The living world - chapter 1 - class 11 Biology by Dr. Saiful Alom Siddique

The living world -chapter 1 - class 11 Biology by Dr. Saiful Alom Siddique

1. Dr. Saiful Alom Siddique , M.Sc.(Gold Medalist), Ph.D. in Biotechnology Former, DST-INSPIRE Fellow, Annamalai University, Tamilnadu Vice- Principal, Howly National Science Academy [HNSA], Howly , Barpeta [email protected] Chapter 1 The Living World

2. WHAT IS ‘LIVING’?

3. Characteristics of living organisms The characteristic of living organisms is given below – 1) Growth: All living organisms can undergo the process of growth and development that results in an increase in the mass and number of cells. The growth of plants and animals takes place with the help of cell division. In the case of plants, the cell division occurs throughout their life while in the case of animals the cell division occurs up to a certain age, and then the cells lose their capability to divide.

4. 2 ) Metabolism: As the body and organs are the constituents of different chemicals, they perform various metabolic functions that result in the conversion of chemicals into other biomolecules . All plants, animals, and microbes exhibit metabolism. It is absent in the case of non-living organisms.

5. 3) Sensitivity: The living organisms whether prokaryotes or eukaryotes respond according to their surroundings and the stimuli present around them, it may be physical, chemical, or biological.

6. 4) Reproduction: The ability to produce young ones is the process of reproduction which is observed only in the case of the living organisms.

7. 5) Cellular Organization: It is the defining characteristic of living organisms since all living organisms are made up of cells that help in performing various cellular functions resulting in the growth and development, reproduction, metabolism, etc in the body. Since non-living organisms are not made up of cells so they do not have cellular organization.

8. 6) Movement: The living organisms show movement and locomotion by which they can move from one place to another and more specifically plants move according to the movement of the sun.

9. BIODIVERSITY Biodiversity refers to the number and types of organisms present on the earth. The number of species identified and studied is 1.7-1.8 million . They all together make a natural diversity of life in the world which is generally called biological diversity or biodiversity.

10. Nomenclature (naming): The naming of living organisms is called nomenclature. There are two types of names, one is vernacular (common names) and the other is the scientific name. Local names are used in local languages or common language and are easy for the local peoples but these names are not used by biologists because: 1. For many species a single local name is often used. 2. The local names sometimes lead to incorrect meanings about the organism. NOMENCLATURE

11. Scientific names: The names are given according to certain rules and are followed by the biologist all over the world. To make it common around the world various international codes have been established. These codes are: ICBN -International Code of Botanical Nomenclature. ICZN -International Code of Zoological Nomenclature. ICVN -International Code of Viral Nomenclature ICBN -International Code for Bacteriological Nomenclature Scientific names

12. Carl Linnaeus is the one credited for the introduction of the binomial nomenclature of the plants and animals with his work in the book Species Plantarum in 1753. Binomial nomenclature is the biological system of naming the organisms in which the name is composed of two terms , where, the first term indicates the genus , and the second term indicates the species of the organism. E.g., Mangifera indica Linn. Mangifera is the genus name and indica is the species name Binomial Nomenclature Carl Linnaeus

13. Universal rules of nomenclature are as follows : 1. Biological names are generally in Latin and written in italics. They are Latinised or derived from Latin irrespective of their origin . 2. The first word in a biological name represents the genus while the second component denotes the specific species/ epithet. 3. Both the words in a biological name, when handwritten, are separately underlined, or printed in italics to indicate their Latin origin . 4. The first word denoting the genus starts with a capital letter while the specific species starts with a small letter. It can be illustrated with the example of Magnifera indica .

14. Potato Solanum tuberosum Tiger Panthera tigris Housefly Musca domestica Indian cobra   Naja naja Rohu fish Labeo rohita Indian elephant Elephas   indicus

15. Taxonomy is the study of the classification, characterization, nomenclature, and identification of organisms and it is a branch of science. Taxonomic Categories: In 1956 the term Taxon was introduced and in 1964, Mayr defined taxon to be the various categories based on different characters of the organisms that consist of a taxonomic group of any rank. Taxonomic Hierarchy: Various organisms in different categories depend upon their common characters to make classification easier. These groups together are called taxonomic hierarchies. Taxonomy

16. ↑ Species TAXONOMIC HIERARCHIES ↑ Kingdom ↑ Phylum (Division in case of plants) ↑ Class ↑ Order ↑ Family ↑ Genus

17. Division Animal Kingdom Plant Kingdom

18. It is the lowest category of the taxonomic hierarchy. It refers to a group of organisms that are similar in shape, form, generative options. Species E.g.: sapiens.

19. A category that is placed above species as they consist of a group of related species. For e.g., the genus Panthera constitutes both lion and tiger. Genus

20. This taxonomic category consists of related genera having similar characteristics. For e.g., the families Canidae , Felidae , Ursidae , etc come under one order Carnivora . Family

21. This taxonomic category is more specific than the class as it consists of one or more similar families. The class Mammalia consists of around twenty-six orders that include primates, Carnivora , etc. Order

22. It was the most general taxonomic category before the introduction of phyla . This category includes related orders. In the animal kingdom, there are around 108 classes that include Pisces, reptilia , aves , etc. Class

23. This category includes classes with few similarities. This category is more specific than the kingdom. In the animal kingdom, there are around thirty-five phyla that include phylum Arthropoda , Chordata , etc Phylum

24. The highest level of classification is the kingdom which is further divided into various subgroups. The total kingdoms of the living organisms are five in number that includes Monera , Protista , Fungi, Plantae , and Animalia . Animal in Kingdom Animalia Plant in Kingdom Plantae Kingdom

25. The taxonomical aids help us in the study of knowing our bioresources and are also useful in agriculture, forestry, and industry. It can be used both in the field as well as in the laboratory. There are various taxonomical aids that are used by the taxonomists that help them in the identification, nomenclature, and classification of organisms. The important taxonomic area includes herbaria , botanical gardens, museums, zoological parks, and keys. TAXONOMICAL AIDS

26. HERBARIUM A herbarium is a collection of preserved plant specimens that are dried and labeled . The plant species that are collected are first dried, pressed, mounted, and then labeled on the herbarium sheets.

27. These specialised gardens have collections of living plants for reference. Plant species in these gardens are grown for identification purposes and each plant is labelled indicating its botanical/scientific name and its family. The famous botanical gardens are at Kew (England), Indian Botanical Garden , Howrah (India) and National Botanical Research Institute, Lucknow (India). Botanical Gardens

28. Indian Botanical Garden, Howrah

29. MUSEUM Biological museums are generally set up in educational institutes such as schools and colleges. Museums have collections of preserved plant and animal specimens for study and reference. Specimens are preserved in the containers or jars in preservative solutions. Plant and animal specimens may also be preserved as dry specimens . Insects are preserved in insect boxes after collecting, killing and pinning . Larger animals like birds and mammals are usually stuffed and preserved. Museums often have collections of skeletons of animals too.

30. ZOOLOGICAL PARKS These are the places where wild animals are kept in protected environments under human care and which enable us to learn about their food habits and behaviour. All animals in a zoo are provided, as far as possible, the conditions similar to their natural habitats. Children love visiting these parks , commonly called Zoos

31. Key Key is another taxonomical aid used for identification of plants and animals based on the similarities and dissimilarities . The keys are based on the contrasting characters generally in a pair called couplet. It represents the choice made between two opposite options. This results in acceptance of only one and rejection of the other. Each statement in the key is called a lead. Keys are generally analytical in natur e .

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