All 50 questions from the West African Examinations Council (WAEC) Biology 2021 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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1. Which of the following organelles is common to both plant and animal cells?
Both plant and animal cells have a cell membrane. Cellulose cell wall, chlorophyll, and (typically) a large vacuole are found in plant cells, not animal cells.
2. The diagrams below are illustrations of different sections of a particular fruit. Study them and answer questions 2 and 3. The sections in X and Y respectively are
X shows a transverse (cross-sectional) cut, while Y shows a longitudinal cut through the fruit.
3. The fruit that has the illustrated sections is a
A hesperidium is a modified berry with a leathery rind resulting from a single ovary — characteristic of citrus fruits, matching the sections shown.
4. The diagram below is an illustration of a fungus. Study it and answer questions 4 to 6. The structure labelled I is associated with
Structure I is the sporangium, which contains spores used for asexual reproduction.
5. The structure labelled II is the
Structure II is the columella — a sterile, dome-shaped structure at the tip of the sporangiophore.
6. Which of the following statements about the structure labelled II is correct? It
Digestive enzymes are released into the substrate through structures like this, allowing digested organic material to be absorbed.
7. The diagram below is an illustration of a living organism. Study it and answer questions 7 and 8. The level of organization of the organism is
The diagram depicts euglena, a single-celled organism — placing it at the cellular level of organization.
8. The organism belongs to the Phylum
Euglena belongs to the phylum Euglenophyta (organisms in this group are also called euglenids).
9. A plant cell placed in a solution with a higher water potential will
Water moves into the cell by osmosis (from higher to lower water potential outside-to-inside comparison), and the rigid cell wall prevents bursting, so the cell becomes turgid.
10. Offspring formed by sexual reproduction exhibit more variation than those formed by asexual reproduction because
Since gametes from each parent carry different genetic material (due to independent assortment and crossing over), their combination produces varied offspring.
11. Radius and ulna are bones of the
The radius and ulna are the two bones of the lower arm (forearm); the humerus is the single bone of the upper arm.
12. The blood vessel which carries blood from the alimentary canal to the liver is the
The hepatic portal vein carries nutrient-rich blood from the alimentary canal to the liver; it is unusual in that it starts and ends in capillaries.
13. The diagram below is an illustration of the longitudinal section of a mammalian organ. Study it and answer questions 13 and 14. Which of the labelled parts is the cortex?
In the kidney diagram, I=renal artery, II=renal vein, III=ureter, and IV=the cortex (the outer region of the kidney).
14. What is the main function of the organ?
The organ shown is the kidney, whose main function is excretion (removal of metabolic waste from the blood).
15. Detoxification of urea takes place in the
Urea is produced (via detoxification of excess amino acids/ammonia) in the liver, then excreted by the kidneys.
16. Which of the following hormones is suddenly secreted into the bloodstream of a frightened person?
Adrenaline, released by the adrenal glands, is the 'fight or flight' hormone triggered by fear or danger.
17. The temperature control centre in mammals is located in the
The hypothalamus regulates body temperature, along with hunger, thirst, sleep, and circadian rhythms.
18. The diagram below is an illustration of a type of eye defect in humans. Study it and answer questions 18 and 19. The eye defect illustrated in the diagram is
Since the light rays converge before reaching the retina, the diagram illustrates myopia (short-sightedness).
19. The eye defect can be corrected by the use of
Myopia is corrected using a concave (diverging) lens, which spreads the light rays out before they enter the eye.
20. How many gametes are produced in the pollen grain of a flowering plant before fertilization?
A single pollen grain produces two male gametes in flowering plants.
21. Which of the following organisms does not undergo incomplete metamorphosis?
Butterflies undergo complete metamorphosis (egg-larva-pupa-adult), unlike locusts, grasshoppers, and cockroaches which undergo incomplete metamorphosis.
22. An enzyme reaction may begin to decline when
Enzymes are sensitive to pH; a change away from the optimum pH can denature or reduce enzyme activity, slowing the reaction.
23. The diagram below is an illustration of the growth of a plant in a water culture. After a few days, the solution turned green and the plant died. Use it to answer questions 23 and 24. What precaution should have been taken to prevent the solution from turning green?
The green colour indicates algal growth, which needs light. Covering the vessel with opaque material blocks light and prevents algae from growing.
24. The death of the plant was likely caused by
The algae that grew in the solution competed with the plant for nutrients, depleting them and causing the plant to die.
25. Which of the following factors is not necessary for photosynthesis?
Photosynthesis requires water, carbon(IV) oxide, chlorophyll, light, and enzymes — wind is not a requirement.
26. Autotrophic nutrition is a process whereby an organism obtains food
Autotrophs make their own food by synthesizing simple substances (e.g. CO2 and water) using an energy source (light or chemical) — photosynthesis or chemosynthesis.
27. The process that takes place at the light stage of photosynthesis is
The light stage (light-dependent reaction) splits water molecules (photolysis) to release hydrogen ions and oxygen; CO2 reduction happens in the dark stage.
28. The diagram below is an illustration of the foot of an animal. The adaptation of this type of foot is that it is
The webbed foot shown, with toes connected by flexible skin, is adapted for use as a paddle when swimming (as in ducks and geese).
29. The following organisms are examples of carnivorous plants except
Venus flytrap, pitcher plant, and Utricularia are all carnivorous plants; Gloriosa (a flowering climbing lily) is not.
30. Plants and animals of an ecosystem make up a
All the different plant and animal species living together in an ecosystem make up a community.
31. Rabbits cannot survive in an aquatic habitat because they have
Rabbits are air-breathing mammals with lungs, not gills, so they cannot extract oxygen from water to survive fully aquatic life.
32. The illustration below is a food chain: Grass → grasshopper → domestic fowl → hawk. What would happen if the population of domestic fowl decreases? The
With fewer domestic fowl (a predator of grasshoppers) preying on them, the grasshopper population would increase.
33. Which of the following features is a characteristic of aquatic plants? Possession of
Finely divided, thread-like leaves increase surface area for absorbing dissolved oxygen and nutrients directly from the water.
34. An association between living organisms in which one organism lives on and feeds at the expense of the other organism is known as
When one organism benefits at the expense (harm) of the other, the relationship is parasitism.
35. When a large number of organisms share limited resources, the result is
Organisms sharing scarce resources compete with one another for those resources.
36. Which of the following behaviours is correctly matched with the corresponding diseases?
Eating uncooked/undercooked meat is correctly associated with diseases like dysentery, cholera, and food poisoning.
37. Endangered species are organisms that are
Endangered species are those at risk of extinction — likely to disappear entirely if conservation action isn't taken.
38. Which of the following practices is a wildlife conservation method?
Discouraging poaching directly protects wildlife populations from being illegally hunted to extinction.
39. Which of the following resources cannot be conserved?
Garbage is waste meant to be discarded/managed, not a natural resource that is conserved.
40. The diagrams below are illustrations of types of comb found in domestic fowl. Study them and answer questions 40 and 41. The types of comb show
The different comb shapes shown are examples of (morphological) variation within the species.
41. Which factor is most likely responsible for the various types of comb?
An organism's observable traits (phenotype) are shaped by both genes and environment; per the given answer, environment is identified as the most likely factor here.
42. Which of the following statements about mitosis is not correct?
Mitosis produces two daughter cells (not four) — four daughter cells is a feature of meiosis, making this statement incorrect about mitosis.
43. A mixture of blood with antigen A and blood containing antibody A will
When blood containing a given antigen is mixed with blood containing the matching/contrasting antibody, the red cells clump together — agglutination.
44. Plants suitable for experiments in genetics must not
A long generation time makes it impractical to study inheritance patterns across generations within a reasonable research timeframe.
45. Which of the following statements about sickle cell anaemia is correct?
Sickle cell anaemia is not sex-linked; when both parents are carriers (heterozygous), there is a chance that a child inherits the sickle allele from both, resulting in a sickling (affected) child.
46. In humans, pointed eyebrows (B) is a dominant trait over smooth eyebrows (b). A student and the mother have smooth eyebrows while the father has pointed eyebrows. What is the genotype of the father?
Since the child (student) has smooth eyebrows (bb), each parent must carry a recessive 'b' allele. Since the father shows pointed eyebrows (dominant), his genotype must be heterozygous, Bb.
47. A woman with Rhesus negative blood group was advised not to marry a man with Rhesus positive blood group because
Rhesus incompatibility between an Rh-negative mother and Rh-positive father can cause the mother's immune system to attack the blood cells of an Rh-positive baby, risking serious illness or death of the offspring.
48. Which of the following statements exhibits division of labour?
Termites are social insects with distinct castes (workers, soldiers, queen) each performing specialized roles — a clear example of division of labour.
49. Natural selection arises as a result of
Mutations create new genetic variations, providing the raw material upon which natural selection acts to drive evolution.
50. Which of the following statements is not Lamarck's postulate on evolution?
The idea that survivors in a competitive community must have inherited useful traits reflects Darwin's theory of natural selection, not Lamarck's postulate of inheritance of acquired characteristics.
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