WAEC 2025 BIOLOGY ANSWER



UPDATE:

I think WAEC gave each center same questions but different centers get different shuffling.

This means that my center number 1 Question might be your own center number 10.

You're to trace the Obj answer we're giving you and choose them as the answer where ever you see them on your Obj Question.

BIOLOGY OBJ ANSWERS:










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VERSION 2 SOLUTION IS DOWN DOWN THE PAGE
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(1a)
(PICK ANY ONE)
Excretion is the process by which living organisms remove waste products of metabolism and other non-useful materials from their body to maintain a healthy internal environment.

OR

Excretion is the removal of waste substances produced in the cells of living organisms to prevent harm and maintain proper body function.

(1b)
(i) Mammals:
(PICK ANY TWO)

(i) Carbon dioxide
(ii) Urea
(iii) Water
(iv) Salts

(1b) (ii) Plants:
(PICK ANY TWO)
(i) Oxygen
(ii) Carbon dioxide
(iii) Water
(iv) Resins
(v) Gums
(vi) Alkaloids

(1c)


(1d)
(PICK ANY THREE)
(i) Excretion of nitrogenous waste products.
(ii) Regulation of water and salt balance (osmoregulation).
(iii) Regulation of blood pH.
(iv) Production of hormones such as erythropoietin and renin.
(v) Regulation of blood pressure

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(2a)


(2bi)
(PICK ANY ONE)
Saprophytes are organisms, primarily fungi and some bacteria, that obtain their nutrition from dead or decaying organic matter

OR

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

(2bii)
(PICK ANY TWO)
(i) Rhizopus
(ii) Mucor
(iii) Mushroom
(iv) Penicillium
(v) Some species of bacteria (e.g., Bacillus subtilis)

(2biii)
(PICK ANY ONE)
Saprophytes feed on dead and decaying matter through a process called extracellular digestion. They secrete digestive enzymes into the surrounding environment to break down complex organic molecules into simpler forms, which are then absorbed by the saprophyte through its cell membrane

OR

Saprophytes secrete digestive enzymes from their cell on dead organic matter to break it down externally and then absorb the simple nutrients

(2biv)
(PICK ANY THREE)
(i) They help in the decomposition of dead plants and animals, recycling nutrients back into the soil.
(ii) Some saprophytes like Penicillium are used in the production of antibiotics
(iii) They help in the production of alcoholic beverages, bread, and other fermented foods
(iv) They are used in the treatment of sewage and organic waste.
(v) They help improve soil fertility through the breakdown of organic matter.
(vi) Some are used in biotechnology and research for producing enzymes and organic acids.

(2c)
(PICK ANY THREE)
(i) They have special structures to trap insects.
(ii) They secrete digestive enzymes.
(iii) They absorb nutrients from their prey.
(iv) They grow in nutrient-poor soils.
(v) They carry out photosynthesis.
(vi) They can have active or passive traps.

(2d)
(i) Butterfly: Siphoning feeding habit
(ii) Mosquito larva: Filter-feeding habit
(iii) Mucor: Saprophytic feeding
(iv) Housefly: Sponging feeding

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(3a)
(PICK ANY ONE)
Carbon (IV) oxide is removed from the air by plants during photosynthesis and oxygen is released.
Animals and plants use oxygen for respiration and release carbon (IV) oxide. These two processes balance the levels of both gases in nature.

OR

Plants take in carbon (IV) oxide for photosynthesis and give out oxygen. Animals and humans breathe in oxygen and exhale carbon (IV) oxide during respiration. This cycle keeps both gases balanced in the atmosphere.

OR

Carbon (IV) oxide is absorbed by green plants during photosynthesis, releasing oxygen. Oxygen is used in respiration by living organisms, releasing carbon (IV) oxide. This continuous exchange maintains the balance of the gases in nature.

(3b)
(PICK ANY FIVE)
(i) Light intensity
(ii) Temperature
(iii) Water availability
(iv) Soil type and pH
(v) Wind
(vi) Availability of nutrients
(vii) Human activities (e.g., deforestation, farming)

(3ci)
(PICK ANY ONE)
Overcrowding in an ecosystem refers to a situation where the number of organisms in a particular area exceeds the carrying capacity of that environment.

OR

Overcrowding in an ecosystem is when too many organisms live in a limited space, causing competition for resources such as food, water, and shelter.

OR

Overcrowding in an ecosystem is a condition where the population of organisms is more than the resources and space available to support them.

(3cii)
(i) Increased competition for resources
(ii) Spread of diseases
(iii) Poor growth of organisms
(iv) Migration of organisms
(v) Death of weaker organisms
(vi) Reduced reproduction rate
(vii) Environmental degradation

(3di)
(PICK ANY ONE)
Density-dependent factors are factors whose effects increase as population size increases while Density-independent factors affect the population regardless of its size.

OR

Density-dependent factors affect populations based on their density while density-independent factors affect populations regardless of their density.

(3dii)
(PICK ANY ONE)
(i) Competition for food and space.
(ii) Predation.
(iii) Spread of diseases.
(iv) Parasitism.
(v) Accumulation of waste products.

(3diii)
(PICK ANY ONE)
Density-dependent factors regulate population through competition and disease.
Density-independent factors cause sudden changes like floods and droughts.

OR

Density-dependent factors regulate population by increasing their effects as population grows, helping maintain balance.
Density-independent factors affect populations regardless of size, causing sudden changes that can disrupt or restore equilibrium.

OR

Density-dependent factors regulate population size by increasing their effects as the population grows, helping maintain balance.
Density-independent factors cause sudden changes regardless of population size, disrupting the equilibrium temporarily.

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(4ai)
(PICK ANY TWO)
(i) Inheritance of recessive short-height genes from both parents.
(ii) Genetic recombination resulting in unexpected traits.
(iii) Mutation affecting the genes responsible for height.
(iv) Hormonal imbalance during growth and development.

(4aii)


(4aiii)
tt (short)

(4bi)
(PICK ANY ONE)
Genotype refers to the complete set of genes that an individual organism possesses, determining its genetic makeup and traits.

OR

Genotype is the genetic makeup of an organism that determines its specific traits or characteristics.


(4bii)
(PICK ANY TWO)
(i) Genetic recombination during meiosis.
(ii) Mutation in genes or chromosomes.
(iii) Environmental influences such as nutrition or climate.
(iv) Random fertilization of gametes.

(4ci)
(PICK ANY ONE)
An allele is an alternative form of a gene found at the same position on a chromosome, which controls a specific trait in an organism.

OR

An allele is a variant of a gene that occupies a specific location on a chromosome.

(4cii)


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(5a)
(PICK ANY FIVE)
(i) Increased rate of evaporation leading to water loss in plants and animals
(ii) Heat stress in animals causing reduced productivity
(iii) Wilting and drying of plants due to water loss
(iv) Disruption of enzyme activity affecting metabolism
(v) Migration of animals to cooler areas
(vi) Death of temperature-sensitive organisms
(vii) Increased rate of transpiration in plants

(5b)
(PICK ANY FIVE)
(i) Destruction of vegetation and wildlife habitats
(ii) Death of soil organisms
(iii) Reduction in soil fertility due to loss of organic matter
(iv) Increase in soil erosion
(v) Air pollution from smoke and particulates
(vi) Disruption of food chains and food webs
(vii) Loss of biodiversity

(5c)
(PICK ANY FOUR)
(i) Surveillance and monitoring of disease outbreaks
(ii) Provision of technical assistance to countries
(iii) Coordination of international response efforts
(iv) Dissemination of public health information and guidelines
(v) Support in vaccine development and distribution
(vi) Training of health personnel and capacity building

(5di)
(PICK ANY ONE)
Countershading is an adaptation where the upper side of the tilapia is darker, while the ventral side is lighter which helps the fish blend with the environment, making it less visible to predators from above and below.

OR

Countershading in tilapia refers to the coloration pattern where the dorsal side of the tilapia is darker, while the ventral side is lighter to provide camouflage in the water.

OR

Countershading in tilapia is a color pattern with a darker back and lighter belly, providing camouflage and reducing visibility to predators from above and below, increasing survival chances in freshwater habitats.

(5dii)
(PICK ANY ONE)
Seasonal migration in birds is the regular, often annual, movement of birds from one region to another, usually between breeding and non-breeding areas, in response to changes in temperature, food availability, or daylight.

OR

Seasonal migration in birds is the regular movement of birds between different geographical areas during specific seasons to breed, find food, or avoid harsh weather conditions.

(5ei)
(i) Bacteria
(ii) Viruses
(iii) Fungi
(iv) Protozoa
(v) Algae

(5eii)
(i) Bacteria
(ii) Viruses

(5fi)
(PICK ANY TWO)
(i) Blood group A
(ii) Blood group B
(iii) Blood group AB

(5fii)
(PICK ANY TWO)
(i) Clumping of red blood cells
(ii) Hemolysis (destruction of red blood cells)
(iii) Kidney failure
(iv) Potential death
(iv) Death due to immune reaction



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VERSION 2
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(5)