SS1 BIOLOGY 2ND TERM NOTE (1-5) 20242025.pptx

biology

1. CLASSIFICATION OF LIVING THINGS

2. Classification is the sorting of organisms into different groups based on their shared / similar features which distinguish them from other groups. Biologists have examined and described more than 1.8 million kinds of living organisms. There are still many more to be discovered. Classification enables Biologists to; 1. Identify organisms. 2. Distinguish one organism from another. 3. Understand the diversity of life. The general principle of classification is called Taxonomy or systematic. Aristotle (384-322 BC) a Greek philosopher was the first to make an attempt to classify living organisms. The present classification was proposed by Carolus Linnaeus (1707-1778), a Swedish naturalist. His work brought about the binomial system of nomenclature.

3. Hierarchy Of Classification Kingdom Phylum/Division Class Order Family Genus Species Sometimes, intermediate levels like sub and super are added. E g sub-phylum and super-class. The largest hierarchy is the kingdom which embraces other groups while Species is the smallest and the last link of classification. Organisms at the species level can interbreed together to produce fertile off-springs of their kind.

4. The system of giving two names to an living organism which is generally recognized by biologists world wide is called Binomial nomenclature. The first name is the genus or generic name which always start with a capital letter. The second name is the species or specific name which always start with a small letter. They are written in italic form if typed or underlined separately if handwritten. Examples; Orange- Citrus sinensis Dog- Canis domestica Rat- Rattus rattus

5. Classification of maize plant Classification Name Characteristics Kingdom Plantae All Plants Division Tracheophyta Vascular plants( having vessel for water and food conduction) Superclass Spermatophyta Seed-producing plants Class Angiospermae Flowering plant Subclass Monocotyledoneae Flowering plant Order Graminales Grasses, leaves with shealthing leaf bases Family Graminacae Cereals, millets, bamboo, grasses Genus Zea Maize plants, female inflorescent develops into cob Species mays Cultivated maize plant

6. Classification of African elephant Classification of Human being Classification Name Characteristics Kingdom Animalia All Animals Phylum Chordata Animals with notochord Subphylum Vertebrata Animals with backbone Class Mammalia Animals with hair Order Proboscidea Large animal with long flexible trunk Family Elephantidae Elephant found in Asia and Africa Genus Loxodonta Elephant found in Africa with long trunk, large ears and two finger-like lips Species Africana African elephant Classification Name Characteristics Kingdom Animalia All Animals Phylum Chordata Animals with notochord Subphylum Vertebrata Animal with backbone Class Mammalia Animal with fur Order Primate Mammals with grasping hands and feet Family Hominidae Ape-man, primitve man and modern man Genus Homo Primitive man and Modern man Species Sapiens Modern man

7. Kingdom Linaeus placed all living organisms into two kingdoms; Plants and Animals. Recently, scientists have added other kingdoms. The five kingdoms include: The kingdom Monera Kingdom Protista / Protoctista Kingdom Fungi Kingdom Plantae Kingdom Animalia

8. Kingdom- Monera The monerans are the single-celled motile or non-motile organisms. Organisms are microscopic with procaryotic cells ( cell that lacks membrane-bound organelles). Examples are the bacteria, nostoc and oscillatoria . Bacteria are found everywhere: air, water, soil and inside living organisms. While others can produce food themselves (Chemosynthesis), others can decompose organic substance ( Saprophtes ). Some bacteria can live in their host and cause diseases (Parasites). Cyano -bacteria(Blue-green algae) are found mainly in fresh water and in damp places. They contain chlorophyll not contained in chloroplast and are regarded as the smallest plant. (Structure of Bacterium Draw)

9. ii. Phylum Protozoa : These protists are animal-like. They feed on ready-made food and have no cellulose cell wall. Examples are Amoeba, Paramecium , Plasmodium, Chlamydia etc. Euglena viridis is a protist that shows both plant-like and animal-like features Structure of Chlamydomonas Draw) Structure of Paramecium Draw) Protists are single-celled or unicellular organisms. They are made up eucaryotic cells (Cell with membrane-bound organelles) 1. Phylum Protophyta : These protists are plant- like.They have cellulose cell wall and organelles called chloroplast which contains chlorophyll which help them to make their food. Examples Includes Chlamydomonas , Chlorella, Diatom etc Kingdom- Protista / Protoctista

10. Kingdom- Fungi Fungi are multicellular organisms. They are eucaryotes . General characteristics of fungi They lack chloroplast in their cells hence can’t carryout photosynthesis. They possess cell wall made of chitin. They are non-motile except for slime mould They are made up of branching thread-like structure called hyphae . Reproduction is sexual(Conjugation) and asexual(spore formation). Feeding is saprophytic (decomposition) and parasitic. Rhizopus (Draw)

11. E conomic importance of Fungi They cause food spoilage eg mould or Rhizopus They cause diseases both in plant and animals eg yam rust and candidacies in female They are decomposer hence they improve soil fertility and recycle inorganic material on earth They are used in food industry to carryout fermentation eg yeast They are used in pharmaceutical industry for the production of penicillin eg penicillum notatum Some mushrooms are edible and serve as food. Examples of fungi are Rhizopus , Toadstood , Penicillum , Aspergillus , Yeast, Mushrooms, Slime mould. Yeast. Mushroom.

12. Kingdom Plantae All green plants belong to this kingdom. General characteristics Presence of chloroplast which contains chlorophyll for making it food. Presence of cellulose cell wall. They have eucaryotic cells’ They are non-motile 3 Divisions of plants are known. These are; 1. Thallophyta 2. Bryophyta 3. Tracheophyta

13. Thallophyta 1 . They are simple microscopic plants 2. Some are unicellular eg Chlamydomonas while others are multicellular eg spirogyra 3. Algae are maily autotrophic plants 4. They lack stem root and leaves Examples of simple aquatic plants like algae. Types of algae i . Brown algae( Phacophyta ) eg Sargassium , They have chlorophyll ( Fucoxanthin ) ii. Green algae( Chlorophyta ) eg Volvox , spirogyra, diatom. iii. Red algae ( Rhodophyta ) chlorophyll iv. Golden yellow algae ( Xanthophyta ) e g Tribonera . Structure of Spirogyra (Draw)

14. Bryophyta They are non-vascular plants(lacks xylem and phloem) They grow in damp places They show alternation of generation; sporophytic generation and gametophytic generation. They possess chlorophyll and can carryout photosynthesis They are non-flowering plants Water is essential for their fertilisation Presence of false stem, roots and leaves Examples are moss and liverwort.

15. Tracheophyta i . They are vascular plants ( conductiing vessel i e xylem and phloem) ii. They have true roots, stems and leaves iii. Presence of chlorophyll for photosynthesis iv. Stores cellulose in their cell walls Subdivision of Tracheophyta are; Pteridophyta Spermatophyta Subdivision: Pteridophyta They are multicellular and vascular green plants They are non-flowering plants They have true roots, stem and leaves They are non-seed producing plants They show alternation of generation I e sporophytic (Spore-forming) and gametophytic generation ( Gamete-producing).

16. Spermatophyta : i . They are multicellular seed-producing flowering plants ii. They are vascular plants with well developed vascular tissues iii. They have true root, stems and leaves iv. Reproduction is sexual and water is not required for reproduction Spermatophyta are divided into two: Gymnospermeae Angiospermeae Gymnospermeae : These are plants with Ved -seed. They do not bear flowers. They have true roots, stem and leaves. Seeds are borne on special structure called cone. They are vascular green plants. Examples are conifers and pines. Structure of cone with naked seed b

17. Angiospermeae : They are the most complex green flowering plants They are vascular plants i.e presence of xylem and phloem They have well developed and complete flowers They are seed-producing plants with their seeds enclosed in fruits They are terrestrial plants There classes are; Class: Dicotyledoneacea ( Dicotyledonous) Class: Monocotyledoneacea ( Monocotyledonous) Class : Dicotyledoneacea ) They bear seeds with two-seed leaves or cotyledons Vascular bundle of their stem, root and leaves are arranged in a regular pattern Their floral parts eg sepal, petals, carpel, and stamen exist in the groups of four to five Their leaves have net venation They have tap root system Examples of dicot plants are Mangoes, beans, pawpaw, groundnut, peas etc

18. Monocotyledoneacea ( Monocot plant) They bear seeds with one cotyledon the vascular bundles of the stem are scattered They have parallel venation in their leaves They have fibrous root system Their floral parts exist in the group of three or multiple of three Examples are Maize, Grasses, Rice plant, coconut, etc

19. Kingdom: Animalia All animals belong to this kingdom They are multicellular organisms. Feeding is heterotrophic or holozoic . They cells lack cell wall and chloroplast. Classification of Animals based on some important Features. Animals are classified based on Body symmetry Body cavity Body design Also, animals are divided into two groups namely - Invertebrata -Vertebrata-

20. INVERTEBRATA Super Phylum Invertebrata has the following phyla: Phylum Porifera Phylum Coelenterata / Cnidaria Phylum Platyhelminthes Phylum Nematoda Phylum Annelida Phylum Mollusca Phylum Arthropoda Phylum Echinodermata

21. Phylum: Porifera They are simple aquatic organisms. They do not move about but are attached to rocks and shells. They live in colony and their larva stage is motile They have assymetrical body e g spongy. Vase-like body Openings

22. Phylum : Coelenterata ( Cnidaria ) i . They are multicellular organisms ii. The body is made up of two layers ie ectoderm and endoderm iii. They are mainly aquatic organisms iv. Their bodies are radially symmetrical v. They have soft jelly-like bodies vi. They have tentacles and stinging cells Examples are Jelly fish, Sea anemone, Coral, Hydra

23. Phylum: Platyhelminthes i . They are multicellular flat worms ii. They are bilaterally symmetrical iii. They don’t have body cavity or lumen iv. The body is made up of 3 germ cells: the ectoderm, mesoderm and endoderm v. They are mostly parasitic in man than in animals Vi. They are hermaphrodites Examples include Tapeworm, Planaria , Liver fluke, Blood fluke.

24. Phylum: Nematoda i . They have round and cylindrical body. ii. They lack body cavity ie they have pseudocoelom body cavity iii. They are bilaterally symmetrical iv. Their body is made up of 3 germ cells. v. Some are hermaphrodite Examples are round worm, hookworm, guinea worm, filarial worm, threadworm etc.

25. Phylum: Annelida They have internal and external segmented bodies. The body is long and cylindrical. They have true body cavity/ coelomate bodies. Some are aquatic while others are terrestrials . Alimentary canal has two openings: the mouth and the anus. They are hermaphrodites. Examples are earthworm, leeches, tubeworm

26. Phylum: Mollusca They have soft unsegmented bodies They have tentacles in their head They have muscular foot adapted for crawling or burrowing The body is covered by a soft tissue called mantle Some have calcerous shells eg snail, while others have no shell eg octopus Their eyes and tentacles are used for sensitivity. Examples are Squid, periwinkles, snails, oysters, octopus, slug.

27. Phylum: Arthropoda They have segmented bodies They have hard rigid exoskeleton made of chitin They have jointed appendages or jointed legs used for feeding, movement, reproduction or sensory organs They exhibit moulting or ecdysis ie they shed their skeleton Their bodies are divided into two or three segments such as head, thorax and abdomen They are triploblastic ie 3 body layers They are billaterally symmetrical They have various means of respiration e g gills, trachea, lungbook or body surface

28. Classes of Arthropods Class Crustacea e g crab, crayfish, shrimp, prawn, lobsters Class: Insecta eg Grasshopper, Cockroach, housefly, butterfly Myriapoda eg Centripedes and Millipedes Arachnida : eg Spider, scorpion, mites, ticks

29. S/N Features Crustacea Insecta Arachnida Myriapoda 1. Body division Two body divisions , Cephalothorax and abdomen Three body divisions ie head, thorax and abdomen Two body divisions ie Prosoma and Opisthosoma Two body divisions 2. Wings Absent Present Absent Absent 3. Eyes A pair of stalked eyes A pair of compound eyes Eight simple eyes Simple eyes 4. Antenna Two pairs of antennae A pair of antennae None A pair 5. Walking leg Five pairs of jointed legs Three pairs of jointed legs Four pairs of jointed legs 2 pairs in each segment 6. Respiratory organ Gills Trachea (Spiracle) Lung books Trachea (Spiracle)

30. Phylum: Echinodermata i . They are mainly marine animals ii. Echinoderms have spiny skin. iii. Their bodies are radially symmetrical iv. They are triploblastic animals i e they have three body layers. v. They have neither head nor brain and no segment vi. It has tube feet which is used for movement. Examples are Starfish, Sea urchins, sea cucumbers and brittle stars etc.

31. Phylum : Chordata Subphylum: Vertebrata The vertebrate are organisms with backbones. They are grouped into 5 classes. These are: Class Pisces eg fishes. Class Amphibia eg toad, frog. Class Reptilia eg lizard. Class Aves eg birds. Class Mammalia eg sheep

32. Class PISCES They are aquatic animals i e they can be found in marine, fresh water, pond, lakes, rivers. Their skin are covered by scales but few are without scales. They have fins which are used for movement in water. They are poikilotherms or cold-blooded animals. They have gills which are used for gaseous exchange. They have lateral line system which is used for detection of vibration and pressure in water. They have swim-bladder which enables them to maintain buoyancy in water. Reproduction is sexual and they have external type of fertilization They are oviparous animals I e they lay eggs in the environment outside their body. No parental care. Examples are Tilapia, Shark, Markerel , Salmon etc.

33. They are poikilothermic or cold-blooded animals. They have two pairs of limbs-fore limbs and hind limbs. They have naked or moist and glandular skin with no external scales. They carry out gaseous exchange using gills, lungs, skin and mouth. Presence of poison glands on their skin for defense. They have 3-chambered heart. They have sticky tongue which is protruded and retracted quickly to capture prey. Examples are frogs, Salamander, newt and Toad. Class: AMPHIBIA

34. They are poikilothermic or cold-blooded animals. They have dry skin covered with scales. They have 2 pairs of limbs except snakes. They have lungs for gaseous exchange. Reproduction is sexual and fertilization is internal. They have an incomplete developed 4-chambered heart. They have oviparous mode of reproduction. They have homodont dentition. Examples are lizard, wall gecko, tortoise, snakes, crocodiles, chameleon, turtle etc Class: REPTILIA

35. They are homoiothermic or warm blooded animals. Entire bodies are covered with feathers except the hind legs which are covered with scales. They have two pairs of limbs. They have wings that are used for flight. They have beak without teeth that are used for feeding. Presence of rigid and hollow bones with air sacs for lightness in air. Exhibit oviparous mode of reproduction. Examples: Pigeons,domestic fowl, ducks, ostrich, hawks, sparrows Class: AVES

36. They are homoiothermic or warm-blooded animals. Their bodies are covered with hairs. They have heterodont dentition. They have lungs for gaseous exchange They have two pairs of limbs The skin contains glands like sweat gland and mammary gland Reproduction is sexual and fertiliZation is internal. Mode of reproduction is viviparous Presence of 4-chambered heart Bilaterally symmetrical body Examples are a. Protheria - The monotremes and egg-laying mammals eg Platypus. b. Metatheria - Pouched mammals or Marsupials(without placenta) e g Kangaroo. c. Eutheria - Placenta mammals eg man, horse and lion. Class: MAMMALIA

37. Viruses A virus is extremely small and can only be seen through an electron microscope. It does not fit into any of the kingdoms known as it does not have a cell structure but made up of a coiled strand of nucleic acid (RNA or DNA) enclosed within a protein coat. Virus as a Living thing Virus can reproduce(replicate) Its nucleic acid can be transmitted. Virus as a non-living thing Virus forms crystals outside their host cells. Virus can’t respire, feed, excrete, respond to stimuli etc.

38. Dichotomous key A dichotomous key is a series of choices statements and clues that lead to the correct name of a given organism; that allows the user to determine the identity of organism such as trees, mammals, reptiles, and fish. Dichotomous means "divided into two parts" therefore, dichotomous keys always give two choices in each step. Examples are

39. Class Activity

40. THE CHEMICALS OF LIFE

41. OBJECTIVES OF LESSON By the end of the lesson, the students should be able to; 1. list the various chemicals in organisms. 2. mention the elements that make up each. 3. state the types of carbohydrate and examples 4. mention at least 3 functions of each chemical.

42. Cells in the body of living organisms need chemical substances inside them to make new cytoplasm and p roduce energy. Most of these chemical substances are gotten from the food we eat and they include w ater, lipids, salts, carbohydrate, proteins, vitamins and their derivatives. Each of these are vital for their life processes.

43. CARBOHYDRATES Contain three kinds of atom which are Carbon (C), Hydrogen (H), and Oxygen (O) in 1:2:1. Carbohydrate can be classified into: 1. Monosaccharides: These are the simplest kind of carbohydrates ( C 6 H 12 O 6 ) . Glucose, Fructose, galactose, ribose are simple sugar. Although they contain many atoms, simple sugar molecules are very small, soluble in water and taste sweet.

44. 2. D isaccharides are larger molecules formed if two simple sugar join together. It is a more complex sugar and examples include Sucrose (in sugarcane) Maltose (in malt). They are also soluble in water and taste sweet. Eg - Glucose + Fructose = Sucrose - - Glucose + galactose = Lactose 3. Polysaccharides: Polysaccharides are many simple sugars join together to form a very large molecule in a long chain. Examples are Cellulose of plant cell walls, Starch and Glycogen. Most polysaccharides are insoluble and they do not taste sweet.

45. FUNCTIONS OF CARBOHYDRATES It provides energy for daily activities. Energy is released by respiration. Used to build body parts like exoskeleton / chitin. Serves as building block of most nutrients. Mucus which serves as lubricant in the body is composed of carbohydrate.

46. LIPIDS Fats and oil are examples of lipids. Fats is solid and oil liquid at room temperature. They contain 3 different atoms – carbon, hydrogen and little oxygen. The molecule is made up of four smaller molecules joined together (One glycerol and three fatty acid molecules). Lipid is Insoluble in water. FUNCTIONS OF FATS Fats as secondary source of energy, even more that carbohydrate. Supply essential fatty acids and glycerol to the body Provides fat soluble Vitamins Serves as insulators in the body. It maintains body temperature in the body.

47. WATER Water is made up of Hydrogen and Oxygen atoms. 60 % of the human body is made up of water. Water is necessary for most metabolic reactions that occur in body serving as an important solvent. Water is useful because if the cells dry out, their reactions will stop and the organism dies. Water is needed to dissolve enzyme and nutrients in the alimentary canal for digestion to take place. Water help to get rid of waste product from body. Water is the constituent of blood plasma needed to transport useful substances round the body.

48. PROTEIN Protein contains carbon, hydrogen, oxygen, nitrogen and sulfur. Protein molecules are made of long chains of smaller molecules; amino acids joined end to end. There are 20 different amino acid and some are soluble in water such as hemoglobin while some are insoluble like keratin found in hair and fingernails. FUNCTION OF PROTEIN Used for making new cells and tissues /body building. For growth For repairing damaged body parts; worn-out cells and tissues. Used for antibody production. Used for enzymes and hormones production. Supply amino acids to the body

49. FUNCTIONS OF PROTEIN Some protein are soluble in water example hemoglobin. Insoluble protein – keratin, hair and fingernails. Used for making new cells. Used for growing and repairing damaged body parts. Used for antibody production.

50. DNA DNA stands for deoxyribonucleic acid. It is a chemical that are inherited from parent organisms to makes up genes and chromosomes. DNA is made up of two long strands twisted together to form spiral called helix and held together by a weak hydrogen bond. Each strand has f our series of bases arranged along it. They are Adenine, Thiamine, Guanine and Cytosine. The sequence of the bases provide code to made protein and determine how our cells, tissues and organ develop. A=T G=C

51. NUTRITION

52. One of the main characteristics of living things is their ability to feed. This is called nutrition. Both plants and animals feed. TYPES OF NUTRITION There are two types of nutrition namely’ AUTOTROPHIC NUTRITION : This occurs in organisms which can manufacture their own food. They are plants and can also be called autotrophs . Most autotrophs can manufacture their own foods through two processes namely Photosynthesis. Chemosynthesis 2. HETEROTROPHIC NUTRITION : This occurs in organisms which cannot manufacture their own food but depend directl or indirectly on plants for food. All animals are autotrophs and can also be called consumers.

53. PLANT NUTRITION

54. PHOTOSYNTHESIS Photosynthesis is defined as the process by which green plants manufacture their food using carbon dioxide and water in the presence of sunlight trapped by chlorophyll. The food manufacture is an organic compounds while water and carbon dioxide are inorganic compounds. It is an endothermic reaction and can also be said to be holophytic mode of nutrition . Spirogyra, maize plants, nostoc and other flowering plants are common examples. The equation representation of photosynthesis is; . 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 ( Carbondioxide ) (Water) (Glucose) (Oxygen )

55. LIGHT STAGE/REACTION: This reaction occurs during the day or in the presence of light. The chlorophyll in the green plant absorb sun energy. The solar energy is used to split water into hydrogen ions and hydroxyl ions in a process called photolysis. The hydroxyl ions is further converted into water and oxygen released by reduction process. Chlorophyll 4H 2 O 4 H + + 4OH - Sunlight 4(OH - ) 2 H 2 O + 4O 2 2. DARK STAGE/REACTION : This reaction occurs at night or in the absence of light. The carbon dioxide reacts with the hydrogen ions from the light stage to form their food (glucose). 6CO 2 + 4H + 6C 6 H 12 O 6 + 6H 2 O STAGES OF PHOTOSYNTHESIS

56. Materials and Conditions Necessary for Photosynthesis Carbon (iv) oxide – This is derived from the atmosphere and it diffuses into the intercellular spaces through the stomata of the leaves. Water - Water is derived from the soil. Mineral Salts – Mineral salts are derived from the soil. Sunlight – This is obtained from solar energy. The light from the sun is trapped by the chlorophyll of the leaves. Optimum Temperature – This is derived partly from Solar energy and partly from chemical reactions witin the leaves during which heat is generated. Chlorophyll – Green coloring found in pallisade and spongy mesophyll of the leaves where food is synthesized within the plant.

57. Structure of the leaf Photosynthesis occurs in the leaves. CO 2 enters the leaf through tiny openings on its surfaces called stomata and water enters the root then pass through the xylem to the leaf. The glucose is converted to sucrose and moved via the phloem to the stem and root.

58. Epidermis: Tightly packed layer that secretes waxy cuticle. Cuticle: It prevents water loss from the leaves. Palisade mesophyll : Tightly packed layer containing many chloroplast for photosynthesis. Spongy mesophyll : Loosely packed layer containing fewer chloroplast for photosynthesis . 4. Air space: Hold gases (Oxygen and carbondioxise ) 5. Stomata: Openings surrounded by guard cells for gaseous exchange.

59. Chemosynthesis Chemosynthesis is the process by which non-green plants and certain organisms like bacteria, use chemical energy derived from inorganic materials to produce their food (carbohydrates). The inorganic materials include ; Carbodioxie , ammonia, water or nitrite. Nitrosomonas and Nitrobacter are common examples of chemosynthetic bacteria.

60. ANIMAL NUTRITION

61. All living organisms need food for their survival and daily activities. Plants can manufacture their own food through a process called photosynthesis, hence they are called autotrophs . On the other hand, animals cannot manufacture their own food as they depend on plants directly or indirectly for their food, hence they are called heterotrophs . Animals sometimes are classified according to the type of food they eat. On this basis, they are classified into three groups, namely: 1. Carnivorous animals: These animals feed only on flesh or other animals, e.g Dog , Lion , Lizard , Snake , Cat etc . 2. Herbivorous animals: These animals feed on plants, e.g. goat, sheep, rabbit etc. 3. Omnivorous animals: These animals feed on both plants and animals, e.g. man, pig etc.

62. Carbohydrates : Carbohydrates are mainly energy giving food and may be classified as monosaccharides , disaccharides, or polysaccharides depending on the number of monomer (sugar) units they contain. They constitute a large part of foods. Sources : Rice, noodles, bread, plantain, pasta, yam and other grain based products. Classes And Sources Of Food

63. 2. Protein Breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. Sources of protein are Beans, Milk, Eggs, Meat, Nuts etc .

64. 3. Fats and oil Fats may be classified as saturated or unsaturated depending on the detailed structure of the fatty acids involved. Fats is solid at room temperature while oil is liquid at room temperature. • Trans fats are a type of unsaturated fat with trans-isomer bonds; these are rare in nature and in foods from natural sources; they are typically created in an industrial process called (partial) hydrogenation. , Sources of Fats and oil: Butter, egg yoke, lard, fatty meat, margarine, vegetable oil, palm oil etc.

65. 4. Vitamins Vitamins are recognized as essential nutrients, necessary in the diet for good health. Human body has some capacity to produce certain vitamins useful for survival and health while others are derived from food. (Vitamin D is the exception: it can alternatively be synthesized in the skin, in the presence of UVB radiation.) • Excess of some vitamins is also dangerous to health (notably vitamin A), and for at least one vitamin, B6, toxicity begins at levels not far above the required amount. There are two types of vitamins which are; Water – soluble Vitamins : These are vitamins that dissolved in water. They include Vit B and C. Fat – soluble Vitamins : These are vitamins that dissolved in fat. They include Vit A, D, E and K.

66. 5. Minerals Dietary minerals are the chemical elements required by living organisms in small quantity to promote health. Mineral elements are grouped into 2 namely; 1. Macronutrients/ Major elements: These are elements or minerals needed in large amount. They include; Potassium, oxygen, iron, phosphorus, Nitrogen, calcium, hydrogen, magnesium, sulphur , carbon 2. Micronutrients/ Minor or trace elements: These are elements or minerals needed in small amount in the body. They include; Zinc, copper, Molybdenum, Manganese and silicon. Sources are sea foods, dairy food, table salt, liver, milk, kidney • On the other hand, minerals are often artificially added to the diet as supplements; the most famous is likely iodine in iodized salt which prevents goiter .

67. 6. Water About 70% of the non-fat mass of the human body is made of water. To function properly, the body requires between one and seven liters of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors. Water aids digestion and is needed by the body to also wash away toxic materials. Sources of water: Fruits, drinking water, soft drinks etc.

68. Others include roughages or fibres Dietary fiber consists mainly of cellulose, a large carbohydrate polymer that is indigestible because humans do not have the required enzymes to disassemble it. There are two subcategories: soluble and insoluble fibre . Whole grains, fruits (especially plums, prunes figs, and vegetables are good sources of dietary fibre . • Fibre is important to digestive health and is thought to reduce the risk of colon cancer. - It can help in alleviating both constipation and diarrhea. Fiber provides bulk to the intestinal contents, and Insoluble fiber stimulates peristalsis (the rhythmic muscular contractions of the intestines which moves along the digestive tract). • Some soluble fibers produce a solution of high viscosity which slows the movement of food through the intestines. • Fiber, help lessen insulin thereby controlling sugar level.

69. Balanced Diet Balanced diet is a diet containing all the six classes of food substances required by an organism or man in the correct proportion or right amount . Balanced diet is also refers to as adequate diet. The balance diet must contain the six food nutrients such as carbohydrates, proteins, fats and oil, minerals, vitamins and water in their correct proportion. Importance of Balanced Diet Balanced diet is important to the body in the following ways: 1. Balanced diet makes us healthy and by so doing, makes us to be resistance to diseases. 2. It encourages growth and normal development of the body. 3. It also provides energy required for normal activities. 4. Balanced diet prevents malnutrit ion, deficiency diseases. Lack of some food substances, e.g protein in a diet can cause a nutritional disease called kwashiokor in children which is characterized by a very big head, narrow neck, big, swollen and shiny stomach, flat buttock, and very slender and narrow legs.

70. Digestive Enzymes An enzyme is an organic c atalyst usually proteinous in nature, which promotes or speeds up chemical changes in living cells but are not themselves used up in the process. Enzymes accelerate metabolic reactions without changing in the process. Characteristics 1. All enzymes are proteins in nature. 2. Enzymes are usually involved in reversible reactions. 3. Enzymes are affected by the pH (acidity or alkalinity) of their surrounding. They are destroyed by strong acids or alkali. 4. Enzymes accelerate the rate of chemical reaction. 5. Each enzyme is specific in action, i.e., an enzyme or a group of enzymes deals with only one process.. All living organisms need food for their survival and daily activities. Plants can manufacture their own food through a process called photosynthesis, hence they are called autotrophs. On the other hand, animals cannot manufacture their own food as they depend on plants directly or indirectly for their food, hence they are called heterotrophs. Animals sometimes are classified according to the type of food they eat. On this basis, they are classified into three groups, namely: 1. Carnivorous animals: These animals feed only on flesh or other animals, e.g dog, lion, lizard, snake, cat, etc. 2. Herbivorous animals: These animals feed on plants, e.g. goat, sheep, rabbit, etc. 3. Omnivorous animals: These animals feed on both plants and animals, e.g. man, pig, etc. Classes And Sources Of Food There are seven major classes of nutrients – Carbohydrates, Fats, Fibre , Minerals, Protein, Vitamin, and Water. The macronutrients (excluding fiber and water) provide structural material (amino acids from which proteins are built, and lipids from which cell membranes and some signaling molecules are built) and energy. Some of the structural material can be used to generate energy internally, and in either case it is measured in joules or calories (sometimes called “kilocalories” and on monomers bound to glycerol backbone. Some fatty acids, but not all, are essential in the diet: they cannot be synthesized in the body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen. The fundamental components of protein are nitrogen-containing amino acids, some of which are essential in the sense that humans cannot make them internally. Some of the amino acids are convertible (with the expenditure of energy) to glucose and can be used for energy production just as ordinary glucose. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs normally only during prolonged starvation. Other micronutrients include antioxidants and phytochemicals which are said to influence (or protect) some body systems. Their necessity is not as well established as in the case of, for instance, vitamins. Most foods contain a mix of some or all of the nutrient classes, together with other substances such as toxins or various sorts. Some nutrients can be stored internally (e.g., the fat soluble vitamins), while others are required more or less continuously. Poor health can be caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient. For example, both salt and water (both absolutely required) will cause illness or even death in too large amounts. other rare occasions written with a capital C to distinguish them from little ‘c’ calories). Carbohydrates and proteins provide 17 kJ approximately (4 kcal) of energy per gram, while fats provide 37 kJ (9 kcal) per gram.though the net energy from either depends on such factors as absorption and digestive effort, which vary substantially from instance to instance. Vitamins, minerals, fiber, and water do not provide energy, but are required for other reasons. A third class dietary material, fiber (i.e., non-digestible material such as cellulose), seems also to be required, for both mechanical and biochemical reasons, though the exact reasons remain unclear. Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates range from simple monosaccharides (glucose, fructose, galactose) to complex polysaccharides (starch). Fats are triglycerides, made of assorted fatty acid Carbohydrates • Carbohydrates may be classified as monosaccharides, disaccharides, or polysaccharides depending on the number of monomer (sugar) units they contain. • They constitute a large part of foods such as rice, noodles, bread, and other grainbased products. Monosaccharides – one sugar unit, disaccharides – two sugar units, and polysaccharides three or more units. • Polysaccharides are often referred to as complex carbohydrates because they are typically long multiple branched chains of sugar units. • The difference is that complex carbohydrates take longer to digest and absorb since their sugar units must be separated from the chain before absorption. • The spike in blood glucose levels after ingestion of simple sugars is thought to be related to some of the heart and vascular diseases which have become more frequent in recent times. • Simple sugars form a greater part of modern diets than formerly, perhaps leading to more cardiovascular disease. The degree of causation is still not clear, however. Fat • A molecule of dietary fat typically consists of several fatty acids (containing long chains of carbon and hydrogen atoms), bonded to a glycerol. • They are typically found as triglycerides (three fatty acids attached to one glycerol backbone). Fats may be classified as saturated or unsaturated depending on the detailed structure of the fatty acids involved. • Saturated fats have all of the carbon atoms in their fatty acid chains bonded to hydrogen atoms, whereas unsaturated fats have some of these carbon atoms doublebonded , so their molecules have relatively fewer hydrogen atoms than a saturated fatty acid of the same length. • Unsaturated fats may be further classified as monounsaturated (one double-bond) or polyunsaturated (many double-bonds). • Furthermore, depending on the location of the double-bond in the fatty acid chain, unsaturated fatty acids are classified as omega-3 or omega-6 fatty acids. • Trans fats are a type of unsaturated fat with trans-isomer bonds; these are rare in nature and in foods from natural sources; they are typically created in an industrial process called (partial) hydrogenation. Fiber • Dietary fiber is a carbohydrate (or a polysaccharide) that is incompletely absorbed in humans and in some animals. • When metabolized it can produce four calories (kilocalories) of energy per gram. But in most circumstances it accounts for less than that because of its limited absorption and digestibility. • Dietary fiber consists mainly of cellulose, a large carbohydrate polymer that is indigestible because humans do not have the required enzymes to disassemble it. There are two subcategories: soluble and insoluble fibre . Whole grains, fruits (especially plums, prunes, and figs), and vegetables are good sources of dietary fibre . • Fibre is important to digestive health and is thought to reduce the risk of colon cancer.[citation needed] For mechanical reasons it can help in alleviating both constipation and diarrhea. • Fiber provides bulk to the intestinal contents, and insoluble fiber especially stimulates peristalsis—the rhythmic muscular contractions of the intestines which moves along the digestive tract. • Some soluble fibers produce a solution of high viscosity; this is essentially a gel, which slows the movement of food through the intestines. • Additionally, fiber, perhaps especially that from whole grains, may help lessen insulin spikes and reduce the risk of type 2 diabetes. Protein • Most meats such as chicken contain all the essential amino acids needed for humans. • Proteins are the basis of many animal body structures (e.g. muscles, skin, and hair). They also form the enyzmes which control chemical reactions throughout the body. • Each molecule is composed of amino acids which are characterized by inclusion of nitrogen and sometimes sulphur (these components are responsible for the distinctive smell of burning protein, such as the keratin in hair). • The body requires amino acids to produce new proteins (protein retention) and to replace damaged proteins (maintenance). • As there is no protein or amino acid storage provision, amino acids must be present in the diet. Excess amino acids are discarded, typically in the urine. • For all animals, some amino acids are essential (an animal cannot produce them internally) and some are non-essential (the animal can produce them from other nitrogen-containing compounds). • About twenty amino acids are found in the human body, and about ten of these are essential, and therefore must be included in the diet. • A diet that contains adequate amounts of amino acids (especially those that are essential) is particularly important in some situations: during early development and maturation, pregnancy, lactation, or injury (a burn, for instance). • A complete protein source contains all the essential amino acids; an incomplete protein source lacks one or more of the essential amino acids. Minerals • Dietary minerals are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen that are present in nearly all organic molecules. • The term “mineral” is archaic, since the intent is to describe simply the less common elements in the diet. Some are heavier than the four just mentioned—including several metals, which often occur as ions in the body. • Some dietitians recommend that these be supplied from foods in which they occur naturally, or at least as complex compounds, or sometimes even from natural inorganic sources (such as calcium carbonate from ground oyster shells). • Some are absorbed much more readily in the ionic forms found in such sources. • On the other hand, minerals are often artificially added to the diet as supplements; the most famous is likely iodine in iodized salt which prevents goiter Vitamins • Some vitamins are recognized as essential nutrients, necessary in the diet for good health. (Vitamin D is the exception: it can alternatively be synthesized in the skin, in the presence of UVB radiation.) • Certain vitamin-like compounds that are recommended in the diet, such as carnitine, are thought useful for survival and health, but these are not “essential” dietary nutrients because the human body has some capacity to produce them from other compounds. • Thousands of different phytochemicals have recently been discovered in food (particularly in fresh vegetables), which may have desirable properties including antioxidant activity (see below); experimental demonstration has been suggestive but inconclusive. • Other essential nutrients not classed as vitamins include essential amino acids (see above), choline, essential fatty acids (see above), and the minerals discussed in the preceding section. • Vitamin deficiencies may result in disease conditions: goitre , scurvy, osteoporosis, impaired immune system, disorders of cell metabolism, certain forms of cancer, symptoms of premature aging, and poor psychological health (including eating disorders), among many others. • Excess of some vitamins is also dangerous to health (notably vitamin A), and for at least one vitamin, B6, toxicity begins at levels not far above the required amount. • Deficiency or excess of minerals can also have serious health consequences. Water • About 70% of the non-fat mass of the human body is made of water. Analysis of Adipose Tissue in Relation to Body Weight Loss in Man. • To function properly, the body requires between one and seven liters of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors. • With physical exertion and heat exposure, water loss increases and daily fluid needs will eventually increase as well. • It is not fully clear how much water intake is needed by healthy people, although some experts assert that 8–10 glasses of water (approximately 2 liters) daily is the minimum to maintain proper hydration. • The notion that a person should consume eight glasses of water per day cannot be traced to a credible scientific source. The effect of, greater or lesser, water intake on weight loss and on constipation is also still unclear. • Water aids digestion and is needed by the body to also wash away toxic materials. Balanced Diet Balanced diet is a diet containing the correct proportion or the right amount of all the six food substances required by an organism or man. The balanced diet must contain the six food substances such as carbohydrates, proteins, fats and oil, minerals, vitamins and water. Importance of Balanced Diet: Balanced diet is important to the body in the following ways: 1. Balanced diet makes us healthy and by so doing, makes us to be resistance to diseases. 2. It encourages growth and normal development of the body. 3. It also provides energy required for normal activities. 4. Balanced diet prevents malnutrition, deficiency or diseases. Lack of some food substances, e.g protein in a diet can cause a nutritional disease called kwashiokor in children which is characterised by a very big head, narrow neck, big, swollen and shiny stomach, flat buttock, and very slender and narrow legs. Digestive Enzymes An enzyme is an organic catalyst usually proteinous in nature, which promotes or speeds up chemical changes in living cells but are not themselves used up in the process. Enzymes accelerate metabolic reactions without changing their composition in the process. Characteristics 1. All enzymes are proteins in nature. 2. Enzymes are usually involved in reversible reactions. 3. Enzymes are affected by the pH (acidity or alkalinity) of their surrounding. They are destroyed by strong acids or alkali. 4. Enzymes accelerate the rate of chemical reaction. 5. Each enzyme is specific in action, i.e., an enzyme or a group of enzymes deals with only one process. Classes of Enzymes The new method of classifying enzymes is based on the nature of chemical changes brought about on a substrate. Such changes may involve oxidation in which case the enzyme will be called an oxidase. It is important to note that the earlier classification based on the substrate enzyme works on, e.g. amylases for maltose, proteases for protein or lipases for lipids are no longer correct or biochemically acceptable. From the above classification, it is clear that all digestive enzymes belong to the class called hydrolases. the class, hydrolases generally refer to enzymes that break up various bonds (i.e. breaking large molecules into smaller particles) in the presence of water. Test Questions 1. Plants can manufacture their own food through a process called photosynthesis are called …………. a) heterotrophs b) autotrophs c) autetrophs d) heterotrophic plants 2. Animals that cannot manufacture their own food who depend on plants directly or indirectly for their food, are called ……….. a) heterotrophs b) autrophs c) autotrophs d) canivores 3. ………… are animals that feed on flesh or other animals a) Herbivores b) Carnivores c) Omnivores d) Autovores 4. ………… are animals that feed on both flesh and plants a) Herbivors b) Carnivores c) Rativores d) Omnivores 5. ………… is a diet containing the correct proportion or the right amount of all the six food substances required by an organism or man. a) Balance diet b) Complete diet c) Balanced diet d) Missing diet 6. All digestive enzymes belong to the class called ……… a) Hydrolase b) Oxidase c) Peptolase d) Hydralase 7. One of these is not a characteristic of enzymes a) Enzymes are specific in action b) Enzymes are affected by the pH c) Enzymes reduce the rate of chemical reaction d) Enzymes are proteins in nature 8. Carbohydrates may be classified as monosaccharides, disaccharides, or ………. depending on the number of monomer (sugar) units they contain. a) starch b) peptosaccharides c) cellulose d) polysaccharides 9. Lack of some food substances, e.g protein in a diet can cause a nutritional disease called ……….. a) kwashiokor b) beriberi c) scurvy d) polio 10. List the classes of food and give one function each It is clear that all digestive enzymes belong to the class called hydrolases . the class, hydrolases generally refer to enzymes that break up various bonds (i.e. breaking large molecules into smaller particles) in the presence of water .