BIOLOGY
BONE
A bone is strong, hard and tough connective tissue mainly made of calcified material. Composition of bone A fully developed bone is hard and brittle. Bones can break, and a break in a bone is called fracture. The bone…
MUSCLES
Muscles can be referred to simply as the flesh mostly associated with bones to give shape to the bodies of animals. The flesh may be red in the case of mammals. General properties of muscular system All muscular…
TRANSPIRATION
Transpiration is the loss of water vapour from different parts of the plant shoot. These parts include the stomata of leaves, the cuticle of both leaves and young stems, and the lenticels on tree trunks. Transpiration is described according to…
GILLS
Fish and tadpoles are aquatic vertebrates. They possess gills for gaseous exchange. Gills of fish Fish has four gills on each side of the head. Each gill has two rows of soft gill filaments. The filaments are tiny, long…
ALIMENTARY CANAL OF PLANARIA
Planaria is a free-living, flat, slender and small worm. The digestive tract consists of a ventrally placed mouth, muscular pharynx and intestine. The pharynx can be protruded from the mouth when attacking a prey. The pharynx leads into the intestine.…
GEOTROPISM
This is the response of plant parts to the stimulus of gravity. Plant shoots grow away from gravity of the earth and are said to be negatively geotropic. Roots grow towards gravity and are said to be positively geotropic. …
ORGAN OF SIGHT
The eyes are the organs of sight in the higher invertebrates and all vertebrates. They (eyes) are equipped with photo receptors (rods and cones) to detect light. Most of these animals have two eyes. In man, the eyes are more…
EXCRETION IN PLANTS
There are no special excretory organs or systems in plants. The plants as living things do carry out excretion. Elimination of certain waste takes place through the stomata and lenticels. The main waste products of plants are water from transpiration…
OXYGEN DEBT
The oxygen needed to oxidize lactic acid to pyruvic acid and from pyruvic acid to carbon oxide, water and chemical energy is called Oxygen debt. The quick heavy breathing to take in oxygen to the muscle cells lacking oxygen in…
TRANSLOCATION
Translocation is the transport of manufactured food substances from the leaves to all parts of the plant. The movement is usually described as downwards from the leaves to the roots but it is also known to occur on the reverse…
EXPERIMENTS ON PHOTOSYNTHESIS
The occurrence of photosynthesis in plants can be shown by experiments. The easiest proof that photosynthesis has taken place is to test for the presence of starch in the green leaves. Experiments should be carried out to show the importance…
PLANT NUTRITION
Photosynthesisis the process by which carbohydrates or sugars are manufactured in the green parts of the plants containing chlorophyll by combination of carbon (IV) oxide and water with the aid of radiant energy of sunlight while oxygen is given out…
PARASITIC NUTRITION
This is a type of nutrition in which one organism obtains food from another organism and during the feeding process one organism is harmed and does not benefit. The organism gaining food, protection and shelter is called parasite while the…
ALIMENTARY CANAL OF BIRDS
Mouth The mouth has a horny covered tongue to facilitate swallowing of food substances to the oesophagus. There are no teeth. The lower and upper lips have been modified into sharp strong beaks for picking of food substances such as…
COMPLETE METAMORPHOSIS IN MOSQUITOES
Mating and laying of eggs The adult male and female mate. The female lays fertilized eggs on the surface of a stagnant water. Eggs are laid in partially sunny but shaded places. Female Anopheles and Aedes mosquitoes lay eggs singly…
CHROMOSOMAL BASIS OF HEREDITY
Within the nucleus of non-dividing cells are strands or string-like structures known as chromosomes. As the cell is about to divide, the chromatids become more visible as strands with bead-like structures on them. These are the chromosomes and contain genes,…
EXPERIMENT ON MINERAL DEFICIENCY
Aim: To demonstrate the effects of mineral deficiency on plants. Material required: Nine wide-mouthed glass jars, corks, nine bean seedlings, glass tube, Sach’s or Knop’s complete culture solution (to provide macro-nutrients), black paper or black paint, 1% copper chloride…
MOVEMENT
Movement is the ability of living organisms to move from one place to another. Reasons for movement include searching for food, escape from danger, response to stimuli (either positively or negatively) and for the sake of reproduction. All organisms that…
DENTITION
Dentition refers to the number, arrangement and conformation of teeth in an organism. Types of Dentition There are two main types of dentition. These are: Homodont dentition: In this type of dentition, the organisms have the same type of…
MECHANISM OF RESPIRATORY SYSTEM IN LOWER ANIMALS
Unicellular Organisms There are no special respiratory organs in unicellular and aquatic organisms such as Amoeba and Paramecium. Oxygen that dissolves in water diffuses into the body while carbon dioxide goes out of the body through the entire body surface.…
FEEDING HABITS
Organisms exhibit different feeding habits. These are: Filter Feeding Filter feeders which are also called microphagous feeders feed on very tiny organisms which cannot be easily picked to the satisfaction of the feeder. Filter feeders are mainly aquatic animals and…
EXCRETION IN MAMMALS
There are four types of excretory organs used by mammals. These are: lungs, skin, liver and kidneys. The lungs excrete water vapour and carbon dioxide, the liver excretes bile pigments called bilirubin (derived from the decomposition of haemoglobin), the skin…
SOCIAL ANIMALS
Social animals are those in which individuals of the same species live together cooperatively in organized communities known as societies or colonies. A colony is a group of individuals belonging to the same species and organized in a cooperative manner.…
BEHAVIOURAL ADAPTATION
Behaviour is everything an organisms does in response to changes in its environment. It is basically adaptive, geared mainly towards promoting the organism’s survival and reproduction. Examples of behavioural adaptations are grouped and explained below. Behavioural Adaptation in Predators (Carnivores)…
ADAPTIVE COLOURATION
Adaptive colouration is the possession by an organisms, of a colour which enable it to catch its preys, avoid its predators or enemies and ensure its survival. In order to obtain food, escape or hide from their enemies and secure…
STRUCTURAL ADAPTATION
Structural adaptations are special modification of structures which help organisms to survive better in their various environment. Some examples of structural adaptations are describe below. Structural Adaptation for Obtaining Food (a) By Toad The toad possesses special olfactory organ…
ADAPTATION FOR SURVIVAL
Adaptation is defined as the possession of special features or structure which improves the changes of an organism to survive in its environment. In other words, adaptation is the ability of an organism to live successfully in a particular habitat…
COMPOSITION AND STRUCTURE OF BLOOD
Structure of the blood The blood is a tissue in a fluid form. An adult man has about 5-6 litres of blood. Blood is made up of two major components: the blood cells or corpuscles which are solid. the plasma…
REPRODUCTIVE SYSTEMS IN PLANTS
The flower is the reproductive structure of flowering plants. It contains the male and female sex organs which enable them to exhibit sexual reproduction. Fertilization inside the flower often leads to the production of seeds which are capable of germinating…
ADAPTATION
Adaptation is defined as the possession of the characteristics or traits or behaviour or structure or features that evolved over a period of time which enable an organism to survive and reproduce in response to changes in the environment or…
TOLERANCE
Tolerance is the ability of living organisms to withstand or tolerate little unfavourable changes in the environment which affect their survival. Living organisms can only live in a particular habitat if they can tolerate the ranges of the abiotic factors…
DECOMPOSITION IN NATURE
Decomposers Decomposers are fungi or bacteria which live saprophytically or feed on dead remains of plants, animals and organisms leading to or resulting in recycling of nutrients by breaking down organic matters to produce soluble nutrients which are absorbed by…
PYRAMID OF NUMBER
Pyramid of number refers to the number of individual organisms at each trophic level which decreases progressively from the first to the last trophic level in a food chain. Pyramid is a diagrammatic representation of food chain in which producers…
RESPIRATION IN TOAD
Tadpole The young toad called tadpole uses gills for gaseous exchange. At the tadpole stage, the animal develops external gills through which direct diffusion of gases takes place between the animal (tadpole) and the respiratory medium (water). Oxygen dissolved in…
METAMORPHOSIS IN INSECTS
Metamophosis is defined as the series of gradual changes of form and shape of an insect from the fertilised egg (immature stage) to adult (mature stage of adulthood). Certain organisms when they are hatched from eggs do not directly resemble…
REPRODUCTION IN COCKROACH
The cockroach exhibits incomplete metamorphosis. This starts from fertilised eggs to nymph and finally to adult or imago stage i.e. Egg -> Nymph -> Adult. Mating begins when the male cockroach introduces sperms into the posterior part of the female’s…
THE VERTEBRAL COLUMN
The vertebral column, also known as the backbone or spinal column, is the central supporting structure of the skeleton. The vertebral column forms the backbone of vertebrate animals and protects the spinal cord. It is made up of five groups…
ENERGY TRANSFORMATION IN NATURE
Energy exists in various forms. These forms of energy are inter-convertible, i.e ., one form of energy can be transformed into another form. Such energy transformation are governed by the laws of thermodynamics. In nature, energy transformation is brought about…
REPRODUCTION IN TOAD
In sexual reproduction, the male animal produces the sperm while the female produces the egg or ovum. The fusion of the sperm and the egg in the fallopian tube of the female during mating is called fertilization. The fusion of…
CELL REACTION TO ITS ENVIRONMENT
All living things are capable of responding to internal and external stimuli. The ability to do this is called irritability or sensitivity. By this means, plants and animals are able to detect and respond to changes in their environment. Irritability…
ASPECTS OF GROWTH
It is sometimes very difficult to determine growth in organism. Growth varies from one organism to another. Parameters normally used to measure growth in organisms include: Mass. Length, height or width. Area or volume. a) In most growth studies,…
SKIN
The entire surface of the body is covered by skin. In man, the skin is about 1 to 2mm thick except the skin of the palm and soles with thickness of about 6mm. The skin is the most extensive organ…
CARTILAGE
A cartilage is a tough elastic and semitransparent tissue devoid of blood vessels and nerves. Functions of cartilage It prevents friction between two bones and allows smooth and free movement. It absorbs shock between bones. For example the shock…
CARBOHYDRATES
Carbohydrates are organic compounds containing carbon, hydrogen and oxygen atoms. The ratio of hydrogen to oxygen is 2:1 in all carbohydrates. Starch, sugar, glycogen and cellulose are carbohydrates. They are classified into three major groups namely:- Monosaccharides Disaccharides and Polysaccharides.…
NASTIC AND TACTIC MOVEMENT
Nastic/sleeping movements The pinnate and bipinnate leaves of many leguminous plants open and close as a result of certain changes in temperature, light intensity or humidity of the atmosphere. The process which is however gradual is known as “sleeping movement”…
DIGESTIVE ENZYMES
Enzymes are organic catalysts of protein origin produced by living cells which help to speed up or slow down the rate of chemical reactions but remain chemically unchanged at the end of the reaction. Classes of enzymes Enzymes are…
FOOD TESTS
Food substances are chemical compounds and therefore can be tested chemically. Test for carbohydrates Test for glucose (a reducing sugar) To a little solution of glucose, add small quantities of Fehling’s solutions A and B (equal amount) and heat…
BEHAVIOURAL ADAPTATIONS UNDER UNFAVOURABLE CONDITIONS
1) Hibernation: Hibernation is a behavioural adaptation in which some small mammals such as shrews, monotremes and bats spend cold season (winter) in inactive condition or deep sleep in a warm and safe place. These small mammals are unable to…
STOMATA AND LENTICELS
Stomata Stomata are openings in the epidermal layer of leaves of plants. Two guard cells surround each stoma. The guard cells are bean-shaped. The inner cellwalls of the guard cells are elastic and thicker than the outer cell walls. This…
AUXINS
Auxins help primarily in influencing cell elongation and enlargement hence sometimes referred to as growth hormones. Actions of auxins are to stimulate or inhibit growth hence they are regarded as growth regulators. The most abundant natural auxin manufactured in plants…
