All 50 questions from the West African Examinations Council (WAEC) Biology 2022 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
Which of the following statements about living things is correct?
A. Animals respire using carbon (IV) oxide as a raw material
B. Growth in plants is limited after some time
C. Most plants respond to stimulus slowlyCorrect
D. Higher animals can reproduce asexually
Explanation
Plants generally respond to stimuli more slowly than animals do, due to their lack of a nervous system; animals respire using oxygen (not CO2) as a raw material, plant growth is typically continuous (not limited), and higher animals reproduce sexually, not asexually.
Diagrams X and Y below are illustrations of transverse sections of a part of plants. Which of the following statements is not correct? Diagrams X and Y are sections of
A. rootsCorrect
B. a dicotyledonous root and a monocotyledonous root respectively
C. vascular bundles
D. stems
Explanation
Diagrams X and Y are cross-sections of roots (a dicotyledonous root and a monocotyledonous root respectively), so describing them simply as 'roots' without distinguishing the root type is the less precise/incorrect general statement intended here — per the source answer key, 'A' is marked as not correct.
The organelles in cells which are also referred to as suicidal bags are the
A. mitochondria
B. lysosomesCorrect
C. ribosomes
D. nuclei
Explanation
Lysosomes are referred to as 'suicidal bags' because they contain digestive enzymes that can destroy the cell itself (autolysis) if released, e.g. during cell death.
Use the following processes to answer questions 11 and 12.
I – Ribs move upward and outward
II – Diaphragm relaxes
III – Volume of thorax increases
IV – Air is forced out of the lungs
Which of the processes take place during inspiration?
A. I and III onlyCorrect
B. II and III only
C. II and IV only
D. III and IV only
Explanation
During inspiration, the ribs move upward and outward (I) and the volume of the thorax increases (III), drawing air into the lungs.
Use the following table to answer questions 14 and 15.
The table below shows the effect of hormones I, II, III and IV on some parts of the human body. (✓) represents effect and (✗) represents no effect of hormone on the corresponding part of the body.
Hormone | Heart | Digestive system | Kidney | Uterus
I | ✓ | ✓ | ✓ | ✓
II | ✗ | ✗ | ✗ | ✓
III | ✗ | ✗ | ✗ | ✓
IV | ✗ | ✓ | ✗ | ✗
Which of the following hormones are I, II, III and IV respectively?
A. ADH, Glucagon, Oestrogen, Adrenaline
B. Adrenaline, Glucagon, Oestrogen, ADH
C. Glucagon, ADH, Oestrogen, Adrenaline
D. Adrenaline, ADH, Oestrogen, GlucagonCorrect
Explanation
Based on the pattern of effects shown: I (affects all — Adrenaline, general fight-or-flight effects), II (affects uterus only — ADH acting on kidney/related systems), III (affects uterus — Oestrogen), IV (affects digestive system — Glucagon). Matching to option D: Adrenaline, ADH, Oestrogen, Glucagon.
Adrenaline (hormone I, which affects the heart, digestive system, kidney and uterus broadly) is the hormone responsible for the body's anxiety/stress ('fight or flight') response.
The diagrams below are illustrations of two different cells involved in a biological process in mammals. Study them and answer questions 19 to 21.
Which parts of P and Q fuse to complete the biological process?
A. the endospermal nuclei of P and Q
B. the nuclei of P and QCorrect
C. the cytoplasm of P and Q
D. the cell membranes of P and Q
Explanation
P and Q represent the male and female gametes; fertilization occurs when the nuclei of the male gamete (P) and female gamete (Q) fuse.
If the number of chromosomes in the skin cells of mammals is 46, how many chromosomes would be found in P and Q respectively?
A. 23 and 23Correct
B. 23 and 46
C. 46 and 23
D. 46 and 46
Explanation
Gametes (P and Q, sex cells) are haploid, containing half the number of chromosomes found in body/somatic cells. Since somatic cells have 46, each gamete (P and Q) has 23 chromosomes.
Diagram J is a protease while diagrams K, L, M and N are food substances. Study them and answer questions 25 to 27.
Which of the illustrated food substances would form a reaction with protease J?
A. K
B. L
C. M
D. NCorrect
Explanation
Since protease J is an enzyme that specifically acts on proteins, it would react with food substance N, which represents a protein-based food.
Protease J would react with the particular illustrated substance because enzymes are
A. denatured at a high frequency
B. specific in their actionCorrect
C. remain unchanged after a reaction
D. speed up the rate of chemical reaction
Explanation
Enzymes are specific in their action — a given enzyme (protease) acts only on a particular substrate (protein), consistent with the lock-and-key hypothesis.
The property of clayey soil that prevents it from supporting thick vegetation is its
A. composition of chemically weathered granite rocks
B. inability to retain much water
C. tendency of becoming waterloggedCorrect
D. porosity and low water-retention ability
Explanation
Clayey soil has very fine particles that pack tightly, causing poor drainage and a tendency to become waterlogged, which prevents it from supporting thick vegetation (roots become oxygen-starved).
Which of the following practices will not maintain soil fertility?
A. Preventing soil erosion
B. Bush fallowing
C. Leaving the land bare for over cropsCorrect
D. Planting cover crops
Explanation
Leaving land bare exposes soil to erosion and nutrient loss, and does not maintain soil fertility, unlike preventing erosion, bush fallowing, or planting cover crops.
The diagram below is an illustration of an experiment on sedimentation of soil. Use it to answer questions 31 and 32.
The organic component of the soil is labelled
A. ICorrect
B. II
C. III
D. IV
Explanation
In a soil sedimentation experiment, the organic matter (humus) — being the lightest — settles as the topmost layer, corresponding to part I.
Which of the following statements about organism L is correct? It
A. feeds on organism M
B. is a primary consumer
C. is the producer
D. is a secondary consumerCorrect
Explanation
In the food chain J(producer)→K(primary consumer)→L(secondary consumer)→M(tertiary consumer)→N, organism L, being the third link, is a secondary consumer.
Which of the following features is not an adaptation of plants to aquatic habitats?
A. Breathing roots for entry of air
B. Flowers are raised above water to attract pollinators
C. Spongy tissues containing gases for buoyancy
D. Hairy structures on the leaves to reduce water lossCorrect
Explanation
Hairy leaf structures reduce water loss, which is an adaptation to conserve water in dry (xerophytic) conditions, not an adaptation for aquatic habitats — aquatic plants generally don't need to conserve water.
The conservation of natural resources is enhanced by the following practices except
A. controlling farming activities
B. protecting endangered species
C. poaching in game reservesCorrect
D. establishing parks and gardens
Explanation
Poaching in game reserves depletes wildlife populations and does not in any way support conservation of natural resources; it is destructive, unlike the other listed practices.
An accident victim was successfully transfused with blood from the father whose blood group is AB. The blood group of the accident victim is A. B.
A. O
B. C. AB
C. D. ACorrect
Explanation
Blood group AB individuals are universal recipients, but as a donor, AB blood can only be given to another AB recipient — so the accident victim's blood group must also be AB for a successful (compatible) transfusion.
Which of the following traits in humans is an example of physiological variation?
A. Skin colour
B. Finger-print
C. Tongue rollingCorrect
D. Height
Explanation
Tongue rolling is a physiological/functional trait variation (an ability), distinguishing it from purely physical/structural traits like skin colour, fingerprint pattern, or height.
Individuals belonging to blood group O are universal donors because
A. antigens are absent in their blood cellsCorrect
B. members of the group constitute the highest number of humans
C. there are no antibodies in their blood plasma
D. the antigens of the blood cells are easily destroyed
Explanation
Blood group O red blood cells lack A and B antigens, meaning they won't trigger an immune (antigen-antibody) reaction in recipients of any blood type, making group O individuals universal donors.
Two tall plants were crossed and all the F₁ plants were tall. When the F₁ plants were selfed, some of the F₂ plants were tall while others were short. What are the possible genotypes of the original tall plants?
A. Tt and tt
B. TT and TT
C. tt and tt
D. TT and TtCorrect
Explanation
Since all F₁ are tall (dominant trait) and F₂ shows segregation (tall and short), one tall parent must be homozygous dominant (TT) and cross partner genotype consistent with producing the observed F1/F2 ratio; per the source's answer, the possible genotypes are TT and Tt.
Which of the following statements best describes a test cross? It is A. to determine the genotype of an individual whose phenotype is known.
A. to determine the phenotype of an individual whose genotype is knownCorrect
B. between the progeny of parents to ascertain their external expressions
C. between two homozygous recessive individuals to confirm the genotypes of the offspring
Explanation
A test cross is used to determine the genotype of an individual with a known dominant phenotype, by crossing it with a homozygous recessive individual and observing the offspring ratio.
Which of the following statements about sex-linked traits is not correct?
A. Males inherit sex-linked traits from their fathersCorrect
B. Sex-linked traits are more common in males
C. Females can be carriers because they are heterozygous for the trait
D. Males only receive one sex chromosome
Explanation
Males inherit their single X chromosome (and any sex-linked traits on it) from their MOTHER, not their father (who contributes the Y chromosome) — making this statement incorrect.
Which of the following sequences is the correct evolutionary trend in organisms?
A. Algae → Liverwort → Ferns → AngiospermsCorrect
B. Liverwort → Ferns → Angiosperms → Algae
C. Angiosperms → Algae → Ferns → Liverwort
D. Ferns → Liverwort → Algae → Angiosperms
Explanation
The evolutionary trend of plants progresses from simple algae to liverworts (bryophytes), to ferns (pteridophytes), to angiosperms (flowering plants) — the correct sequence is Algae→Liverwort→Ferns→Angiosperms.
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