2025 WAEC GCE Biology OBJ/Essay Questions and Answers Expo/Runs

WAEC GCE 2025 Biology Essay (Theory) Questions and Answers

(1a) Characteristics Used to Classify Arthropods

(i) Based on Body Structure:

1. Number of body segments (e.g., presence of cephalothorax).
2. Presence or absence of an exoskeleton.

(ii) Based on Appendages:

1. Number and structure of legs.
2. Number and structure of antennae.

(iii) Based on Wings and Mouthparts:

1. Presence and structure of wings (if applicable).
2. Type of mouthparts and feeding structures.

(1b) Materials Required for an 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:

$$\text{Length of Drawing}=\text{Actual Length}\times \text{Magnification}$$Given:

• Actual length = 10 cm
• Magnification = 1.5

$$\text{Length of Drawing}=10\times 1.5=15\text{ cm}$$

(1d) Characteristics of a Good Biological Drawing

1. Accuracy: The drawing should precisely represent the structure.
2. Proportion: All parts should be correctly sized relative to each other.
3. Labeling: All important features should be clearly marked.
4. Clarity: The drawing should be neat, with clean lines and minimal clutter.

(1dii) Types of Views in Biological Drawings

1. Dorsal View: Viewing the organism from the back or top.
2. Ventral View: Viewing the organism from the front or bottom.
3. Lateral View: Viewing the organism from the side.

(2a) Why Lizards’ Feces Are More Solid Than Mammals’

Lizards are ectothermic (cold-blooded), meaning they rely on external heat sources. Their slower metabolism allows them to extract more water from their food, leading to drier, more solid feces compared to mammals, whose higher metabolic rate results in more liquid waste.

(2b) Digestive Juices in Humans (Pick Any Five)

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

(2c) Enzymes Responsible for Protein Digestion (Pick Any Three)

1. Pepsin
2. Trypsin
3. Chymotrypsin
4. Elastase
5. Carboxypeptidase A
6. Carboxypeptidase B

(2d) Similarities Between Hormones and Enzymes (Pick Any Three)

1. Both are biological catalysts.
2. Both regulate biological processes.
3. Both are produced by specialized cells or tissues.
4. Both have specific targets or substrates.
5. Both require specific conditions (pH, temperature, etc.).
6. Both can be affected by inhibitors.

(2dii) Differences Between Hormones and Enzymes

(2e) Products of Photosynthesis

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

(3a) Definitions

(3ai) Ecology

Ecology is the study of the relationships between living organisms and their environment. It examines how organisms interact with each other and with non-living components like air, water, and soil.

(3aii) Ecosystem

An ecosystem is a community of living organisms (plants, animals, and microorganisms) interacting with each other and with their physical environment.

(3aiii) Biosphere

The biosphere is the part of the Earth that supports life, including the atmosphere, hydrosphere, and lithosphere.

(3b) Components of an Ecosystem

(3bi) Types (Pick Any Two)

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

(3bii) Functions (Pick Any Two)

• Producers: Synthesize food through photosynthesis.
• Consumers: Obtain energy by eating other organisms.
• Decomposers: Break down dead matter and recycle nutrients.
• Abiotic factors: Non-living elements like water, sunlight, and soil that influence life.

(3c) Characteristics of Rainforest (Pick Any Four)

1. High species diversity
2. Lush vegetation and dense canopy
3. Warm and humid climate year-round
4. High annual rainfall (over 2,000 mm)
5. Nutrient-poor soil
6. Vertical stratification of plants

(3cii) Plant Adaptations in Rainforests (Pick Any Two)

1. Tall, straight trunks for sunlight competition.
2. Broad leaves for maximum light absorption.
3. Buttress roots for stability in nutrient-poor soil.
4. Shedding leaves in dry seasons to conserve water.
5. Bark resistant to pests and fire.

(4a) Organic Evolution and Evidence

(4ai) Definition of Organic Evolution

Organic evolution is the gradual change in species over time, leading to the development of new species from common ancestors through genetic variation and natural selection.

(4aii) Evidence of Evolution (Pick Any Five)

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

(4b) Theory of Use and Disuse

(4bi) Explanation

This theory suggests that frequently used body parts develop, while unused parts shrink or disappear over generations.

(4bii) Founder of the Theory

Jean-Baptiste Lamarck

(4biii) Examples

1. Giraffes – Longer necks developed from constant stretching.
2. Aquatic organisms – Amphibians developing stronger legs over time.

(4c) Mutation and Evolution

A mutation is a sudden, random change in an organism’s DNA. Some mutations provide survival advantages, leading to species evolution over time.

(4d) Examples of Animal Adaptations

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