50 Objective Questions, 5 Theory Questions, and Full Answers
Introduction
Biology is one of the three core Science subjects for WAEC 2026/2027 candidates on the Science track. It is also among the most widely studied subjects because many students aspire to careers in Medicine, Nursing, Pharmacy, Agriculture, and related fields. Scoring an A in WAEC Biology requires a solid grasp of living systems, processes, structures, and their functions, presented clearly in both objective and essay formats.
WAEC Biology covers Cell Biology, Nutrition and Digestion, Respiration, Reproduction, Genetics, Ecology, and the classification of living organisms. Year after year, questions from nutrition, reproduction, genetics (with Mendel’s laws), ecology, and cell structures dominate both papers. The practical exam also tests your ability to observe, draw, and describe biological specimens.
This guide gives you 50 likely objective questions and 5 full theory questions with complete model answers. Work through each one, understand the reasoning, and supplement your reading with actual textbook diagrams that you practice drawing and labelling.
50 Likely WAEC 2026/2027 WAEC 2026/2027 Biology Objective Questions
Each question includes four options. The correct answer is marked with ✅. Study the reasoning behind each correct choice, not just the answer itself.
Q1. The basic unit of life is the:
A. Nucleus
B. Tissue
C. Cell ✅
D. Organ
Q2. Which of the following is a function of the cell membrane?
A. Producing energy
B. Controlling what enters and leaves the cell ✅
C. Storing genetic information
D. Making proteins
Q3. Osmosis is defined as:
A. Movement of solutes from low to high concentration
B. Movement of water from high to low water potential through a selectively permeable membrane ✅
C. Active transport of molecules
D. Diffusion of gases through a membrane
Q4. The organelle responsible for photosynthesis in plant cells is the:
A. Mitochondrion
B. Ribosome
C. Chloroplast ✅
D. Vacuole
Q5. Which of the following is the correct equation for photosynthesis?
A. C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
B. 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ ✅
C. C₆H₁₂O₆ → CO₂ + H₂O
D. 6CO₂ + H₂O → C₆H₁₂O₆
Q6. Mitosis produces:
A. Four haploid cells
B. Two genetically identical diploid cells ✅
C. Two genetically different cells
D. Four diploid cells
Q7. The enzyme that breaks down starch is:
A. Lipase
B. Pepsin
C. Amylase ✅
D. Trypsin
Q8. Which part of the human alimentary canal is responsible for most nutrient absorption?
A. Stomach
B. Large intestine
C. Small intestine ✅
D. Oesophagus
Q9. The blood group that is the universal donor is:
A. A
B. B
C. AB
D. O ✅
Q10. Which of the following is a function of the liver?
A. Producing urine
B. Producing blood cells in adults
C. Detoxifying harmful substances and producing bile ✅
D. Absorbing oxygen from air
Q11. The term ‘heterozygous’ means:
A. Having two identical alleles for a gene
B. Having two different alleles for a gene ✅
C. Having no alleles for a gene
D. Having three alleles for a gene
Q12. Mendel’s law of segregation states that:
A. Genes on different chromosomes are inherited together
B. Each organism has two alleles for each gene, which separate during gamete formation ✅
C. Dominant alleles always suppress recessive alleles completely
D. All offspring inherit the same combination of traits
Q13. Which of the following is an example of a vector-borne disease?
A. Cholera
B. Tuberculosis
C. Malaria ✅
D. Typhoid
Q14. Transpiration in plants occurs mainly through:
A. Roots
B. Stem
C. Leaves through stomata ✅
D. Flowers
Q15. The human heart has how many chambers?
A. Two
B. Three
C. Four ✅
D. Six
Q16. In a food chain, energy flows from:
A. Consumers to producers
B. Decomposers to producers
C. Producers to consumers ✅
D. Carnivores to herbivores
Q17. Which of the following is a characteristic of all living organisms?
A. They all have wings
B. They all can swim
C. They all reproduce ✅
D. They are all the same colour
Q18. DNA stands for:
A. Dioxynucleic acid
B. Deoxyribonucleic acid ✅
C. Diribonucleic acid
D. Deoxyribose acid
Q19. The process by which organisms produce offspring is called:
A. Respiration
B. Excretion
C. Reproduction ✅
D. Assimilation
Q20. Which type of reproduction does NOT involve fertilization?
A. Sexual reproduction
B. Internal fertilization
C. Asexual reproduction ✅
D. Cross-fertilization
Q21. The part of the plant that carries water and mineral salts from the roots is:
A. Phloem
B. Xylem ✅
C. Cortex
D. Epidermis
Q22. Aerobic respiration produces:
A. Alcohol and CO₂
B. Lactic acid and CO₂
C. CO₂, water, and ATP ✅
D. Glucose and oxygen
Q23. Haemoglobin is important because it:
A. Clots the blood
B. Fights infection
C. Carries oxygen from the lungs to body tissues ✅
D. Produces antibodies
Q24. An ecosystem is best defined as:
A. A community of plants only
B. A group of the same species living together
C. A community of living organisms interacting with each other and their environment ✅
D. All the animals in a forest
Q25. Which of the following is an example of a secondary consumer?
A. Grass
B. Grasshopper
C. Frog ✅
D. Hawk
Q26. The hormone insulin is produced by:
A. The liver
B. The adrenal glands
C. The pancreas ✅
D. The thyroid gland
Q27. Which of the following diseases is caused by a virus?
A. Malaria
B. Typhoid
C. Cholera
D. Measles ✅
Q28. The process of maintaining a stable internal environment in the body is called:
A. Metabolism
B. Homeostasis ✅
C. Digestion
D. Respiration
Q29. Which kingdom includes organisms that are unicellular and prokaryotic?
A. Fungi
B. Protista
C. Plantae
D. Monera ✅
Q30. In humans, sex is determined by:
A. The X chromosome from the mother only
B. The Y chromosome from the father ✅
C. The age of the parents
D. The blood group of the parents
Q31. The scientific study of heredity is called:
A. Ecology
B. Physiology
C. Genetics ✅
D. Taxonomy
Q32. Which of the following is the correct hierarchy of biological classification from largest to smallest?
A. Kingdom, Phylum, Class, Order, Family, Genus, Species ✅
B. Species, Genus, Family, Order, Class, Phylum, Kingdom
C. Order, Class, Phylum, Kingdom, Family, Genus, Species
D. Kingdom, Class, Phylum, Order, Family, Genus, Species
Q33. The nitrogen cycle involves:
A. Conversion of glucose to proteins
B. The movement of nitrogen through living organisms and the environment ✅
C. Photosynthesis and respiration
D. The carbon cycle only
Q34. Which of the following best describes a parasite?
A. An organism that benefits both itself and its host
B. An organism that feeds on or in another organism, harming it ✅
C. An organism that lives near another without affecting it
D. An organism that only eats dead matter
Q35. The function of the mitochondria is:
A. To produce hormones
B. To synthesize proteins
C. To produce energy (ATP) through cellular respiration ✅
D. To store water
Q36. Sickle cell anaemia is caused by:
A. A virus
B. A bacterium
C. A deficiency of vitamin C
D. An abnormal haemoglobin gene inherited from both parents ✅
Q37. Which of the following organisms reproduces by binary fission?
A. Fern
B. Mushroom
C. Amoeba ✅
D. Earthworm
Q38. The function of the white blood cells is:
A. To carry oxygen
B. To clot the blood
C. To fight infection and produce antibodies ✅
D. To transport nutrients
Q39. Which of the following glands produces growth hormone?
A. Pancreas
B. Thyroid
C. Adrenal
D. Pituitary ✅
Q40. Which type of teeth is used for grinding food?
A. Incisors
B. Canines
C. Molars ✅
D. Premolars only
Q41. Eutrophication in water bodies is caused by:
A. Oil spills
B. Excess nutrients (especially nitrates and phosphates) leading to algal bloom ✅
C. Heavy metal pollution
D. Radioactive waste
Q42. The process of breaking down food into absorbable nutrients is called:
A. Excretion
B. Assimilation
C. Digestion ✅
D. Respiration
Q43. Which of the following is a non-renewable resource?
A. Solar energy
B. Wind energy
C. Crude oil ✅
D. Biomass
Q44. The part of the brain that controls balance and coordination is the:
A. Cerebrum
B. Medulla oblongata
C. Cerebellum ✅
D. Hypothalamus
Q45. In a Mendelian cross between two heterozygous tall plants (Tt × Tt), the expected ratio of tall to short plants is:
A. 1:1
B. 2:1
C. 3:1 ✅
D. 4:0
Q46. The skin is an organ of excretion because it:
A. Absorbs water
B. Produces oil
C. Excretes sweat containing water, salt, and urea ✅
D. Regulates breathing
Q47. Which of the following is a saprophyte?
A. Grass
B. Fern
C. Mushroom ✅
D. Moss
Q48. Deficiency of vitamin C causes:
A. Rickets
B. Pellagra
C. Scurvy ✅
D. Night blindness
Q49. The backbone (vertebral column) is part of the:
A. Appendicular skeleton
B. Axial skeleton ✅
C. Muscular system
D. Nervous system
Q50. Which of the following processes converts atmospheric nitrogen into compounds usable by plants?
A. Decomposition
B. Nitrification
C. Nitrogen fixation ✅
D. Denitrification
5 Likely WAEC 2026/2027 WAEC 2026/2027 Biology Theory Questions with Model Answers
Theory questions require organized, well-explained answers. Use the model answers below as a guide for structure, depth, and language. Practise writing your own answers and comparing them to the models.
Theory Question 1
(a) What is photosynthesis? Write the overall equation for photosynthesis.(b) State FOUR conditions necessary for photosynthesis to occur.(c) Describe ONE experiment to show that chlorophyll is necessary for photosynthesis.
MODEL ANSWER:
(a) PHOTOSYNTHESIS:
Photosynthesis is the process by which green plants and other autotrophic organisms use sunlight energy, water, and carbon dioxide to manufacture glucose and release oxygen.
Overall Equation:
6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂ ✓
(b) FOUR CONDITIONS NECESSARY FOR PHOTOSYNTHESIS:
1. Light energy (usually from sunlight)
2. Chlorophyll (the green pigment that absorbs light)
3. Carbon dioxide (absorbed through stomata in leaves)
4. Water (absorbed through the roots and transported up the xylem)
(c) EXPERIMENT TO SHOW CHLOROPHYLL IS NECESSARY:
Use a variegated leaf (a leaf with both green and non-green/white areas, such as a Coleus or Pelargonium leaf).
Step 1: Leave the plant in sunlight for several hours.
2: Pick the variegated leaf and remove the chlorophyll by placing the leaf in boiling ethanol (in a water bath, not directly over a flame, as ethanol is flammable).
3: Wash the leaf in water to soften it, then spread it flat on a white tile.
4: Add iodine solution to the entire leaf.
Observation: The green parts of the leaf turn blue-black (indicating the presence of starch, showing photosynthesis occurred). The white/non-green parts remain brown/orange (no starch, showing photosynthesis did not occur because there was no chlorophyll).
Conclusion: Chlorophyll is necessary for photosynthesis. ✓
Theory Question 2
Using appropriate genetic symbols, work out the cross between a homozygous tall pea plant and a homozygous short pea plant.(a) State the genotype and phenotype of the F1 generation.(b) Cross two F1 plants and state the genotype ratio and phenotype ratio of the F2 generation.(c) State Mendel’s law of dominance.
MODEL ANSWER:
Let T = tall (dominant), t = short (recessive)
PARENTAL CROSS:
Parents: TT (homozygous tall) × tt (homozygous short)
Gametes: T (from tall parent) and t (from short parent)
F1 Generation:
Punnett Square:
T T
t Tt Tt
t Tt Tt
(a) F1 Genotype: All Tt (heterozygous)
F1 Phenotype: All tall ✓
(All plants appear tall because T is dominant over t)
F1 × F1 CROSS:
Parents: Tt × Tt
Gametes: T and t from each parent
Punnett Square:
T t
T TT Tt
t Tt tt
(b) F2 Genotype ratio: 1 TT : 2 Tt : 1 tt ✓
F2 Phenotype ratio: 3 tall : 1 short ✓
(c) MENDEL’S LAW OF DOMINANCE:
When two contrasting characters are brought together in a cross (i.e., when a pure-breeding dominant individual is crossed with a pure-breeding recessive individual), only the dominant character is expressed in the F1 offspring. The recessive character is hidden but not lost.
Theory Question 3
(a) List FIVE characteristics of living organisms.(b) Distinguish between sexual and asexual reproduction in plants, giving ONE example of each.(c) State TWO advantages and TWO disadvantages of sexual reproduction.
MODEL ANSWER:
(a) FIVE CHARACTERISTICS OF LIVING ORGANISMS:
1. Nutrition: All living organisms take in food or manufacture food to obtain energy for life processes.
2. Respiration: Living organisms break down food to release energy.
3. Excretion: Living organisms remove metabolic waste products from their bodies.
4. Growth: Living organisms increase in size and complexity over time.
5. Reproduction: Living organisms produce offspring of their own kind to continue the species.
(Others include: movement, irritability/sensitivity, and adaptation)
(b) SEXUAL vs ASEXUAL REPRODUCTION IN PLANTS:
Sexual Reproduction: Involves the fusion of male and female gametes (sex cells) to produce offspring that are genetically different from both parents.
Example: Seed formation in flowering plants, where pollen (male gamete) fertilizes the ovum (female gamete) to form a seed.
Asexual Reproduction: Does not involve the fusion of gametes. Offspring are produced from a single parent and are genetically identical to the parent.
Example: Vegetative propagation in sweet potato, where the tubers (storage roots) give rise to new plants.
(c) SEXUAL REPRODUCTION:
TWO ADVANTAGES:
1. Genetic variation: Because offspring receive genes from two parents, they are genetically different from each other. This variation helps the species adapt to changing environments.
2. Healthier populations: Sexual reproduction reduces the accumulation of harmful mutations because mixing of genes can mask or eliminate them.
TWO DISADVANTAGES:
1. It requires two parents, which can be difficult when population numbers are low or partners are scarce.
2. It is slower and requires more energy than asexual reproduction, with many stages (mating, fertilization, development) before new individuals are produced.
Theory Question 4
(a) What is a food chain? Give ONE example from a Nigerian habitat.(b) What is a food web? Explain why a food web is a more accurate representation of feeding relationships than a food chain.(c) State THREE effects of human activities on the ecosystem.
MODEL ANSWER:
(a) FOOD CHAIN:
A food chain is a linear sequence showing how energy and nutrients pass from one organism to another through feeding. Arrows show the direction of energy flow.
Example from a Nigerian habitat:
Grass → Grasshopper → Lizard → Hawk ✓
(The grass produces food through photosynthesis. The grasshopper eats grass. The lizard eats the grasshopper. The hawk eats the lizard.)
(b) FOOD WEB:
A food web is a network of interconnected food chains in an ecosystem. It shows all the feeding relationships between organisms in a community.
A food web is more accurate than a food chain because in nature, most organisms eat more than one type of food and are eaten by more than one predator. For example, a hawk does not eat only lizards. It also eats snakes and rodents. A lizard does not eat only grasshoppers. It also eats other insects. A food chain represents only one possible path, which is a simplification. A food web shows the full, complex network of all feeding relationships, which is closer to what actually happens in an ecosystem.
(c) THREE EFFECTS OF HUMAN ACTIVITIES ON THE ECOSYSTEM:
1. Deforestation: Clearing forests for farming, logging, and urban expansion destroys habitats, reduces biodiversity, and increases soil erosion and flooding.
2. Pollution: Industrial waste, oil spills, sewage, and agricultural chemicals contaminate water, soil, and air, harming plants, animals, and humans.
3. Overhunting and Overfishing: Hunting animals beyond what populations can sustain leads to the extinction of species and disrupts food chains throughout the ecosystem.
Theory Question 5
(a) Define excretion. (b) Name THREE organs of excretion in humans and state ONE waste product removed by each. (c) Explain the role of the kidney in maintaining water balance in the body.
MODEL ANSWER:
(a) EXCRETION:
Excretion is the process by which living organisms remove metabolic waste products (substances produced as a result of chemical reactions inside cells) from their bodies. These are harmful substances that must be removed to maintain the organism’s health.
(b) THREE ORGANS OF EXCRETION AND THEIR WASTE PRODUCTS:
1. Kidney: Removes urea (produced from the breakdown of excess amino acids in the liver) in the form of urine.
2. Lungs: Remove carbon dioxide (produced during cellular respiration) and excess water vapour through exhalation.
3. Skin: Removes water, salt, and small amounts of urea through sweat produced by sweat glands.
(c) THE KIDNEY AND WATER BALANCE (OSMOREGULATION):
The kidney maintains the water content of the body through a process called osmoregulation. This is how it works:
When the body is dehydrated (not enough water), receptors in the hypothalamus of the brain detect that the blood is too concentrated. The hypothalamus signals the pituitary gland to release more ADH (antidiuretic hormone). ADH makes the kidney tubules more permeable to water, so more water is reabsorbed back into the blood. The result is that a smaller volume of highly concentrated urine is produced.
When the body has too much water (e.g., after drinking a lot), less ADH is produced. The kidney tubules become less permeable to water. Less water is reabsorbed, and a larger volume of dilute urine is produced.
This feedback mechanism ensures the blood stays at the right concentration for the body to function properly.
Study Tips: How to Score A in WAEC WAEC 2026/2027 Biology 2026/2027
Tip 1: Draw and label biological diagrams with care. WAEC awards marks for accurately labelled diagrams.
Tip 2: Learn all organelles and their functions. These appear in almost every Biology exam.
Tip 3: Practice Punnett square crosses for genetics questions. Know the difference between dominant, recessive, and codominant traits.
Tip 4: For ecology questions, know the trophic levels and be able to construct both food chains and food webs.
Tip 5: Know the symptoms, causes, and prevention of common diseases: malaria, cholera, typhoid, HIV/AIDS, tuberculosis.
Frequently Asked Questions
Q: What topics are most important in WAEC Biology 2026/2027?
A: Cell structure and function, photosynthesis, nutrition and digestion, genetics (Mendelian crosses), ecology (food chains and cycles), reproduction, and excretion are among the most consistently tested topics in WAEC Biology.
Q: Is WAEC Biology practical compulsory?
A: Yes. WAEC Biology Paper 3 is a practical examination. You are required to observe, draw, and describe specimens, and answer questions about biological processes. Prepare by practicing biological drawings from your textbook and school laboratory sessions.
Q: How do I score high marks in WAEC Biology theory?
A: Start each answer with a clear definition of any biological term asked. Use numbered or lettered points for lists. Support explanations with examples from the Nigerian environment where possible. Label all diagrams clearly, using a ruler for straight lines.
