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WAEC (WASSCE) 2021

2021 WAEC (WASSCE) Biology Past Questions and Answers

The 2021 WAEC (WASSCE) Biology past questions with answers: 49 objective questions from the 2021 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.

Past questions © the examination body (JAMB/WAEC/NECO). DeeepSolve is not affiliated with them. Rights holders: see /copyright.

Questions

  1. 1.

    Plants suitable for experiments in genetics must not

    1. A.produce numerous seeds within a short time
    2. B.have a small number of chromosomes
    3. C.have a relatively short life cycle
    4. D.produce one generation in a large period
    Show answer

    Answer: D. produce one generation in a large period

    AI explanation

    Analyze the question: We are asked which characteristic a plant suitable for genetic experiments must not have. So we look for the undesirable trait.

    Concept: Good organisms for genetics experiments (like Mendel's garden pea, or Arabidopsis) share these features:

    • They produce many offspring (numerous seeds), so results can be analyzed statistically.
    • They have a short life cycle, so many generations can be studied quickly.
    • They have a small number of chromosomes, which makes it easier to track and study inheritance.
    • They are easy to grow and cross-pollinate, and they show clear contrasting traits.

    Checking each option:

    • A. Producing numerous seeds in a short time is desirable, so it is not the answer.
    • B. A small chromosome number is desirable because it makes studies simpler, so it is not the answer.
    • C. A relatively short life cycle is desirable, so it is not the answer.
    • D. Producing one generation over a large period of time is undesirable. It would take too long to observe several generations, so this is what a suitable plant must not do.

    Answer: The correct option is D.

    Exam tip: When a question says "must not" or "except," flip your thinking. Find the disadvantage and eliminate the good qualities. For genetics organisms, remember "fast, many, simple": a fast life cycle, many offspring, and simple chromosomes.

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  2. 2.

    The structure labeled II is the

    1. A.spore
    2. B.stolon
    3. C.columella
    4. D.sporangium
    Show answer

    Answer: C. columella

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  3. 3.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

  4. 4.

    Which of the following organisms exhibits division of labour?

    1. A.butterfly
    2. B.cockroach
    3. C.termite
    4. D.housefly
    Show answer

    Answer: C. termite

    AI explanation

    Step 1: Analyze the question The question asks which organism shows division of labour. This means members of the same group do different jobs for the benefit of the whole colony.

    Step 2: Explain the concept Division of labour is a feature of social insects. They live in organized colonies where individuals are specialized into castes, each with a particular function. Examples are termites, ants, and bees.

    In a termite colony:

    • Queen: lays eggs
    • King: mates with the queen
    • Workers: gather food, feed the colony, and build and repair the nest
    • Soldiers: defend the colony against enemies
    • Reproductives (alates): form new colonies

    Step 3: Evaluate the options

    • A. Butterfly: Solitary. Each butterfly lives independently, with no castes.
    • B. Cockroach: Lives in groups, but they are not organized into castes with specialized roles.
    • C. Termite: Social insect with distinct castes (king, queen, workers, soldiers). This shows clear division of labour.
    • D. Housefly: Solitary. There are no castes or colonies.

    Step 4: Answer The correct option is C. termite.

    Exam tip: Remember the social insects as "T-A-B": Termites, Ants, Bees (and wasps). If a WASSCE question mentions castes, colonies, or division of labour, think of these three first.

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  5. 5.

    In humans, pointed eyebrows (B) is a dominant trait over smooth eyebrows (b). A student and the mother have smooth eyebrows while the father has pointed eyebrows. What is the genotype of the father?

    1. A.BB
    2. B.Bb
    3. C.bb
    4. D.BBbb
    Show answer

    Answer: B. Bb

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  6. 6.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

  7. 7.

    A woman with Rhesus negative blood group was advised not to marry a man with Rhesus positive blood group because

    1. A.it will hinder her from having blood transfusion from her husband
    2. B.it will result in sickness and probably death of the offspring
    3. C.her children may all resemble her husband
    4. D.it may affect her childbearing ability
    Show answer

    Answer: B. it will result in sickness and probably death of the offspring

    AI explanation

    Analyze the question: It asks why a Rhesus negative (Rh⁻) woman is advised against marrying a Rhesus positive (Rh⁺) man. This is about Rhesus incompatibility between mother and baby.

    Concept:

    • Rh⁺ is dominant (the Rh factor/antigen is present on red blood cells). Rh⁻ is recessive (no Rh antigen).
    • If an Rh⁻ mother carries an Rh⁺ baby (inherited from an Rh⁺ father), some of the baby's red blood cells can enter the mother's blood, especially at birth.
    • The mother's immune system sees the Rh antigen as foreign and makes anti-Rh antibodies.
    • In the first pregnancy, the baby is usually unaffected because the antibodies develop late. In later pregnancies, the antibodies cross the placenta and destroy the red blood cells of an Rh⁺ foetus.
    • This causes haemolytic disease of the newborn (erythroblastosis fetalis), which leads to severe anaemia, jaundice, brain damage, stillbirth or death of the baby.

    Checking the options:

    • A. Wrong. The problem is not about transfusing blood from her husband. The issue is the baby's blood.
    • B. Correct. Rhesus incompatibility can make the offspring sick and may cause death.
    • C. Wrong. Resemblance has nothing to do with blood group.
    • D. Wrong. It does not reduce her ability to conceive. The risk is to the foetus or baby, not her fertility.

    Answer: B

    Exam tip: Remember "Rh⁻ mother + Rh⁺ baby = mother's antibodies attack the baby's blood" (usually from the second pregnancy onward). Whenever you see Rhesus factor with marriage or pregnancy, think of the baby's health, not the mother's fertility.

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  8. 8.

    Which of the following behaviours is correctly matched with the corresponding diseases?

    1. A.Smoking cigarette / Liver cirrhosis. Lung cancer, AIDS
    2. B.Having multiple sexual partners / liver cirrhosis, syphilis, AIDS.
    3. C.Living near dirty gutter / Lung cancer, syphilis, river blindness.
    4. D.Eating uncooked meatf/fdysentery, cholera. food poisoning.
    Show answer

    Answer: D. Eating uncooked meatf/fdysentery, cholera. food poisoning.

    AI explanation

    Analyze the question: We need the option where the behaviour is correctly linked to diseases it can cause or spread.

    Check each option:

    • A. Smoking cigarette / liver cirrhosis, lung cancer, AIDS. Smoking causes lung cancer, but AIDS is caused by HIV, which is not spread by smoking. Liver cirrhosis is mainly linked to alcohol, not cigarettes. Wrong.
    • B. Multiple sexual partners / liver cirrhosis, syphilis, AIDS. Syphilis and AIDS are sexually transmitted, so those two fit. Liver cirrhosis is mainly caused by excessive alcohol, though hepatitis B/C can also damage the liver. As a list, it is not fully correct. Wrong.
    • C. Living near dirty gutter / lung cancer, syphilis, river blindness. Dirty gutters breed mosquitoes and harbour rats and flies, which spread malaria, cholera and similar diseases. Lung cancer and syphilis are not caused by gutters, and river blindness is spread by blackflies that breed in fast-flowing rivers. Wrong.
    • D. Eating uncooked meat / dysentery, cholera, food poisoning. Raw or undercooked food can carry bacteria, protozoa and parasites. These can cause dysentery, food poisoning and related gastrointestinal infections. Cholera is more typically spread by contaminated water or food handled in unhygienic conditions, but it is the only option where all the listed diseases are food/water-borne and plausibly linked to the behaviour. Best match.

    Conclusion: Option D is the only one in which the behaviour is reasonably matched with the diseases listed. Strictly speaking, cholera is mostly waterborne, but D is clearly the best choice among the four.

    Exam tip: When matching behaviours with diseases, ask two questions: "How is each disease transmitted?" and "Does the behaviour expose me to that route?" Quickly eliminate options that contain one obviously wrong disease, such as AIDS from smoking or lung cancer from gutters.

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  9. 9.

    How many gametes are produced in the pollen grain of a flowering plant before fertilization?

    1. A.one
    2. B.two
    3. C.three
    4. D.four
    Show answer

    Answer: B. two

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  10. 10.

    Which of the following features is a characteristic of aquatic plants possession of ?

    1. A.multiple epidermis
    2. B.heavily lignified tissue
    3. C.finely divided leaves
    4. D.succulent stem
    Show answer

    Answer: C. finely divided leaves

    AI explanation

    Analyze the question: The question asks which feature is characteristic of aquatic plants (hydrophytes), such as water lettuce, water lily, and Ceratophyllum.

    Concept: Aquatic plants live in water, so they don't face water shortage. Their adaptations include:

    • Thin or absent cuticle, since water loss isn't a problem
    • Poorly developed or reduced xylem and supporting tissue, because water supports them
    • Large air spaces (aerenchyma) for buoyancy and gas exchange
    • Stomata on the upper surface of floating leaves
    • Finely divided (feathery) leaves in submerged plants, which increase surface area for absorbing dissolved gases and light, and reduce resistance to water currents

    Evaluating the options:

    • A. Multiple epidermis: This is a feature of xerophytes (desert plants), which need to reduce water loss. Not aquatic.
    • B. Heavily lignified tissue: Lignin gives rigid support, which aquatic plants don't need because water buoys them. Not aquatic.
    • C. Finely divided leaves: This is typical of submerged aquatic plants, since it increases surface area for gas exchange and lets water currents flow through without tearing the leaves. Correct.
    • D. Succulent stem: This is for water storage in xerophytes such as cactus. Not aquatic.

    Answer: C, finely divided leaves.

    Tip: Think "water is plentiful, support is free." Features that save water (multiple epidermis, succulent stems) or give strong support (lignin) belong to land and desert plants. Aquatic plants have thin, reduced, or feathery structures.

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  11. 11.

    A plant cell placed in a solution with a higher water potential will

    1. A.expand and then shrink
    2. B.enlarge and become turgid.
    3. C.expand and then burst
    4. D.decrease in size and become flaccid
    Show answer

    Answer: B. enlarge and become turgid.

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  12. 12.

    The following organisms are examples of carnivorous plants except.

    1. A.gloriosa
    2. B.venus flytrap
    3. C.pitcher plant
    4. D.Utricularia
    Show answer

    Answer: A. gloriosa

    AI explanation

    Analyze the question: We need the one plant that is NOT carnivorous (insectivorous).

    Concept: Carnivorous plants grow in nutrient-poor soils (often nitrogen-deficient, like bogs). They trap and digest insects to get nitrogen and other nutrients. They have special trapping structures.

    Going through the options:

    • A. Gloriosa – Gloriosa superba (flame lily or climbing lily) is a flowering plant that grows from tubers. It has tendril-tipped leaves for climbing but does not trap or digest animals. It is not carnivorous.
    • B. Venus flytrap (Dionaea muscipula) – Its hinged leaf lobes snap shut on insects. It is carnivorous.
    • C. Pitcher plant (Nepenthes) – Its leaves form a pitcher-shaped trap filled with digestive fluid. Insects fall in and are digested. It is carnivorous.
    • D. Utricularia (bladderwort) – It has small bladder-like traps that suck in tiny aquatic organisms. It is carnivorous.

    Answer: Since the question asks for the exception, the correct option is A. gloriosa.

    Tip: For "except" questions, first identify the options you are sure about (Venus flytrap, pitcher plant, bladderwort are the classic three), and the leftover one is your answer. Also remember: Sundew (Drosera) is another common carnivorous plant that may appear in exams.

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  13. 13.

    The organism belongs to the Phylum

    1. A.Rhizopoda
    2. B.Ciliophora
    3. C.Euglenophyta
    4. D.Rhodophyta
    Show answer

    Answer: A. Rhizopoda

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  14. 14.

    Which of the following statements about mitosis is not correct?

    1. A.chiasmata are not formed
    2. B.Bi-valents are not formed
    3. C.It does not lead to variation
    4. D.Four daughter cells are produced
    Show answer

    Answer: D. Four daughter cells are produced

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  15. 15.

    Autotrophic nutrition is a process whereby an organism obtains food

    1. A.by utilizing its store energy
    2. B.by synthesizing simple substances using energy
    3. C.from other organisms in exchange for some products
    4. D.in a synthesized form, from other living organisms
    Show answer

    Answer: B. by synthesizing simple substances using energy

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  16. 16.

    Which of the following practices is a wildlife conservation method?

    1. A.use of cover crops
    2. B.crop rotation
    3. C.mulching
    4. D.discouraging poaching
    Show answer

    Answer: D. discouraging poaching

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  17. 17.

    When a large number of organisms share limited resources, the result is?

    1. A.mutualism
    2. B.extinction
    3. C.commensalism
    4. D.competition
    Show answer

    Answer: D. competition

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  18. 18.

    Which of the following statements about sickle cell anaemia is correct?

    1. A.it is caused by sex-linked genes
    2. B.it is more common in males than in females
    3. C.two sickle cell carrier parents may have a sickling child
    4. D.it is caused by recessive genes
    Show answer

    Answer: C. two sickle cell carrier parents may have a sickling child

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  19. 19.

    Which of the following resources cannot be conserved?

    1. A.forest
    2. B.water
    3. C.soil
    4. D.garbage
    Show answer

    Answer: D. garbage

    AI explanation

    Analyze the question: We are asked which resource cannot be conserved. Conservation means protecting, managing, and using resources wisely so they last for future generations.

    Explain the concept: Natural resources that can be managed, protected, or replenished can be conserved:

    • Forest: conserved through afforestation, reforestation, forest reserves, and controlled logging.
    • Water: conserved by avoiding wastage, protecting water sources, and preventing pollution.
    • Soil: conserved through crop rotation, mulching, cover cropping, terracing, and contour ploughing to prevent erosion and loss of fertility.
    • Garbage: this is waste. It is not a natural resource that we protect or preserve. We do not "conserve" garbage; we dispose of, recycle, or manage it. The goal is to reduce it, not to keep it for future use.

    Step-by-step solution:

    1. Check A (forest): can be conserved, so it is not the answer.
    2. Check B (water): can be conserved, so it is not the answer.
    3. Check C (soil): can be conserved, so it is not the answer.
    4. Check D (garbage): it is waste material, not a resource to be preserved, so it does not fit the idea of conservation.

    Answer: D. garbage

    Tip: Conservation applies to useful natural resources (forests, water, soil, wildlife, minerals). When you see words like "garbage," "waste," or "refuse" in a conservation question, think of waste management (reduce, reuse, recycle), not conservation.

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  20. 20.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

  21. 21.

    The temperature control centre in mammals is located in the?

    1. A.skin
    2. B.hypothalamus
    3. C.pituitary gland
    4. D.adrenal gland
    Show answer

    Answer: B. hypothalamus

    AI explanation

    Step 1: Analyze the question The question asks which part of the body acts as the "thermostat" (temperature control centre) in mammals.

    Step 2: Explain the concept Mammals are homeoiotherms (endotherms), meaning they keep their body temperature roughly constant (about 37°C in humans) regardless of the surroundings. This process is called thermoregulation, and it is a type of homeostasis.

    Thermoregulation works through a feedback system:

    • Receptors: Thermoreceptors in the skin detect external temperature changes. Receptors in the hypothalamus detect the temperature of the blood passing through it.
    • Control centre: The hypothalamus, a part of the brain, receives this information and compares it with the "set point".
    • Effectors: Skin (sweat glands, blood vessels, hair erector muscles) and muscles carry out the response.

    Step 3: Work through the options

    • A. Skin: The skin is an effector and receptor (it sweats, and its blood vessels dilate or constrict), but it does not control the process. ✗
    • B. Hypothalamus: Part of the brain that coordinates the body's response to temperature changes. It triggers sweating and vasodilation when we are too hot, and shivering and vasoconstriction when we are too cold. ✓
    • C. Pituitary gland: It secretes hormones (e.g. growth hormone, ADH) and is called the "master gland", but it is not the temperature centre. ✗
    • D. Adrenal gland: It secretes adrenaline and other hormones, mainly for "fight or flight" responses. ✗

    Step 4: Answer

    Exam tip: Remember "Hypo-thermostat": the hypothalamus is the body's thermostat. When a question asks about the control centre in homeostasis, think brain (hypothalamus). When it asks about response organs, think skin, muscles and glands.

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  22. 22.

    Natural selection arises as a result of?

    1. A.gene mutation
    2. B.change of habitat
    3. C.reduction in population
    4. D.climate change
    Show answer

    Answer: A. gene mutation

    AI explanation

    1. Analyze the question We are asked what natural selection "arises as a result of". Natural selection is the process by which organisms best suited to their environment survive and reproduce more successfully than others.

    2. Explain the concept Natural selection (Darwin's theory) depends on three things:

    • Variation among individuals in a population
    • Struggle for existence (competition for limited resources)
    • Survival of the fittest, with favourable traits passed to offspring

    The key requirement is variation. Without differences between individuals, there is nothing for the environment to "select". The ultimate source of new variation is gene mutation (along with recombination during sexual reproduction). Mutations create new alleles, and natural selection then acts on them.

    3. Step-by-step solution

    • A. Gene mutation: It produces new heritable variation. Selection acts on this variation, so natural selection arises from it. ✔
    • B. Change of habitat: It can change which traits are favoured, but it is an environmental pressure, not the source of the variation.
    • C. Reduction in population: This is often a result of selection or other factors, not its cause.
    • D. Climate change: It is a selection pressure that can drive natural selection, but it is not the basic origin of the heritable differences that selection works on. It is also only one of many pressures.

    Of all the options, gene mutation is the only one that supplies the raw material for natural selection, so it is the best answer.

    4. Answer A. gene mutation

    5. Exam tip Remember the chain: Mutation → Variation → Selection → Adaptation → Evolution. If a question asks about the origin of variation or what selection "arises from", think mutation. If it asks about what drives selection, think environmental factors such as climate, predation or competition.

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  23. 23.

    The diagrams above are illustrations of types of comb found in domestic fowl. Study them and answer this question. The types of comb show ?

    1. A.variation
    2. B.inheritance
    3. C.cell theory
    4. D.courtship behaviour
    Show answer

    Answer: C. cell theory

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  24. 24.

    Offspring formed by sexual reproduction exhibit more variation than those formed by asexual reproduction because

    1. A.greater amount of DNA is involved in sexual reproduction
    2. B.gametes of parents have different genetic composition
    3. C.genetic materials come from parents of two different species
    4. D.sexual reproduction is a lengthy process
    Show answer

    Answer: B. gametes of parents have different genetic composition

    AI explanation

    Step 1: Analyze the question We are asked why sexual reproduction produces more variation among offspring than asexual reproduction.

    Step 2: Explain the concept

    • Asexual reproduction involves only one parent and mitosis. The offspring are genetically identical to the parent (clones), apart from rare mutations.
    • Sexual reproduction involves two parents, each contributing a gamete (sperm or egg, pollen or ovule). Gametes are made by meiosis, which shuffles genes through: • Crossing over, where chromosomes exchange segments. • Independent assortment, where chromosomes are distributed randomly into gametes. • Random fertilisation, where any sperm can fuse with any egg.

    As a result, each gamete has a different genetic makeup, and the offspring get a new combination of genes from both parents.

    Step 3: Evaluate the options

    • A. Greater amount of DNA is involved. Wrong. Offspring have the same amount of DNA as the parents (the chromosome number is restored at fertilisation). The amount of DNA is not what causes variation.
    • B. Gametes of parents have different genetic composition. Correct. Gametes from the two parents carry different gene combinations, so their fusion produces new combinations in the offspring.
    • C. Genetic materials come from parents of two different species. Wrong. Sexual reproduction normally occurs within the same species. Parents of different species rarely produce fertile offspring.
    • D. Sexual reproduction is a lengthy process. Wrong. The time taken has no effect on genetic variation.

    Step 4: Answer The correct option is B.

    Exam tip: Remember "sexual = shuffle and mix". Whenever a question asks about variation, look for words like gametes, meiosis, crossing over, fertilisation or two parents. For asexual reproduction, think "one parent, mitosis, clones".

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  25. 25.

    Which of the following statements is not Lamarck's postulate on evolution?

    1. A.great changes in the environment result in corresponding changes in species
    2. B.frequently used organs become well developed while the ones not used become vestigial
    3. C.well developed acquired characters are inheritable
    4. D.survivors in a competitive community must have inherited useful traits
    Show answer

    Answer: D. survivors in a competitive community must have inherited useful traits

    AI explanation

    Analyze the question: We need the statement that is not part of Lamarck's theory. Three options are Lamarckian ideas, and one belongs to someone else (Darwin).

    Concept: Lamarck's theory (Lamarckism) Jean-Baptiste Lamarck proposed that:

    1. Environmental change creates new needs in organisms, leading to changes in species.
    2. Use and disuse: organs used often become well developed, while those not used degenerate (become vestigial).
    3. Inheritance of acquired characters: features developed during an organism's lifetime are passed to offspring.

    Darwin's theory (Natural Selection) is different. It says:

    • Organisms produce more offspring than can survive.
    • There is variation and a struggle for existence.
    • Those with useful inherited traits survive and reproduce ("survival of the fittest").

    Checking each option:

    • A. Environmental changes cause corresponding changes in species. This is Lamarckian.
    • B. Use and disuse of organs. This is Lamarckian.
    • C. Acquired characters are inheritable. This is Lamarckian.
    • D. Survivors in a competitive community must have inherited useful traits. This is Darwinian natural selection, based on competition and survival of the fittest, not Lamarck.

    Answer: D

    Tip: Link the names to keywords:

    • Lamarck = use and disuse and acquired characters inherited (think of the giraffe stretching its neck).
    • Darwin = competition, variation, survival of the fittest, natural selection.

    If you see "competition" or "fittest," think Darwin, not Lamarck.

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  26. 26.

    The fruit that has the illustrated sections is a

    1. A.hesperidium
    2. B.capsule
    3. C.drupe
    4. D.cypsela
    Show answer

    The answer for this question isn't available yet.

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  27. 27.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

  28. 28.

    Radius and ulna are bones of the?

    1. A.pectoral girdle
    2. B.upper arm
    3. C.pelvic girdle
    4. D.lower arm
    Show answer

    Answer: D. lower arm

    AI explanation

    Step 1: Analyze the question The question asks which part of the skeleton contains the radius and ulna. This is a question on the appendicular skeleton (the limbs and girdles).

    Step 2: Explain the concept The forelimb (arm) of a human has three regions:

    • Upper arm: one bone, the humerus
    • Lower arm (forearm): two bones, the radius and ulna
    • Hand: carpals, metacarpals, and phalanges

    The girdles are different:

    • Pectoral girdle (shoulder): the scapula and clavicle
    • Pelvic girdle (hip): the ilium, ischium, and pubis (fused hip bones)

    Step 3: Work through the options

    • A. Pectoral girdle: No. This holds the scapula and clavicle.
    • B. Upper arm: No. This has only the humerus.
    • C. Pelvic girdle: No. This belongs to the hip region.
    • D. Lower arm: Yes. The radius (on the thumb side) and the ulna (on the little-finger side) make up the forearm.

    Step 4: Answer The radius and ulna are bones of the lower arm, so the answer is D.

    Exam tip: Remember the pattern "1-2-5" for the forelimb: 1 bone in the upper arm (humerus), 2 bones in the forearm (radius and ulna), and then the hand bones. The same pattern in the hind limb is femur (1) in the thigh, then tibia and fibula (2) in the lower leg.

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  29. 29.

    Which of the following factors is not necessary for photosynthesis?

    1. A.water
    2. B.carbon (IV) oxide
    3. C.wind
    4. D.sunlight
    Show answer

    Answer: C. wind

    AI explanation

    Step 1: Analyze the question We are asked which factor is not needed for photosynthesis. So we look for the option that plays no role in the process.

    Step 2: Recall the concept Photosynthesis is the process by which green plants make food (glucose) using light energy.

    Word equation: Carbon (IV) oxide + Water → (sunlight, chlorophyll) → Glucose + Oxygen

    Chemical equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of light and chlorophyll)

    Step 3: Check each option

    • A. Water: a raw material. It is needed, and its splitting in the light reaction supplies hydrogen. ✔ Necessary
    • B. Carbon (IV) oxide: a raw material. It is the source of carbon for making glucose. ✔ Necessary
    • C. Wind: it plays no part in the reactions of photosynthesis. Wind helps with things like transpiration and pollen or seed dispersal, but it is not required. ✘ Not necessary
    • D. Sunlight: the energy source that drives the process. ✔ Necessary

    Step 4: Answer The factor that is not necessary for photosynthesis is wind, which is option C.

    Exam tip: Remember the four essentials as C-W-L-C: CO₂, Water, Light, Chlorophyll. Anything outside this list, such as wind, soil type, or oxygen, is not required for photosynthesis itself. Oxygen is a product, not a requirement.

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  30. 30.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

  31. 31.

    The level of organization of the organism is

    1. A.tissue
    2. B.cell
    3. C.organ
    4. D.system
    Show answer

    Answer: A. tissue

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  32. 32.

    The sections in X and Y respectively, are

    1. A.longitudinal and transverse
    2. B.transverse and longitudinal
    3. C.cross and transverse
    4. D.transverse and cross
    Show answer

    Answer: A. longitudinal and transverse

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  33. 33.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

  34. 34.

    Which of the following organelles is common to both plant and animal cells

    1. A.Cellulose cell wall
    2. B.Chlorophyll
    3. C.Cell membrane
    4. D.Large vacuole
    Show answer

    Answer: C. Cell membrane

    AI explanation

    Step 1: Analyze the question We need the structure found in both plant cells and animal cells.

    Step 2: Review each option

    • A. Cellulose cell wall: Found only in plant cells (and also in fungi and bacteria, but made of different materials). Animal cells have no cell wall. ❌
    • B. Chlorophyll: The green pigment for photosynthesis, found in the chloroplasts of plant cells. Animal cells have no chloroplasts. ❌
    • C. Cell membrane: Every living cell is surrounded by a cell membrane. It controls what enters and leaves the cell. In plants it lies just inside the cell wall. ✅
    • D. Large vacuole: A large, permanent central vacuole is a feature of mature plant cells. Animal cells have only small, temporary vacuoles. ❌

    Step 3: Answer The cell membrane is present in both plant and animal cells, so the answer is C.

    Note: Strictly speaking, the cell membrane is a structure rather than a true "organelle" in some textbook definitions, but WASSCE questions usually treat it as one. Among the options, it is the only one common to both cell types.

    Exam tip: Remember the plant-only structures with the phrase "CCV": Cell wall, Chloroplast (chlorophyll), and large Vacuole. If an option is on that list, it is not common to both. Cell membrane, cytoplasm, nucleus, mitochondria, and ribosomes are shared.

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  35. 35.

    Detoxification of urea takes place in the?

    1. A.pancreas
    2. B.heart
    3. C.liver
    4. D.testes
    Show answer

    Answer: C. liver

    AI explanation

    Analyze the question: It asks where urea is detoxified, meaning where the body deals with harmful nitrogenous waste.

    Explain the concept: When proteins and amino acids are broken down, the process (deamination) releases ammonia (NH₃), which is very toxic to cells. The body converts it into urea, which is much less toxic, so it can be carried safely in the blood to the kidneys and removed in urine.

    Step-by-step solution:

    1. Excess amino acids are deaminated in the liver, and this produces ammonia.
    2. The liver converts the ammonia into urea through the ornithine (urea) cycle.
    3. Urea is released into the blood and carried to the kidneys.
    4. The kidneys filter it out and it leaves the body as urine.

    Checking the options:

    • A. Pancreas: produces digestive enzymes and insulin/glucagon, so it is not involved in making urea.
    • B. Heart: pumps blood only.
    • C. Liver: site of deamination and urea formation, and it also detoxifies other harmful substances such as alcohol and drugs. ✔
    • D. Testes: produce sperm and testosterone.

    Answer: The liver, which is option C.

    Exam tip: Remember "Liver makes urea, kidney removes urea." The liver is the body's main detoxification organ, so when you see "detoxification" in an exam question, think liver first.

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  36. 36.

    Which of the following organisms does not undergo incomplete metamorphosis?

    1. A.locust
    2. B.grasshopper
    3. C.butterfly
    4. D.cockroach
    Show answer

    Answer: C. butterfly

    AI explanation

    1. Analyze the question We need the organism that does NOT undergo incomplete metamorphosis. In other words, we are looking for the one that undergoes complete metamorphosis.

    2. Explain the concept

    • Complete metamorphosis (holometabolous): has four stages: egg → larva → pupa → adult. The larva looks very different from the adult.
    • Incomplete metamorphosis (hemimetabolous): has three stages: egg → nymph → adult. There is no pupa stage, and the nymph looks like a small version of the adult, growing through moulting.

    3. Solution, step by step

    • A. Locust: egg → nymph → adult. This is incomplete metamorphosis.
    • B. Grasshopper: egg → nymph → adult. This is incomplete metamorphosis.
    • C. Butterfly: egg → caterpillar (larva) → pupa (chrysalis) → adult butterfly. This is complete metamorphosis.
    • D. Cockroach: egg (in an ootheca) → nymph → adult. This is incomplete metamorphosis.

    Only the butterfly has a pupa stage, so it is the only one that does not undergo incomplete metamorphosis.

    4. Answer C. Butterfly.

    5. Exam tip Remember: "Pupa = Complete." If an insect has a pupa stage (butterfly, housefly, mosquito, bee, moth), it is complete metamorphosis. If the young one is a nymph (locust, grasshopper, cockroach, termite), it is incomplete. Keep going, you are doing well!

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  37. 37.

    The structure labelled I is associated with

    1. A.sexual reproduction
    2. B.asexual reproduction
    3. C.bud formation
    4. D.gamete formation
    Show answer

    Answer: D. gamete formation

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  38. 38.

    A mixture of blood with antigen A and blood containing antibody a will?

    1. A.lead to agglutination
    2. B.facilitate dissolution of clot
    3. C.have no effect on blood composition
    4. D.change the blood group
    Show answer

    Answer: A. lead to agglutination

    AI explanation

    Analyze the question The question asks what happens when blood containing antigen A is mixed with blood containing antibody a (anti-A).

    Concept

    • Antigens are found on the surface of red blood cells (e.g., antigen A in blood group A).
    • Antibodies are found in the plasma (e.g., antibody a, or anti-A, in blood group B).
    • An antibody binds specifically to its matching antigen. When antigen A meets antibody a, the red blood cells clump together. This clumping is called agglutination.

    Step-by-step solution

    1. Blood with antigen A is group A or group AB.
    2. Blood with antibody a (anti-A) is group B or group O.
    3. Mixing them brings antigen A into contact with its matching antibody.
    4. The antibody binds the antigen and the red cells stick together, which is agglutination.

    Checking the options

    • A. Lead to agglutination: Correct. This is the antigen-antibody reaction.
    • B. Facilitate dissolution of clot: Wrong. Dissolving a clot is fibrinolysis, which has nothing to do with this reaction.
    • C. No effect: Wrong. Matching antigen and antibody always react.
    • D. Change the blood group: Wrong. The reaction does not alter anyone's blood group. It only causes clumping.

    Answer: A. lead to agglutination

    Exam tip: Remember "matching antigen and antibody means clumping." This is why blood transfusion needs compatible blood. For example, group A blood given to a group B person (who has anti-A) causes agglutination, which can be fatal. Group O is the universal donor because its red cells have no A or B antigens.

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  39. 39.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

  40. 40.

    Which of the following statements about the structure labeled III is correct?

    1. A.secretes digestive enzymes into the substrate
    2. B.absorbs mineral salts from the soil
    3. C.forms the root hairs of the organism
    4. D.develops into stolon
    Show answer

    Answer: B. absorbs mineral salts from the soil

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  41. 41.

    Endangered species are organisms that are?

    1. A.likely to migrate to other favourable lands
    2. B.likely to disappear from the surface of the earth
    3. C.reproducing profusely in an area
    4. D.dangerous to humans and attacking other animals
    Show answer

    Answer: B. likely to disappear from the surface of the earth

    AI explanation

    Step 1: Analyze the question The question asks for the meaning of "endangered species" in ecology and conservation.

    Step 2: Explain the concept An endangered species is a species whose population has become so small, or whose habitat has been so reduced, that it is at serious risk of becoming extinct. Examples in Nigeria and West Africa include the Cross River gorilla, the drill monkey, the African elephant, and the pangolin. Causes include:

    • Habitat destruction (deforestation, urbanization)
    • Overhunting and poaching
    • Pollution
    • Climate change

    Step 3: Evaluate the options

    • A. Likely to migrate to other favourable lands: Migration is movement from place to place. It is not what "endangered" means.
    • B. Likely to disappear from the surface of the earth: This matches the definition. Endangered means at risk of extinction.
    • C. Reproducing profusely in an area: This describes a thriving or overpopulated species, the opposite of endangered.
    • D. Dangerous to humans and attacking other animals: This describes dangerous or predatory animals and has nothing to do with conservation status.

    Step 4: Answer

    Tip: Link the word to its meaning: "endangered" means "in danger" of extinction. Also remember the related terms:

    • Endangered: at high risk of disappearing
    • Extinct: already gone
    • Threatened/Vulnerable: likely to become endangered if conditions do not improve

    Keep it up. Definition questions like this are easy marks once you know the key terms.

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  42. 42.

    Rabbits cannot survive in an aquatic habitat because they have

    1. A.no scales
    2. B.no gills
    3. C.fore limbs
    4. D.lateral line
    Show answer

    Answer: B. no gills

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  43. 43.

    Plants and animals of an ecosystem make up a?

    1. A.habitat
    2. B.succession
    3. C.community
    4. D.population
    Show answer

    Answer: C. community

    AI explanation

    Step 1: Analyze the question The question asks what term describes all the plants and animals (all living organisms) living together in an ecosystem.

    Step 2: Explain the concepts

    • Habitat: The place where an organism lives, such as a pond, a forest, or a termite mound. It is a location, not a group of organisms.
    • Succession: The gradual, orderly change in the species that occupy an area over time, such as grass being replaced by shrubs and then by trees.
    • Community: All the different populations of plants and animals living and interacting in the same area.
    • Population: A group of organisms of the same species living in one area, such as all the tilapia fish in a pond.

    Step 3: Apply to the question The question refers to plants and animals, which means many different species together. That rules out population, which covers only one species. Habitat is a place, and succession is a process. So the answer is community.

    An ecosystem is made up of:

    • Biotic part: the community of living things (plants, animals, microbes)
    • Abiotic part: non-living things (soil, water, light, temperature)

    Step 4: Answer The correct option is C. community.

    Exam tip: Remember the ladder of ecological organization: Individual → Population → Community → Ecosystem → Biosphere

    • Population = one species
    • Community = many species
    • Ecosystem = community plus the non-living environment

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  44. 44.

    Which of the following hormones is suddenly secreted into the bloodstream of a frightened person?

    1. A.insulin
    2. B.adrenaline
    3. C.thyroxine
    4. D.parathormore
    Show answer

    Answer: B. adrenaline

    AI explanation

    Step 1: Analyze the question The question asks which hormone is released suddenly when a person is frightened. This is the "fight or flight" response.

    Step 2: Explain the concept When a person is scared, the brain (hypothalamus) signals the sympathetic nervous system. This stimulates the adrenal medulla, which sits on top of the kidneys, to release adrenaline (epinephrine) into the blood very quickly.

    Adrenaline prepares the body for emergency action by:

    • Increasing heart rate and breathing rate
    • Raising blood glucose, since glycogen is converted to glucose in the liver
    • Diverting blood to the muscles and away from the skin and gut (so the person may look pale)
    • Dilating the pupils
    • Making hairs stand on end

    Step 3: Check each option

    • A. Insulin: Made by the pancreas. It lowers blood sugar, so it is the opposite of what is needed in an emergency.
    • B. Adrenaline: Released in sudden emergencies such as fear, anger or danger. ✔
    • C. Thyroxine: Made by the thyroid gland. It controls the metabolic rate over the long term and is not released suddenly.
    • D. Parathormone: Made by the parathyroid glands. It regulates calcium levels in the blood and has nothing to do with fear.

    Step 4: Answer The correct answer is B. adrenaline.

    Exam tip: Remember "Adrenaline = Alarm, Action". Whenever you see fear, anger, danger, fight or flight, think adrenaline. Also remember that adrenaline acts fast, while thyroxine acts slowly and steadily.

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  45. 45.

    The process that takes place at the light stage of photosynthesis is?

    1. A.splitting of water molecules to form hydrogen ions
    2. B.reduction of carbon (IV) oxide to form carbohydrate
    3. C.formation of two molecules of phosphoglyceric acid
    4. D.breaking down of ATP molecules to produce energy
    Show answer

    Answer: A. splitting of water molecules to form hydrogen ions

    AI explanation

    Step 1: Analyze the question The question asks which process happens in the light stage (light-dependent reaction) of photosynthesis.

    Step 2: The concept Photosynthesis has two stages:

    1. Light stage (light-dependent reaction) • Takes place in the grana of the chloroplast. • Needs light and chlorophyll. • Light energy splits water molecules (photolysis): 2H₂O → 4H⁺ + 4e⁻ + O₂ • The hydrogen ions are picked up by NADP to form NADPH. • ATP is made (photophosphorylation). • Oxygen is released as a by-product.
    1. Dark stage (light-independent reaction, Calvin cycle) • Takes place in the stroma. • CO₂ is fixed and reduced to carbohydrate (glucose) using the ATP and NADPH from the light stage. • This involves the formation of phosphoglyceric acid (PGA).

    Step 3: Check each option

    • A. Splitting of water molecules to form hydrogen ions: This is photolysis, which happens in the light stage. ✔
    • B. Reduction of carbon (IV) oxide to form carbohydrate: This is the dark stage. ✘
    • C. Formation of two molecules of phosphoglyceric acid: This is CO₂ fixation in the dark stage (Calvin cycle). ✘
    • D. Breaking down of ATP molecules to produce energy: ATP is formed in the light stage and used in the dark stage. ✘

    Step 4: Answer

    💡 Exam tip: Remember "Light = Lysis of water" (photolysis, producing O₂, H⁺ and ATP). "Dark = Deposits carbon" (CO₂ fixed into sugar). If an option mentions water splitting, oxygen release, or ATP formation, think light stage. If it mentions CO₂, glucose, or PGA, think dark stage.

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  46. 46.

    An association between living organisms in which one organism lives on and feeds at the expense of the other organism is known as?

    1. A.mutualism
    2. B.commensalism
    3. C.parasitism
    4. D.predation
    Show answer

    Answer: C. parasitism

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  47. 47.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

  48. 48.

    The diagrams above are illustrations of types of comb found in domestic fowl. Study them and answer this question. Which factor is most likely responsible for the various types of comb?

    1. A.environment
    2. B.genetics
    3. C.physiology
    4. D.morphology
    Show answer

    Answer: B. genetics

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  49. 49.

    An enzyme reaction may begin to decline when?

    1. A.the optimum temperature is attained
    2. B.the ph of the medium is altered
    3. C.there is an increase in substrate concentration
    4. D.the atmospheric pressure is altered
    Show answer

    Answer: B. the ph of the medium is altered

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