2025 WAEC GCE Biology (Objective/Essay) Questions and Answers

Question 1

(1ai) Characteristics used to classify arthropods:

1. Body structure (number of segments, presence of cephalothorax, etc.)
2. Number and structure of appendages (legs, antennae, etc.)
3. Presence and structure of wings (if applicable)
4. Type of mouthparts and feeding structure

(1aii) Features for classifying animals based on their habitat:

1. Presence of gills or book lungs (indicating aquatic or terrestrial habitat)
2. Structure and adaptation of legs (e.g., webbed feet for aquatic habitat)

(1b) Materials needed for osmosis experiment:

1. A semipermeable membrane (e.g., dialysis tubing)
2. A sucrose solution of varying concentrations
3. A potato or other plant tissue
4. A balance or scale to measure mass changes

(1c) Calculation of drawing length:
Formula: Length of drawing = actual length × magnification
= 10 cm × 1.5
= 15 cm

(1di) Essential features of a good biological drawing:

1. Accuracy – The drawing should accurately represent the organism or structure.
2. Proportion – All parts of the structure should be correctly sized relative to each other.
3. Labeling – Important features must be clearly labeled.
4. Clarity – The drawing should be neat and easy to understand.

(1dii) Common views used in biological drawings:

1. Dorsal view – A view from the back or top.
2. Ventral view – A view from the front or bottom.
3. Lateral view – A side view of the organism.

Question 2

(2a) Why are lizard feces more solid than those of mammals?
Lizards, being ectothermic animals, have a slower metabolism, allowing them to extract more water from their food. This results in their feces being drier and more solid compared to mammals, which have a higher metabolic rate and produce more watery waste.

(2b) Five digestive juices in the human body:

1. Saliva
2. Gastric juice
3. Pancreatic juice
4. Bile
5. Intestinal juice

(2c) Three digestive enzymes:

1. Pepsin
2. Trypsin
3. Chymotrypsin

(2di) Similarities between hormones and enzymes:

1. Both are biological catalysts.
2. Both regulate biological processes.
3. Both are produced by specialized cells or tissues.
4. Both act on specific targets.
5. Both function optimally under specific conditions (temperature, pH, etc.).

(2dii) Differences between hormones and enzymes:

(2e) Reactants and products of photosynthesis:

1. Glucose – 1 molecule
2. Water – 6 molecules
3. Oxygen – 6 molecules

Question 3

(3ai) Definition of ecology:
Ecology is the study of interactions between living organisms and their environment, including relationships among species and between organisms and their physical surroundings.

(3aii) Definition of an ecosystem:
An ecosystem consists of a community of living organisms interacting with each other and with their non-living environment.

(3aiii) Definition of the biosphere:
The biosphere is the global ecological system that includes all living beings and their relationships with the air, water, and land.

(3bi) Major components of an ecosystem:

1. Producers
2. Consumers
3. Decomposers
4. Abiotic factors

(3bii) Functions of ecosystem components:

1. Producers – Synthesize their own food through photosynthesis.
2. Consumers – Obtain energy by consuming other organisms.
3. Decomposers – Break down dead organisms and recycle nutrients.
4. Abiotic factors – Include water, air, soil, and sunlight that support life.

(3ci) Features of a rainforest:

1. High species diversity
2. Dense vegetation and canopy
3. Warm and humid climate year-round
4. High annual rainfall
5. Poor soil nutrients
6. Vertical plant stratification

(3cii) Adaptations of plants in rainforests:

1. Tall trees with straight trunks to reach sunlight.
2. Large leaves to maximize photosynthesis.
3. Buttress roots for stability in shallow soil.
4. Thick bark to reduce water loss.

Question 4

(4ai) Definition of organic evolution:
Organic evolution is the gradual change in species over time due to genetic variations, inheritance, and natural selection, leading to the development of new species.

(4aii) Evidence of evolution:

1. Fossil records
2. Comparative anatomy
3. Embryology
4. Molecular biology
5. Biogeography

(4bi) Theory of Use and Disuse:
This theory suggests that body parts used frequently develop and strengthen, while those not in use diminish over generations.

(4bii) Proponent of the theory:
Jean-Baptiste Lamarck.

(4biii) Examples of the theory:

1. Giraffes developing longer necks.
2. Amphibians adapting to aquatic environments.

(4c) Definition of mutation and its role in evolution:
Mutation is a random change in an organism’s DNA, introducing genetic variations. Beneficial mutations improve survival, leading to evolutionary changes over generations.

(4d) Examples of adaptive behaviors in animals:

1. Aestivation – Lizard
2. Basking – Bat
3. Territoriality – Monkey
4. Hibernation – Polar bear