sigmoid or S-curve affect plot the parameter of growth against time. This is shown in Fig. 15.4.
A sigmoid curve is a characteristic of living organism growing in a natural environment.

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In Fig. 15.5 two leaves, A and B, are drawn that are of different sizes but shows absolute
increase in area in the given time to give leaves, A1 and B1. One of them shows much higher
relative growth rate and it can be seen.
Water, oxygen and nutrients are very essential elements for growth. The plant cells, growth
requires water. Turgidity of cells facilitates extension growth. Water also provides the medium
for enzymatic activities needed for growth. Oxygen facilitates in releasing metabolic energy
essential for growth activities. Nutrients are needed by plants for the synthesis of protoplasm.
The growth in plants is open. The final structure at maturity of a cell/tissue is also determined
by the location of the cell within. The cells positioned away from root apical meristems
differentiate as root-cap cells.

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Development
Development that includes all changes that an organism goes through during its life cycle from
germination of the seed to senescence. Diagrammatic representation of the sequence of
processes which constitute the development of a cell of a higher plant. It is also applicable to
tissues/organs. See Fig. 15.6.

Plants follow different pathways in response to environment or phases of life to form different
kinds of structures. In such plants, the leaves of the juvenile plant are different in shape from
those in mature plants. Difference in shapes of leaves produced in air and those produced in
water in buttercup also represent the heterophyllous development due to environment.
Growth, differentiation and development are very closely related events. Development is
considered as the sum of growth and differentiation. Development in plants is under the
control of intrinsic and extrinsic factors. The intense factors includes both intracellular or
intercellular factors and the exoteric factors includes light, temperature, water, oxygen,
nutrition, etc.

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Plant Growth Regulators
The plant growth regulators (PGRs) are small, simple molecules of diverse chemical
composition. The PGRs have two groups based on their functions. One group of PGRs is
involved in growth promoting activities. The PGRs of the other group play an important role in
plant responses to wounds and stresses of biotic and a biotic origin. The PGR abscise acid
belongs to this group. The gaseous PGR, ethylene, could fit either of the groups.
Auxins as first isolated from human urine. The term ‘auxin’ is the indole-3- acetic acid (IAA),
and to other natural and synthetic compounds having certain growth regulating properties.
The growing apices of the stems and roots are produced by them. This is from where they
migrate to the regions of their action. Axons like IAA and insole butyric acid (IBA) have been
isolated from plants. NAA (naphthalene acetic acid) and 2, 4-D (2, 4-dichbrophenoxyacetic) are
synthetic auxins.
The growing apical bud inhibits the growth of the lateral (axillary) buds in higher plants.
Removal of shoot tips usually results in the growth of lateral buds as shown in Fig. 15.8. Tea
plantations and hedge-making are the application.

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Spraying juvenile conifers with GAs hastens the maturity period, thus leading to early seed
production. Gibberellins also promote bolting in beet, cabbages and many plants with rosette
habit. Ethylene initiates flowering and for synchronizing fruit-set in pineapples, induces
flowering in mango.
The most widely used compound as source of ethylene is ethephon. Ethephon in an aqueous
solution is readily absorbed and transported within the plant and releases ethylene slowly.
Ethephon hastens fruit ripening in tomatoes and apples and accelerates abscission in flowers
and fruits.
Abscisic acid (ABA) has role in regulating abscission and dormancy. It also has other wide
ranging effects on plant growth and development. It plays role of plant growth inhibitor and
an inhibitor of plant metabolism. ABA inhibits seed germination. ABA helps seeds to withstand
desiccation and other factors unfavorable for growth. ABA acts as an antagonist to GAs.
For any and every phase of growth, differentiation and development of plants, one or the
other PGR has some role to play. Such roles could be complimentary or antagonistic. These
could be individualistic or synergistic.
Similarly, there are a number of events in the life of a plant where more than one PGR interact
to affect that event, e.g. for example, dormancy in seeds/ buds, abscission, senescence, apical
dominance, etc., They play an important role in plant growth and development.

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THE ANGIOSPERM LIFE CYCLE
Plants have a life cycle split between two multicellular stages: a haploid stage—with cells
containing one set of chromosomes—and a diploid stage—with cells containing two sets of
chromosomes. The haploid stage is the gamete-producing gametophyte, and the diploid stage
is the spore-producing sporophyte.
Today, most plants grow from seeds and produce flowers and fruit; such plants are called
angiosperms. Angiosperms begin as seeds—structures consisting of a protective seed coat, a
nutrient supply, and an embryo. The seed develops into a sporophyte—the familiar, flower-
producing plant form.
The reproductive life cycle of angiosperms begins with flowering. Stamens and carpels contain
sporangia, structures with spore-producing cells called sporocytes. Sporophytes produce
spores as either eggs or sperm, depending on their origin.
For example, male spores—called microspores—are produced within anthers at the tips of
stamens. A microspore develops into a pollen grain—the male gametophyte. A pollen grain
contains a tube cell and a generative cell, which develops into sperm.
A carpel consists of an ovary and its ovules. Female spores, called megaspores, are produced
within ovules. A megaspore develops into an embryo sac—the female gametophyte—which
contains the egg.
Pollination allows the sperm-producing pollen grain to reach the egg-containing embryo sac.
While the embryo sac is stationary, pollen grains can be carried by wind, water, or animals.
For sperm to fertilize an egg, pollen released from the anthers must reach the sticky stigma at
the tip of a carpel. Then, the tube cell of the pollen grain becomes a pollen tube, extending
down the carpel to the ovule.
Angiosperms undergo a type of double fertilization that produces an embryo and an
endosperm, a nutrient store. The embryo and endosperm are packed into a seed coat, forming
a seed. As the ovules become seeds, the ovary typically develops into fruit that helps protect
and distribute the seeds.
REPRODUCTION IN ANGIOSPERMS
VEGETATIVE PROPAGATION
Generally Angiosperms propagate by producing seeds, which is the result of sexual
reproduction. However they resort to other methods of reproduction, such as vegetative
propagation.
Plants belonging to this category propagate by a part of their body other than the seed. The
structural unit that is employed in place of seed is called propagule.
Lower plants reproduce vegetatively through budding, fission, fragmentation, gemmae, resting
buds, spores etc.
Methods of vegetative propagation have been further divided into two types.
A) Natural vegetative propagation and
B) Artificial vegetative propagation
A. Natural Methods of Vegetative Propagation

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Vegetative Propagation by Roots
Some modified tuberous roots can be propagated vegetatively, when planted in soil. The buds
present on the roots grow as leafy shoots called slips above ground and adventitious roots at
their bases. Each slip gives rise to a new plant. eg. Sweet potato, Topioca, yam, Dahlia and
Tinospora.
Adventitious buds develop on the ordinary roots of Dalbergia sisoo, Populus, Guava, Murraya
sp, etc. which grow to form new plants.

Vegetative Propagation by Stem
In many plants, stem is modified to perform different functions. The modified stems perform
three distinct functions (a) perennation, (b) vegetative propagation and (c) storage of food.
Modified stems which help in propagation can be classified into following three categories:
1. Underground
2. Subaerial
3. Aerial.
Propagation by Underground Stem
These plants develop non-green, under ground perennial stems. These store reserve food,
propagate vegetatively and are adapted for perennation. They give rise to aerial shoots that
grow actively during favourable conditions. On the approach of unfavourable conditions, the
aerial shoots die. The underground stems remain dormant during the unfavourable conditions.
Once the conditions become favourable, they produce new aerial shoots.
The various types of underground stems are
1. Rhizome,
2. Tuber,
3. Bulb,

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4. Corm
Bulb
The stem is shortest and somewhat disc-like and does not contain any food material. Stem is
covered by numerous thickened, overlapping leaves or leaf bases (usually called scales). The
whole structure takes the form of a bulb. The short and reduced stem bears numberous
adventitious roots at its base:
(a) Tunicated bulbs: In this case, the fleshy scales completely surround the reduced stem
forming the concentric layers around stem forming the concentric layers around one another.
On the outside they are covered by a few dry scales forming a membranous covering, called
the tunic. The fleshy scales are bases of the foliage leaves, eg., Onion, etc.
Scaly bulbs: Here, the leaves are small and scale-like and only overlap at the margins. There is
also no outer tunic. The scaly bulbs are found in lilies, garlic, etc.
In both the above types, axillary buds frequently develop in the axil of the fleshy scales. These
develop into new bulbs or on separation from the parent bulb develop into new plants. They
serve both for food storage and vegetative propagation.

Corm
It is more or less a condensed form of rhizome. It is a short, stout, solid and fleshy
underground stem growing in the vertical direction. It is more or less rounded in shape or
often somewhat flattened from top to bottom. It contains excessive deposits of food material
and grows to a considerable size. It bears one or more buds in the axil of scale leaves and

42. SECTION 3: PLANT DEVELOPMENT; CELL AND TISSUE MORPHOGENESIS MCQs
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1. What is the main function of the phloem?
A. Transporting nutrients from a source to a
sink
B. Transporting nutrients from a sink to a
source
C. Transporting water from a sink to a
source
D. Transporting water from a source to a
sink
Answer: A
Explanation: The main function of the
phloem is to transport nutrients from the
source where they are produced (e.g. the
leaves through photosynthesis) to the sink
(e.g. flowers and fruits) where they are
used.
2. What service does the companion cell
not provide to the sieve element?
A. Providing energy
B. Communication between cells
C. Physical rigidity
D. Unloading photoassimilates to sink
tissues
Answer: C
Explanation: The companion cell is
important for providing energy, transferring
materials and transmitting signals. The
parenchyma and sclerenchyma provide
strength and rigidity to a plant.
3. What does the P-protein do?
A. Increases the rate of metabolism within
the companion cell
B. Builds the sieve plates
C. Forms a clot over a sieve plate when the
phloem is damaged
D. Works within the phloem to transport
sap
Answer: C
When the phloem is damaged, the P-
protein, which is produced in the sieve
element lumen, accumulates on the sieve
plate to prevent loss of nutrient rich sap.
4. What type of cells are NOT a part of
xylem?
A. Vessel elements
B. Parenchyma
C. Sieve elements
D. Tracheids
Answer: C
Explanation: Vessel elements, parenchyma,
and tracheids are all found in xylem, along
with fibers that provide support. Sieve
elements are not a part of xylem; they are
found in phloem.
5. Xylem transports all of the following
materials except what?
A. Sucrose
B. Water
C. Minerals
D. Inorganic ions
Answer: A
Explanation: Xylem transports water and
some water-soluble nutrients, including
minerals and inorganic ions. Phloem
transports sucrose, along with other sugars,
proteins, and organic molecules.
6. Which of the following statements is true
about xylem?
A. Xylem is made up of dead cells.
B. Xylem transports substances
bidirectionally.
C. Xylem is not found in gymnosperms.
D. Xylem surrounds phloem tubes.
Answer: A
Explanation: Xylem is made of dead cells
that do not have any cell contents. Choices
B, C, and D are incorrect; xylem transports
substances in one direction, is found in
gymnosperms (although vessel elements
are not), and is surrounded by phloem
instead of surrounding phloem.

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7. Which of the following is NOT a condition
required for germination?
A. Temperature
B. Water
C. Sunlight
D. All of the above
Answer: C
Explanation: While soil depth, temperature,
and water are all required for germination,
sunlight is not required until after the
seedling has emerged from the soil surface.
8. Which of the following statements is
TRUE regarding water imbibition?
A. Water imbibition is not required for
germination.
B. Water imbibition is required for the seed
to rupture.
C. Water imbibition refers to the expulsion
of water from the seed.
D. None of the above responses are true.
Answer: B
Explanation: Water imbibition refers to the
influx of water into the seed, required for
the seed to rupture and release the root
and shoot.
9. The transfer of pollen from the anther to
the stigma of a flower is termed:
A. Endoporation
B. Germination
C. Pollination
D. Microsporogenesis
Answer: C
Explanation: The term pollination refers to
the transfer of pollen grains from the
anther to the stigma of a flower. Cross-
pollination involves the transfer of pollen
from one flower to the stigma of another
flower. In contrast, self-pollination involves
the transfer of pollen from one flower to
the stigma of the same flower.
10. The primary function of the exospore is:
A. Pollination
B. Protect the plant’s male genetic material
C. Protect the plant’s female genetic
material
D. Endoporation
Answer: B
Explanation: The exospore is the hard outer
wall of the pollen grain, which serves to
protect the male genetic material from UV
radiation and other potential sources of
damage.
11. Coconut milk contains a cytokinin called
____ which promotes plant growth.
1. Naphthalene acetic acid
2. Indole-3-acetic acid
3. Gelatin
4. Zeatin
Answer: 4
12. One of the following is not an auxin
1. Indole-3-acetic acid
2. Malic Hydrazide
3. Indole butyric acid
4. Naphthalene acetic acid
Answer: 2
13. _________can stimulate the
germination of barley seeds
1. α-amylase
2. Abscisic acid
3. Benzoic acid
4. Coumarin
Answer: a
14. Seed dormancy is triggered by
1. Indole-3-ethanol
2. Abscisic acid
3. Carbon dioxide
4. None of the above
Answer: 2

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15. The significance of the day length in
plants was first shown in:
1. Barley
2. Lettuce
3. Tobacco
4. Tomato
Answer: 3
16. Uneven distribution of auxins may lead
to
1. Phototrophic curvature
2. Day-neutral curvature
3. Both (1) and (2)
4. None of the above
Answer: 1
17. Tendrils of garden peas coiling around
any support signifies:
1. Seismonasty
2. Thigmotaxis
3. Gravitropism
4. Thigmotrophism
Answer: 4
18. ____________ tissues synthesize
natural cytokinins
1. Old
2. Rapidly dividing
3. Storage
4. None of the above
Answer: 2
19. ________ is a plant hormone generally
present in the gaseous state
1. Ethylene
2. Ethane
3. Argon
4. None of the above
Answer: 1
20. _________ is a colourless gas that
serves as a signalling hormone.
1. Benzene
2. Nitric Oxide
3. Ozone
4. None of the above
Answer: 2
21. All the cells of the plant are descendants
of which of the following?
a) Apical tissue
b) Intercalary tissue
c) Meristem
d) Zygote
Answer: d
Explanation: All cells of a plant are
descendants of the zygote. Trees continue
to increase in height or girth over some
time. However, the leaves, flowers and
fruits of the same tree appear and fall
periodically and sometimes repeatedly.
22. Development is the sum of how many
processes?
a) One
b) Two
c) Three
d) Four
Answer: b
Explanation: Development is the sum of
two processes-growth and differentiation.
To begin with, it is essential and sufficient
to know that the development of a mature
plant from a zygote follows a precise and
highly ordered succession of events.
23. What is the first step in the process of
plant growth?
a) Seed fermentation
b) Seed desiccation
c) Seed germination
d) Seed dormancy
Answer: c
Explanation: The first step in the process of
plant growth is seed germination. The seed
germinates when favourable conditions are

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available like the presence of oxygen, water
and certain enzymes. If these conditions are
not available, then a seed may suspend its
activities and will germinate only when
these conditions become available.
24. Which of the following is the most
fundamental characteristic of a living being?
a) Growth
b) Differentiation
c) Height
d) Heart
Answer: a
Explanation: Growth is regarded as one of
the most fundamental and conspicuous
characteristics of a living being. Growth can
be defined as an irreversible permanent
increase in the size of an organ or its part or
even of an individual cell.
25. Growth occurs by only anabolic
processes.
a) True
b) False
Answer: b
Explanation: Growth is accompanied by
metabolic processes which include both
anabolic and catabolic processes, that occur
at the expense of energy. Therefore, for
example, expansion of a leaf is growth.
26. Unlimited growth of the plant, is due to
the presence of which of the following?
a) Meristems
b) Tissues
c) Apical cells
d) Special organs
Answer: a
Explanation: Unlimited growth of the plants
is due to the presence of meristems which
are actively dividing cells and are present at
the tips of root and shoot. The cells of these
meristems are small and have dense
protoplasm. They also have a high nucleo-
cytoplasmic ratio.
27. Which of the following kinds of growth
is exhibited by plants?
a) Closed-form of growth
b) The open form of growth
c) Both open and closed form of growth
d) Fused form of growth
Answer: b
Explanation: Open form of growth is
exhibited by the plants as at the tips of root
and shoot, continuously dividing cells of
meristems are present which are ultimately
responsible for their unlimited growth.
Viruses cannot multiply in these
continuously dividing cells.
28. Which of the following meristem is
responsible for the primary growth of the
plant?
a) Apical meristem
b) Lateral meristem
c) Vascular cambium
d) Cork cambium
Answer: a
Explanation: Root apical meristem and
shoot apical meristem are responsible for
the primary growth of the plants and
principally contribute to the elongation of
the plants along their axis.
29. Which of the following meristem is not
responsible for the secondary growth of
plants?
a) Lateral meristem
b) Vascular cambium
c) Apical meristem
d) Cork cambium
Answer: c
Explanation: In dicotyledonous plants and
gymnosperms, the lateral meristems,
vascular cambium and cork cambium
appear later in life. These are the meristems

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PLANT PHYSIOLOGY AND BIOCHEMISTRY
Plant physiology and biochemistry make up the backbone of successful horticultural
production, and our plant physiology/biochemistry research programs cover a range of areas
from whole-plant physiology to plant metabolism and enzymology. Collaborations with faculty
in several departments university-wide showcase integrated research projects that address
important issues in plant physiology and biochemistry.

These are foundational areas for research in the Department of Plant Agriculture. The
outcomes of this research include advancements in knowledge of the determinants of light
interception, nutrient use, water use and biochemical conversions by plants at molecular,
cellular, whole plant and crop levels. The information is applied to develop protocols for
selecting plants with greater stress tolerance, identifying critical periods for weed control, and
modifying storage conditions for harvested fruits and vegetables.
The seed for the Division of Plant Physiology and Biochemistry at ICAR-IISR, Lucknow was sown
in September 1958 as a Plant Physiology Section which subsequently, with a joining of senior
biochemist, flourished into a full-fledged division in 1976.
The foundation of sugarcane physio-biochemical research was laid by emphasising on issues
pertaining to physio-biochemical attributes related germination, tillering, dry
matteraccumulation, sucrose storage and ripening. These studies are being carried forward for
augmenting cane and sugar productivity through development of alternate seed materials,
improving physiological efficiency, sucrose metabolism, source-sink dynamics, attributes
associated with abiotic stress and climate resilience with special reference to transcriptomics
and proteomics.Post-harvest management and conversion of lignocellulosic biomass to
bioethanol are underway for improved sucrose recovery and utilization of sugarcane
wastes,respectively. Alongwith, division also offers trainings to students and sugarcane
personnel’s.
The mission of Division of Plant Physiology & Biochemistry today is to address the yield both
cane and sugar barriers, biotic and abiotic stresses in the changing climate scenario through
“physio-biochemical” and “omics” approaches for overcoming major bottlenecks to cane and
sugar productivity in sub-tropics.
Mandate
Major research areas

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 Augmenting cane and sugar productivity through development of alternate seed
materials, improving physiological efficiency, sucrose metabolism, source-sink dynamics,
attributes associated with abiotic stress and climate resilience with special reference to
transcriptomics and proteomics.
 Post-harvest management and conversion of lignocellulosic biomass to bioethanol are
underway for improved sucrose recovery and utilization of sugarcane wastes,
respectively


PLANT WATER RELATIONS
ABSORPTION OF WATER AND ASCENT OF SAP
Water is an important factor for plant growth as it helps to fulfill all the vital activities of
plants. Water is essential for photosynthesis, respiration, absorption of minerals and nutrients,
metabolism and even to maintain the soil temperature too. Beside this, water is also
important in various other processes too, as it helps in the germination of seeds and in the
process of transpiration etc. Water helps a plant by transporting nutrients through the roots.
Nutrients are drawn from the soil and used by the plant. Without enough water in the cells,
the plants droop so water helps a plant stand. Water carries the dissolved sugar and other
nutrients through the roots. Plants absorb water through their entire surface- roots, stems and
leaves. However, the majority of water is absorbed by root hairs.
To maintain the level of water inside the plant cells, it is necessary, to loss excess water from
plant cells either in the form of evaporation or through transpiration. Evaporation of water
from leaves is primarily controlled by stomata, sometimes lenticels and pores also helps in this
process. This shows that, plants have a strong and significant relationship with water. Plant
water relation means plants control the hydration of their cells including the collection of
water from the soil, its transport within the plants and its loss by evaporation from the leaves.

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Transpiration also includes a process called guttation, which is the loss of water in liquid form
from the uninjured leaf or stem of the plant principally through water stomata known as
hydathodes. Studies have revealed that about 10 percent of the moisture found in the
atmosphere is releases by plants through transpiration.
IMPORTANCE OF WATER TO PLANT LIFE
Water is most important and prime factor for life processes, as life itself has been originated in
an aqueous environment. In course of evolution it became fully dependent on water in a
number of ways. Thus we can say that water is the liquid of life or elixir of life. In general water
is essential for life and is the main constituent of the protoplasm comprising 90 to 95% of its
total weight. In absence of water, protoplasm becomes inactive and even killed. Water is a
source of hydrogen atoms for the reduction of carbon dioxide in the reaction of
photosynthesis and as mentioned earlier that water helps to fulfill different vital activities.
Beside this water present in the vacuoles which helps in maintaining the turgidity of cells
which is essential for proper activities of life. Due to absorption of water the cell becomes
turgid. The turgidity of cell helps in the elongation of cells resulting in growth. It is a well-
known fact that the availability of water during winter and summer season is different and is
the reason of formation of annual rings in higher plants. In summer the turgidity is less and
hence formation of small cells, comparatively to winter when due to higher turgidity,
formation of larger cells takes place. In nature we have different type plants e.g. aquatic,
terrestrial, halophytes, xerophytes etc. and different plants absorb water in different ways.
While orchids, absorb moisture directly from the atmosphere and not from soil. Land plants
get their water supply from soil which serves as the source of water and minerals to them. The
way in which water from soil enters into roots, particularly to root xylem is called “Mechanism
of water absorption”.
PHYSICAL PROPERTIES OF WATER
As per studies on global water covers about 73% of earth‘s surface and provides the most
extensive medium for all aquatic life because of its unique properties from ecological point of
view. Water occurs in all three physical forms in the earth at moderate temperature. It is
present in either in the form of fresh water or in saline water form in sea and salt lakes. The
fresh water of active ground water, glaciers and ice caps, rivers, lakes dams, streams, soil
moisture etc. represents only 1.92% of the total water stock. But even from this small segment
as much as 98.65% is shared between active ground water and ice on mountain tops and
poles, lakes and rivers constitute only 0.98% and 0.004% fresh water stock respectively.

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Fig. 1.1 Different states of matter

Fig.1.2 Water Cycle in the Atmosphere
Water
Structure and Properties: Water comprises over about 90% of the chemical content of many
organisms and so we can say justifiably that water is the fluid of life but before this it is
necessary to understand the different physiological processes related to the diffusion and

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absorption of water, and fundamental chemical and physical properties of water and its
interaction with other substances. Water participates in all metabolic reactions either directly
or indirectly. Water is a remarkable compound with unique properties that results from its
molecular configuration and hydrogen bonding.
Molecular Structure of Water: A single water molecule is composed of two hydrogen atoms
bonded covalently to one side of an oxygen atom. Water absorbs large quantity of heat and
tolerates other physical stresses without breakage of the bonds. Water is a polar inorganic
compound at the room temperature at room temperature associates with each other because
of the asymmetrical distribution hence due to these association i.e. adhesion or cohesion that
are critical to the movement of water in soils and the translocation of water in plants.

The chemical composition of water in which the hydrogen atoms are attached to the oxygen
atom causes one side of the molecule to have a negative charge and the area in the opposite
direction to have a positive charge causes molecules of water to be attached to each other
forming strong molecular bond. The strong hydrogen bond of water molecule results due to
the attraction of the positive hydrogen bond of water molecule for the negative oxygen atom
of another water molecule.

The resulting polarity of charges causes molecules of water to be attached to each other
forming strong molecular bond. Water is a tasteless, odorless liquid at ambient temperature
and pressure and appears colorless in small qualities, although it has its own intrinsic very light
blue hue.
The most important property of water to the living cell is its solvent action. Water is referred
as the “universal solvent” because it forms a solution with a vast array of compounds. The
solvent action of water is of tremendous importance for the living plants as all the essential
elements necessary for normal plant growth and the compounds necessary for energy transfer
and storage require water as a translocation and reaction medium. All these materials are
present in water in the dissolved form this form, distributed throughout the plant. Thus all the
physiological processes i.e. diffusion, osmosis, and imbibition are intimately associated with
the essential function of translocation of water and solutes from site of origin of site of
activity.
Adhesive and Cohesive Forces of Water

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Water is attracted to many other substances because of its polar nature. This attraction
between unlike or different molecules is called adhesion. In case of water, it involves hydrogen
bonding between the water and other molecules. While the attraction of like molecules due to
hydrogen bonding, is called cohesion. Cohesion force allows water to be the pulled to the tops
of trees through xylem elements in the form of a thin film of water. The cohesion between
water molecules creates surface tension and then the molecules at the surface of a liquid are
continually being pulled into the liquid by the cohesive (hydrogen bond) forces. This type of
adhesion is called capillary action. Capillary action in a glass tube is caused by adhesive forces
exerted by the internal surface of the glass exceeding the cohesive forces between the water
molecules themselves. Due to surface tension a single drop of water works as spherical. The
surface tension of water is high than that of most other liquids and the surface tension plays a
great role in the physiology of plants.
There are various factors determined the rate of diffusion i.e. temperature, relative density,
concentration gradient, concentration medium etc. the rate of diffusion increases as the
temperature increases. Hydrogen diffuses 4 times faster as far as Oxygen and 5 times as fast as
carbon dioxide, these rates are determined by the relative intensity of the gas. The gas diffuses
through gases, liquids and solids, liquid diffuses through gases, liquids and solids and likewise
solid diffuses through gases, liquids and solids. In some cases the rate of diffusion may be very
fast or may be very low as per condition. There important example of diffusion as follows-
Blowing of wind, dispersal of scent, perfumes & agarbatti in a room, intake of CO2 and
liberation of O2 in photosynthesis, and intake of O2 and liberation of CO2 during respiration,
dissolution of sugar and salt in water, dissolution of KMnO4 particles in water all are examples
of diffusion. Some other interesting examples of diffusion are-

i) Gas into liquid- Foam, ii) Liquid into gas- Clouds, iii) Solid into solid- Smoke, iv) Solid into
solid- Diffusion of copper into zinc and zinc into copper, although this process takes pretty long
time, if the basis of two metals are kept upon one another.
Most animals and plants contain more than 60% water by volume. Water H2O is a polar
organic compound that is at room temperature a tasteless and unique liquid. In nature water

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can naturally occur in these as a liquid (water), solid (ice), and gaseous form (water
vapour).Water is transported in plants through both cohesive and adhesive forces. These
cohesive forces are related to waters property of adhesive forces on the attraction between
water molecules and other molecule. Strong bonds determine almost every physical property
of water and many of its chemical properties. This property of water of water allows for the
transport of nutrients vital to life in animals and plants.
Diffusion: The diffusion means to spread; to flow out, to extend Diffusion can be simply
defined as the movement of particles of matter due to their kinetic energy or the net
movement from one point to another because of the random kinetic activities of molecules or
ions is called diffusion. Diffusion refers to the process by which molecules intermingle as a
result of their kinetic energy of random motion. However, the direction of movement of
diffused particles is form the region of higher concentration to the region of lower
concentration till both the concentrations equalize. The molecules in the region of higher
concentration contain more kinetic energy and that is why they allow fast movement. The
diffusion of particles still continues in both the directions though it is not detectable. Diffusion
is random movement of molecules but has a net direction towards regions of lower
concentration in order to reach equilibrium. Simple and passive diffusion occurs when small
molecules pass through the lipid bilayer of a cell membrane.

In a solution the diffusion of particles of one substance is quite independent of the diffusion of
particles of another substance. The diffusion of particles of both the substances is quite
independent in the rate of flow of the particles as well as the direction. Each substance differs
according to its own concentration and flow. There are various factors determined the rate of
diffusion i.e. temperature, relative density, concentration gradient and concentration medium
etc. Rate of diffusion of substances increases as the temperature increases.
The gases diffuse through gases. Liquids and solids; liquids diffuses through gases, liquids and
solids and likewise solids diffuses through gases, liquids and solids. In some cases the rate of

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diffusion may be either very fast or very slow as per the condition. Hydrogen diffuses four
times faster as far as oxygen and five times as fast as carbon dioxide, these rates are
determined by the relative intensity of the gas.
Examples of diffusion are:
Gas into liquid- Foam,
Liquid intogas- Clouds,
Solid into gas-Smoke
Solid into solid- diffusion of copper into zinc and zinc into copper, although this process takes
pretty long time, if the basis of two metals are kept one another.
Osmosis: A plant cell has a cell membrane and cell wall as its boundary. The cell wall is freely
permeable to water hence it is not buried to movement of water. Osmosis is the net
movement of solvent molecule through a semipermeable membrane into a region of higher
solvent concentration to the region of lower solvent concentration in the direction that tends
to equalize the solute concentration on the two sides. If two solutions of different
concentrations are separated by a semi-permeable membrane which is permeable to a small
solvent molecules but not to the larger solute molecules than the solvent will tend to diffuse
across the membrane from the less concentrated to more concentrated solution. Osmosis is
essentially a special type of diffusion of liquids. In simple words, osmosis may be considered as
diffusion when two solutions of different concentrations are separated by means of a semi-
permeable.
The diffusion of water or in other words solvent from the solution of lower concentration to
the solution of higher concentration until both the concentrations equalize. This process is
defined simply as” the phenomenon, whereby, when a solution is separated from a weaker
one by a semi-permeable into the stronger solution diffuses through the membrane into the
stronger solution in an effort to equalize the strength of the two solutions. Actually the
diffusion of particles of solvent takes place both ways across the semi-permeable membrane
buy the diffusion of solvent is more from the solution of lesser concentration to that of the
higher concentration.
The main difference between diffusion and osmosis is that in osmosis two substances are
separated from each other by a semi-permeable membrane while in case of diffusion it is
absent. The word semi-permeable membrane is used for a membrane that allows the passage
for certain substances while checking the passage of others.
Osmosis Phenomenon: To explain osmosis if two different solutions of different concentration
are separated by a semi-permeable and will not allow or permit soluble molecules to pass
through it. As per the lows of diffusion the movement of solvent molecules will be from the
region of higher concentration to the region of lower concentration or from dilute solution to
concentrated solutions. The reason behind this is that the concentration of solvent molecules
will lower in the concentrated solution and higher in the dilute solution. On the basis of
concentration of solute molecules the solutions may be defined as hypertonic and hypotonic
solutions.

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Hypertonic Solution: A hypertonic solution is one in which the concentration of solutes is
greater inside the cell than outside of it, while hypotonic solution: A hypotonic solution is one
where the concentration of solute is greater outside the cell than inside it. When a cell is
immersed into a hypertonic solution, the tendency is for water to flow out of the cell in order
to balance the concentration of the solutes. Likewise, the symbol of the cell is conversely
categorized as hypotonic, opposite of the outer solution hypotonic refers to a letter
concentration.

Exosmosis: Osmosis towards the inside of a cell or vessel or the flow of a substance from an
area of lesser concentration to one of greater concentration, while the movement of water
molecules from outside to inside of a cell through osmosis is known as endosmosis.
Or the process by which water molecules move out of the cell is called exosmosis. A solution is
a mixture of two or more than two substance in which the concentration of the solute in
solvent may be expressed as weight of solute per unit of solvent or in terms of molarity,
normality or equivalent to this.
Osmotic Pressure or Osmotic Potential: If in a chamber a solute is added to water, so to keep
the pressure constant an amount of water removed and concentration of water in the solution
is decreased. If this solution is separated from pure water by a semi-permeable membrane a
gradient of water potential is created and osmotic diffusion of water starts taking place from
the chamber of higher water potential to that of lower water potential. If a mechanical
pressure is applied to lower water solution and is gradually increased it will raise the water
potential of the solution until the gradient no longer exists, this solution is separated from
pure water by semi-permeable membrane and stop osmosis by applying the pressure. This
pressure is termed the ―osmotic pressure and is usually expressed by the symbol π. Thus the

57. SECTION 4: PLANT PHYSIOLOGY AND BIOCHEMISTRY MCQS
DIWAKAR EDUCATION HUB Page 2
1. The maximum absorption of water by
roots occurs in the zone of-
(a) Cell division
(b) Root cap
(c) Cell elongation
(d) Root-hairs
Answer: d
2. The movement of water is along-
(a) Diffusion gradient
(b) DPD gradient
(c) Turgor gradient
(d) Osmotic- gradient
Answer: b
3. Water supply in the plant is due to-
(a) Guttation
(b) Osmosis
(c) Cohesive forces
(d) Imbibition
Answer: c
4. The principle by which blotting paper
absorbs water is
(a) Capillary action
(b) Absorptive capacity
(c) Root- pressure
(d) Transpiration pull
Answer: a
5. Which one explains ascent of sap-
(a) Cohesion-tension theory of Dixon and
Jolly
(b) Photosynthesis
(c) Starch- sugar inter conversion
(d) None of the above
Answer: a
6. The process in which loss of water occurs
in the form of water vapour is-
(a) Guttation
(b) Respiration
(c) Transpiration
(d) Exosmosis
Answer: c
7. Ascent of sap takes place through-
(a) Phloem
(b) Cambium
(c) Xylem
(d) Epidermis
Answer: c
8. Who was the first to evolve vital force
theory?
(a) Godlewski (1884)
(b) Janes (1887)
(c) Priestley (1886)
(d) Westermeir (1883)
Answer: d
9. Who demonstrated that the ascent of sap
occurs to the pulsatory activity of innermost
cortical cells?
(a) Strasburger (1891)
(b) J.C. Bose (1923)
(c) Janes (1887)
(d) Molisch (1828-29)
Answer: b
10. Most accepted theory of ascent of sap
was given by-
(a) Bose
(b) Dixon and Jolly
(c) Sachs
(d) Strasburger
Answer: b
11. Imbibition theory was given by-
(a) Schas
(b) Scolander
(c) Boehm
(d) Curtis
Answer: a
12. The process in which loss of water
occurs in the form of water vapors is-
(a) Guttation
(b) Respiration

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(c) Transpiration
(d) Exosmosis
Answer: c
13. Hydathode occurs in-
(a) Roots
(b) Leaves
(c) Stem
(d) All of above
Answer: b
14. The stomatal type of cereals which open
only for a few hours during the day is-
(a) Barley type
(b) Bean type
(c) potato type
(d) alfalfa type
Answer: a
15. Transpiration is high under-
(a) Low atmospheric temperature
(b) Dry environment
(c) High temperature
(d) All the above
Answer: d
16. Sunken stomata-
(a) Hinder transpiration
(b) Decrease environment
(c) Increase transpiration
(d) Stop transpiration
Answer: b
17. Stomatal frequency indicates-
(a) Number of stomata per unit area
(b) Rate of gaseous exchange
(c) Rate of water loss
(d) All the above
Answer: a
18. Excess of Co2 (0.05%) in the
atmosphere will-
(a) Has no effect
(b) Will reduce the transpiration
(c) Enhance the transpiration
(d) Reduce transpiration
Answer: a
19. When Oxygen is deficient in the
atmosphere-
(a) Stomata start closing
(b) Stomata open fully
(c) Stomata close up provided
temperature is high
(d) Stomata open provided water in the
soils is maximum
Answer: a
20. The number stomata per unit area of
leaf are generally more on lower surface in
case of –
(a) Herbaceous stem
(b) Dorsiventral leaf
(c) Isobilateral stem
(d) In woody stem
Answer: b
21. A leaf with hair on its surface-
(a) Reduces guttation
(b) Reduced transpiration
(c) Increases transpiration
(d) Reduces exchange of gaseous
Answer: b
22. Guttation takes place through-
(a) Lenticels
(b) Stomata
(c) Hydathode
(d) Wounds
Answer: c
23. Who proposed the term guttation?
(a) Bergerstein
(b) Levitt
(c) Shantz
(d) Darwin
Answer: a

59. SECTION 4: PLANT PHYSIOLOGY AND BIOCHEMISTRY MCQS
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24. A passive hydathodes comprises a group
of loosely arranged colorless and
parenchymatous cells known as-
(a) Arenchyma
(b) Spongy parenchyma
(c) Epithem
(d) Prosenchyma
Answer: c
25. Anti respirants-
(a) Reduces the rate of transpiration
without affecting carbon dioxide
assimilation
(b) Reduces the rate of transpiration
affecting protein synthesis of plant
(c) Reduces the rate of transpiration
affecting growth of plant
(d) Reduce the rate of transpiration
affecting carbon assimilation.
Answer: a
26. One of the following is an
antitranspirant but its effect persists only
for a few hours-
(a) Malic acid
(b) Abscissic acid
(c) Phenyl mercuric acetate
(d) Silicon emulsion
Answer: b
27. In which type the stomata are present
exclusively on the upper surface of the
leaves-
(a) Barley leaf
(b) Potamogeton type
(c) Potato type
(d) water lily type
Answer: d
28. Number of stomata present per cm2 of
a common leaf is about-
(a) 1 million
(b) More than 100,000
(c) Less than 100
(d) 1000
Answer: d
29. Transpiration differs from evaporation
in-
(a) Transpiration is a physical process
while evaporation is a physiological
process
(b) Rate of water loss
(c) Transpiration is a physiological
process while evaporation is a
physical process
(d) Frequency of water loss
Answer: b
30. During light phase of photosynthesis
______ is oxidized and ______ is reduced.
(a) CO2 and Water
(b) Water and CO2
(c) Water and NADP
(d) NADPH2 and CO2
Answer: c
31. During dark phase of photosynthesis
______ is oxidized and ______ is reduced.
(a) CO2 and Water
(b) Water and CO2
(c) Water and NADP
(d) NADPH2 and CO2
Answer: d
32. The visible product of photosynthesis is
______
(a) glucose
(b) cellulose
(c) starch
(d) fructose
Answer: c
33. Glycolytic reversal is a part of ______
(a) aerobic respiration
(b) anaerobic respiration
(c) light phase of photosynthesis

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(d) dark phase of photosynthesis
Answer: d
34. The source of CO2 during calvin cycle in
C4 plant is
(a) Malic acid
(b) OAA
(c) PEP
(d) RuDP
Answer: a
35. Absorption spectrum of chlorophyll is
maximum in _____ light.
(a) red
(b) blue
(c) yellow
(d) blue-violet
Answer: b
36. The oxygen molecule in glucose formed
during photosynthesis comes from
(a) Water
(b) Organic acids
(c) CO2
(d) atmosphere
Answer: c
37. Light reaction of photosynthesis results
in formation of
(a) O2
(b) NADPH +H+
(c) ATP
(d) All of these
Answer: d
38. Reduction of co-enzyme NADP depends
on
(a) Reduction of CO2
(b) Evolution of O2
(c) Photolysis of water
(d) Formation of ATP
Answer: c
39. Calvin cycle involves
(a) Oxidative phosphorylation
(b) Oxidative carboxylation
(c) Reductive carboxylation
(d) Reductive phophorylation
Answer: c
40. The process of respiration in green
plants occurs
(a) only when stomata are open
(b) only when photosynthesis ceases
(c) only when photosynthesis is in progress
(d) At all times
Answer: d
41. Respiratory enzymes are located in
(a) mitochondrial matrix
(b) cristae
(c) perimitochondrial space
(d) outer membrane
Answer: b
42. The net gain of ATP produced during the
oxidation of one glucose molecule in a plant
cell
(a) 38 ATP molecules
(b) 30 ATP molecules
(c) 36 ATP molecules
(d) 24 ATP molecules
Answer: c
43. The ultimate respiratory substrate,
yielding maximum number of ATP
molecules, is
(a) glycogen
(b) glucose
(c) amylose
(d) ketogenic amino acid
Answer: b
44. End product of fermentation are
(a) O2 and C2H5OH