WAEC Biology 2003 past questions

Checked by the Skolra question team · Last updated 15 October 2026

Ten questions from the 2003 WAEC Biology paper, with answers and explanations. We hold 40 questions from this paper, and the Skolra app has all of them.

WAEC Biology 2003 questions and answers

1. 1.Which of the following is considered to be the first product of photosynthesis?
   1. A
      Water
   2. B
      Carbon dioxide
   3. C
      Glucose
      Correct
   4. D
      Oxygen
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   Answer: C

   The first stable organic product of photosynthesis is glucose. In the light-independent (dark) stage, carbon dioxide is fixed using ATP and NADPH produced in the light stage, ultimately yielding glucose through the Calvin cycle. Oxygen is a by-product released during the light stage from photolysis of water, but glucose is regarded as the primary product of the overall process.

2. 2.Which of the following is the function of the iris of the mammalian eye?
   1. A
      Focuses light rays onto the retina
   2. B
      Controls the amount of light entering the eye
      Correct
   3. C
      Detects colour and light intensity
   4. D
      Provides nutrients to the lens and cornea
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   Answer: B

   The iris is the coloured, muscular diaphragm of the eye that surrounds the pupil. Its circular and radial muscles adjust the size of the pupil to regulate how much light enters the eye — the pupil constricts in bright light and dilates in dim light. Focusing is done by the lens, not the iris.

3. 3.The gas produced during decomposition of matter is
   1. A
      Carbon dioxide
      Correct
   2. B
      Oxygen
   3. C
      Nitrogen
   4. D
      Hydrogen
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   Answer: A

   During aerobic decomposition of organic matter by decomposers (bacteria and fungi), carbon and hydrogen in organic molecules are oxidised. The main gas produced and released into the atmosphere is carbon dioxide (CO₂). Methane (CH₄) is produced in anaerobic conditions, but CO₂ is the primary gaseous product of decomposition overall.

4. 4.The layer of light-sensitive cells in the human eye is called the
   1. A
      Retina
      Correct
   2. B
      Sclera
   3. C
      Cornea
   4. D
      Choroid
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   Answer: A

   The retina is the innermost, light-sensitive layer of the human eye. It contains photoreceptor cells — rods (for dim light and peripheral vision) and cones (for colour and detail in bright light). When light hits the retina, it triggers nerve impulses that travel via the optic nerve to the brain for interpretation.

5. 5.Which of the following statements about water in humans is not correct? it
   1. A
      Helps regulate body temperature through sweating
   2. B
      Acts as a solvent for biochemical reactions
   3. C
      Facilitates transport of nutrients and waste in blood
   4. D
      Provides energy for metabolic activities
      Correct
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   Answer: D

   Water performs many vital roles in the human body: it dissolves substances, regulates temperature (through sweating and evaporation), transports nutrients and wastes in blood, and participates in chemical reactions. However, water does not provide energy — energy is derived from carbohydrates, fats, and proteins, not from water.

6. 6.Fish cannot survive on land because it has
   1. A
      Scales that prevent gaseous exchange through the skin
   2. B
      Fins instead of limbs for locomotion
   3. C
      A streamlined body shape unsuitable for land
   4. D
      Gills that require water for breathing
      Correct
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   Answer: D

   Fish breathe using gills, which extract dissolved oxygen from water passing over their gill filaments. On land, the gills collapse, dry out, and can no longer carry out gaseous exchange. Fish also lack lungs and cannot extract oxygen from atmospheric air, making terrestrial survival impossible.

7. 7.Competition among individuals of a population increases the
   1. A
      Rate of reproduction
   2. B
      Food supply in the habitat
   3. C
      Total size of the population
   4. D
      Survival of the fittest individuals
      Correct
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   Answer: D

   When individuals within a population compete for limited resources such as food, space, and mates, only the best-adapted individuals survive to reproduce. This intraspecific competition therefore increases the survival of the fittest individuals, which is the mechanism of natural selection described by Darwin. It tends to decrease, not increase, total population size and food supply.

8. 8.Which of the following is not a behavioural adaptation used by social animals?
   1. A
      Communication through signals and calls
   2. B
      Cooperative defence against predators
   3. C
      Camouflage to avoid predators
      Correct
   4. D
      Division of labour among group members
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   Answer: C

   Behavioural adaptations of social animals include division of labour (e.g. worker bees), cooperative defence (e.g. meerkat sentinel duty), and communication through signals, pheromones, or calls. Camouflage is a structural (physical) adaptation — it involves body colouration or pattern, not a behaviour — and it is typically an individual rather than social strategy.

9. 9.Which of the following values showing the total biomass of organisms in a food chain represents the secondary consumer?
   1. A
      10 kg
   2. B
      10,000 kg
   3. C
      100 kg
      Correct
   4. D
      1,000 kg
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   Answer: C

   In a pyramid of biomass, biomass decreases at each successive trophic level because energy is lost as heat. In a typical food chain: producers (10,000 kg) → primary consumers (1,000 kg) → secondary consumers (100 kg) → tertiary consumers (10 kg). The secondary consumer occupies the third trophic level, so it has the third-highest biomass value.

10. 10.Sickle-cell anaemia has persisted in the human race due to
    1. A
       Protection against malaria conferred on heterozygous carriers
       Correct
    2. B
       Resistance to all blood-borne infectious diseases
    3. C
       High frequency of spontaneous mutations in the sickle-cell gene
    4. D
       Increased fertility observed in homozygous sickle-cell individuals
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    Answer: A

    Sickle-cell anaemia has persisted in populations in malaria-endemic regions because individuals who are heterozygous carriers (HbAS) — carrying one normal and one sickle-cell allele — have a selective advantage: their red blood cells are less hospitable to Plasmodium falciparum, giving them significant protection against severe malaria. This balanced polymorphism maintains the allele at high frequency despite the lethal effects of the homozygous (HbSS) state.

The questions come from past JAMB, WAEC and NECO papers. We use software to help write the answer options and explanations, and every answer is checked twice before it goes on the site. How we check

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