WAEC Biology 2018 past questions

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

Ten questions from the 2018 WAEC Biology paper, with answers and explanations. We hold 67 questions from this paper, and the Skolra app has all of them.

WAEC Biology 2018 questions and answers

1. 1.

   LIST OF SPECIMENS

   • Specimen A - Fresh/wet preserved mosquito larva in a Petri dish containing water.
   • Specimen B - Fresh/wet preserved maggot in a Petri dish containing water.
   • Specimen C - Gill of fish (freshly procured) in a Petri dish containing water.
   • Specimen D - Lung of a small mammal (freshly preserved).
   • Specimen E - Dicotyledonous leaf (freshly plucked).
   • Specimen F - Membranous wing of a Cockroach.
   • Specimen K - Flower of Pride of Barbados or Caesalpinia.
   • Specimen L - Mature Elephant grass or Guinea grass.
   • Specimen M - Flower of Hibiscus plant.

   1. Study specimens A and B and answer questions 1(a) to 1(c).

   (a)(i) Name the habitat of each of specimens A and B.

   (ii) Name the adult stage into which each of specimens A and B would develop.

   (iii) Name the phylum and class common to the adult stages of specimens A and B.

   (b) State three observable features of biological significance in:

   (i) Specimen A;

   (ii) Specimen B.

   (c)(i) State four observable structural differences between specimens A and B.

   (ii) State three observable similarities between specimens A and B.

   1. A
      Flowing freshwater streams
   2. B
      Decaying organic matter in compost
   3. C
      Dry sandy soil
   4. D
      Stagnant or still water
      Correct
   Show answerHide answer

   Answer: D

   Mosquito larvae are aquatic and thrive specifically in stagnant (still) water such as ponds, puddles, water-filled containers, and swamps. They hang from the water surface and breathe atmospheric air through a siphon tube. Flowing water does not suit them because currents would dislodge and sweep them away. Controlling mosquito populations therefore involves eliminating stagnant water around human settlements.
2. 2.

   Active transport differs from diffusion in that active transport

   1. A
      requires metabolic energy (ATP) and can move substances against a concentration gradient
      Correct
   2. B
      always moves substances from regions of high to low concentration
   3. C
      occurs only in plant cells and never in animal cells
   4. D
      does not require the presence of a cell membrane
   Show answerHide answer

   Answer: A

   Active transport differs fundamentally from diffusion in that it requires metabolic energy (ATP) and uses specific carrier proteins to move substances against their concentration gradient — from low to high concentration. Diffusion is a passive process driven by the concentration gradient, requiring no energy. Active transport is essential for processes such as the absorption of glucose and amino acids in the small intestine, the reabsorption of glucose in the kidney tubule, and the uptake of mineral ions by plant root cells against a gradient.
3. 3.

   Which of the following practices may lead to infection of the eye? Use of

   1. A
      prescribed antibiotic eye drops
   2. B
      a common towel shared among several people
      Correct
   3. C
      protective safety glasses in a laboratory
   4. D
      clean running water to wash the eyes
   Show answerHide answer

   Answer: B

   Using a common (shared) towel is a major route of transmission for eye infections such as conjunctivitis (pink eye), which can be caused by bacteria (Staphylococcus), viruses (adenovirus), or even the trachoma agent (Chlamydia trachomatis). Pathogens deposited on the towel by an infected person are transferred directly to the next user's eye. Using clean water, prescribed drops, or protective glasses does not spread infection — these are protective practices. Hygiene education emphasises individual towels and handwashing to prevent eye disease.
4. 4.

   The greatest contribution to genetic studies was made by

   1. A
      Louis Pasteur
   2. B
      Charles Darwin
   3. C
      Robert Hooke
   4. D
      Gregor Mendel
      Correct
   Show answerHide answer

   Answer: D

   Gregor Mendel (1822–1884) is considered the father of genetics. Through careful, quantitative experiments on pea plants, he formulated the laws of segregation and independent assortment, establishing the foundational principles of heredity. Darwin contributed to evolutionary theory; Robert Hooke discovered cells; Louis Pasteur disproved spontaneous generation and developed germ theory. Mendel's work, rediscovered in 1900, directly underpins modern molecular genetics, genomics, and biotechnology.
5. 5.

   An association between living organisms in which one lives on and feeds at the expense of the other is known as

   1. A
      Commensalism
   2. B
      Predation
   3. C
      Parasitism
      Correct
   4. D
      Mutualism
   Show answerHide answer

   Answer: C

   Parasitism is an interspecific relationship in which the parasite benefits by living on or in a host organism, feeding at the host's expense and often causing it harm. Examples include tapeworms in mammals, Plasmodium in humans, and mistletoe on trees. Mutualism benefits both organisms; commensalism benefits one while the other is unaffected; predation involves one organism killing and consuming another, which is distinct from parasitism where the host usually survives (at least temporarily).
6. 6.

   Which of the following instruments is used to determine the turbidity of water?

   1. A
      Anemometer
   2. B
      Secchi disc
      Correct
   3. C
      Thermometer
   4. D
      Hygrometer
   Show answerHide answer

   Answer: B

   A Secchi disc is a simple instrument used to measure water turbidity (cloudiness or clarity). It is a white disc lowered into the water until it disappears from view; the depth at which it vanishes is the Secchi depth, which indicates water transparency. High turbidity reduces light penetration and can affect aquatic photosynthesis and dissolved oxygen levels. A hygrometer measures humidity; a thermometer measures temperature; an anemometer measures wind speed.
7. 7.

   (a) Explain briefly the following terms:

   1. ecosystem;
   2. abiotic environment.

   (b) List three ecological factors each which are specific to:

   1. aquatic habitats;
   2. terrestrial habitats.

   (c) State briefly the relationship between green grass and a rabbit in a given habitat.
   (d) Draw a typical pyramid of energy using four feeding levels.

   1. A
      All organisms of the same species living together in one area
   2. B
      The total number of species found in a given geographic region
   3. C
      A community of living organisms interacting with their physical environment
      Correct
   4. D
      All the physical and chemical components of an environment only
   Show answerHide answer

   Answer: C

   An ecosystem is defined as a system comprising a community of living organisms (biotic components) interacting with each other and with their non-living (abiotic) physical environment. Examples include a pond, a forest, or a grassland. The biotic components include producers, consumers, and decomposers, while abiotic components include sunlight, temperature, water, and soil. The concept of an ecosystem emphasises the interdependence of living and non-living components in energy flow and nutrient cycling.
8. 8.

   (a) State five processes involved in the water cycle.
   (b) Name one instrument used for measuring each of the following physical factors:

   1. pH;
   2. light intensity;
   3. turbidity;
   4. temperature.

   (c) Explain briefly the contributions of the following scientists to the formulation of the cell theory:

   1. Robert Hooke;
   2. Theodore Schwann.

   (d) What is meant by each of the following terms:

   1. Nastism
   2. Taxism

   (e) Make a diagram, 6 cm – 8 cm long of the human tongue illustrating the four areas of taste.
   (f)(i) List four ways through which microorganisms enter the human body.
   (ii) State three harmful effects of microorganisms to humans.

   1. A
      Secchi disc
   2. B
      pH meter
      Correct
   3. C
      Anemometer
   4. D
      Thermometer
   Show answerHide answer

   Answer: B

   A pH meter (or pH probe) is the instrument used to measure the acidity or alkalinity of water. pH is an important abiotic factor that affects aquatic organisms and nutrient availability. A thermometer measures temperature; an anemometer measures wind speed; and a Secchi disc measures water turbidity (clarity). Accurate pH measurement helps ecologists assess habitat suitability and monitor the effects of pollution such as acid rain.
9. 9.

   The exchange of genes between homologous chromosomes is called

   1. A
      Mutation
   2. B
      Segregation
   3. C
      Crossing over
      Correct
   4. D
      Linkage
   Show answerHide answer

   Answer: C

   Crossing over (recombination) occurs during prophase I of meiosis, when homologous chromosomes pair up (synapsis) and exchange corresponding segments at points called chiasmata. This process reshuffles alleles between homologues, generating new combinations of genetic material in the resulting gametes and increasing genetic diversity. Mutation involves changes in the DNA sequence; linkage describes genes on the same chromosome; segregation refers to the separation of alleles during gamete formation.
10. 10.

    Conservation of wildlife is necessary mainly because

    1. A
       it helps maintain biodiversity and the balance of natural ecosystems
       Correct
    2. B
       it prevents all natural disasters such as floods and droughts
    3. C
       it generates tourism revenue for government treasuries
    4. D
       it supplies bushmeat protein to growing rural communities
    Show answerHide answer

    Answer: A

    The primary reason for wildlife conservation is to maintain biodiversity and protect the stability and balance of natural ecosystems. Every species plays a role in its ecosystem — as a predator, prey, pollinator, decomposer, or otherwise — and the loss of species can trigger cascading ecological effects. Biodiversity also provides genetic resources for medicine, agriculture, and biotechnology. While tourism revenue is a secondary benefit and wildlife provides food in some cultures, these are not the main scientific justification for conservation.

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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