The diagram is an illustration of an experimental set-up. Study it and answer the question; The set-up directly measure

B. evaporation of water from the leaves

A. transpiration of water by the shoot

B. evaporation of water from the leaves

C. absorption of water by the shoot

D. loss of mineral salts from the leaves

Which of the following statements best explains the reason why termites swarm at night?

A. Light is not necessary for swarming

D. They can only see in the dark

Which of the following statements about a mixture of a protein-digesting enzyme and starch solution would be correct? The protein-digesting enzyme

A. has no effect on the starch solution

B. leads to the production of amino acids

C. leads to the production of glucose

Conservation of natural resources does not

D. threaten the survival of species

A. maintain a balanced ecosystem

B. preserve the beauty of nature

D. threaten the survival of species

Which of the following statements about chromosomes is correct?

B. The number present in a specie is constant

A. All the chromosomes of a species are the same shape

B. The number present in a specie is constant

C. They are neatly arranged in a cytoplasm

D. They bear ribosomes on their outer membranes

What happens when the ciliary muscles of the eye contract? The

C. lens gets a longer focal length

D. suspensory ligament becomes tight

The properties of endocrine system include the following except

D. release of secretion into ducts

B. transportation by blood to target organ

D. release of secretion into ducts

The diagram is an illustration of a part of a flower. Study it and answer the question below; The function of the part labeled I is

C. germination of the pollen grain

D. site for double fertilization in the plant

The mutualism type of relationship is different from a parasitic relationship because in mutualism

A. both organisms involved benefit

B. none of the organisms benefits or harm each other

C. both organisms harm each other

D. only one of the organisms is harmed

In an experiment, mould and yeast cells were transferred into an environment with low oxygen concentration. After a few days, the mould dies while the yeast cells did not. Which of the following statements best explains the following observation.

C. Respiration can take place in yeast cells in the absence of oxygen

A. The yeast cells carried out photosynthesis while the mould did not

B. Photosynthesis does not take place in the absence of oxygen

C. Respiration can take place in yeast cells in the absence of oxygen

D. Respiration does not occur in the mould

The diagram below is an illustration of an ecological instrument. Study it an answer the question below; When the instrument is in use, it is usually?

A. placed slightly above soil level

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WAEC (WASSCE) 2020

2020 WAEC (WASSCE) Biology Past Questions and Answers

The 2020 WAEC (WASSCE) Biology past questions with answers: 49 objective questions from the 2020 paper in the DeeepSolve question bank, each with its answer behind "Show answer". Try each question before you check, then practise the paper as a timed WAEC-style CBT.

Practise this paper as a timed WAEC-style CBT All WAEC (WASSCE) Biology years

Questions

1.
The respiratory organ of a cockroach
1. A.air sac
2. B.trachea
3. C.lung book
4. D.lung
Show answer
Answer: B. trachea
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2.
The part of the central nervous system that controls unconscious actions in humans is the
1. A.cerebellum
2. B.cerebrum
3. C.spinal cord
4. D.optic nerves
Show answer
Answer: C. spinal cord
AI explanation
Step 1: Analyze the question We need the part of the central nervous system (CNS) that controls unconscious (involuntary/reflex) actions.
Step 2: Key concepts
The CNS consists of the brain and the spinal cord.
Cerebrum: controls voluntary actions, thinking, memory, and conscious sensation.
Cerebellum: coordinates balance, posture, and muscle coordination. It works automatically, but it is mainly responsible for coordination and balance, not reflex actions.
Spinal cord: coordinates reflex actions (e.g., withdrawing your hand from a hot object). These are automatic and happen without conscious thought. The spinal cord is the reflex centre.
Optic nerves: part of the peripheral nervous system. They carry impulses from the eye to the brain and are not part of the CNS.
Step 3: Eliminate options
D is out because optic nerves are not part of the CNS.
B is out because the cerebrum controls conscious, voluntary activities.
A is mainly for balance and coordination of voluntary movement.
C fits: the spinal cord controls reflex (unconscious) actions.
Step 4: Answer The spinal cord is the correct choice.
Note: The medulla oblongata (in the brain) controls involuntary actions such as breathing and heartbeat, but it is not listed here. Among the options given, the spinal cord is the best answer.
Exam tip: Remember "Cerebrum = Conscious, Cerebellum = Coordination/balance, Spinal cord = Spontaneous reflexes." Also, always check whether an option is part of the CNS (brain and spinal cord) or the peripheral nervous system (nerves).
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3.
The network of double membrane that conveys materials through the cytoplasm is the
1. A.plasma membrane
2. B.nuclear membrane
3. C.mitochondrion
4. D.endoplasmic reticulum
Show answer
Answer: D. endoplasmic reticulum
AI explanation
Step 1: Analyze the question The question asks for the cell structure that is a network of double membranes which transports materials through the cytoplasm.
Step 2: Explain the concept The endoplasmic reticulum (ER) is a system of flattened sacs and tubes (cisternae) made of membranes, running throughout the cytoplasm. It is continuous with the nuclear envelope. Its main functions are:
Rough ER (with ribosomes): makes and transports proteins.
Smooth ER: makes lipids and transports materials, and in the liver it helps with detoxification.
Because its membrane layers form channels, it acts as the cell's "transport system" or "highway."
Step 3: Check each option
A. Plasma membrane: this is the outer boundary of the cell. It controls what enters and leaves, but it is not a network inside the cytoplasm.
B. Nuclear membrane: this surrounds the nucleus and controls movement into and out of it. It is not a network spread through the cytoplasm.
C. Mitochondrion: this is the site of aerobic respiration, where energy (ATP) is released. It has a double membrane but is not a transport network.
D. Endoplasmic reticulum: this is a membrane network that conveys materials through the cytoplasm, so it fits the description.
Step 4: Answer The correct option is D. Endoplasmic reticulum.
Exam tip: Think of "reticulum" as meaning "network" (like a net). When you see "network" and "transport within the cytoplasm" together, it points to the ER. Remember: ER = Eco-Route for moving materials around the cell.
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4.
The diagram below is an illustration of a part of a flower. Study it and answer the question below. The part labeled II is the
1. A.unfused stigma
2. B.fused style
3. C.fused ovaries
4. D.unfused anther
Show answer
Answer: D. unfused anther
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5.
Use the list of insects below to answer the question below; I. Cotton stainer II. Honeybee III. Termite IV. Weevil The insects whose activities are both beneficial and harmful to humans are;
1. A.I and II
2. B.II and III
3. C.II and IV
4. D.III and IV
Show answer
Answer: B. II and III
AI explanation
Analyze the question: We need insects whose activities are both beneficial and harmful to humans, not just one or the other.
Go through each insect:
I. Cotton stainer: It feeds on cotton bolls and stains the lint, so it is a pest. It has no real benefit to humans. Harmful only.
II. Honeybee: It gives honey and wax and pollinates crops (beneficial). It can also sting people and sometimes disturbs farm workers (harmful). Both.
III. Termite: It destroys wooden structures, crops and paper (harmful). It also aerates and enriches the soil, and its alates (winged termites) are eaten as food by many Nigerians and used as feed for poultry and fish (beneficial). Both.
IV. Weevil: It destroys stored grains, beans and cereals. It is harmful only.
Conclusion: The insects with both beneficial and harmful effects are II (honeybee) and III (termite).
Exam tip: Remember that a "both" question needs two sides. Think of cotton stainers and weevils as pure pests (crops and stored produce). Honeybees and termites are the classic "double-role" insects: honeybees give honey but sting, and termites give food and soil improvement but destroy wood.
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6.
The cell as the basic unit of life consists of
1. A.cell wall and vacuole
2. B.nucleus and cell wall
3. C.cytoplasm and nucleus
4. D.cytoplasm and vacuole
Show answer
Answer: C. cytoplasm and nucleus
AI explanation
Step 1: Analyze the question The question asks what the cell, as the basic unit of life, consists of. We need the parts that every living cell has, whether it is an animal cell or a plant cell.
Step 2: Explain the concept A cell is made up of these main parts:
Cell membrane (plasma membrane): found in all cells.
Cytoplasm: the jelly-like living material where chemical reactions take place.
Nucleus: controls the activities of the cell and holds the genetic material (DNA).
Some parts are found only in certain cells:
Cell wall: found in plant cells, fungi and bacteria, but not in animal cells.
Large central vacuole: typical of mature plant cells. Animal cells have only small vacuoles, or none.
Step 3: Work through the options
A. Cell wall and vacuole: both are features of plant cells, and neither is found in every cell. Wrong.
B. Nucleus and cell wall: the cell wall is absent in animal cells. Wrong.
C. Cytoplasm and nucleus: these are the two essential living components found in cells generally. The cytoplasm carries out metabolism, and the nucleus controls the cell. This fits.
D. Cytoplasm and vacuole: the vacuole is not universal. Wrong.
Step 4: Answer The correct option is C. cytoplasm and nucleus.
Tip: For "basic unit of life" questions, choose the parts every cell has (membrane, cytoplasm, nucleus). Be careful with the cell wall and the large vacuole, because they belong to plant cells only. Remember: "Cell wall and big vacuole = plants only."
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7.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.
8.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.
9.
Which of the following substances is not a conservable natural resource?
1. A.Mineral
2. B.Air
3. C.Soil
4. D.Water
Show answer
Answer: B. Air
AI explanation
Analyze the question: We are asked which substance is not a conservable natural resource. Conservation means managing and protecting resources so they last, or so they are not wasted, polluted, or degraded.
Explain the concept: Natural resources are often grouped as:
Renewable: water, soil (with care), forests, wildlife
Non-renewable: minerals, fossil fuels
Conservation applies to both groups. We conserve minerals by recycling and avoiding wasteful mining, soil by crop rotation and cover cropping to prevent erosion, and water by avoiding wastage and pollution.
Work through the options:
A. Mineral: Finite, so it must be conserved through recycling and careful mining. It is conservable.
B. Air: Air is the odd one out. It is abundant and universally available, and it cannot be stored, rationed, managed, or "conserved" in the way the others can. We can control pollution of air, but we cannot conserve the air itself. It is therefore usually treated as the non-conservable resource in this type of question.
C. Soil: Conserved by preventing erosion, using manure, and practicing terracing and crop rotation. It is conservable.
D. Water: Conserved through dams, avoiding wastage, and preventing pollution. It is conservable.
Note on the reasoning: Air pollution control is a real environmental concern, so this question is a bit loose in its wording. But among the four options, air is the only one that cannot be directly managed, stored, or rationed.
Answer: B. Air
Exam tip: In WASSCE conservation questions, resources you can physically manage, such as soil, water, forests, wildlife, and minerals, are "conservable." Air is typically given as the exception because it is freely and universally available.
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10.
The diagram is an illustration of an experimental set-up. Study it and answer the question; The set-up directly measure
1. A.transpiration of water by the shoot
2. B.evaporation of water from the leaves
3. C.absorption of water by the shoot
4. D.loss of mineral salts from the leaves
Show answer
Answer: B. evaporation of water from the leaves
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11.
A company was prohibited from producing bags made from natural leopard skin. This is an attempt to conserve
1. A.land
2. B.water
3. C.wildlife
4. D.minerals
Show answer
Answer: C. wildlife
AI explanation
Step 1: Analyze the question A company was banned from making bags from natural leopard skin. We need to identify which natural resource this ban is meant to protect.
Step 2: Explain the concept Conservation means protecting and wisely managing natural resources. These resources include:
Land/soil: protected by afforestation, crop rotation, and terracing
Water: protected by preventing pollution and overuse
Wildlife: protected by game reserves, national parks, anti-poaching laws, and bans on trading animal products
Minerals: protected by controlled mining and recycling
Step 3: Apply it to the question A leopard is an animal, and animals living in the wild are called wildlife. Bags made from natural leopard skin require killing leopards. If the practice is prohibited, fewer leopards are hunted, so the species is protected from decline or extinction. The ban has nothing to do with land, water, or minerals.
Step 4: Identify the answer The correct option is C. wildlife.
Tip: In conservation questions, match the item to its resource type:
Animal skins, ivory, or hunting → wildlife
Logging or deforestation → forests
Oil spills or dumping waste → water
Erosion or bush burning → soil/land
In Nigeria, the Endangered Species Act and the protection of places like Yankari Game Reserve are examples of wildlife conservation.
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12.
Variation which exhibits a wide range from one extreme to the other is
1. A.phenotypic variation
2. B.discontinuous variation
3. C.continuous variation
4. D.genotypic variation
Show answer
Answer: C. continuous variation
AI explanation
Analyze the question: It asks for the type of variation that shows a wide range from one extreme to the other, with many intermediate forms in between.
Explain the concept:
Continuous variation: The trait shows a full range of values between two extremes, with no distinct categories. Examples are height, weight, skin colour, and finger length. These traits are usually controlled by many genes (polygenic) and are also influenced by the environment. A graph of the data gives a bell-shaped curve.
Discontinuous variation: The trait falls into a few distinct groups, with no intermediates. Examples are blood group (A, B, AB, O), tongue rolling, and sex. These traits are usually controlled by one or two genes, and the environment has little effect on them.
Phenotypic variation: This is any observable difference in appearance or characteristics. It can be continuous or discontinuous, so it is too general to be the answer.
Genotypic variation: This is a difference in genetic makeup. It is not a description of a range of observable traits.
Solution:
The question stresses a "wide range from one extreme to the other", which means there are many gradual intermediate values.
Discontinuous variation has distinct categories, so it does not fit.
Phenotypic and genotypic variation describe the source or type of difference, not the pattern of a range.
Continuous variation is the one that shows a gradual range between extremes.
Answer: C. continuous variation
Exam tip: Think "continuous = a continuous line of values, like height." Think "discontinuous = distinct boxes, like blood groups." If the question mentions a range or intermediates, choose continuous.
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13.
Who proposed the theory of evolution by natural selection
1. A.Darwin
2. B.Lamark
3. C.Aristotle
4. D.Linnaeus
Show answer
Answer: A. Darwin
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14.
The part of the mammalian kidney that stores urine is the
1. A.capsule
2. B.medulla
3. C.pelvis
4. D.bladder
Show answer
Answer: C. pelvis
AI explanation
Analyze the question: The question asks which structure "stores urine." The wording "part of the mammalian kidney" matters, because the bladder is not part of the kidney.
Explain the concept: The kidney has these main regions:
Capsule: a tough outer covering that protects the kidney.
Cortex: the outer region where filtration occurs (glomeruli and Bowman's capsules).
Medulla: the inner region containing the loops of Henle and collecting ducts, which concentrate urine.
Pelvis: a funnel-shaped cavity that collects urine from the collecting ducts and passes it into the ureter.
The bladder stores urine, but it is a separate organ. Urine reaches it through the ureter, and it is not inside the kidney.
Step-by-step solution:
Capsule: protective covering, so it does not store urine. ✗
Medulla: it concentrates urine and does not store it. ✗
Pelvis: it is the part of the kidney that collects and holds urine before it drains into the ureter. ✓
Bladder: it stores urine, but it is outside the kidney. ✗
Answer: The question asks for a part of the kidney, so the best answer is C. pelvis.
Tip: Remember the urine path as: Cortex → Medulla → Pelvis → Ureter → Bladder → Urethra. If a question says "part of the kidney," rule out the bladder, since it is a separate organ. Pelvis is the kidney's "collecting room."
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15.
Replication of DNA molecules is catalysed by an enzyme called
1. A.polymerase
2. B.ptyalin
3. C.pepsin
4. D.amylase
Show answer
Answer: A. polymerase
AI explanation
Step 1: Analyze the question The question asks which enzyme catalyses DNA replication, which is the copying of a DNA molecule before cell division.
Step 2: Explain the concept During DNA replication:
The double helix is unwound and the two strands separate (helicase does this).
Each strand acts as a template.
Free nucleotides pair with the template by complementary base pairing (A with T, G with C).
DNA polymerase joins these nucleotides into a new strand. It is the main enzyme that catalyses replication.
Step 3: Check each option
A. Polymerase: Correct. DNA polymerase builds the new DNA strand.
B. Ptyalin: This is salivary amylase. It digests starch in the mouth, so it is not involved in DNA replication.
C. Pepsin: This is a stomach enzyme that digests proteins, so it is not involved either.
D. Amylase: This digests starch to maltose, so it is also unrelated.
Step 4: Answer The correct option is A. polymerase.
Tip: Link the word to the job. Polymer means "many units," and polymerase joins many nucleotides into a long chain. The other options are all digestive enzymes (ptyalin, pepsin and amylase), and digestive enzymes do not copy DNA. In an exam, any name ending in "-ase" that has to do with nucleic acids, such as polymerase, is a strong clue.
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16.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.
17.
Which of the following statements best explains the reason why termites swarm at night?
1. A.Light is not necessary for swarming
2. B.They avoid day-flying birds
3. C.Light destroys their wings
4. D.They can only see in the dark
Show answer
Answer: B. They avoid day-flying birds
AI explanation
Analyze the question: The question asks why winged termites (alates) swarm at night. Look for the answer that best explains this behavior.
Concept: Swarming is the mating flight, when winged reproductive termites leave the colony to find mates and start new colonies. Alates are weak fliers and have soft bodies, so they are easy prey for many animals. Many termite species swarm at dusk or at night, often after the first rains. This is an adaptation that reduces predation and helps them avoid harsh daytime conditions.
Evaluate each option:
A. Light is not necessary for swarming. This is not an explanation of why they swarm at night. Many termites are in fact attracted to lights once they are airborne. ✗
B. They avoid day-flying birds. Birds, lizards and other predators hunt alates by day. Swarming at night lowers the risk of being eaten, which improves the chance of survival and mating. ✓
C. Light destroys their wings. This is false. Termites shed their wings naturally after the mating flight, and light does not destroy them. ✗
D. They can only see in the dark. This is false. Alates have functional eyes and are drawn to light sources at night. ✗
Answer: Option B. Swarming at night is a predator-avoidance strategy.
Exam tip: For "why does an animal do X at night/day" questions, look for the option that gives a survival benefit, such as avoiding predators or conserving water. Be wary of options that make absolute claims such as "can only see" or "destroys".
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18.
Which of the following statements about a mixture of a protein-digesting enzyme and starch solution would be correct? The protein-digesting enzyme
1. A.has no effect on the starch solution
2. B.leads to the production of amino acids
3. C.leads to the production of glucose
4. D.digest the starch
Show answer
Answer: A. has no effect on the starch solution
AI explanation
Step 1: Analyze the question We have a protein-digesting enzyme (a protease, such as pepsin or trypsin) mixed with a starch solution. We need to decide what the enzyme does to the starch.
Step 2: Explain the concept Enzymes are substrate-specific. This is the "lock and key" idea: the active site of an enzyme fits only one kind of substrate.
Protease acts on proteins and breaks them into amino acids.
Amylase acts on starch and breaks it into maltose, and later glucose.
Lipase acts on fats and breaks them into fatty acids and glycerol.
Step 3: Work through the options
A. Has no effect on the starch solution. Correct. Starch is not the substrate of a protease, so the enzyme cannot bind to it and nothing happens.
B. Leads to the production of amino acids. Wrong. Amino acids come from protein digestion. The mixture contains only starch, which has no protein to break down.
C. Leads to the production of glucose. Wrong. Glucose comes from starch digestion by amylase, not by a protease.
D. Digest the starch. Wrong. A protease cannot digest starch because of enzyme specificity.
Step 4: Answer The correct option is A. The protein-digesting enzyme has no effect on the starch solution.
Exam tip: When a question pairs an enzyme with the wrong substrate, think "specificity". Use the name of the enzyme as a clue: Protease → Protein, Amylase → Starch (amylum), Lipase → Lipids. If the enzyme and substrate do not match, the answer is "no effect".
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19.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.
20.
Conservation of natural resources does not
1. A.maintain a balanced ecosystem
2. B.preserve the beauty of nature
3. C.attract tourists
4. D.threaten the survival of species
Show answer
Answer: D. threaten the survival of species
AI explanation
Analyze the question: The question uses "does not," so we are looking for the statement that is not a result of conservation. Three options will be benefits of conservation, and one will be false.
Explain the concept: Conservation is the careful management and protection of natural resources (forests, wildlife, water, soil) so they last for future generations. Its main aims are:
Maintaining ecological balance
Protecting species from extinction
Preserving natural beauty and habitats
Supporting tourism and the economy (e.g., Yankari Game Reserve and Cross River National Park in Nigeria)
Step-by-step solution:
A. Maintain a balanced ecosystem. Conservation does this, since protected species and habitats keep food chains and nutrient cycles stable. This is true of conservation, so it is not the answer.
B. Preserve the beauty of nature. Conservation does this, since protected landscapes, forests, and wildlife stay intact. This is true, so it is not the answer.
C. Attract tourists. Conservation does this, since reserves and parks draw visitors and earn revenue. This is true, so it is not the answer.
D. Threaten the survival of species. Conservation does the opposite. It protects species from extinction. Since conservation does not do this, D completes the sentence correctly.
Answer: D. Conservation protects species. It does not threaten their survival.
Tip: When a question says "does not," "except," or "which is NOT," first mark the options that are true, and the leftover false one is your answer. Here, the one negative-sounding option (threaten) clashes with the positive purpose of conservation.
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21.
Measurements of height and weight of students in a class show
1. A.discontinuous variation
2. B.continuous variation
3. C.shortness is more prevalent
4. D.fatness is less prevalent
Show answer
Answer: B. continuous variation
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22.
Which of the following statements about chromosomes is correct?
1. A.All the chromosomes of a species are the same shape
2. B.The number present in a specie is constant
3. C.They are neatly arranged in a cytoplasm
4. D.They bear ribosomes on their outer membranes
Show answer
Answer: B. The number present in a specie is constant
AI explanation
Analyze the question: We need the one true statement about chromosomes.
Concept: Chromosomes are thread-like structures of DNA and protein found in the nucleus of eukaryotic cells. Each species has a characteristic, fixed chromosome number (e.g., humans 46, maize 20, fruit fly 8). This constancy is maintained from generation to generation through mitosis and meiosis, and fertilisation.
Evaluate each option:
A. All the chromosomes of a species are the same shape. False. Chromosomes differ in length and in centromere position (metacentric, submetacentric, acrocentric, telocentric), so they are not all the same shape.
B. The number present in a species is constant. True. Every normal member of a species has the same diploid number of chromosomes in its body cells, and the gametes have the haploid number.
C. They are neatly arranged in a cytoplasm. False. Chromosomes are located in the nucleus (nucleoplasm), not the cytoplasm. They are only arranged neatly at the equator during metaphase, and that happens within the dividing cell, not "in the cytoplasm" as a general statement.
D. They bear ribosomes on their outer membranes. False. Chromosomes have no membrane. Ribosomes are attached to the rough endoplasmic reticulum.
Answer: B. The chromosome number is constant for a species.
Exam tip: Remember "constant number, not constant shape." Whenever you see a question on chromosomes, think of the fixed number per species (diploid 2n, haploid n), and remember that they are found in the nucleus and have no membrane.
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23.
What happens when the ciliary muscles of the eye contract? The
1. A.lens become more concave
2. B.lens become more convex
3. C.lens gets a longer focal length
4. D.suspensory ligament becomes tight
Show answer
Answer: B. lens become more convex
AI explanation
Analyze the question: It asks about accommodation in the eye, which is how the eye focuses on near or far objects. Specifically, it asks what happens when the ciliary muscles contract.
Concept: The lens is held in place by the suspensory ligaments, which attach to the ciliary body (the ciliary muscles). The lens is elastic, so its shape depends on the tension pulling on it.
Step-by-step solution:
Ciliary muscles contract. They are ring-shaped, so contraction makes the ring smaller, like a drawstring tightening.
Tension on the suspensory ligaments drops. The ligaments become slack or loose.
The lens is no longer pulled flat. Because it is elastic, it bulges and becomes thicker, which means more convex.
Focal length becomes shorter. A thicker, more curved lens bends light more strongly. This lets the eye focus on near objects.
Checking the options:
A. Lens more concave: Wrong. The eye's lens is biconvex and never becomes concave.
B. Lens becomes more convex: Correct.
C. Longer focal length: Wrong. A more convex lens has a shorter focal length.
D. Suspensory ligament becomes tight: Wrong. It becomes slack. Tightening happens when the ciliary muscles relax.
Answer: B
Memory tip: "Contract = Close-up = Convex =カ slack ligaments." Better still, remember this pair:
Ciliary muscles contract → ligaments loose → fat lens → near vision.
Ciliary muscles relax → ligaments tight → thin lens → distant vision.
Many students get this wrong because they think "contract" means "tighten" for the ligaments, but the ligament does the opposite of the muscle.
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24.
The properties of endocrine system include the following except
1. A.secretion of hormones
2. B.transportation by blood to target organ
3. C.having specific effect
4. D.release of secretion into ducts
Show answer
Answer: D. release of secretion into ducts
AI explanation
Step 1: Analyze the question We are asked which option is NOT a property of the endocrine system. This is an "except" question, so three options are true of endocrine glands and one is false.
Step 2: Key concept The endocrine system is made up of ductless glands, such as the pituitary, thyroid, adrenal glands and the islets of Langerhans in the pancreas. They release hormones directly into the bloodstream, not through ducts. Glands that release their secretions through ducts are exocrine glands, such as the salivary glands, sweat glands and the digestive-enzyme part of the pancreas.
Step 3: Check each option
A. Secretion of hormones: This is the main function of endocrine glands, so it is a property.
B. Transportation by blood to the target organ: Hormones travel in the blood to their target organs, so it is a property.
C. Having specific effect: Each hormone acts on specific target cells or organs, so it is a property.
D. Release of secretion into ducts: This describes exocrine glands. Endocrine glands are ductless, so it is not a property of the endocrine system.
Step 4: Answer
Exam tip: Remember "Endo = Enter blood, Exo = Exit through ducts." Whenever you see "ducts" in a question about endocrine glands, think exocrine. Also, "ductless" is the word WASSCE often uses to describe endocrine glands.
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25.
The first stable product of photosynthesis is
1. A.starch
2. B.fructose
3. C.glucose
4. D.sucrose
Show answer
Answer: C. glucose
AI explanation
Analyze the question: It asks for the first stable product of photosynthesis, which is different from the final storage product or the transport form of sugar.
Explain the concept: Photosynthesis has two stages:
Light reaction (in the grana): water is split (photolysis), and ATP and NADPH are produced, releasing oxygen.
Dark reaction / Calvin cycle (in the stroma): CO₂ is fixed and reduced using ATP and NADPH.
In the Calvin cycle, CO₂ combines with RuBP, and the first stable compound formed is a 3-carbon molecule, 3-phosphoglycerate (PGA). This is then reduced to triose phosphate (G3P), which is used to build glucose. So in strict biochemical terms, the first stable product is PGA, but PGA is not among the options.
Working through the options:
A. Starch: a storage product. Glucose units are joined together to form it later, so it is not the first.
B. Fructose: a sugar formed along the way, but it is not the main first sugar product.
C. Glucose: the first stable carbohydrate product that is made from the triose phosphates. This is the answer at WASSCE level.
D. Sucrose: the transport form of sugar. It is made from glucose and fructose, so it comes later.
Sequence: CO₂ + H₂O → glucose → (converted to) sucrose for transport, or starch for storage.
At secondary school level, glucose is the expected answer, because PGA is not offered as an option and the other choices are all made from glucose.
Exam tip: Remember the order Glucose → Sucrose (transport) → Starch (storage). If a question asks for the "first" carbohydrate product, choose glucose. Starch is what you test for with iodine in a leaf, but it is made afterward from glucose.
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26.
The reagent used in testing for carbon (IV) oxide is
1. A.copper sulphate solution
2. B.lime water
3. C.hydrochloric acid
4. D.sodium hydroxide solution
Show answer
Answer: B. lime water
AI explanation
Step 1: Analyze the question You're asked which reagent is used to test for carbon (IV) oxide (CO₂).
Step 2: The concept The standard laboratory test for CO₂ uses lime water, which is a solution of calcium hydroxide, Ca(OH)₂. When CO₂ is bubbled through it, the clear solution turns milky (cloudy) because insoluble calcium carbonate forms:
Ca(OH)₂ + CO₂ → CaCO₃ (white precipitate) + H₂O
If you keep passing CO₂ through, the milkiness disappears. This is because soluble calcium hydrogencarbonate forms:
CaCO₃ + H₂O + CO₂ → Ca(HCO₃)₂
Step 3: Check each option
A. Copper sulphate solution: used to test for water (anhydrous copper(II) sulphate turns from white to blue) or in Benedict's and Biuret tests. It does not test for CO₂.
B. Lime water: turns milky with CO₂. ✔
C. Hydrochloric acid: it is used to produce CO₂ from carbonates, not to detect it.
D. Sodium hydroxide solution: it absorbs CO₂, but it gives no visible change, so it is not a test. In biology it is used to remove CO₂ in experiments.
Step 4: Answer The correct option is B. lime water.
Exam tip: Remember "Lime water = Limits CO₂": lime water goes milky for CO₂. In biology practicals, such as respiration or photosynthesis experiments, lime water shows CO₂ was given out, while sodium hydroxide or potassium hydroxide is used to absorb CO₂. Don't mix up the two.
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27.
The depletion of the ozone layer will result in the earth surface receiving more
1. A.gamma rays
2. B.infra-red rays
3. C.ultraviolet rays
4. D.X-rays
Show answer
Answer: C. ultraviolet rays
AI explanation
Step 1: Analyze the question The question asks which type of radiation reaches the earth's surface in greater amounts when the ozone layer thins out.
Step 2: Explain the concept The ozone layer (O₃) is found in the stratosphere. Its main job is to absorb most of the harmful ultraviolet (UV) radiation, especially UV-B, from the sun. Chemicals such as CFCs (chlorofluorocarbons, from old refrigerators, aerosol sprays and air conditioners) break down ozone molecules and thin the layer.
Step 3: Work through the options
A. Gamma rays: These are almost entirely absorbed higher in the atmosphere, and ozone is not the main shield against them. Not correct.
B. Infra-red rays: These are heat rays. They are related to the greenhouse effect and global warming, not to ozone depletion. Not correct.
C. Ultraviolet rays: Ozone absorbs these. When the layer is depleted, more UV reaches the earth. Correct.
D. X-rays: These are also absorbed high in the atmosphere, and ozone is not what blocks them. Not correct.
Step 4: Answer The correct answer is C. ultraviolet rays.
Effects of increased UV on living things:
Skin cancer and sunburn in humans
Cataracts (eye damage)
Reduced crop yields and damage to plankton
Weakened immune systems
Exam tip: Remember "Ozone = UV shield" and "CO₂ = infra-red/heat trap." WASSCE often tests the difference between ozone depletion (UV) and the greenhouse effect (heat/infra-red), so keep them separate in your mind.
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28.
The diagram is an illustration of a part of a flower. Study it and answer the question below; The function of the part labeled I is
1. A.receiving the pollen grain
2. B.attract pollinators
3. C.germination of the pollen grain
4. D.site for double fertilization in the plant
Show answer
Answer: A. receiving the pollen grain
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29.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.
30.
The position occupied by an organism in food chain is the
1. A.energy level
2. B.niche
3. C.trophic level
4. D.biomass
Show answer
Answer: C. trophic level
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31.
The excretory product of some reptiles, birds and insects is
1. A.urea
2. B.urine
3. C.ammonia
4. D.uric acid
Show answer
Answer: D. uric acid
AI explanation
1. Analyze the question The question asks for the main nitrogenous waste excreted by some reptiles, birds and insects.
2. Explain the concept Animals break down proteins and amino acids, which produces nitrogenous waste. The form of waste depends on how much water the animal can afford to lose:
Ammonia is very toxic and needs a lot of water to dilute it. Aquatic animals such as bony fish and tadpoles excrete it.
Urea is less toxic and needs moderate water. Mammals (including humans) and amphibians excrete it.
Uric acid is almost insoluble in water and non-toxic. It is excreted as a semi-solid paste with very little water loss, so it suits animals that must conserve water. Birds, many reptiles (lizards, snakes) and insects excrete it.
3. Step-by-step solution
Reptiles, birds and insects live mostly on land, and their eggs are laid with shells or hard coverings. The embryo cannot get rid of waste, so a harmless, insoluble waste is needed.
Water conservation is therefore important, which points to uric acid.
Checking the options: • A. Urea is for mammals and amphibians. ✗ • B. Urine is a fluid containing waste, not a specific excretory chemical. ✗ • C. Ammonia is for aquatic animals. ✗ • D. Uric acid is for birds, reptiles and insects. ✓
4. Answer The correct option is D. uric acid.
5. Exam tip Remember "Birds, Reptiles, Insects = Uric acid", the water-savers. Link the waste to habitat: water animals excrete ammonia, mammals excrete urea, and dry-land egg-layers excrete uric acid.
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32.
The mutualism type of relationship is different from a parasitic relationship because in mutualism
1. A.both organisms involved benefit
2. B.none of the organisms benefits or harm each other
3. C.both organisms harm each other
4. D.only one of the organisms is harmed
Show answer
Answer: A. both organisms involved benefit
AI explanation
Step 1: Analyze the question The question asks what makes mutualism different from parasitism. So we need the feature that is true of mutualism but not of parasitism.
Step 2: Explain the concepts
Mutualism: a close association between two different species in which both benefit. Examples: nitrogen-fixing Rhizobium bacteria in the root nodules of legumes (beans, groundnut), where the bacteria get food and shelter and the plant gets nitrates; lichens (alga and fungus); and the bacteria in the human gut.
Parasitism: a relationship in which one organism (the parasite) benefits while the other (the host) is harmed. Examples: tapeworm in humans, Plasmodium in humans, and mistletoe on a host tree.
Step 3: Evaluate the options
A. Both organisms involved benefit. Correct. This is the definition of mutualism, and it is the key difference from parasitism, where only one side gains.
B. None benefits or harms the other. This describes neutralism, not mutualism.
C. Both organisms harm each other. This is closer to competition or antagonism, not mutualism.
D. Only one of the organisms is harmed. This fits parasitism (the host is harmed), so it is not what distinguishes mutualism.
Answer: A. In mutualism both partners benefit, while in parasitism one benefits at the other's expense.
Exam tip: Remember the pattern of "+" and "−" signs:
Mutualism: + / +
Parasitism: + / −
Commensalism: + / 0
Questions like this appear often in WASSCE, NECO, and JAMB, so learn these three patterns well.
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33.
The diagram below is an illustration of a cross between plants A and B of the same species. Study it and answer the question below; If the F1 generation are plants with high yield and resistance, the genotype of the F1 generation plants would be
1. A.YYRR
2. B.YyRr
3. C.yyRr
4. D.yyrr
Show answer
Answer: B. YyRr
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35.
Which of the following diseases can be inherited?
1. A.Pneumonia
2. B.Whooping cough
3. C.Sickle cell anemia
4. D.Malaria
Show answer
Answer: C. Sickle cell anemia
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36.
In an experiment, mould and yeast cells were transferred into an environment with low oxygen concentration. After a few days, the mould dies while the yeast cells did not. Which of the following statements best explains the following observation.
1. A.The yeast cells carried out photosynthesis while the mould did not
2. B.Photosynthesis does not take place in the absence of oxygen
3. C.Respiration can take place in yeast cells in the absence of oxygen
4. D.Respiration does not occur in the mould
Show answer
Answer: C. Respiration can take place in yeast cells in the absence of oxygen
AI explanation
Step 1: Analyze the question Mould and yeast are both fungi, and neither can photosynthesize because they have no chlorophyll. Both were placed in low oxygen. The mould died, but the yeast survived. We need the best explanation for the difference.
Step 2: The concept
Aerobic respiration needs oxygen. It releases a lot of energy: glucose + oxygen → carbon dioxide + water + energy (about 38 ATP).
Anaerobic respiration (fermentation) does not need oxygen. In yeast, it gives: glucose → ethanol + carbon dioxide + a small amount of energy (2 ATP).
Yeast is a facultative anaerobe, so it can switch between aerobic and anaerobic respiration. Most moulds are strict (obligate) aerobes, so they need oxygen to get enough energy.
Step 3: Evaluate the options
A. Wrong. Yeast is a fungus and has no chlorophyll, so it cannot photosynthesize.
B. Wrong. It is a true statement only in the sense that photosynthesis needs light, water and CO₂, not the absence of oxygen. It also does not explain why yeast survived while mould died.
C. Correct. Yeast can respire anaerobically and gets energy without oxygen, so it survives. The mould cannot, so it dies.
D. Wrong. Mould does respire, but it does so aerobically, and that is why it died when oxygen was low.
Step 4: Answer The correct answer is C: respiration can take place in yeast cells in the absence of oxygen.
Tip: Remember "Yeast = ferments." Whenever a question compares an organism that survives with one that dies in low oxygen, look for the option about anaerobic respiration. Also remember that fungi never photosynthesize, which lets you eliminate any option that says they do.
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37.
Use the list of insects below to answer the question below; I. Cotton stainer II. Honeybee III. Termite IV. Weevil Which of the insects destroys grains?
1. A.I
2. B.II
3. C.III
4. D.IV
Show answer
Answer: D. IV
AI explanation
Analyze the question: You are asked which insect in the list destroys stored grains (like maize, rice, beans, and wheat).
Explain the concept: Insects are classified by their roles and the damage they cause:
Cotton stainer (I): A bug that feeds on cotton bolls and stains the lint. It is a pest of cotton, not of stored grains.
Honeybee (II): A useful insect. It pollinates flowers and produces honey and beeswax.
Termite (III): It destroys wood, paper, and crops in the field, and it damages buildings. It is not the typical grain pest.
Weevil (IV): A small beetle. The adult and its larvae bore into stored grains and seeds. They eat the inside and leave the grain hollow and powdery. Examples are the maize weevil (Sitophilus zeamais) and the rice weevil.
Solution:
Cotton stainer attacks cotton, so it is eliminated.
Honeybee is beneficial, so it is eliminated.
Termite attacks wood and buildings, so it is eliminated.
Weevil destroys stored grains, so it is the answer.
Tip: Link each pest to what it attacks:
Cotton stainer → cotton
Weevil → stored grains
Termite → wood
Honeybee → honey and pollination
If you see "grains" in a question, think of weevils.
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38.
An example of a trace elements is
1. A.potassium
2. B.calcium
3. C.magnesium
4. D.copper
Show answer
Answer: D. copper
AI explanation
Step 1: Analyze the question The question asks which option is a trace element. Trace elements (micronutrients) are minerals that organisms need only in very small amounts.
Step 2: Explain the concept Mineral elements needed by living things fall into two groups:
Macronutrients (major elements): needed in large amounts. Examples: calcium, potassium, magnesium, nitrogen, phosphorus, sulphur, sodium, chlorine.
Micronutrients (trace elements): needed in very small amounts. Examples: iron, copper, zinc, manganese, iodine, fluorine, cobalt, molybdenum, boron.
Step 3: Check each option
A. Potassium: a macronutrient, needed for nerve function and for opening and closing stomata. Not a trace element.
B. Calcium: a macronutrient, needed for bones, teeth and blood clotting. Not a trace element.
C. Magnesium: a macronutrient, needed to make chlorophyll in plants. Not a trace element.
D. Copper: needed only in tiny quantities, for enzyme activity and for some respiratory pigments. It is a trace element.
Step 4: Answer The correct option is D. copper.
Tip: Remember the "big" minerals with the phrase "Ca-K-Mg-N-P-S" (calcium, potassium, magnesium, nitrogen, phosphorus, sulphur), which are the macronutrients. Metals like iron, copper, zinc and manganese, along with iodine and fluorine, are the trace elements that appear again and again in WASSCE, JAMB and NECO questions.
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39.
Which of the following tissues does not provide support in flowering plants?
1. A.Collenchyma
2. B.Parenchyma
3. C.Xylem
4. D.Phloem
Show answer
Answer: D. Phloem
AI explanation
Analyze the question: We need the tissue that does NOT provide support in a flowering plant. Three options support the plant in some way, and one does not.
Explain the concept: Supporting tissues in flowering plants include:
Collenchyma: its cell walls are thickened with cellulose and pectin, so it supports young stems, petioles and leaves.
Sclerenchyma: its cell walls are thickened with lignin, so it gives strong, rigid support.
Xylem: its vessels and fibres are lignified, so it conducts water and also gives strength to the plant (wood is mostly xylem).
Parenchyma: its thin-walled cells are packed with water, so they become turgid and give support to herbaceous plants. When they lose water the plant wilts.
Phloem: Its main job is to transport manufactured food (sucrose and amino acids) from the leaves to other parts of the plant. It contains sieve tubes and companion cells. It does have some fibres, but its basic function is translocation, not support.
Step-by-step elimination:
A. Collenchyma gives support. Eliminate.
B. Parenchyma gives support through turgidity. Eliminate.
C. Xylem gives support through lignified walls. Eliminate.
D. Phloem is mainly for transport of food. It is the one that does not provide support.
Answer: D. Phloem
Exam tip: Remember it this way: "Xylem supports and carries water, phloem only carries food." In questions like this, ask what each tissue's main job is. Collenchyma and sclerenchyma are the "support" tissues, xylem is the "water and support" tissue, and phloem is the "food transport" tissue.
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41.
Soil with the finest texture is?
1. A.silt
2. B.clay
3. C.sand
4. D.gravel
Show answer
Answer: B. clay
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42.
The organism with spiral chloroplasts and nucleus suspended by cytoplasmic strands is
1. A.Volvox
2. B.Spirogyra
3. C.Paramecium
4. D.Euglena
Show answer
Answer: B. Spirogyra
AI explanation
Analyze the question: We need the organism with two features: (1) chloroplasts shaped like a spiral ribbon, and (2) a nucleus suspended in the cell's center by cytoplasmic strands.
Explain the concept: Spirogyra is a filamentous green alga found in ponds and slow-moving freshwater. Its name comes from its spiral (helical) chloroplasts. Each cell has a large central vacuole, and the nucleus is held in the middle of the cell by thin strands of cytoplasm that stretch across the vacuole.
Go through the options:
A. Volvox: A spherical colony of many flagellated cells. Each cell has a single cup-shaped chloroplast, not a spiral one.
B. Spirogyra: Has ribbon-like spiral chloroplasts, and its nucleus is suspended in the center by cytoplasmic strands. This fits both clues.
C. Paramecium: A slipper-shaped protozoan with no chloroplasts at all. It is not photosynthetic.
D. Euglena: Has several disc-shaped or star-shaped chloroplasts and a flagellum. Its nucleus is not suspended by strands.
Answer: The correct option is B. Spirogyra.
Tip: Link the name to the feature: Spiro-gyra means "spiral" (think of a coil). If a question mentions spiral or ribbon-shaped chloroplasts, think Spirogyra right away.
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43.
Oxygen comes out of the stomata during photosynthesis through the process known as
1. A.diffusion
2. B.transpiration pull
3. C.osmosis
4. D.active transport
Show answer
Answer: A. diffusion
AI explanation
Step 1: Analyze the question During photosynthesis, oxygen is produced as a by-product inside the leaf. The question asks how it leaves through the stomata.
Step 2: Explain the concept
Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration, with no energy needed.
Osmosis is the movement of water across a semi-permeable membrane, so it does not apply to a gas.
Transpiration pull is the force that draws water up the xylem as water vapour is lost from leaves. It is about water, not oxygen.
Active transport moves substances against a concentration gradient and uses energy (ATP). Gas exchange in leaves does not need this.
Step 3: Apply it to the leaf
Photosynthesis in the chloroplasts of the mesophyll cells produces oxygen.
The concentration of oxygen inside the leaf becomes higher than in the outside air.
Oxygen moves down this concentration gradient through the open stomata into the atmosphere.
No energy is used, and the movement is a passive process: diffusion.
Step 4: Answer The correct option is A. diffusion.
Exam tip: Remember that gases move by diffusion. Whenever a question is about oxygen, carbon dioxide, or water vapour moving through stomata, think diffusion. Osmosis is only for water across membranes, and active transport needs energy against a gradient.
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44.
The diagram below is an illustration of an ecological instrument. Study it an answer the question below; When the instrument is in use, it is usually?
1. A.placed slightly above soil level
2. B.placed on a table
3. C.suspended in air
4. D.suspended to moving water
Show answer
Answer: A. placed slightly above soil level
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45.
Which of the following materials is not a living semi-permeable membrane?
1. A.pig's bladder
2. B.Unripe pawpaw fruit
3. C.Yam tuber
4. D.Sheet of cellophane
Show answer
Answer: D. Sheet of cellophane
AI explanation
Analyze the question: The question asks which material is not a living semi-permeable membrane. A living membrane comes from living tissue (plant or animal) and selectively allows some substances to pass through.
Explain the concept: Osmosis is the movement of water through a semi-permeable membrane from a region of high water potential (dilute solution) to a region of low water potential (concentrated solution).
Semi-permeable membranes fall into two groups:
Living (biological) membranes: from living or once-living tissue, such as animal bladder, plant tissues, and the cell membrane.
Non-living (artificial) membranes: made from non-biological material, such as cellophane (Visking tubing) and parchment paper.
Go through the options:
A. Pig's bladder: animal tissue, so it is a biological membrane.
B. Unripe pawpaw fruit: plant tissue, so it is biological.
C. Yam tuber: plant tissue, commonly used in osmosis experiments, so it is biological.
D. Sheet of cellophane: a synthetic material made from processed cellulose. It is semi-permeable but was never a living tissue, so it is not a living membrane.
Answer: The correct option is D. Sheet of cellophane.
Tip: In osmosis experiments, remember that cellophane and Visking tubing are the standard artificial membranes. When a question says "not living," look for the manufactured material. Pig's bladder, yam, and pawpaw all come from living organisms.
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46.
A child that can receive blood donation from anybody belongs to the blood group
1. A.O
2. B.A
3. C.B
4. D.AB
Show answer
Answer: D. AB
AI explanation
Analyze the question The question asks which blood group lets a person receive blood from anybody. That person is called a universal recipient.
Explain the concept Blood groups are decided by the antigens on red blood cells and the antibodies in the plasma:
| Blood group | Antigens on red cells | Antibodies in plasma | |---|---|---| | A | A | anti-B | | B | B | anti-A | | AB | A and B | none | | O | none | anti-A and anti-B |
A recipient's antibodies attack any donor red cells carrying antigens the recipient lacks. This causes agglutination (clumping).
Step-by-step solution
Group O has anti-A and anti-B antibodies, so it can only receive from O. It is the universal donor, not the universal recipient.
Group A has anti-B antibodies, so it cannot receive B or AB blood.
Group B has anti-A antibodies, so it cannot receive A or AB blood.
Group AB has no anti-A or anti-B antibodies, so nothing in its plasma attacks donated red cells of any group. It can receive from A, B, AB and O.
So the group that can receive blood from anybody is AB, the universal recipient.
Answer: D. AB
Exam tip
O = universal donor (no antigens, so nothing to trigger a reaction).
AB = universal recipient (no antibodies, so nothing to attack).
Remember it as: "O gives to all, AB receives from all."
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48.
Use the following Classes of Arthropoda to answer the question below I. Crustacea II. Insecta III. Arachinda IV. Chilopoda Which of the classes is characterised by the possession of two pairs of antennae?
1. A.I
2. B.II
3. C.III
4. D.IV
Show answer
Answer: A. I
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49.
Use the following Classes of Arthropoda to answer the question below I. Crustacea II. Insecta III. Arachinda IV. Chilopoda Which members of the classes live mainly in an aquatic habitat?
1. A.I
2. B.II
3. C.III
4. D.IV
Show answer
Answer: A. I
AI explanation
Analyze the question: It asks which of the four arthropod classes has members that live mainly in water (an aquatic habitat).
Explain the concept: Arthropoda is divided into classes based on body structure and habitat:
Crustacea (crabs, prawns, shrimps, lobsters, crayfish, water fleas): mostly aquatic. They breathe with gills, and they have two pairs of antennae.
Insecta (cockroach, grasshopper, housefly, butterfly): mainly terrestrial, with some aerial. They have 3 pairs of legs and breathe with tracheae.
Arachnida (spiders, scorpions, ticks, mites): mainly terrestrial. They have 4 pairs of legs and no antennae.
Chilopoda (centipedes): terrestrial. They live under stones and logs and have one pair of legs per body segment.
Step-by-step solution:
Check each class for its typical habitat.
Insecta, Arachnida and Chilopoda are all mainly land dwellers.
Only Crustacea has members that live mainly in water (fresh and marine), such as crabs, prawns and Daphnia.
Answer: Crustacea (I), which is option A.
Tip: Think "Crustacea = Crab, Crayfish, and water." Crabs and prawns are the seafood you know, so Crustacea is the aquatic class. Remember that "mainly" matters here: a few insects, like water beetles, live in water, but most insects are terrestrial.
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