All 40 questions from the Joint Admissions and Matriculation Board (JAMB) Biology 2022 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
1. A circulatory system is very essential in mammals but not in smaller organisms like amoeba because
A. (A) Amoeba lives in fresh water
B. (B) Diffusion is sufficient to transport materials in AmoebaCorrect
C. (C) Amoeba lacks blood containing haemoglobin
D. (D) Amoeba exhibits anaerobic respiration
Explanation
Amoeba, being a unicellular organism, has a large surface area to volume ratio; diffusion alone is sufficient as a means of transport, so it does not need a circulatory system.
2. In vascular plants, the sieve tubes and companion cells are present in the
A. (A) phloemCorrect
B. (B) cambium
C. (C) xylem
D. (D) cortex
Explanation
The phloem has four elements: sieve tubes, companion cells, phloem parenchyma and phloem fibres. Xylem, by contrast, comprises tracheids, vessels, xylem parenchyma and xylem fibres.
5. The study of how and why population size changes over time is
A. (A) population cycle
B. (B) population estimation
C. (C) population ecology
D. (D) population dynamicsCorrect
Explanation
Population dynamics is the study of how and why populations change in size and structure over time, including rates of reproduction, death and migration.
6. The soil with the highest water-retaining capacity is
A. (A) loamy soil
B. (B) clayey soilCorrect
C. (C) sandy soil
D. (D) stoney soil
Explanation
Clay soil has the highest water-retaining capacity and highest capillarity. Sandy soil, by contrast, has the lowest water-retaining capacity and lowest capillarity, and is the least water-logged.
Poikilothermic (cold-blooded) animals are those whose body temperature varies with that of their environment; fishes, amphibians and reptiles (like the lizard) are poikilothermic, while birds and mammals are homeothermic (warm-blooded).
9. The process by which complex substances are broken down into simpler ones is referred to as
A. (A) photosynthesis
B. (B) respiration
C. (C) anabolism
D. (D) catabolismCorrect
Explanation
Catabolism is the process by which complex substances are broken down into simpler ones (anabolism, by contrast, is the process by which simple substances are joined to form complex ones).
13. The blood circulatory system of vertebrates consists of
A. (A) heart, vena cava, arteries and veins
B. (B) heart, arteries, veins and capillariesCorrect
C. (C) heart, aorta, arteries and veins
D. (D) heart, aorta, capillaries and veins
Explanation
The blood circulatory system of vertebrates consists of the heart, arteries, veins and capillaries (note that the aorta is itself an artery and the vena cava is itself a vein).
16. Which of the following is caused by Treponema pallidum?
A. (A) SyphilisCorrect
B. (B) Leprosy
C. (C) Gonorrhea
D. (D) Tuberculosis
Explanation
Syphilis is caused by Treponema pallidum. Gonorrhea is caused by Neisseria gonorrhoeae, Tuberculosis by Mycobacterium tuberculosis, and Leprosy by Mycobacterium leprae.
18. One of the adaptations of Cactus to conserve water is the reduction of
A. (A) flower size
B. (B) internodes
C. (C) leavesCorrect
D. (D) stem
Explanation
Since the rate of transpiration depends on the surface area of leaves, the reduction of leaves to spines (as seen in Cactus opuntia) is one way the plant conserves water.
26. The absence of an alimentary canal in the parasitic flatworm can be attributed to the fact that
A. (A) it has suckers on the scolex
B. (B) it does not feed
C. (C) it has no enzymes
D. (D) its body absorbs digested foodCorrect
Explanation
Parasitic flatworms such as tapeworms do not possess an alimentary canal because they absorb already digested food directly through their body surface (they use their suckers only for attachment to the host's intestine).
27. Rhizobium which lives in the root nodules of leguminous plants is an example of the association known as
A. (A) saprophytism
B. (B) mutualismCorrect
C. (C) epiphytism
D. (D) commensalism
Explanation
The relationship between Rhizobium and leguminous plants is an example of mutualism: the bacterium helps the plant fix nitrogen, while the plant provides food and shelter for the bacterium.
28. The gene that is only located on X-chromosomes is said to be
A. (A) expressed in males only
B. (B) dominant
C. (C) expressed in females only
D. (D) sex linkedCorrect
Explanation
Sex-linked characters are located only on the X-chromosome and are usually recessive; a male, having only one copy of the X-chromosome, is either normal or affected, while a female may be normal, a carrier, or affected.
35. Which of the following instruments is used for measuring air pressure?
A. (A) Secchi disc
B. (B) photometer
C. (C) barometerCorrect
D. (D) hygrometer
Explanation
The barometer is the instrument for measuring air pressure (a Secchi disc measures water turbidity, a photometer measures light intensity, and a hygrometer measures relative humidity).
37. Which of the following diseases is transmittable through genes?
A. (A) Presbyopia
B. (B) Diabetes
C. (C) sickle cell anaemiaCorrect
D. (D) HIV/AIDS
Explanation
Sickle cell anaemia is a heritable (genetically transmitted) disease that affects the red blood cells, turning them from round flexible discs into sickle-shaped cells that do not live as long as normal red blood cells.
38. Bees are of great importance to the farmer because they
A. (A) provide him with honey
B. (B) sting crop pests to death
C. (C) pollinate flowersCorrect
D. (D) destroy flowers
Explanation
Bees are of great importance to the farmer because they pollinate flowers (flowers that are pollinated by insects like bees are called entomophilous flowers).
40. Which of the following organisms is both carnivorous and autotrophic?
A. (A) sundewCorrect
B. (B) Tapeworm
C. (C) Rhizopus
D. (D) Loranthus
Explanation
Insectivorous plants like the sundew are both carnivorous (they trap and digest insects to supplement their nitrogen needs) and autotrophic (they manufacture their own food through photosynthesis).
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