BIOLOGY
PEPSIN IS SECRETED AS AN INACTIVE PRECURSOR CALLED PEPSINOGEN BECAUSE
A. pepsin as an enzyme is quickly destroyed by the alkaline food from the mouth B. all digestive enzymes pass through a precursor stage ✓ C. pepsin is a proteolytic enzyme and might attack the stomach tissues D. pepsin is not required in…
THE MESOPHYLL LAYER OF A LEAF CONSISTS OF
A. wax and cutin B. cells with lignified walls C. irregularly shaped collenchyma cells D. photosynthetic parenchyma cells ✓ The mesophyll layer of a leaf consists of photosynthetic parenchyma cells. These cells are responsible for carrying out photosynthesis, the process by…
THE MUSCLE CELL FLUID OF AN ATHLETE WAS TESTED IMMEDIATELY AFTER A 10 M RACE AND WAS FOUND TO CONTAIN A HIGH CONCENTRATION OF LACTIC ACID. EXPLAIN WHAT COULD HAVE CAUSED THIS. THE
A. athlete must have eaten food containing lactic acid just before the race B. Athlete must have injected lactic acid into his blood just before the race C. athletes muscle must have carried out anaerobic respiration during the race ✓ D. athlete…
THE DISADVANTAGE OF COMPLEXITY OF ORGANISATION IN THE HIGHER ORGANISMS IS THAT IT LEADS TO
A. mutual interdependence between component cells B. internal structural specialization C. increased adaptation to environment D. slower rate of diffusion of oxygen to individual cells ✓ The disadvantage of complexity of organization in higher organisms, such as multicellular organisms, is that it…
THE GROUP OF MICRO-ORGANISMS THAT PLAYS A VITAL ROLE IN THE BAKING INDUSTRY IS
A. algae B. bacteria C. fungi ✓ D. protozoa E. viruses The answer to the question is: C. fungi In the baking industry, fungi play a vital role. Fungi are a diverse group of microorganisms that include yeasts and molds. Yeasts, in particular, are essential in baking…
THE MOST LIKELY MODE OF AN ORGANISM THAT POSSESSES ATTACHMENT STRUCTURE, THIN OUTER SURFACE LAYER AND ABSENCE OF AN ELABORATE DIGESTIVE TRACT IS
A. Autotrophic B. holophytic C. parasitic ✓ D. saprophytic E. symbiotic The answer to the question is: C. parasitic An organism that possesses attachment structures, a thin outer surface layer, and the absence of an elaborate digestive tract is most likely to be a…
TWO IDENTICAL TWIN BOYS HAD DIFFERENT FINGER PRINT. THIS PROVES THAT
A. finger print is a sex-linked character B. the genotypes of the twins are similar C. the phenotypes of the twins are similar D. there are morphological variations ✓ E. there are physiological variation in the twins The answer to the question is: D. there…
MODERN METHOD OF CLASSIFICATION OF LIVING THINGS IS BASED ON SIMILARITY OF
A. colour B. habitat C. shape D. size E. structure ✓ The answer to the question is: E. structure The modern method of classification of living things is based primarily on the similarity of their structures. This approach, known as structural classification, allows scientists to…
THE PROCESS WHICH ENSURES THAT THE CHROMOSOME NUMBER FOR EACH SPECIES OF ORGANISM REMAINS CONSTANT FROM GENERATION TO GENERATION IS CALLED
A. fission B. fusion C. meiosis D. mitosis ✓ E. oogenesis The answer to the question is: D. mitosis In the context of genetics and biology, the process that ensures the chromosome number for each species of organism remains constant from generation to generation is…
THE STREAMING MOVEMENT OF CYTOPLASM OBSERVED IN A FRESHLY CUT LEAF OF A WATER PLANT IS TERMED
A. amoeboids B. centrifugal motion C. ciliary motion D. cyclosis ✓ E. osmosis The answer to the question is: D. cyclosis Cyclosis, also known as cytoplasmic streaming, is the movement of the cytoplasm within a cell. This phenomenon is commonly observed in plant cells, particularly…
ANIMAL HORMONES
Animal hormones are chemical messengers produced by various glands and tissues in animals that regulate physiological processes and behaviors. These hormones are secreted into the bloodstream and carried to target organs or tissues, where they bind to specific receptors and…
REPRODUCTIVE SYSTEMS IN MAMMALS
Mammals are biparental in reproduction that is sexual reproduction involves two distinct and separate individuals, sexually mature male and female. A) Male reproductive system The male reproductive system in man consists of testes (singular = testis), vasa efferentia, vas…
EVIDENCES IN SUPPORT OF ORGANIC EVOLUTION
1) Evidence from comparative anatomy Homologous structures can be used to explain the evidence of comparative anatomy. Homologous structures are those structures which are built in the same common plan but yet modified to perform different functions. For example the…
EVOLUTION OF NEW SPECIES BY MUTATION AND ISOLATION
A) Mutation theory of organic evolution Mutation is a change in genetic material resulting in a new stable characteristic which can be inherited by offspring. Hugo De Vries, a Dutch botanist propounded the mutation theory of organic evolution in 1901…
DARWIN’S THEORY AND MODERN THEORIES OF ORGANIC EVOLUTION
Charles Darwin, a British biologist, in 1859 propounded a theory of organic evolution by Natural Selection leading to the origin of species. His theory of natural selection is as follows: 1) Overproduction: All living organisms produce more offspring than can…
LAMARCK’S THEORY OF ORGANIC EVOLUTION
Jean Baptiste Lamarck, a French biologist was one of the first biologists to put forward the theory of organic evolution in 1801. His idea of organic evolution was hinged on three theories. 1) The theory of need This states that…
DIVINE CREATION AND ORGANIC EVOLUTION
The world is occupied by millions of different kinds of plants and animals. These plants and animals are adapted to different kinds of habitats and niches. How did these different organisms come to exist in the world? This is the…
MECHANISM OF TRANSPORTATION IN PLANTS
The lower plants All the plants from the single-celled Chlamydomonas, bacterium, Phacus to the simple multicellular Spirogyra, Funaria (Bryophyta) that lack conducting vessels use their cytoplasm for the movement and distribution of materials. Most of these lower plants live in…
LYMPHATIC SYSTEM
The part of plasma which filters into the spaces among the tissues and flows in vessels similar to arteries and veins constitute the lymphatic system. The lymph is clear colourless tissue fluid. The vessels that convey lymph are called lymphatic…
THE CIRCULATION OF BLOOD
There are three plans or types of blood circulation in human beings, other mammals and birds. They are the pulmonary circulation, systemic circulation and the coronary circulation. The pulmonary circulation (Heart ->lung ->heart) The pulmonary circulation transports blood between…
HEART
The heart is an muscular organ that pumps blood to all human parts of the body. It lies at the centre of the thoracic cavity in the pericardial cavity and being flanked on either side by and left lungs. It…
TRANSPORT SYSTEM
The transport system carries food and oxygen to all tissues and removes waste materials of metabolism, convenes hormones from ductless glands to their target organs and the body temperatures are equalized. Needs for transportation In Amoeba and many simple…
FERN
The group – Pteridophyta consists of ferns and club-mosses. Dryopteris is a fern. It is seen growing in large number as epiphytes on oil palm trees. Dryopteris has a tuft of strong adventitious roots, a short unbranching stem and leaves…
MOSSES
Mosses are small, green and simple land plants belonging to phylum Bryophyta and class Musci. They are found growing on damp places. A common example of mosses is Funaria hygrometrica commonly found growing on old blocks, block fences, tree trunks…
SEEDS AND FRIUTS
Seeds A seed is a structure which develops from the ovule after fertilization. A seed consists of an embryo and one or two cotyledons. It may contain an endosperm or food reserve. The embryo is made up of a radicle…
DISPERSAL OF FRUITS AND SEEDS
After the maturation of fruits, an abscission layer is formed at the point of attachment of the fruits to the stems. This layer later dries up and the fruits drop from the plant. Some times the fruits split up to…
MOVEMENTS IN FISH
Swimming movements Each side of the vertebral column (flexible backbone) of a fish is made of muscle blocks or myotomes. The muscle blocks are arranged in a zig-zag fashion from head to tail. Each muscle block starts from the transverse…
APPENDICULAR SKELETON
The appendicular skeleton is made up of the limb girdles (pectoral and pelvic girdles) and the limbs (fore limbs and hind limbs). The pectoral girdles The pectoral girdle consists of a triangular plate of bone called scapula or…
CLASSIFICATION (TAXONOMY) OF LIVING THINGS
There are over 2,000,000 known different organisms in the world today and probably over 1,000,000 are left to be discovered and named. All these living things have different characteristics such as shape, size, colour, and height. It will, therefore, be…
CLASSIFICATION OF ANIMALS
The animal kingdom is divided into invertebrates (animals without backbones) and vertebrates (animals with backbones). Invertebrates The subphylum invertebrate (the invertebrates is made up mainly of the following phyla: Protozoa, Coelenterata, Platyhelminthes, Nematoda, Annelida, Mollusca, Echinodermata and Arthropoda. …
NEW SYSTEM OF CLASSIFICATION
The modern classification system based on physiology, biochemistry and embryology have revealed distinct similarities between living organisms which external appearances of organisms will not show or discover. Not all biologists have agreed on this new classification of five kingdoms instead…
ALIMENTARY CANAL OF COCKROACH
Cockroach is an omnivorous animal eating anything ranging from starchy and sweet things to papers, clothes etc. Its alimentary canal is therefore adapted to suit its type of diet. The alimentary canal consists of foregut, midgut and hindgut. 1) Foregut…
MOVEMENTS IN HYDRA AND EARTHWORM
Movements in Hydra 1) Swaying Sometimes Hydra comes to rest on rock or other suitable hard surface in water and fixes itself temporarily with mucus substances at the basal disc. Even when Hydra is fixed, it is continuously swaying and…
FIRST AID IN HAEMORRHAGE
Haemorrhage (bleeding) is the coming out of blood from the blood vessels which have been damaged. When the loss of blood is to the outside, it is called external haemorrhage and when it is to the tissues, it is called…
POLLINATION IN PLANTS
Pollination is defined as the transfer of mature pollen grains from the anthers of one flower to the mature stigma of the same flower or another flower of the same plant or closely related species. Pollination is the first step…
FERTILIZATION IN FLOWERING PLANTS
Immediately after pollination, fertilization follows. Fertilization is the union of male and female gametes to form a zygote. In a flower, the male gametes develop from the pollen grains while the female gametes develop from the ovules which are retained…
SHOOT SYSTEM
This is the part of the plant which grows above the soil except the modified aerial roots. The shoot system consists of two main organs – the stem and the leaves. During the reproductive stage, flowers and fruits may be…
ROOT SYSTEM
The root system is the part of the plant growing in the soil. This excludes the underground stems which are organs of perennation (survival from year to year by vegetative means). There are two kinds of root systems, namely: tap…
EXTERNAL FEATURES OF FLOWERING PLANTS
The flowering plants form a group of plants known as Angiosperms. They are characterized by the possession of flowers for sexual reproduction. They bear flowers in their various breeding seasons and after pollination and fertilization, seeds are formed enclosed in…
PRIMATES
Primates are the most highly developed of all mammals with large brain, forward-facing eyes with bilocular vision, grasping fingers and toes equipped with flat nails. Characteristic features of Primates 1) Well developed arms and hands The arms and hands…
THE STRUCTURE OF MAMMALIAN GAMETES
The mammalian gametes are male gametes called sperm or spermatozoa (singular = spermato-zoon), while the female gametes are called eggs or ova (singular = ovum) The reproductive sex cells are also known as gametes. The formation of gametes or gametogenisis…
GERMINATION
Germination is a process by which the embryo of a seed grows out of its testa and develops into a seedling. In other words, Germination is the series of changes by which an embryo in a seed grows into seedling.…
PARTURITION OR CHILD BIRTH
Parturition (labour) is the expulsion of the foetus, placenta and foetal membranes from the uterus. After about 270-280 days in the uterus, the foetus is now prepared to come to the world. The foetus at this stage has turned its…
EXTRAEMBRYONIC MEMBRANES
When the embryo has been implanted, it produces four extraembryonic membranes (membranes outside the body of the embryo namely: amnion, chorion, allantois and yolk sac). Since these membranes are located outside the body of the embryo, they are referred to…
LIVER
The liver is the largest gland in the body. It is dark-red, spongy and lobed. The lobes are: caudate lobe, left lobe, right lobe and median lobe. It is hung from the posterior surface of the diaphragm by a ligament…
STOMACH
The stomach is a thick-walled large muscular sac which lies in the left portion of the abdominal cavity below the diaphragm. It is made of three layers of muscles arranged longitudinally, circularly and obliquely. The contractions of these muscles in…
EXPERIMENTS TO SHOW THE CHARACTERISTICS OF ENZYMES
Experiment 1 Aim: To demostrate the action of ptyalin (saliva) on cooked starch. Method: Some saliva is introduced into a test tube X and diluted with little amount of water. Two test tubes are labelled E and F. To test…
SEX DETERMINATION
Genetic traits are determined by genes located on the chromosomes. The sex of an organism is a genetic trait which like other traits is transmitted from parent to offspring during sexual reproduction. In all organisms with sexual reproduction there is…
FRACTURE AND DISLOCATION
A fracture is any break in a bone. There are two kinds of fracture namely simple (closed) and compound (open). Simple or closed fracture If the broken bone does not come out through the skin and injury to the…
STRUCTURE AND FUNCTION OF NEURONE
Neurones are specialized cells that transmit impulses (messages) around the body in form of electrical charges. The nervous system consists of millions of neurones (nerve cell). Three main types exist in the body namely: sensory, association (intermediate) and motor neurones.…
