SS ONE FIRST TERM NOTE - BIOLOGY - PDF

FIRST TERM NOTE **TOPIC:** BIOLOGY **CLASS:** SSS ONE **SCHEME OF WORK** - **Introduction To Biology** - **Classification Of Living Things 1** - **Classification Of Living Things 2** - **Classification Of Living Things 3** - **The Cell** - **Cell And Its Environment 1** - **M...

FIRST TERM NOTE **TOPIC:** BIOLOGY **CLASS:** SSS ONE **SCHEME OF WORK** - **Introduction To Biology** - **Classification Of Living Things 1** - **Classification Of Living Things 2** - **Classification Of Living Things 3** - **The Cell** - **Cell And Its Environment 1** - **Mid Term Break** - **Cell And Its Environment 2** - **Properties And Functions of Cell 1** - **Properties And Significance of Cell 2** - **Nutrition In Animals** - **Growth** - **Irritability/ Movement** - **Nutrient Cycling** WEEK ONE **INTRODUCTION TO LIVINGTHINGS** Science is the systematic process of making enquiries about nature which includes both (living and non-living things). Biology is a science subject that studies living things in nature. Biology was coined from two Greek words \"Bio\" (life) and "logos\" (study of) which means, biology is the study of LIFE. It can also be said to be the study of plants and animals. Biology is subdivided into two main branches namely: - Botany --the study of plants. - Zoology - the study of animals. - Microbiology -- the study of micro-organisms Other branches of biology include - Ecology - the study of the interaction between organism and its environment - Genetics -- the study of heredity - Taxonomy -- classification of organisms - Ethology - the study of animal behaviour - Entomology - the study of insects **RELEVANCE OF BIOLOGY** As a field of science, biology has found great applications in many areas of human life, some of which include: - **Medicine**: Production of drugs and vaccines e.g., penicillin, organ transplant e.g., kidney (renal) transplant, in-vitro fertilization in infertile couples. - **Agriculture**: Production of hybrid (crops and animals with desired qualities), use of biological pesticides to control agricultural pests - **Bioremediation** i.e., use of naturally occurring bacteria to clean up oil spills and toxic chemicals. - **Biotechnology**: Use of genetic engineering to fight genetic diseases. - **Food** **production**: Production of single cell protein (SCP) to reduce protein deficiency problem, food storage and preservation ##### **PROCESS OR METHOD OF SCIENCE** This is a systematic or step by step approach used to investigate or make enquiries about observations in nature. The scientific methods include the following steps: - Make an observation or ask a question - Gather background information - Create a hypothesis which is an explanation for the observation or question which can be tested [experimentally]. - Create a prediction and perform a test. - Analyse the results and draw a conclusion - A theory is therefore an aggregate of many verified hypotheses. An extensively tested and proven theory becomes a [law or principle] which is still subject to change due to continual experimentation or research. **CHARACTERISTICS OF LIVING THINGS** Everything in nature can be classified into living things non-living things. The living things can be distinguished from their nonliving counterparts through the following characteristics observable in all living things: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. **DIFFERENCES BETWEEN PLANTS AND ANIMALS** All living organisms can be generally classified as plants or animals. However, plants can be distinguished from animals in the following ways: **PLANTS** **ANIMALS** ---- ---------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------- 1. Moves only parts of their body Moves the whole of their bodies. 2. Gaseous exchange takes place through the entire body. Gaseous exchange is through special organs. 3. Green plants photosynthesize i.e., they are autotrophs. Animals do not photosynthesize i.e., they are heterotrophs. 4. They respond to stimuli slowly. They respond to stimuli quickly. 5. Growth is apical and indefinite (continuous). Growth is uniform and definite (limited). 6. No specialized sense organs. Possess specialized sense organs. 7. No specialized excretory systems. They have special and well-developed excretory systems. 8. Cell has rigid non living cellulose cell wall which provides mechanical support. Have thin, flexible cell membrane. Mechanical support is provided by external exoskeleton or internal endoskeleton. 9. They store food (carbohydrates) as starch They store carbohydrates as glycogen **LEVELS OF ORGANIZATION OF LIFE** Every living thing is made up of a cell or a number of cells. A single-celled organism is called unicellular while a many-celled organism is called multicellular. Organization of life is therefore the existence of life from a single-celled organism to a multicellular organism with complex forms that performs different functions. The Four levels of organization of life are: 1. **Cell:** A cell is a functional and structural unit of life. Some living things exist as cell. Examples are Amoeba, Chlamydomonas, Paramecium and Euglena. Common cells that perform distinct functions in plant and animals include sperm cells, nerve cells, bone cells, red blood cells, root hair cells etc. 2. **Tissues:** A tissue is a collection of cells which are similar in structure and perform specific functions. **Hydra, Jelly fish, Sea anemones** are examples of an animals that is made up of tissues only. Examples of tissues in animals and plants are epithelial tissue, blood, nerve tissue, muscle tissue, xylem and phloem tissues etc. 3. **Organ:** An organ is a collection of different tissues that perform a common function or functions e.g., kidney, heart, brain, stem, roots etc. Example of organ in plant is onion bulb. 4. **System:** A system is a set of organs which work as a unit to perform vital functions of life e.g. digestive system, respiratory system, reproductive system, transport system etc. **COMPLEXITY OF ORGANIZATION IN HIGHER ORGANISMS** Higher organisms have bodies that are differentiated into specialised parts performing different functions. The different specialized parts made up of tissues, organs and systems make higher organisms more complex and efficient to carry out various activities of life. **Advantages of complexity** 1. It leads to division of labour and specialization 2. It has led to the efficiency of the various organs of the body. 3. The complexity of higher organism has led to their survival (adaptation) in their different habitats. 4. Various systems operate side by side without adversely affecting each other 5. Reproduction in complex organisms does not lead to the disintegration of the parents **Disadvantages of complexity** 1. Individual cells are not capable of existing independently and therefore depend on one another's activities to exist 2. With complexity, ability to regenerate lost parts decreases. 3. Difficulties in acquisition of food materials and oxygen and loss of waste product 4. Difficulties in reproduction 5. It leads to slower rate of diffusion because the surface area to volume ratio is small and the distance from exterior to the centre of the body is great **ASSIGNMENT** 1. 2. 3. 4. 1. 2. 3. **WEEK TWO** **CLASSIFICATION OF LIVING ORGANISMS II** Nature comprises millions of organisms, hence the need for identification, naming and classifying them in a meaningful manner. The present and widely accepted method of classification of organism was introduced by a Swiss scientist called Carolus Linnaeus. **Classification** can be defined as the grouping of living organism according to their similar or shared features or characteristics which differentiates them from other groups. **Taxonomy** is the branch of biology or science that deals with the identification, naming and classification of living organism. The arrangement of living organisms from the highest to the lowest (with decreasing variety of organisms) is as follows: - KINGDOM - PHYLUM OR DIVISION - CLASS - ORDER - FAMILY - GENUS - SPECIES Carolus Linnaeus is regarded as the father of taxonomy. He divided all living organisms into plants and animals and also introduced the binomial system of naming organisms. **Binomial Nomenclature** is the standard system of naming living organisms. Each type of organism is given two names: - The name of the genus (generic name) - The name of the species (specific name) The generic name is always written first using initial capital letter (underlined or italicized) e.g., [Homo] [sapiens] is man's scientific name. All organisms could not be suitably classified as either plants or animals based on Carolus Linnaeus classification. R.H Whittaker proposed a better system of classifying living things. He divided all living things into FIVE kingdoms based on the following - Cell structure -- prokaryotes or eukaryotes - Body organization -- unicellular or multicellular - Mode of nutrition -- autotrophs or heterotrophs - Evolutionary relationship The five kingdoms have been generally accepted for all living organisms, these include Monera, Protista, fungi, plantae and animalia. **KINGDOM MONERA** ------- ----------------------- ------------------------------- **1** **Cell structure** **Prokaryotes** **2** **Body organization** **Unicellular** **3** **Mode of nutrition** **Autotrophs & heterotrophs** **4** **Mobility** **Non motile** **5** **Cell wall** **Peptidoglycans** **6** **Examples** **Bacteria** **KINGDOM PROTISTA** ------- ----------------------- -------------------------- **1** **Cell structure** **Eukaryotes** **2** **Body organization** **Unicellular** **3** **Mode of nutrition** **Autotrophs** **4** **Mobility** **Motile & non motile** **5** **Cell wall** **Polysaccharides** **6** **Examples** **Amoeba, Euglena etc.** Protists can be broadly divided into two groups; a. b. Note: Euglena is a protist with plant and animal like features. **KINGDOM FUNGI** ------- ----------------------- --------------------------------- **1** **Cell structure** **Eukaryotes** **2** **Body organization** **Unicellular & Multicellular** **3** **Mode of nutrition** **Parasitic & Saprophytes** **4** **Mobility** **Motile & non motile** **5** **Cell wall** **Chitin** **6** **Examples** **Mould, Yeast, Mushroom etc.** Multicellular fungi have filamentous bodies that are made up of a network of fine, branching filaments called **hyphae** (singular: **hypha**). This mass of hyphae is known as **mycelium** (plural: **mycelia**). **REASONS FOR CLASSIFYING ORGANISMS** - To understand diversity better - To learn the differences and similarities of living organisms - To understand evolutionary relationship - For research purpose - To know the origin and evolution of organisms **WEEK THREE** **CLASSIFICATION OF LIVING ORGANISMS II** **KINGDOM PLANTAE** This consists of organisms with cellulose cell wall and chlorophyll for manufacturing their food. **KINGDOM PLANTAE** ------- ----------------------- ---------------------- **1** **Cell structure** **Eukaryotes** **2** **Body organization** **Multicellular** **3** **Mode of nutrition** **Autotrophs** **4** **Mobility** **Non motile** **5** **Cell wall** **Cellulose** **6** **Examples** **Sunflower, Mango** It consists of three major phyla i.e., Thallophyta, Bryophyta and Tracheophyta. a. - These are simple aquatic photosynthetic plants - They are non-vascular plants - They lack true root, stem and leaves. - They are either unicellular or multicellular and may be green, brown or red. - They reproduce asexually (by cell division, fragmentation, spore) or sexually. - They exhibit alternation of generation. **b. BRYOPHTA** These include Hornworts, Liverworts and Mosses - Bryophytes are multicellular, non-vascular plants. - They also lack true roots, stems and leaves. - They have chlorophyll as the only photosynthetic pigment. - They are terrestrial but live in moist place. - They produce spores asexually and also reproduce sexually. Hence, they also show a distinct alternation of generation. **c. TRACHEOPHYTA** - They are referred to as tracheid plant because they have water conducting cells - They are green multicellular, terrestrial vascular plants i.e., they have tissues for conducting water and food. - They have true roots, stem, and leaves. It is the largest group of plants and can be subdivided into two i.e., pteridophytes and spermatophytes. i. Examples include Dryopteris, Platycerium, Ferns etc - - - - - - - - These are seed bearing plants - They bear seeds - They are photosynthetic They can be grouped into two ANGIOSPERM GYMNOSPERM --- ---------------------------------------------------------- ---------------------------------------------------------------------------- 1 They are flowering plants They are non-flowering plants 2 Their seeds are enclosed within an ovary usually a fruit Their seed are bare and not enclosed which are found on leaves or as cones 3 Their life cycle is seasonal They are evergreen 4 These have hardwood These have softwoods 5 Examples are oil palm, water leaf Examples are cycads, conifers and gingko's Angiosperms are grouped into two, monocotyledons and dicotyledons. MONOCOTS DICOTS --- -------------------------------------------------------------------------------------- --------------------------------------------------------------------- 1 One seed leaf Two seed leaf 2 Fibrous root Tap root 3 Parallel venation Reticulate or Vein venation 4 No secondary growth Secondary growth occurs 5 Hypogeal germination (i.e. their cotyledons remain below the ground at germination.) Epigeal germination (i.e. the cotyledons are borne above the soil). 6 Examples are maize, grass, garlic Examples are mangoes, oranges **WEEK FOUR** **CLASSIFICATION OF LIVINGTHINGS III** **KINGDOM ANIMALIA** **KINGDOM ANIMALIA** ------- ----------------------- ---------------------------------------- **1** **Cell structure** **Eukaryotes** **2** **Body organization** **Multicellular** **3** **Mode of nutrition** **Heterotrophs** **4** **Mobility** **Motile** **5** **Cell wall** **Non** **6** **Examples** **Bird, Fish, Hookworm, Sponges etc.** Animals can be classified into two main groups: a. b. These two groups can further be divided and subdivided based on body symmetry, body design and body cavity. **INVERTERBRATES** a. - They are primitive multicellular, aquatic animals (colonies of cells) - They lack true tissues and nervous system - Reproduce asexually and sexually (hermaphrodites) **b. Phylum Coelenterata (Cnidaria: Hydra, Jelly fish, Sea anemones):** - They have two layered bodies surrounding a central hollow cavity called enteron. - They have tentacles and most of them are marine - Possession of stinging cells called nematocysts for protection - There is only one opening called mouth. No anus. **c. Phylum Platyhelminthes (Flatworms: Tapeworm, Planaria, Liver fluke)** - - - - - - **d. Phylum Nematoda (Roundworm, Hookworm, Guinea worm)** - They have thread like, cylindrical, unsegmented body with no body cavity. - They are bilaterally symmetrical. - They have alimentary canal with mouth and anus - Some are parasitic, while others are free living **e. Phylum Annelida (Earthworm, Leeches)** - - - **f. Phylum Mollusca (Snail, Squid, Octopus)** - - - **g. Phylum Echinodermata (Star fish, Bristle star, Sea lily)** - - - - **h. Phylum Arthropoda (**the largest group in the animal kingdom) - They have segmented bodies - They have exoskeleton made up of chitin - Their appendages are jointed. - They have body divisions - They are bilaterally symmetrical They can be subdivided into five classes i. ii. iii. iv. v. **THE VERTEBRATES (PHYLUM CHORDATA)** All vertebrates have the following features: a. b. c. d. e. f. g. h. i. The phylum Chordata (animals with notochord) can be subdivided into five classes. These include **a. Class Pisces (Tilapia, Shark, Dogfish)** - - - - - - - **b. Class Amphibians (Toad, Frog, Newt)** - - - - - - - **c. Class Reptilia (Lizards, Snakes, Crocodiles etc)** - - - - - - **d. Class Aves (Birds)** - - - - - - - **e. Class Mammalia (Rats, Bats, Dogs, Whales, Monkey, Kangaroos, Man etc)** - They are warm-blooded - They have skin covered with hair. - They possess heterodont teeth i.e. different sets of teeth. - They have a well-developed brain - They give birth to their young ones alive (viviparous) - They use lungs for gaseous exchange. - They have four chambered hearts **VIRUS** Virus are noncellular, microscopic infectious particles and have the ability to replicate inside living cells. It consists of a central core of either DNA or RNA (genome) surrounded by a protein coat (capsid). From a biological point of view, virus cannot be classified as a living thing or a non-living-thing because the exhibit features of both living things and non-living things. For instance, a virus cannot replicate itself outside the host cell. This is because viruses lack the required cellular machinery. Therefore, it enters and attaches itself to a specific host cell, injects its genetic material, reproduces by using the host genetic material and finally the host cell splits open, releasing the new viruses. Viruses can also be crystallized, which no other living organisms can do. It is these factors that lead to viruses being classified in the grey area -- between the living and non-living. **Structure and Function of Viruses** Viruses are tiny and smaller in its size, ranging between 30-50 nm. They usually lack a cell wall but are surrounded by a protective protein coating called the capsid. They contain either RNA or DNA as the genetic material Viruses mainly depend on a host to deliver the complex metabolic machinery of prokaryotic or [**eukaryotic cells**](https://byjus.com/biology/eukaryotic-cells/) for propagation. The main task of the virus is to carry its DNA or RNA genome to the host cell, which then can be transcribed by the host cell. **Bacteriophage and HIV** These microbes belong to the family viridae and genus virus.  Viruses could not be placed in any of the kingdoms because they are practically neither living nor dead. The term virus was coined by the Dutch microbiologist, Martinus Willem Beijerinck in the year 1897. It is derived from Latin, which means poison or venomous substance. The study of viruses is called as virology. **Properties of Viruses** 1. They are non-cellular organisms, which is enclosed in a protective envelope. 2. The presence of spikes helps in attaching the viruses to the host cell. 3. These viruses do not grow, neither respire nor metabolize, but they reproduce. 4. They are surrounded by a protein coat -- capsid and have a nucleic acid core comprising DNA or RNA. 5. They are considered both as living and non-living things. These viruses are inactive when they are present outside of host cells, but become active within host cells. These viruses cause several infections and reproduce within the host cell by using the enzymes and raw materials. **WEEKEND ASSIGNMENT** 1. The feature that distinguishes a toad from a fish is the absence of A. scales B. lungs C. tail D. paired appendages 2. Some of the features of an animal are scales, teeth, nails and backbone. The animal is likely to be A. bird B. lizard C. toad D. rat 3. Which of the following animal is cold blooded? A. cat B. Lizard C. Whales D. Bird 4. A peculiar characteristic of mammals is that they A. have teeth B. are warm blooded C. have sebaceous gland D. have lungs 5. The third level of organization of life is A. cell B. tissue C. system D. organs 6. Angiosperms and gymnosperms belong to the plant group known as A. scizophyta B. bryophyta C. pteridophyta D. spermatophyte 7. Sting cells are normally found in A. Flatworms B. Hydra C. Snails D. Paramecium 8. Which of the following are differentiated into true roots, stems and leaves? A. Schizophyta B. Bryophyta C. Pteridophyta D. Algae 9. Each of the following is an arthropod EXCEPT A. crab B. millipede C. spider D. snail 10. In which of the following groups of animals are flagella and cilia found A. Flatworms B. Protozoa C. Nematodes D. Coelenterates WEEK FIVE THE CELLL **DEFINITION AND FORMS OF CELLULAR EXISTENCE** The cell is the simplest, smallest, basic, structural and functional unit of life. The cell can carry out all life activities such as growth, respiration e. t. c. Cells can exist in various forms which include a. **As an Independent Organism** e. g. Amoeba, Chlamydomonas, Chlorella, Euglena i. **Amoeba** (*Amoeba proteus)* Amoeba is a unicellular animal like protest and the simplest organism with heterotrophic mode of feeding. It is shapeless. It digests its complex food with its food vacuole. The undigested food materials are got rid of with excess water through its contractile vacuole. Amoeba moves about and captures its food with the aid of its pseudopodia (''false fe**et**''). At maximum growth, amoeba reproduces asexually by dividing into two daughter cells (binary fission) ii. **Euglena (***[Euglena viridis)]* *[Euglena viridis]* is a protist that has both plant and animal features. As a plant, it has chloroplasts (star shaped) for photosynthesis, pyrenoid for starch storage and paramylon granules (form in which starch is stored). As an animal, it has no cellulose cell wall, but a plasma membrane called pellicle, a gullet, eye spot, contractile vacuole and flagellum for movement. b. **In colonial forms** e. g. Volvox, Sponges, Pandorina **Volvox** Volvox is made up of several [Chlamydomonas-] like cells which are arranged in angular layer to form a hollow ball-like structure. The cells are connected by cytoplasm strands. The cell of Volvox moves about through the beating of the flagella. Most cells of Volvox lose their ability to reproduce. Only a few of them can reproduce to form two daughter cells c. **In filamentous forms** e. g. Spirogyra, Oscillatoria, Oedogonium **Spirogyra** Spirogyra is a filament of identical cells which are joined end to end without branching. Each cell of spirogyra carries out its function independent of another cell. Spirogyra has spirally arranged chloroplast for photosynthesis. The filament grows indefinitely. The break-off cells from the filament have the ability to reproduce asexually to form a new filament. Spirogyra also has ability to reproduce sexually. d. **As a part of multicellular organisms** A multicellular organism is made up of interdependent cells carrying out several special functions. The cells of the multicellular organisms are arranged to perform similar functions and then form tissues. A group of specialized tissues performing similar function forms an organ. Organs are further organized to carry out special functions in form of system or organ system. Ultimately, the interdependent biological system results in the complex multicellular organisms. **CELL STRUCTURES AND THEIR FUNCTIONS** The study of a cell is called cytology. A cell consists of a living material called protoplasm, which is surrounded by a membrane called plasma membrane. In plants, a cell wall (non-living part) is also present surrounding the plasma membrane. The protoplasm is made up of two major parts: - Cytoplasm - Nucleus The cytoplasm contains cell organelles or inclusions, which are cellular structures with specific functions. The cells which contain a nucleus and organelles are called eukaryotic cells. These show a high level of cellular organization. However, some cells lack definite nucleus and organelles. In such cells (prokaryotic cells e.g. bacteria), materials containing instructions for growth and development are found in a particular part of the cell and so are not enclosed in any membrane. Nucleus is the largest cellular organelle enclosed by a double-layered nuclear membrane with many pores. It contains chromosomes and nucleolus which are rich in proteins and nucleic acids. The nucleus performs the following functions: a. Exchange of materials between the nucleus and the cytoplasm through the nuclear pores. b. Storage of hereditary information by the chromosomes c. Control centre of cellular activities **CELL COMPONENTS AND THEIR FUNCTIONS** +-----------------------------------+-----------------------------------+ | **Cell components** | **Functions** | +===================================+===================================+ | i. Mitochondrion | Site of cellular respiration for | | | energy production. It consists of | | | enzymes and DNA. The enzymes | | | convert ADP to ATP. | +-----------------------------------+-----------------------------------+ | ii. Vacuole | It contains cell sap mineral salt | | | and sugar. It acts as an | | | osmoregulator (removing excess | | | water). | +-----------------------------------+-----------------------------------+ | iii. Endoplasmic reticulum (ER) | Aids transport of materials | | | within the cytoplasm. Rough | | | endoplasmic reticulum (RER) | | | (having ribosome attached) is for | | | protein synthesis and | | | transportation. Smooth | | | endoplasmic reticulum (SER) is | | | for lipids and steroids synthesis | | | and transportation. | +-----------------------------------+-----------------------------------+ | iv. Golgi bodies/apparatus | For synthesis, packaging and | | | distribution of materials. | +-----------------------------------+-----------------------------------+ | v. Chloroplast | Contains chlorophyll for | | | photosynthesis in green plants | +-----------------------------------+-----------------------------------+ | vi. Lysosomes | Site for production of enzymes | | | for respiration and destruction | | | of worn-out cells. | +-----------------------------------+-----------------------------------+ | vii. Ribosome | For protein synthesis | +-----------------------------------+-----------------------------------+ | viii. Centrioles | Active in cell division by | | | producing spindle fibres to which | | | chromosomes are attached. | | | (present only in animal cell). | +-----------------------------------+-----------------------------------+ | ix. Cell plasma) membrane | This is flexible and selectively | | | permeable. It controls the | | | materials entering or leaving the | | | cell | +-----------------------------------+-----------------------------------+ | x. Cell wall | It protects the cell, thus | | | providing mechanical support in | | | plants. | +-----------------------------------+-----------------------------------+ **SIMILARITIES BETWEEN PLANT AND ANIMAL CELLS** Both plant and animal cells have the following in common (a)Nucleus (b) Golgi bodies (c) mitochondria (d) cytoplasm (e) chromosomes (f) endoplasmic reticulum (g) nucleolus (h) ribosomes (i) lysosomes (j) cell membrane **DIFFERENCES BETWEEN PLANT AND ANIMAL CELL** **PLANT CELL** **ANIMAL CELL** --- --------------------------------------------- --------------------------------------------------------- 1 Has chloroplast No chloroplast 2 Rectangular and definite in shape Usually spherical or shapeless 3 Has rigid cellulose cell wall No cell wall 4 Centrioles are absent Centrioles are present 5 Cytoplasm is less dense Cytoplasm is dense 6 Starch granules present Glycogen granules present 7 Presence of large central permanent vacuole Vacuoles are absent or small and temporary when present **CELL THEORY** This is the summary of research efforts of many scientists like Robert Hooke, Matthias Schleiden and Theodore Schwann in 1838 and 1839 likewise, Rudolf Virchow (1855) etc. The cell theory states that: a. All living organisms are composed of one or more cells. b. The cell is the structural and functional unit of all living organisms i.e. the basic organizational unit of life. c. All existing cells come from pre-existing ones. **WEEKEND ASSIGNMENT** 1. A cell that is capable of self-existence is a/an A. amoeba B. ovum C. amoeba D. onion epidermal cell 2. Which of these organelles is common to both plants and animals' cells? A. Chloroplast B. Centriole C. Mitochondrion D. Pyrenoid 3. Which scientist did not contribute to the formation of cell theory? A. Isaac Newton B. Robert Hooke C. Matthias Schliemann D. Theodor Schwann 4. The organelle which is contractile in function in Euglena is the A. eye spot B. gullet C. myoneme D. paramylon 5. Which of the following cells are not regarded as specialized? A. Muscle cells B. Root tip cells C. Somatic cells D. Sperm cells WEEK SIX **CELL AND ITS ENVIRONMENT** **Environment/Nature and State of Matter** Living cells are known to be surrounded by a watery environment. This may include: Fresh/salt water in which the unicellular organisms live, Intercellular fluid that bath the bodies of cells of higher animals. The nature of states of matter makes diffusion and osmosis possible. **DIFFUSION** Diffusion is the process by which molecules of substances move from a region of higher concentration to a region of lower concentration (through the medium of air or liquid) until equilibrium is reached. The difference in the concentration of the substances in the two regions before diffusion occurs is called concentration/diffusion gradient. Diffusion is also observed in the --------------------------------- - spread of odour of perfume - insecticide which is used to spray a room and also in the release of gases from the anus - a tea bag immersed in a cup of hot water will diffuse into the water and change its colour, - Sugar gets dissolved evenly and sweetens the water without having to stir it. - As we light the incense stick, its smoke gets diffused into the air and spreads throughout the room. Diffusion is affected by the following factors a. Change in temperature: The higher the temperature, the faster the rate of diffusion b. Molecular size: Diffusion increases with decreasing size of molecule c. State of matter Diffusion of gases is much faster than that of liquid. d. Difference in concentration: The greater the difference in concentration of molecules, the faster the rate of diffusion. **IMPORTANCE OF DIFFUSION IN LIVING ORGANISMS** a. The movement of carbon (IV) oxide through the stomata of leaves during the process of photosynthesis. b. Movement of oxygen into the leaves during respiration. c. Movement of water vapour out of the leaf in the process of transpiration d. Gaseous exchange in the lungs of mammals e. Intake of oxygen and nutrients and the removal of waste product by the foetus from its mother through placenta. f. Movement of digested and soluble food from the villi of small intestine to the blood stream. g. Removal of waste product in small organisms such as amoeba **OSMOSIS** Osmosis can be defined as the movement of water molecules from a region of lower concentration to the region of higher concentration through a semi-permeable membrane. A permeable membrane allows molecules to pass through it freely while a selectively permeable membrane only allows certain molecules to pass through it. Osmosis will only occur when a semi-permeable membrane separates weak and strong solutions. Living cells may find themselves in any of the following situation: - When the fluid surrounding the cell is more concentrated than the inside of the cell, the surrounding fluid is said to be **hypertonic** to the content of the cells. A net movement of water molecules out of the cell into the surrounding fluid occurs and causes the cell to shrink. This process is known as [Exosmosis.] - When the fluid surrounding the cell is less concentrated than the inside of the cell, the surrounding fluid is said to be **hypotonic** to the content of the cell. There is a net movement of water molecules from the surrounding fluid into the cells. This process is known as [Endosmosis.] - When the surrounding fluid and the cell concentration have the same concentration, they are said to be **Isotonic**. A net movement of water molecule in and out of the cells does not occur. Examples of Osmosis. - The absorption of water from the soil is due to osmosis. The plant roots have a higher concentration than the soil. Therefore, the water flows into the roots. - The guard cells of the plants are also affected by osmosis. When the plant cells are filled with water, the guard cells swell up, and the stomata open. - If a freshwater or saltwater fish is placed in the water with different salt concentrations, the fish dies due to the entry or exit of water in the cells of the fish. - Humans suffering from cholera are also affected by osmosis. The bacteria that overpopulate the intestines reverse the flow of absorption and do not allow water to be absorbed by the intestines, which results in dehydration. - When the fingers are placed in water for a longer period of time, they become pruney due to the flow of water inside the cells. **IMPORTANCE OF OSMOSIS** a. It aids the absorption of water from the soil into the vacuole of the root hairs b. It aids the movement of water from the root hairs into the cells of other parts of the plants c. It helps to control the opening and closing of the stomata pores d. It gives turgidity to the plant cells i.e. it gives support. e. It aids intracellular movement of water in animals f. It aids reabsorption of water from the kidney tubules into the blood g. It causes haemolysis of red blood cells. **Difference between Osmosis and Diffusion** **Osmosis** **Diffusion** ---- --------------------------------------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------- 1 It is limited only to the liquid medium. Occurs in liquid, gas and even solids. 2 Requires a semipermeable membrane. Does not require a semipermeable membrane. 3 Depends on the number of solute particles dissolved in the solvent. Depends on the presence of other particles. 4 Requires water for the movement of particles. Does not require water for the movement of particles. 5 Only the solvent molecules can diffuse. Both the molecules of solute and solvent can diffuse. 6 The flow of particles occurs only in one direction. The flow of particles occurs in all the directions. 7 Occurs only between similar types of solutions. Occurs between the similar and dissimilar types of solutions. 8 It involves the movement of only solvent molecules from one side to the other. It involves the movement of all the particles from one region to the other. 9 The concentration of the solvent does not become equal on both sides of the membrane. The concentration of the diffusion substance equalizes to fill the available space. 10 Only water or another solvent moves from a region of high energy or concentration to a region of lower energy or concentration. Any type of substance moves from area of highest energy or concentration to region of lowest energy or concentration. 11 Not associated with uptake of minerals and nutrients. It helps in the uptake of minerals and nutrients **WEEKEND ASSIGNMENT** 1. Which structures must be present in a cell for osmosis to take place? A. cell (sap) vacuole and cell wall B. cell wall and cell membrane C. chloroplast and cytoplasm D. cytoplasm and cell membrane 2. The scent from a bunch of flowers spreads throughout a room. How does the scent spread? A. by conduction B. by diffusion C. by osmosis D. by transpiration 3. Which of the following environmental conditions is ideal for plant cells to remain turgid? A. Hot, dry weather B. Cold, dry weather C. Cool, humid weather D. Windy weather 4. Osmosis occurs through a membrane that can be \_\_\_\_\_ permeable A. Fully B. Slowly C. Differentially D. freely 5. Which of the following processes takes place when a plant cell is put in a hypotonic solution? (a) water moves into the cell and the cell bursts (b) water leaves the cell and the cell becomes flabby (c) water moves into the cell and the cell becomes turgid (d) the cell becomes plasmolysed **WEEK EIGHT** **CELL AND ITS ENVIRONMENT II** **PLASMOLYSIS** Plasmolysis is the shrinkage of the vacuole and pulling away of the cytoplasmic lining from the cell wall when placed in hypertonic solution. When a plant cell is surrounded or place in hypertonic solution, exosmosis will occur i.e. water moves out of the cell into the surrounding fluid leading to the shrinking of the vacuole and pulling the cytoplasm away from the cell wall. When cells are plasmolysed, it eventually leads to wilting or death of the plant. **HAEMOLYSIS** This is the process whereby red blood cells (corpuscles) splits and burst as a result of too much water passing into it. Red blood cells and blood plasma are always isotonic i.e. having the same osmotic concentration, if for some reasons the concentration of blood plasma falls; endosmosis will occur (water moves from the plasma into the red blood cells). Continuous absorption of water into the cell makes it turgid and when fully stretched, it burst. **TURGIDITY AND BIOLOGY SIGNIFICANCE** Turgidity is the condition in which cell absorbs plenty of water up to a point where the cell is fully stretched. Turgidity is observed in plants where it makes them erect and support the stem, leaves and flowers. **FLACCIDITY AND BIOLOGICAL SIGNIFICANCE** Flaccidity is the condition in which plant lose water to their surrounding faster than they can absorb. When a plant loses more water than it absorbs, it becomes flaccid. Flaccidity usually occurs when there is no water in the soil, especially where there is drought. The continuous loss of water can result in the death of the plant. **CRENATION** **This is referred to as the formation of an abnormal notched surfaces on cells as a result of water loss through osmosis.** **Cells are usually in an isotonic solution inside the body, meaning that there is the same concentration of solute and water both inside and outside the cells. This equilibrium allows the cells to keep their shape, with water moving in and out at a constant rate and maintaining the same osmotic pressure across the semipermeable membrane. However, when this equilibrium is disrupted by the presence of a higher concentration of solute in the solution, it creates a hypertonic environment, which causes the intracellular water to diffuse out. The cells start to shrivel and form abnormal spikes and notches on the cell membrane. This process is called crenation.** **Examples of Crenation** - **Red Blood Cell Crenation** **Red blood cells are prone to undergoing crenation as either a response to ionic changes in the blood or abnormalities in the cell membrane, disrupting the cell's ability to maintain an isotonic state.** - **Food pickling is an example of crenation occurring in everyday life. Vegetables such as cucumbers are placed in acidic solutions to pickle, causing water to diffuse out and the characteristic shrinkage of the crenation process.** **ACTIVE TRANSPORT** Active Transport is defined as a process that involves the movement of molecules from a region of lower concentration to a region of higher concentration against a gradient or an obstacle with the use of external energy During the process of active transport, a protein pump makes use of stored energy in the form of ATP, to move molecules **Active Transport in Plants** Like humans and animals, plants also require transport systems which are mainly involved in the transport of materials, such as water, minerals, and necessary nutrients to all parts of the plant for its survival. Active transport is a mode of transportation in plants, which uses stored energy to move the particles against the concentration gradient. In a [plant cell](https://byjus.com/biology/plant-cell/), it takes place in the root cells by absorbing water and minerals. Active transport always leads to accumulation of molecules are ions towards one side of the membrane. This mode of transportation in plants is carried out by membrane proteins and transports the substance from the lower concentration to higher concentration. **Examples of Active Transport** - Some of the best examples of active transport include: - Phagocytosis of bacteria by Macrophages. - Movement of Ca^2+ ^ions out of cardiac muscle cells. - Transportation of amino acids across the intestinal lining in the human gut. - Secretion of proteins like enzymes, peptide hormones, and antibodies from different cells. - Functioning of the White Blood Cells by protecting our body by attacking diseases causing microbes and other foreign invaders. **WEEK NINE** **PROPERTIES AND FUNCTIONS OF CELL** **MINERAL REQUIREMENTS OF PLANTS** Mineral elements are required for normal growth and development of green plants. In addition to Carbon, oxygen, and hydrogen, other mineral requirements are discussed below. Unlike glucose and other carbohydrates made from carbon dioxide and water by green plants, mineral salts are obtained from the soil. **Macronutrients** These are mineral nutrients that are required by plants in large quantities. They include the following; +-----------------------+-----------------------+-----------------------+ | **Macronutrients** | **Importance** | **Deficiency** | +=======================+=======================+=======================+ | Nitrogen (N) | - Protein synthesis | - Stunted growth | | | | and chlorosis | | | - Nucleic acid | | | | synthesis | - Poor flower and | | | | fruit formation | | | - Proper root | | | | development | | | | | | | | - Component of | | | | chlorophyll and | | | | enzymes | | +-----------------------+-----------------------+-----------------------+ | Phosphorus (P) | - Formation of | - Poor root | | | co-enzymes and | development | | | proteins | | | | | - Stunted growth | | | - Formation of DNA, | | | | RNA and ATP | | | | | | | | - Stem, root, fruit | | | | and seeds | | | | formation | | +-----------------------+-----------------------+-----------------------+ | Sulphur (S) | - Formation of | - Stunted growth | | | certain proteins | | | | in the protoplasm | - Chlorosis | +-----------------------+-----------------------+-----------------------+ | Potassium (K) | - Protein synthesis | - Premature death | | | | | | | - Cell membrane | - Leaf margin turns | | | formation | yellow and brown | | | | | | | - Activates | | | | respiration and | | | | photosynthesis | | | | | | | | - Crop maturation | | +-----------------------+-----------------------+-----------------------+ | Magnesium (Mg) | - Formation of | - Poor growth | | | chlorophyll | | | | | - Chlorosis | | | - Helps in cell | | | | division | | | | | | | | - Activates many | | | | co-enzymes | | +-----------------------+-----------------------+-----------------------+ | Calcium (Ca) | - Formation of cell | - Death of terminal | | | wall | buds | | | | | | | - Helps in storage | - Roots develops | | | of protein and | poorly | | | carbohydrates in | | | | roots and tubers | - Stunted growth | | | | | | | - Gives rigidity to | | | | plants | | +-----------------------+-----------------------+-----------------------+ | Iron (Fe) | - Formation of | - Poor growth | | | chlorophyll | | | | | - Yellowing of | | | - Formation of | leaves | | | protein | | +-----------------------+-----------------------+-----------------------+ **MICRO NUTRIENTS** These are mineral nutrients required by plants in small quantities. They include the following; +-----------------------+-----------------------+-----------------------+ | **Micro nutrients** | **Importance** | **Deficiency** | +=======================+=======================+=======================+ | Zinc (Zn) | - Necessary for the | - Poor growth | | | synthesis of the | | | | starting material | | | | of auxin | | | | | | | | - Activates some | | | | enzymes | | | | | | | | - Plays a role in | | | | the synthesis of | | | | protein | | +-----------------------+-----------------------+-----------------------+ | Copper (Cu) | - Component of | - Poor growth | | | respiratory | | | | enzymes | | +-----------------------+-----------------------+-----------------------+ | Manganese (Mn) | - Activates some | - Death of shoot | | | enzymes involved | | | | in cellular | | | | respiration | | +-----------------------+-----------------------+-----------------------+ | Boron (B) | - Translocation of | - Poor growth of | | | sugar and calcium | pollen tubes | +-----------------------+-----------------------+-----------------------+ | Chlorine (Cl) | - Necessary for | - Affects growth | | | oxygen release | | | | during | | | | photosynthesis | | +-----------------------+-----------------------+-----------------------+ | Molybdenum (Mb) | - Necessary for | - Poor growth | | | nitrogen fixation | | | | by | | | | nitrogen-fixing | | | | bacteria | | | | | | | | - Activates the | | | | enzyme that | | | | reduces nitrate | | | | to nitrite | | +-----------------------+-----------------------+-----------------------+ **HETEROTROPHIC NUTRITION** This is a type of nutrition in which organisms depend directly or indirectly on autotrophs for food. All animals, fungi, protozoa and some bacteria belong to this group and they are referred to as heterotrophs **HETEROTROPHIC MODES OF FEEDING** \(a) **Holozoic Nutrition** \(b) **Parasitic Nutrition** \(c) **Saprophytic Nutrition** \(d) **Symbiotic Nutrition** \(e) **Carnivorous / Insectivorous Nutrition** **WEEK TEN** **PROPERTIES AND SIGNIFICANCE OF CELL** **AUTOTROPHIC NUTRITION** Plants are referred to as autotrophs, i.e. being able to manufacture their food (Organic compound from inorganic materials such as water, carbon dioxide). Autotrophs generally have two modes of nutrition which are chemosynthesis and photosynthesis (holophytic). **MODES OF AUTOTROPHIC NUTRITION** **PHOTOSYNTHESIS** This is the process by which green plants synthesize organic compounds from inorganic raw materials in the presence of chlorophyll and light. 6C0~2~ + 6H20 C~6~H~12~O~6~ + 60~2~ Inorganic materials Chlorophyll Organic compound By product The main product of photosynthesis is sugar (carbohydrate) while the oxygen given up is a by-product which is released into the atmosphere. **MECHANISM OF PHOTOSYNTHESIS** Photosynthesis involves two stages a. **Light reaction phase**: it takes place during the day. It involves four stages - **Activation of chlorophyll**: the chlorophyll trap light energy from the sun and get energized - **Photolysis of water**: The energy that is trapped is used to split water molecules H~2~O H^+^ + OH^\--^ OH^−^ H~2~O - **Hydrogen transfer by NADP** (NADP + H^+^ NADPH~2~). The H+ gotten from the hydrolysis of water is carried and transported by NADP to the dark reaction stage. - **Formation of ATP from ADP:** this takes place to store energy for the dark phase reaction During this phase, the hydrogen ion that was caried by NADP combines chemically with carbon dioxide molecule chemically the control of enzymes to form the simple sugar. 4H^+^ + CO~2~ CH~2~O + H~2~O Simple sugar forms the chemical structural basis for other carbohydrates, lipids and proteins. **IMPORTANCE OF PHOTOSYTHESIS** The enzyme-rich product of photosynthesis is used by plants and animals in the following ways: 1. 2. 3. 4. 5. **EXPERIMENTS IN PHOTOSYNTHESIS** The occurrence of photosynthesis in plants can be shown by experiments. Experiment is carried out to show the importance of carbon dioxide, sunlight energy, chlorophyll. There is the need to prove that oxygen is given off. **Testing a leaf for starch** The leaf to be tested is detached from the plant and put into boiling water for about 10-15mins. This kills the protoplasm of the leaf and makes iodine to easily penetrate the starch granules. The boiled leaf is put into alcohol. This is to extract the chlorophyll from the leaf. The leaf becomes white and brittle. It is then dipped into hot water to soften the tissues. The bleached leaf is spread on a white tile a few drop of iodine is added to it. The colour of the leaf is then tested against a light source. If the leaf appears blue-black in colour, it contains starch, if the colour is yellowish-brown, it contains no starch **To show that light is necessary for photosynthesis**. Two potted plants are kept in darkness or 48-72 hours to make it starch-free or carry out the above experiment in destarching leaves. One of the potted plants remains in darkness while the other is exposed to sunlight for 4 hours. Leaves from the potted plants exposed to light turns blue-black when tested with iodine while the leaves kept in darkness remains brown. This shows that without light, photosynthesis cannot take place **To show that oxygen is given off as a by-product of photosynthesis** In this experiment, gas is collected in the test tube placed over the green plant and tested with a glowing splint. If it re-kindles the glowing splint, it shows that oxygen is given off because it is the only colourless gas that re-kindles a glowing splint. **Experiment to show that chlorophyll is necessary for photosynthesis** The same experiment in destarching a leaf is carried out here **Experiment to show that carbon (IV) oxide is necessary for photosynthesis** In this experiment, the leaves are destarched. Two potted plants are placed in two bell jars labelled A and B. Each of the potted plants is place on a Vaseline glass plate to prevent air containing carbon (iv) oxide from leaking into the bell jar. A dish containing lime water is placed in one of the jars to absorb carbon (iv) oxide. Both jars are left exposed to sunlight for about 4 hours and tested for starch. **CONDITIONS (FACTORS) FOR PHOTOSYNTHESIS** The two major conditions necessary for photosynthesis are a. b. **CHEMOSYNTHESIS** This is the process by which non-green plants (e.g. [ ] Nitrosomonas, [ ] Nitrobacter, iron bacteria etc) synthesize organic compound from inorganic materials (carbon dioxide and water). The energy used in this process is gotten from inorganic substances such as ammonia and by hydrogen sulphite. H~2~S + O~2~ S + H~2~O + Chemical energy H~2~O + CO~2~ CH~2~O **WEEKEND ASSIGNMENT** 1. The main photosynthetic organ of plant is \-\-\-\-- (a) leaf (b) seed (c) fruit (d) root 2. Which of these is not a macro element needed for plant growth? A. potassium B. magnesium C. sodium D. molybdenum 3. Yellowing of leaves is a symptom associated with deficiency of A. iron, calcium and magnesium B. nitrogen, sulphur and potassium C. sulphur, phosphorus and iron D. iron, magnesium and nitrogen 4. Trace elements are required by plants mainly for the A. formation of pigments and enzymes B. production of energy and hormones C. manufacture of carbohydrates D. manufacture of protein 5. The dark phase of photosynthesis occurs in the \-\-\-\-\-\-- of chloroplast (a) cells (b) tissues (c) fluid (d) stroma **WEEK ELEVEN** **NUTRITION IN ANIMALS** **ANIMAL NUTRITION** Animals generally cannot manufacture their food. Rather, they depend directly or indirectly on plants for their food. Hence, they are called heterotrophs. Based on their food types, animals are grouped into three: a. Carnivores which feed on flesh or other animals e.g. lion. b. Herbivores which feed on plants e.g. goat. c. Omnivores, which feed on both plants and animals e.g. man. **CLASSES OF FOOD SUBTANNCES** Foods eaten by animals are generally classified into seven i.e. **CARBOHYDRATE** This is got from food like bread, yam rice etc. It basically consists of carbon, hydrogen and oxygen. Carbohydrates are of three types: a. Monosaccharides (Simple sugars) which include glucose, fructose and galactose b. Disaccharides (Reducing sugars) which include maltose, sucrose and lactose. c. Polysaccharides (Complex sugars) e.g. starch, cellulose, chitin under the action of enzymes like ptyalin, maltase, lactase etc, and starch yields glucose as product of its digestion. Excess carbohydrate is stored in the body in form of glycogen in muscles and liver. This can be reconverted to glucose during starvation. **Importance of Carbohydrates** a. It gives animals energy. b. It provides heat needed to maintain body temperature c. It can be used for lubrication e.g. mucus. d. It provides the body with a strong framework e.g. exoskeleton in insects. **PROTEINS** These are complex molecules made up of smaller units called amino acids. Protein is made up of carbon, hydrogen, oxygen, nitrogen and sometimes phosphorus and sulphur. Food like egg, meat, fish, beans etc gives you protein. Proteins are broken down into amino acids under the action of enzymes like pepsin, rennin, trypsin and erepsin. **Importance of Proteins** a. Growth in young ones. b. Repair of worn-out tissues. c. Production of enzymes. d. Production of hormones. e. It supports reproduction. f. It is for tissue and all formation i.e. body building. **FATS & OIL (LIPIDS)** Fats are solid lipids at room temperature while oil is the liquid. Fat and oil consist of carbon, hydrogen and little oxygen. When digested, it gives rise to fatty acids and glycerol. Foods like palm oil, groundnut, Soya beans give fat and oil. Lipids are broken down to fatty acids and glycerol when acted upon by lipase enzymes. **Importance of Fat and Oil** a. It gives you energy even more than carbohydrates b. It supplies essential fatty acids to the body. c. It helps in the maintenance of body temperature d. It provides the body with fat-soluble vitamins **MINERAL SALT** These are usually taken in very small quantity in the food we eat except sodium chloride (table salt) and iron tablet, which can be taken directly by man. The lack of these salts results in nutritional deficiency. The minerals include calcium, magnesium, potassium, Phosphorus, sulphur, chlorine, iron, Iodine, fluorine, manganese, copper, cobalt and sodium. **Importance of Mineral Salts** a. Regulate body metabolisms b. Components of bones and teeth c. Aids blood formation d. Control chemical reactions in the body e. Aids the formation of enzymes and pigments **VITAMINS** These are organic food substances needed by man and other animals in small quantity for normal growth and development. Lack of or inadequate supply of any of these vitamins results in nutritional deficiency. Vitamins can be grouped into two: a. Water-soluble vitamins b. Fat -- soluble vitamins The water-soluble vitamins include: vitamins B complex and vitamin C. Vitamin B complex include vitamin, B~2~, B~3~, B~5~, B~6~ and B~12~ Fat-soluble vitamins include vitamins A, D, E and K. **VITAMINS, SOURCE FUNCTIONS AND DEFICIENCY SYMPTOMS** **Vitamins** **Sources** **Functions** **Deficiency** -------------- ----------------------------------------------------- -------------------------------------------------------------------------------------- ------------------------------------------------ A Liver, eggs, fish, milk, palm oil, fish Vegetables. Normal growth of body cells and skin, Proper vision of the eye Night blindness, Reduced resistance to disease B~1~ Yeast, milk, beans, ground nut Normal growth, Proper functioning of heart and nervous system Beri-beri (wasting of Muscles), paralysis B~2~ Yeast, soya beans, egg, milk, green vegetables Growth, proper functioning of the eye, Formation of co-enzymes Slow growth, Dermatitis B~3~ Yeast, beans, milk, vegetables Formation of co-enzymes for cellular respiration Pellagra B~12~ Kidney, liver, fish, Milk Formation of red blood cells Pernicious, Anaemia C Fresh fruits and green vegetables Aids wound healing, helps to resist infection Scurvy D Fish, milk, egg, Liver, sun's ultraviolet rays Increases absorption of calcium and phosphorus, Calcification and hardening of bones Ricket; Osteomalacia E Green vegetables, Egg, butter, liver Promotion of fertility in animals Sterility, Premature abortion K Fresh green vegetables, liver Aids blood clotting Haemorrhage **WATER** This is of utmost importance to all organisms and it is made up of two elements, hydrogen and oxygen. Water can be got from food, river, stream, pond etc. water makes up 75% of the human body. ###### **IMPORTANCE OF WATER** a. Metabolic activities of the body of animals. b. Digestion of food. c. Maintenance of body temperature. d. It is a medium of transportation for all nutrients. e. It helps to maintain the osmotic balance in body tissues. f. It helps in excretion of metabolic waste from the body e.g urine. **ROUGHAGES** These are indigestible fibrous materials got from vegetables, fruit, carbohydrates and proteins. Roughages aid digestion, lack of which can lead to constipation. **BALANCED DIET** Balanced diet is a diet containing a correct proportion of all the food substances. On a general note, a balanced diet contains 15% protein, 15% fat and oil, 10% vitamin, minerals and water and 60% carbohydrate. Once a food is taken at these proportions, there is a normal growth and development in the body. **FUNCTIONS OF BALANCED DIET** a. It makes us healthy. b. It gives ability to be resistant to diseases c. It makes available energy needed to carry out all biological activities. d. It prevents malnutrition and deficiency symptoms. For examples, a diet that lacks protein results into a nutritional disease called [kwashiorkor] in children. The protein deficient child has the following features a. Retarded growth. b. Loss of weight. c. Swollen legs effect (oedema). d. Cracked / split stomach and thin legs etc. **DIGESTIVE ENZYMES** Enzymes are organic (protein) catalysts produced by living cells which help to speed up and slow down the rate of chemical reactions. Digestive enzymes aid the breaking down of complex food substances into simple, soluble and diffusible form. Enzymes have the following characteristics. a. Enzymes are soluble b. Enzymes are protein c. They are specific in their actions d. Enzymes are sensitive to temperature i. e. they work best between 35^o^C to 40^o^C e. Enzymes are PH specific f. Enzymes brings about reversible reactions g. Enzymes needs co-enzymes to activate them and can be inactivated by inhibitors such as mercury and cyanide **CLASSES AND FUNCTIONS OF ENZYMES** Digestive enzymes are classified based on the type of food they act upon. These include a. Proteases e. g. pepsin, rennin, trypsin and erepsin. They act on protein. b. Amylases e. g. ptyalin, lactase, maltase, sucrose. They act on carbohydrates c. Lipases which act on lipids (fats and oils) **WEEKEND ASSIGNMENT** 1. Vitamins are organic food substances required by animals in \_\_\_\_ quantity A. no B. small C. large D. high 2. The following except one is fat-soluble vitamins A. vitamin A B. Vitamin B C. Vitamin K D. Vitamin E 3. One of the following food substances is indigestible in man A. protein B. lipids C. roughages D. carbohydrates 4. The highest source of energy is from \_\_\_\_\_\_\_ A. carbohydrate B. proteins C. lipids D. vitamins 5. Rickets (poor bone formation) in children is a deficiency symptom of \_\_\_\_ A. potassium B. calcium C. chlorine D. manganese. **WEEK TWELVE** **GROWTH** **GROWTH** Growth is the irreversible increase in dry mass, size and complexity of an organism brought about by the synthesis of new protoplasm. For growth to be effective, building up of materials (anabolism) must exceed the rate of breaking down (catabolism). **BASIS OF GROWTH** The basis of growth involves three major phases i.e. cell division (mitosis), cell enlargement and cell differentiation. Life begins as a single fertilized cell, continuous as the cell divides into two daughter cells then into four and so on. After cell division, the daughter cells increase in mass and size (enlargement). Eventually, each cell develops into a special type of cell (specialization) by changing its shape and structure to carry out a particular function. Most specialized cells, at maturity lose their ability to divide. **TYPES OF CELL DIVISION** There are two types of cell division: (a) Mitosis (b) Meiosis **Mitosis** Mitosis is a cell division to produce two daughter cells with the same number of chromosomes and characteristics as those of the parent cell. This cell division takes place only in somatic cells (i.e. body cells that are not involved in the production of gametes) such as skin, bone marrow and meristematic tissues in plants. Mitotic cell division involve five main stages a. Interphase: This is referred to as the resting stage where the chromosomes become elongated and form a network of fine threads called chromatids b. Prophase: in early prophase chromosomes become visible, nucleolus shrinks, centrioles start moving away from each other in opposite direction and the formation of spindle fibres begins. During the late prophase, chromosomes become shorter, thicker and visible. Each chromosome now forms two distinct chromatids joined by a centromere. Nucleolus and nuclear membrane disappear entirely. c. Metaphase: paired chromatids arrange themselves along the equator of the spindle and are attached to the spindle at the centromere. d. Anaphase: sister chromatids separate and start migrating to the opposite poles of the cell and eventually reach the poles. e. Telophase: the cell starts dividing into two by constricting at the equator, nucleolus and nuclear membrane are reform in each daughter cell, spindle fibres degenerates and chromosomes eventually regain their threadlike form **Importance of mitosis** a. It brings about growth, development and specialization especially in multicellular organisms. b. Asexual reproduction binary and multiple fissions in protozoa, budding in yeasts are result of mitosis. c. It ensures the diploid condition of the cells is retained from generation to generation d. It aids the repair of damaged cells **Life processes involved in mitosis** a. Formation of new cells in Malpighian layer of the skin b. Production of red and white blood cells in the bone marrow c. Healing of wounds d. Growth in meristem e. Binary fission **ASPECTS OF GROWTH** Growth varies from one organism to another. To measure growth, the following parameters are used: a. Mass: the dry mass is more accurate and reliable than the wet mass b. Size and length e.g. height of man c. Increase in number of cells e.g. budding in yeast cell **REGIONS OF FASTEST GROWTH IN PLANTS** The regions of fastest growth in plants are the root and stem apices. Since growth in plants is apical, the root and stem apices can be divided into a. Region of cell division (called the apical meristem) brings about primary growth of a plant b. Region of elongation c. Region of cell maturation/specialization **GROWTH CURVE** The growth rate of a living organism is measured using a growth a curve. The growth pattern of man shows a sigmoid curve. The growth pattern consists of three phases: 1. **Lag phase:** This is the initial stage where slow growth is experienced. At this stage, the cell is still accumulating the necessary material to begin the process. 2. **Log or exponential phase:** This is the phase of rapid of rapid growth. 3. **Stationary phase:** This is a stage where no observable growth is experienced. The growth curve of insect is like a step. Each growth phase (instar) is interrupted by a period of moulting (ecdysis) **\ ** **FACTORS AFFECTING GROWTH** a. **External factors** it includes availability of nutrients, humidity, light, temperature, PH and accumulation of metabolic products. b. **Internal factors** are mainly hormones. The two major growth hormones in plant are auxin and gibberellins. In animals, the hormones concerned with growth are secreted by the anterior pituitary gland, thyroid gland and the gonads. Over or under secretion of any of these hormones leads to abnormal growth. **WEEK THIRTEEN** **IRRITABILITY/MOVEMENT** **IRRITABILITY AND TYPES OF RESPONSES** Irritability is the ability of organisms to respond to stimuli. A stimulus is any change in external or internal environmental condition which can bring about a change in the activity of the whole or part of the organism. Response is the term used for the change in activity of the organism. There are three major types of responses, these include tactic, nastic and tropic movements. a. **Taxis Or Tactic Movement:** is a directional movement or response of a whole organism from one place to another in response to external stimuli such as light, temperature, water and certain chemicals. Examples of tactic movement include; - Euglena or Chlamydomonas swimming away from high light intensity (Negative phototaxis). - In a moss plant, sperm swim towards the chemical produced by the egg cell (positive chemotaxis). b. **Nastism Or Nastic Movement:** is a non-directional sleep movement or response of a part of a plant in response to non-directional stimuli such as light intensity, temperature and humidity. Example of nastic movement include; - The folding of the leaflets of mimosa plant when touched. - Closing of the morning glory flower when light intensity is low. c. **Tropism Or Tropic Movement**: is a unilateral growth and directional movement of a part of a plant in response to directional stimuli. These responses are experienced in growth regions (root and shoot apices) and are controlled by certain plant hormones known as auxins. Tropic movement are named according to the stimuli e.g. - Shoots bend towards light (positive phototropism) while roots bend away from light (negative phototropism). - Shoots bend away from gravity (negative geotropism) while roots bend toward gravity (positive geotropism). - Tendrils of climbing plants twine around a support (positive thigmotropism) while root tips grow away from it (negative thigmotropism). Tactic Tropic --- ----------------------------------------- ------------------------------------- 1 It is locomotory response It is growth response 2 Its temporary Its permanent 3 Responses are fast Response are slow 4 Response are not influenced by hormones Response are influenced by hormones Tropic Nastic --- ------------------------------------------------------------ ------------------------------------------------------ 1 Movement is dependent on direction of stimulus Movement is not dependent on direction of stimulus 2 Occurs in most of the plants Occurs in specialized plants 3 It's slow Its fast 4 It's a growth movement It's both growth and non-growth movement 5 Irreversible It is reversible 6 Examples includes gravitropism, hydrotropism, chemotropism Examples includes chemonasty, hydronasty, photonasty **MOVEMENT** Organisms moves from one place to the other in search of food, water, mates and escaping predator or harsh weather conditions. **Cyclosis in Cell** Cyclosis (cytoplasmic streaming) is the mass rotational movement of the cytoplasm and its contents in cells. Cyclosis brings about the transportation of substances from one part of the cell to the other and the exchange of materials between the cell organelles. Cyclosis occur in a. Protozoa like amoeba known as amoeboid movement. b. Chloroplasts of some plants where they move independently to place their broad surface parallel to the surface of the leaf to receive sufficient sunlight for photosynthesis. **ORGANELLES FOR MOVEMENT** a. **Flagella**: they are long whip like projections usually one or two on the cell surface. Flagella are organelles for movement in Euglena, Trypanosome, Spermatozoa, Chlamydomonas etc. b. **Cilia**: They are short hair like structures, numerous and closely packed together on the cell surface. Cilia can be found in paramecium and on cells lining the human wind pipe. **WEEKEND ASSIGNMENT** 1. Growth includes the following processes except A. differentiation B. meiosis C. mitosis D. elongation 2. When the zygote of an organism continues to grow, it produces new cells by A. meiosis B. mitosis C. crossing-over D. gestation 3. The aspect of growth in living organisms include all the following except A. increase in dry weight B. irreversible increase in length C. reversible increase in size D. increase in number of cells 4. The organelle involved in tissue respiration is the A. endoplasmic reticulum B. Golgi body C. mitochondrion D. ribosome 5. In the absence of oxygen, the pyruvic acid produced during glycolysis is converted to CO~2~ and A. water B. glycerol C. ethanol D. citric acid 6. The response shown by the tips of the root and shoot of a plant to the stimulus of gravity is A. haptotropism B. phototropism C. hydrotropism D. geotropism 7. The streaming movement of cytoplasm observed in a freshly cut leaf of a water plant is termed A. osmosis B. ciliary motion C. amoeboid D. cyclosis 8. The movement of the whole organism to an external stimulus is termed A. tropism B. nastic movement C. taxis D. phototropic movement 9. The Closing of the morning glory flower when light intensity is low is an example of......... movement A. Tactic B. Nastic C. Tropic D. Cyclosis 10. A klinostat is an instrument used to demonstrate A. phototaxis B. chemotropism C. phototropism D. nastism **WEEK FOURTEEN** **NUTRIENT CYCLING IN NATURE** Nutrient cycling refers to the movement of certain nutrients like nitrogen, carbon, water, oxygen and other elements from the environment into various organisms and back into the environment. The path along which the atoms or elements pass is called a cycle. The popular well known nutrients cycles are nitrogen cycle, carbon cycle, water cycle and decomposition in nature. **Carbon Cycle** Carbon Cycle is the cycle of carbon usage by which energy flows through Earth's ecosystem. The basic cycle begins when photosynthesizing plants use carbon dioxide (CO~2~) found in the atmosphere or dissolved in water. The atmosphere gains carbon dioxide through: a. Combustion of organic materials such as coal, wood and petroleum b. The action of volcanoes which releases carbon dioxide c. The respiration by plant and animals d. The death, decay and putrefaction of plants and animals e. Diffusion of carbon dioxide from seas and other bodies of water acting as reservoir of carbon dioxide **Importance of Carbon in Nature** a. Plant uses carbon dioxide obtained from the air to manufacture their food during photosynthesis. b. It provides carbon which is the major building block of all organic matter. c. It helps to purify the atmosphere and maintain atmospheric level of carbon dioxide d. Organic matter which is made from carbon helps to replenish soil nutrient. **CARBON-OXYGEN BALANCE** Oxygen constitutes 21% of the gases in the atmosphere. Respiration, decay and combustion are the processes which remove oxygen from the atmosphere while photosynthesis is the process that releases oxygen into the atmosphere. Human activities such as deforestation lead to the release of less oxygen into the atmosphere while less carbon dioxide is removed from atmosphere. Increase in the combustion of fuel, respiration and decay leads to the removal of more oxygen from the atmosphere while more carbon dioxide is added as a result of the activities mentioned above, oxygen level in the atmosphere decreases while carbon dioxide level increases. A decrease in the atmospheric oxygen level by 2-8% do not cause any significant effect but a slight increase in the atmospheric carbon dioxide may cause greenhouse effect, i.e., increase in-the retention of the sun\'s radiant (heat) energy. This result in the warming of the atmosphere of the earth. So, to prevent this, there is the need to balance the carbon-oxygen level in the atmosphere. **The Oxygen Cycle** This the movement of oxygen gas within the atmosphere, the ecosystem, biosphere and the litosphere Oxygen constitutes about 21% of gases in the atmosphere. This amount is maintained at a fairly constant level by the oxygen cycle. Through the process of photosynthesis, oxygen is released into the atmosphere. Respiration, decay and combustion are processes which remove oxygen from the atmosphere. **The Significance of Oxygen to Living Organisms** a. It is used for respiration by plants and animals. b. It aids combustion. c. It aids decomposition. d. It is used in hospitals to aid patients who have impaired breathing. e. It is used in airplanes that fly at high altitude