WAEC Biology 2015 past questions

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

Ten questions from the 2015 WAEC Biology paper, with answers and explanations. We hold 48 questions from this paper, and the Skolra app has all of them.

WAEC Biology 2015 questions and answers

1. 1.When a Spirogyra filament is placed in a concentrated salt solution for 30 minutes, the cell would become
   1. A
      turgid and enlarged due to water entry
   2. B
      plasmolyzed, with the cytoplasm shrinking away from the cell wall
      Correct
   3. C
      green and more photosynthetically active
   4. D
      swollen with a rigid cell wall pressing outward
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   Answer: B

   When Spirogyra is placed in a concentrated salt solution (hypertonic solution), water moves out of the cell by osmosis down the water potential gradient. This causes the cytoplasm and vacuole to shrink, and the plasma membrane pulls away from the cell wall — a process called plasmolysis. The cell wall remains intact but the protoplast shrinks. This is the opposite of turgidity; turgidity occurs when cells are placed in a hypotonic (less concentrated) solution and water enters the cell. Plasmolysis is used in biology experiments to demonstrate osmosis.

2. 2.Which of the following cells is a specialized cell?
   1. A
      Red blood cell
      Correct
   2. B
      Epithelial skin cell
   3. C
      General fat storage cell
   4. D
      Liver parenchyma cell
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   Answer: A

   The red blood cell (erythrocyte) is a highly specialized cell uniquely adapted for its function of oxygen transport. Its specializations include the biconcave disc shape that maximizes surface area, the absence of a nucleus (allowing more room for haemoglobin), and the presence of large amounts of haemoglobin for oxygen binding. These adaptations represent a complete departure from the generalized cell plan. Liver, skin epithelial, and fat cells retain most standard cell organelles and are considered generalized by comparison.

3. 3.The colour change to be observed in step IV is
   1. A
      blue to yellow then green
   2. B
      colourless to deep purple
   3. C
      yellow to iodine-blue-black
   4. D
      blue to brick-red (orange-red) precipitate
      Correct
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   Answer: D

   When Benedict's solution reacts with a reducing sugar (produced by hydrolysis of the non-reducing sugar in step II), the blue copper(II) sulphate is reduced to copper(I) oxide. This produces a characteristic colour change from blue to brick-red (or orange-red) precipitate. The intensity of the colour (from green → yellow → orange → brick-red) indicates the concentration of reducing sugar present. The iodine test gives a blue-black colour for starch. Deep purple is associated with the Biuret test for proteins. No yellow colour appears in Benedict's test under standard conditions.

4. 4.The main difference between a seed and a fruit is that a fruit
   1. A
      always contains only one seed enclosed in a hard coat
   2. B
      develops directly from the ovule after fertilization
   3. C
      develops from the ovary wall and may contain one or more seeds
      Correct
   4. D
      contains the embryo and food reserves inside the testa
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   Answer: C

   A fruit is a mature ovary (and sometimes associated floral parts) that develops after fertilization. Its wall is the pericarp, which may be fleshy (as in tomato) or dry (as in groundnut). A seed, by contrast, develops from a fertilized ovule and contains the embryo plus food reserves (endosperm or cotyledons) enclosed within the testa (seed coat). Fruits may contain one to many seeds depending on the number of ovules in the original ovary. This structural distinction is fundamental in plant reproductive biology and systematic botany.

5. 5.A person suffering from obstruction of the bile duct is advised not to eat fats and oil because
   1. A
      bile neutralizes the acidity within fat globules before they enter the duodenum
   2. B
      fats cannot be absorbed across the intestinal wall without bile acting as a specific carrier protein
   3. C
      bile contains the enzyme lipase which directly breaks down fat molecules
   4. D
      bile is needed to emulsify fats into tiny droplets so that lipase can act on them efficiently
      Correct
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   Answer: D

   Bile is produced by the liver and stored in the gall bladder. It does not contain digestive enzymes but performs emulsification — breaking large fat droplets into smaller ones, greatly increasing the surface area available for the enzyme lipase to work on. Without bile (due to bile duct obstruction), fats cannot be efficiently digested or absorbed. This leads to fatty stools (steatorrhoea) and deficiency of fat-soluble vitamins (A, D, E, K). Lipase itself is secreted by the pancreas, not contained in bile.

6. 6.

   (a)(i) What is sewage?
   (ii) State five effects of releasing untreated sewage into a stagnant water body.

   (b) Explain surface terracing as a soil conservation method.

   (c) Explain the term adaptation.

   (d) Explain two ways each by which the following organisms adapt to their habitats:
   (i) hydrophytes
   (ii) xerophytes.
   

   1. A
      Liquid waste from domestic, industrial and agricultural activities
      Correct
   2. B
      Treated and purified water released from water treatment plants
   3. C
      Rainwater mixed with eroded soil particles from hillsides
   4. D
      Solid agricultural waste that accumulates along river banks
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   Answer: A

   Sewage is defined as liquid waste water that originates from domestic sources (toilets, sinks), industrial processes, and agricultural runoff. It contains organic matter, pathogens, heavy metals, and chemical pollutants. Releasing untreated sewage into water bodies removes dissolved oxygen, causes eutrophication, and introduces disease-causing organisms. Sewage treatment involves physical, chemical, and biological processes to remove contaminants before the water can be safely returned to the environment.

7. 7.Which of the following natural resources is most readily available to all organisms?
   1. A
      Fresh water from rivers and lakes
   2. B
      Sunlight (solar energy)
      Correct
   3. C
      Soil minerals and nutrients
   4. D
      Fossil fuels and petroleum
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   Answer: B

   Sunlight is the most universally available natural resource, reaching virtually every living organism on Earth at no cost and with no special access requirements. It is the primary energy source driving almost all ecosystems through photosynthesis in producers. Soil minerals require physical access to specific locations, fresh water is unevenly distributed geographically, and fossil fuels are non-renewable and inaccessible to most organisms. Even deep-sea organisms benefit indirectly from solar energy through organic matter that sinks from sunlit surface waters.

8. 8.How many chromosomes will be in a gamete if the normal cell has four chromosomes?
   1. A
      4
   2. B
      2
      Correct
   3. C
      1
   4. D
      8
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   Answer: B

   Gametes are produced by meiosis, which halves the chromosome number from the diploid (2n) number found in somatic cells to the haploid (n) number. If the normal cell has 2n = 4 chromosomes, the gametes produced will each contain n = 2 chromosomes. This reduction is essential so that when two gametes fuse during fertilization, the resulting zygote has the correct diploid number (2n = 4) rather than a doubled count. The process of meiosis I separates homologous chromosome pairs, and meiosis II separates sister chromatids to yield four haploid cells.

9. 9.The following organisms have structures for movement except
   1. A
      mushroom, which lacks any locomotory structure
      Correct
   2. B
      Amoeba, which uses pseudopodia for locomotion
   3. C
      Paramecium, which uses cilia for locomotion
   4. D
      Euglena, which uses a flagellum for locomotion
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   Answer: A

   The mushroom (a fungus) has no locomotory structures and cannot move from place to place. It is a sessile organism attached to its substrate. Paramecium uses numerous cilia for swimming, Euglena uses a flagellum, and Amoeba extends cytoplasmic projections called pseudopodia to move and engulf food. Locomotion in unicellular organisms allows them to move toward nutrients and away from unfavourable conditions. The mushroom disperses by releasing spores into the air rather than by whole-organism movement.

10. 10.Water and salts are both lost from the human body in
    1. A
       expired air only
    2. B
       tears and saliva only
    3. C
       bile secreted into the duodenum
    4. D
       urine and sweat
       Correct
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    Answer: D

    Both urine and sweat contain water and dissolved mineral salts (electrolytes such as sodium, potassium, and chloride ions). Urine is produced by the kidneys as they filter blood and excrete nitrogenous wastes along with excess water and salts. Sweat from eccrine sweat glands also carries water and electrolytes to regulate body temperature. Expired air contains water vapour but essentially no salts. Bile contains bile salts but these are reabsorbed in the ileum and recycled in the enterohepatic circulation.

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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