All 60 questions from the West African Examinations Council (WAEC) Biology 2013 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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In which of the following levels of classification are the members most similar?
Species is the most specific/narrow level of classification, so its members are the most similar to one another.
Use the diagram below to answer questions 2 and 3. The diagram represents a
The diagram shown is the diagram of Spirogyra. Spirogyra is an unbranched filamentous alga; the single cell shown, with its labelled parts, represents a cell.
(Using the same diagram as Q2) Pyrenoid is present in the structure labelled
Pyrenoids are structures adapted for storing starch in algae. They are located within the chloroplasts. The part labelled 'IV' is the pyrenoid while the part labelled 'III' is the chloroplast on which the pyrenoid is borne.
Spirogyra is regarded as a multicellular plant because
Spirogyra is regarded as a multicellular plant because the cylindrical cells are linked end to end.
Which of the following pairs of structures in living organisms do not perform similar functions?
Root hairs and mammalian hairs do not perform similar functions. Root hairs are for absorption of water from the soil, while mammalian hairs aid in temperature conservation.
Which of the following sequences is the correct arrangement of tissues in the anatomy of a young dicotyledonous stem from the inside to the outside?
The correct sequence from the inside to outside is: Pith → xylem → cambium → phloem → collenchyma → parenchyma → epidermis.
An animal which possesses scale, nares and a backbone is likely to be a
An animal which possesses scale, nares and a backbone is likely to be a reptile, e.g. a lizard.
The opening of the guard cells of the epidermis in plants is by the process of
The opening and closing of the stomata is osmotically guarded: water flows into a guard cell by osmosis (due to its relatively high osmotic potential), it becomes turgid, and the stoma opens.
What happens to a plant if the shoot tip is cut off and replaced by an agar block containing auxin?
Auxin, a plant growth substance, is produced at the apices. Growth is expected to be affected when the shoot tip is cut off; however, replacing the tip with an agar block containing auxin will arrest the situation, and the plant will continue to grow normally.
Anaerobic respiration results in the production of
Anaerobic respiration produces less energy than aerobic respiration. The former produces 2 ATPs per molecule of glucose while the latter produces a whopping amount of 36 ATPs.
Which of the following is not a skeletal tissue?
Chitin, cartilage and bone are skeletal tissues, while plasma is a component of blood.
Which of the following statements is not correct about the mammalian heart?
Blood passes from the right ventricle to the pulmonary artery (not to the left auricle through the aorta), so option C is the incorrect statement.
Which of the following organs are used for gaseous exchange in a mature toad?
The structures used for gaseous exchange in a mature toad are the skin, lungs and mouth. Gas exchange through the skin is cutaneous respiration, through the lungs is pulmonary respiration, and through the mouth is buccal respiration.
Which of the following structures is used for respiration in insects?
The spiracles are the holes on the body of an insect for gaseous exchange; air enters/leaves through the trachea via the spiracles.
Which of the following statements about the diaphragm of a mammal is not correct?
The diaphragm separates the thoracic and abdominal cavity, is part of the respiratory apparatus, and is a thick layer of muscle — not made of epithelial cells, so C is the incorrect statement.
A substance present in the glomerular filtrate in the mammalian kidney is
The substances present in the glomerular filtrate in the mammalian kidney are water, urea, mineral salts, sugar (e.g. glucose) and plasma solutes.
In humans, excretion of hypertonic urine is associated with the
The distal convoluted tubule is associated with the production of hypertonic urine (after sufficient absorption of water).
The maintenance of a stable internal environment within the body of a mammal is known as
The maintenance of a fairly stable internal environment is known as homeostasis.
Which part of the nephron is associated with ultra-filtration?
Ultrafiltration, the first process in urine formation, occurs in the Bowman's capsule.
Which of the following conditions would result in a decrease in the production of antidiuretic hormone?
Drinking large quantities of water results in a decrease in anti-diuretic hormone (ADH) secretion, i.e. more water, less ADH — the higher the ADH secretion, the higher the blood pressure.
Which of the following structures is not essential in a wind pollinated flower?
The petal, an attractive part of a flower, is necessary/essential for an insect-pollinated flower only. A wind-pollinated flower does not need to be conspicuous.
Study the diagram below and use it to answer questions 22 to 24. Which part of the flower produces the structure labelled III?
The part labelled 'III' is the pollen tube. Note that pollen grains are produced at the anther of a flower; the ovum (the female reproductive cell) is produced at the stigma.
The parts labelled III and IV respectively are called
The part labelled 'III' is the pollen tube, and the part labelled 'IV' represents the style.
Which of the labelled parts would become a component of the seed after fertilization?
The part labelled 'I' would become a component of the seed after fertilization.
The resolution of a microscope refers to its power to
The resolution of a microscope refers to its power to distinguish clearly between two objects.
The process by which plants manufacture food from carbon dioxide and water using energy from the sun is called
Plants manufacture their food from carbon-dioxide and water using energy from the sun in a process known as photosynthesis.
Conduction of water and mineral salts through the xylem vessels is enhanced because the xylem cells are
The walls of the xylem are strengthened with lignin to withstand pressure changes as water and mineral salts move through the plant.
Which of the following factors is likely to increase the rate of transpiration in plants?
The larger the surface area of a leaf, the higher the rate of transpiration — so an increase in leaf surface area to volume ratio increases transpiration.
The name of the enzyme that catalyses the conversion of glucose to glucose-6-phosphate at the beginning of glycolysis is a
Phosphorylation of glucose is the first step in glycolysis. Here, glucose is converted to glucose-6-phosphate (by hexokinase). This is converted in two steps to fructose 1,6-diphosphate, and the latter splits into two 3-carbon segments, which are converted through five successive steps into molecules of pyruvic acid.
The correct arrangement of food classes of the same quantity in the order of magnitude of energy value in animals in descending order is
The energy value of fats and oils is higher than that of carbohydrate. For instance, 1g of carbohydrate has an energy value of 16.7 kJ whereas 1g of fat has a whopping 37.6 kJ.
Which of the following substances is not a complex carbohydrate?
Complex carbohydrates are the polysaccharides. They include glycogen, cellulose, starch and inulin. Glucose is a monosaccharide and such is not a complex carbohydrate.
Which of the following associations is an example of epiphytism?
An epiphyte is a plant which dwells on another plant without causing any apparent harm to the host plant. Fern on a palm tree is an example of epiphytism.
Study the diagrams below carefully and use them to answer questions 33 and 34. What is the likely food of the bird in I?
The long, pointed beak as in bird 'I' is highly likely to be adapted for nectar feeding.
(Using the same diagrams as Q33) The food of the bird in II is
The short, thick beak as in bird 'II' is highly likely to be adapted for seed cracking.
Ecology simply means the study of
Ecology can be defined as the study of the inter-relationship between organisms and their environment.
The maximum size of a population that a given area can support is known as
The maximum size of a population that a given area can support is known as its carrying capacity.
The producers in a food chain in an aquatic environment are
The producers in an aquatic food chain can be the phytoplanktons.
The frog is considered a better swimmer than the toad because it
The frog is deemed a better swimmer than the toad because it has much more pronounced webbed digits.
The bacteria that reduce nitrates in the soil into gaseous nitrogen are referred to as
Bacteria that release the soil nitrate into gaseous nitrogen are called denitrifying bacteria. A typical example is pseudomonas denitrificans.
A pyramid of numbers is constructed by
A pyramid of numbers involves living organism, not non-living things. The pyramid of numbers represents the number of individuals at each trophic level of a food chain at a particular time.
The main reason for immunizing children is to
The main reason for immunizing children is to stimulate the production of antibodies to combat pathogens and diseases.
Rhizobium which lives in the root nodules of leguminous plants is an example of the association known as
Rhizobium and root nodules of leguminous plants show mutualistic association. The organism helps the plant in nitrogen fixation while the plant, in return, provides food and shelter for the organism.
Ascaris lumbricoides is a parasitic
Ascaris lumbricoides is a parasitic round worm.
The following organisms are pests of plants except
Birds, rodents and nematodes are pest of plant; bacteria, viruses and fungi are better regarded as causes of disease or pathogens.
The absence of alimentary canal in the parasitic flatworm can be attributed to the fact that
The possession of alimentary canal in parasitic flatworms (e.g. tapeworms) is not needed because they absorb already digested food.
Which of the following statements is not a reason for conserving wildlife?
Conservation of wildlife does not increase the amount of rainfall in any way. It attracts tourists, serves as a source of food and income.
Which of the following human activities would help prevent endangered species from extinction?
The maintenance of the species in zoological gardens helps in preventing endangered species from extinction. Other options perform the opposite role.
In genetics, linkages refer to the linking of genes of the
Linkage or genetic linkage describes the way in which two genes that are close together on the same chromosome are inherited during meiosis. (Note: per the printed answer key the labelled correct option is B.)
A man's blood group is AB. What is the probability of the man giving birth to a child with blood group O?
A man with blood AB cannot possibly give birth to a child with blood group O.
When a man who is Rh-positive marries a woman who is Rh-negative, there will be incidence of
A marriage between a man who is Rh-positive and a woman who is Rh-negative may be attended with an appreciable incidence of still-births.
The genotypic ratio of the offspring of a hybrid is 1:2:1, which of the following laws illustrates this ratio?
This is illustrated by the law of segregation of genes.
A gene that is only located on the X-chromosome is said to be
A gene that is located on the X-chromosome is said to be sex-linked. Examples of characters that are controlled by sex-linked genes are baldness, haemophilia and colour blindness.
If a boy has blood type O and his mother has blood type A. what is the genotype of his father?
If a boy has blood type O and his mother has blood type A(AO), the blood type of the father is either AO or O(OO).
A man who suffers from haemophilia marries a woman who is a carrier, what percentage of their children are likely to be haemophilic?
As explained in the related genetics question on incompatibility of Rhesus factor between an intending couple leading to still-births, using the cross for haemophilia carriers, 50% of the children are expected to be affected (note that females will only suffer from the disease when both X-chromosomes are affected).
Which of the following traits may be considered in marriage counselling?
As explained on the Rh-incompatibility question, incompatibility of Rhesus factor between intending couples may lead to still-births, so this is considered in marriage counselling.
Which of the following structures is only formed during cell division in animal cells?
Centrosome is only formed during cell division in animal cells.
The function of the drone in a colony of bees is to
The function of the drone in a colony of bees is to mate with the queen.
Which of the following features is used by chameleons to escape predation?
The chameleon is able to change its colour to blend with that of the environment. This is an adaptation to escape predation.
A scientist who was involved in the development of the evolution theory is
The most popular scientists involved in the development of the evolution theory are Charles Darwin and Jean Lamarck.
Darwin noticed that organisms in similar habitats across the world looked alike. This illustrates
Convergent evolution: a single ancestor gives rise to many species that come to resemble each other due to similar habitats/adaptive pressures, though this general statement is more typically associated with convergence of unrelated organisms adapting similarly to similar environments.
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