WAEC Biology 2017 past questions

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

Ten questions from the 2017 WAEC Biology paper, with answers and explanations. We hold 57 questions from this paper, and the Skolra app has all of them.

WAEC Biology 2017 questions and answers

1. 1.

   A population which exceeds its carrying capacity and then collapses is represented graphically by a

   1. A
      Horizontal flat line showing a stable population
   2. B
      J-shaped curve with a sharp decline after the peak
      Correct
   3. C
      Straight diagonal line showing constant population growth
   4. D
      Sigmoid (S-shaped) curve that levels off at the carrying capacity
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   Answer: B

   When a population overshoots the carrying capacity and then crashes, the growth curve takes a J-shape with a sharp subsequent decline (sometimes called a boom-and-bust or overshoot-and-collapse curve). A sigmoid (S-shaped) curve represents logistic growth where the population stabilises at the carrying capacity without overshooting. The J-curve overshoot occurs when resources are temporarily abundant, population grows unchecked, and then depletes resources leading to a sharp decline.
2. 2.

   An example of osmosis in plants is the

   1. A
      Absorption of water by root hair cells from the soil
      Correct
   2. B
      Transport of sucrose through phloem by mass flow
   3. C
      Active uptake of mineral ions by root cells against a concentration gradient
   4. D
      Movement of carbon dioxide into the leaf through stomata
   Show answerHide answer

   Answer: A

   Osmosis is the movement of water molecules from a region of higher water potential to a region of lower water potential across a semi-permeable membrane. The absorption of water by root hair cells from the soil solution is a classic example of osmosis in plants — the cell sap of root hairs has a lower water potential (higher solute concentration) than the surrounding soil water, so water moves in by osmosis. Active mineral uptake and phloem transport are not osmosis, and CO₂ movement through stomata is diffusion.
3. 3.

   Which of the following ecological factors will result in food shortage?

   1. A
      Overpopulation exceeding the carrying capacity of an environment
      Correct
   2. B
      Balanced nutrient cycling in a mature ecosystem
   3. C
      Low rate of predation in a stable ecosystem
   4. D
      Increased rainfall promoting plant growth
   Show answerHide answer

   Answer: A

   Overpopulation occurs when the number of individuals in a population exceeds the carrying capacity of the environment — the maximum population size the environment can sustainably support. When this happens, demand for food, water, and space exceeds supply, leading to food shortage. Increased rainfall, balanced nutrient cycling, and low predation are factors that generally promote ecosystem stability and food availability rather than causing food shortage.
4. 4.

   (a) Name one instrument used for collecting:

   (i) soil organism from a soil sample

   (ii) tiny insects from a leaf or a stem.

   (b) make a diagram 6 cm - 8 cm long of the instrument named in (a)(ii) above and label fully.

   (c) Explain briefly the relationship between three examples of symbiotic organisms.
   

   1. A
      A Berlese funnel collects soil organisms; a pooter collects tiny insects from leaves; examples of symbiosis include lichen (alga + fungus), legume root nodules (plant + Rhizobium), and oxpecker birds on buffalo
      Correct
   2. B
      A quadrat collects soil organisms; a sweep net is used for tiny insects; symbiosis only describes parasitic relationships like tapeworm in human gut
   3. C
      A pitfall trap collects soil organisms; a pogonotomy collects tiny insects; symbiosis describes predator-prey relationships only
   4. D
      A transect collects soil organisms; a beating tray collects tiny insects; symbiosis only includes mutualistic relationships such as lichen
   Show answerHide answer

   Answer: A

   A Berlese funnel (or heat funnel) is used to extract soil organisms from a soil sample; a pooter is used to collect tiny insects from leaves or stems by suction. Symbiosis describes a close long-term relationship between two different organisms; examples include lichen (mutualism between alga and fungus), Rhizobium bacteria in legume root nodules (mutualism fixing nitrogen), and tapeworm in the human gut (parasitism where one organism benefits at the host's expense).
5. 5.

   Which of the following function is associated with calcium in plants? Formation of

   1. A
      Middle lamella of the cell wall
      Correct
   2. B
      Amino acids and proteins in the cytoplasm
   3. C
      Chlorophyll molecules in the chloroplasts
   4. D
      ATP during photosynthesis
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   Answer: A

   Calcium in plants is primarily associated with the formation of the middle lamella — the layer of calcium pectate that cements adjacent cell walls together, providing structural rigidity to plant tissues. Calcium also activates certain enzymes and is involved in cell signalling. Magnesium (not calcium) is the central atom of the chlorophyll molecule, while phosphorus is needed for ATP, and nitrogen for amino acid synthesis.
6. 6.

   (a) State four characteristics of enzymes

   (b) (i) List two digestive enzymes produced in the duodenum of humans

   (ii) Name the substrate that each enzyme listed in 2(b)(i) acts on.

   (iii) State the products of each enzyme activity in 2(b)(ii)

   (c) (i) State one way in which chlorophyll is important in plants

   (ii) Name two macroelements that are required for the formation of chlorophyll in plants.

   (iii) State one deficiency symptom of each macroelement named in 2 (c) (ii) above

   (d) Outline the proce-dure used for testing for starch in a leaf
   

   1. A
      Enzymes are inorganic catalysts that are consumed in reactions; duodenal enzymes include pepsin (acts on protein) and amylase (acts on fat); chlorophyll requires phosphorus and calcium
   2. B
      Enzymes can act on any substrate and are not specific; duodenal enzymes include gastrin (acts on proteins) and secretin (acts on fats); chlorophyll requires potassium and sulphur
   3. C
      Enzymes are inorganic proteins, work at any temperature, and are not affected by pH; duodenal enzymes include trypsin (acts on glucose) and amylase (acts on starch); chlorophyll requires iron and zinc
   4. D
      Enzymes are organic catalysts, specific, sensitive to temperature and pH, and reusable; duodenal enzymes include maltase (acts on maltose) and lipase (acts on fat); chlorophyll formation requires nitrogen and magnesium
      Correct
   Show answerHide answer

   Answer: D

   Enzymes are biological catalysts (organic, protein-based), highly specific to their substrates, sensitive to changes in temperature and pH, and are not consumed in reactions (reusable). Duodenal enzymes include trypsin (breaks down proteins into peptides) and lipase (breaks down fats into fatty acids and glycerol). Chlorophyll formation requires nitrogen (for the porphyrin ring protein components) and magnesium (central atom of the porphyrin ring); nitrogen deficiency causes yellowing of older leaves and magnesium deficiency causes interveinal chlorosis.
7. 7.

   Which of the following processes are associated with photosynthesis? I. Energy from sunlight is absorbed II. Carbon dioxide is evolved III. Oxygen is given off IV. Glucose is synthesized

   1. A
      I and II only
   2. B
      I, III and IV only
      Correct
   3. C
      II and III only
   4. D
      I, II and IV only
   Show answerHide answer

   Answer: B

   Photosynthesis involves: (I) absorption of light energy by chlorophyll, (III) release of oxygen as a by-product of the light-dependent stage (photolysis of water), and (IV) synthesis of glucose during the Calvin cycle (light-independent stage). Statement II is incorrect — photosynthesis absorbs carbon dioxide (CO₂) as a raw material; CO₂ is evolved during respiration, not photosynthesis. Therefore the correct processes are I, III, and IV.
8. 8.

   The natural dwelling place of an organism is called its

   1. A
      Habitat
      Correct
   2. B
      Biome
   3. C
      Niche
   4. D
      Ecosystem
   Show answerHide answer

   Answer: A

   A habitat is the natural dwelling place or environment where an organism lives and to which it is adapted. It provides the organism with food, shelter, and conditions for reproduction. An ecosystem includes all living organisms and their physical environment in an area, a biome is a large-scale ecosystem defined by climate and vegetation, and a niche refers to the functional role an organism plays within its ecosystem.
9. 9.

   Which of the following statements is true about mutation?

   1. A
      Mutations involve a sudden heritable change in the genetic material of an organism
      Correct
   2. B
      Mutations can only occur naturally and cannot be induced artificially
   3. C
      Mutations only affect somatic cells and are never passed to offspring
   4. D
      Mutations are always beneficial to the organism and increase fitness
   Show answerHide answer

   Answer: A

   A mutation is a sudden, random, and heritable change in the genetic material (DNA sequence or chromosome structure/number) of an organism. Most mutations are harmful or neutral; only a small proportion are beneficial. Mutations can be induced by mutagens such as X-rays, UV radiation, and certain chemicals. Germline mutations in reproductive cells are heritable and can be passed to offspring, unlike somatic mutations which are confined to body cells.
10. 10.

    Which of the following pyramids gives the most accurate picture of the relationships between at the various trophic levels in a food chain? A pyramid of

    1. A
       Energy
       Correct
    2. B
       Producers
    3. C
       Numbers
    4. D
       Biomass
    Show answerHide answer

    Answer: A

    A pyramid of energy gives the most accurate picture of trophic relationships because it accounts for the rate of energy flow per unit area per unit time, overcoming the distortions of pyramids of numbers (affected by organism size) and pyramids of biomass (affected by timing of measurement). A pyramid of energy is always upright and cannot be inverted, reflecting the fundamental thermodynamic principle that energy is lost at each trophic level.

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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