WAEC 2025/2026 Biology Obj & Theory Answers

BIOLOGY OBJ

1: Homo.

2: cockroach.

3: moulting.

4: apex, midrib, lamina, axil.

5: II.

6: support

7: I

8: haemolysed

9: 18

10: mechanical support.

11: phagocytosis

12: circulatory

13: Light and chlorophyll must be present for it to occur

14: much water has been removed from urine

15: indole acetic acid.

16: constriction of the arteries.

17: convex lens

18: malleus

19: fibrous covering.

20: annuals

21: breakdown.of complex molecules into simple molecules.

22: K.

23: II.

24: I and II

25: digestion of food and absorption of nutrients

26: Two pairs of incisors are on the upper jaw and three pairs of premolars are on the lower jaw

27: competition

28: pressure

29: Secchi disc

30: in water

31: remains unchanged

32: Energy decreases from the base to the apex of the pyramid

33: Excessive phosphates massive algal growth aquatic organisms lack of oxygen death of

34: Tilapia in a lake

35: 18.50/m²

36: Eating balanced diet

37: Tuberculosis

38: loss of soil particles.

39: Domestic wastes

40: Felling of trees

41: Height and blood group

42: physiological variation

43: chromosomes.

44: 1/4.

45: DNA replication.

46: 32%.

47: Females are not carriers.

48: organisms transfer acquired characters to their offspring.

49: drones, queen, and workers.

50: Charles Darwin.

Completed

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(1a)

Excretion is the biological process by which living organisms remove metabolic waste products from their body to maintain internal balance and prevent harm.

(1b)

-Mammals-

(PICK ANY TWO)

(i) Urea

(ii) Carbon dioxide

(iii) Water

(iv) Uric acid

(v) Creatinine

(vi) Excess salts

-Plants-

(PICK ANY TWO)

(i) Oxygen

(ii) Water vapor

(iii) Tannins

(iv) Alkaloids

(v) Resins

(vi) Latex

(1c)

Check the image below

(1d)

(PICK ANY THREE)

(i) Removal of nitrogenous wastes like urea

(ii) Regulation of water and salt balance (osmoregulation)

(iii) Regulation of blood pH

(iv) Secretion of erythropoietin to stimulate red blood cell production

(v) Regulation of blood pressure through renin

(vi) Activation of vitamin D for calcium absorption

(2a)

[TABULATE]

=Photosynthetic Nutrition=

(i) Energy is obtained from sunlight.

(ii) It occurs in green plants and some bacteria.

=Chemosynthetic Nutrition=

(i) Energy is obtained from chemical reactions involving inorganic substances.

(ii) It occurs in certain bacteria like nitrifying bacteria.

(2bi)

Saprophytes are organisms that feed on dead and decaying organic matter for their nutrition.

(2bii)

(i) Rhizopus

(ii) Mucor

(2biii)

Saprophytes secrete digestive enzymes onto dead organic material to break it down into simpler substances, which are then absorbed into their bodies.

(2biv)

(i) They decompose organic waste, helping in nutrient recycling.

(ii) They are used in the production of antibiotics.

(iii) Some are used in food production processes like fermentation.

(2c)

(i) They trap and digest small animals or insects.

(ii) They have specialized structures like sticky leaves or pitfall traps.

(iii) They often grow in nutrient-poor soils, hence the need for alternative nitrogen sources.

(2d)

(i) Butterflies feed by sucking nectar from flowers using a proboscis.

(ii) Mosquito larvae are filter feeders, feeding on microorganisms and organic matter in water.

(iii) Mucor feeds saprophytically by breaking down dead organic matter with enzymes and absorbing the nutrients.

(iv) Housefly feeds by sucking up liquid or semi-liquid food, often after regurgitating digestive enzymes to liquefy solid food.

(3a)

Carbon dioxide (CO₂) and oxygen (O₂) are balanced through the processes of photosynthesis and respiration. Plants take in CO₂ during photosynthesis and release O₂. Animals and humans breathe in O₂ and release CO₂ during respiration. This cycle maintains the balance of both gases in nature.

(3b)

(PICK ANY FIVE)

(i) Light intensity

(ii) Soil type

(iii) Water availability

(iv) Temperature

(v) Wind

(vi) pH level of the soil

(vii) Availability of nutrients

(viii) Human activities

(3ci)

Overcrowding in an ecosystem refers to a situation where the number of organisms exceeds the carrying capacity of the environment, leading to competition for limited resources such as food, water, and space.

(3cii)

(PICK ANY FIVE)

(i) Increased competition for food and space

(ii) Spread of diseases

(iii) High mortality rate

(iv) Migration of some organisms

(v) Decrease in reproductive rates

(vi) Poor growth and development

(vii) Accumulation of waste

(viii) Stress and aggressive behavior among organisms

(ix) Depletion of natural resources

(3di)

Density-dependent factors are environmental factors whose effects on the population vary with population density, such as competition, disease, and predation. WHILE Density-independent factors affect the population regardless of its size or density, such as natural disasters, temperature, and pollution.

(3dii)

(PICK ANY TWO)

(i) Predation

(ii) Disease

(iii) Competition for resources

(iv) Parasitism

(v) Availability of mates

(vi) Accumulation of waste products

(3diii)

Density-dependent factors limit population through crowding effects like disease or competition. Density-independent factors, such as weather, affect populations regardless of size. Together, they influence balance and stability in an ecosystem.

(4a)

(PICK ANY TWO)

(i) Genetic recombination resulting in inheritance of two recessive alleles (tt).

(ii) Poor nutrition during the child’s developmental years.

(iii) Hormonal imbalance, especially low levels of growth hormone.

(iv) Genetic mutations affecting height-related genes.

(v) Chronic illnesses or medical conditions during growth.

(vi) Lack of physical activity or inadequate health care.

(4aii)

(4aiii)

Genotype: tt

(4bi)

Genotype is the genetic makeup of an organism in terms of the alleles present, e.g, TT, Tt, or tt.

(4bii)

(PICK ANY TWO)

(i) Genetic recombination during meiosis.

(ii) Mutations in genes or chromosomes.

(iii) Environmental influences such as diet or climate.

(iv) Random fertilization during sexual reproduction.

(v) Crossing over during meiosis.

(vi) Effects of diseases or infections during development.

(4ci)

An allele is an alternative form of a gene found at the same locus on homologous chromosomes.

(4cii)

In a Tabular form

-Genotype-

(PICK ANY TWO)

(i) It refers to the genetic makeup of an organism.

(ii) It is determined by the combination of alleles inherited from parents.

(iii) It cannot be observed directly.

(iv) It remains constant throughout the life of the organism.

(v) It can be represented using letters such as TT, Tt, or tt.

-Phenotype-

(PICK ANY TWO)

(i) It refers to the observable characteristics of an organism.

(ii) It is influenced by both genotype and environmental factors.

(iii) It can be seen and measured (e.g., height, skin color).

(iv) It may change due to environmental conditions.

(v) It is the physical expression or outcome of the genotype.

(5a)

(i) Increased rate of evaporation leading to water loss and dehydration in organisms.

(ii) Denaturation of enzymes affecting metabolic processes.

(iii) Reduced reproductive success due to stress or death of gametes.

(iv) Migration or death of heat-sensitive species.

(v) Altered behavior such as seeking shade or burrowing to escape heat.

(5b)

(i) Destruction of vegetation and loss of plant cover.

(ii) Death of animals and destruction of habitats.

(iii) Soil erosion due to loss of protective plant cover.

(iv) Reduction in soil fertility as nutrients are lost through burning.

(v) Air pollution from smoke and release of greenhouse gases.

(5c)

(i) Coordination of international response to disease outbreaks.

(ii) Provision of guidelines and information on disease prevention and control.

(iii) Distribution of vaccines and medical supplies to affected areas.

(iv) Monitoring and surveillance of disease spread globally.

(5di)

Countershading in Tilapia is a camouflage adaptation where the back is dark and the belly is light. It helps the fish blend with its surroundings, protecting it from predators.

(5dii)

Seasonal migration in birds is the regular movement of birds from one region to another in response to changes in seasons. Birds often migrate to warmer areas to find food, breed, or escape harsh weather.

(5ei)

(i) Bacteria

(ii) Viruses

(iii) Fungi

(iv) Protozoa

(v) Algae

(5eii)

(i) Bacteria

(ii) Viruses

(5fi)

(i) Blood group A

(ii) Blood group B

(5fii)

(i) Agglutination (clumping) of red blood cells, which can block blood vessels and cause organ damage.

(ii) Hemolytic reaction, where the immune system destroys the transfused blood cells, leading to fever, chills, kidney failure, or even death

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