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WAEC WASSCE 2020

WAEC Biology 2020 past questions

7 objective questions from the 2020 WAEC Biology paper. Answer each one, then reveal the answer and explanation.

All WAEC Biology past questions

  1. Question 1

    Food tests

    Which food substance turns blue-black with iodine solution?

    1. Option A: Protein
    2. Option B: Fat
    3. Option C: Starch
    4. Option D: Glucose
    Show the answer to question 1

    Answer: C, Starch

    Iodine solution turns blue-black in the presence of starch.

  2. Question 2

    Ecology

    In the food chain grass → grasshopper → lizard → hawk, the secondary consumer is the

    1. Option A: grasshopper
    2. Option B: grass
    3. Option C: lizard
    4. Option D: hawk
    Show the answer to question 2

    Answer: C, lizard

    The lizard eats the primary consumer.

  3. Question 3

    Nutrition

    Starch turns iodine solution

    1. Option A: brick-red
    2. Option B: purple
    3. Option C: blue-black
    4. Option D: milky
    Show the answer to question 3

    Answer: C, blue-black

    Iodine gives a blue-black colour with starch.

  4. Question 4

    Genetics

    In fruit flies, the allele for normal wings (N) is dominant over the allele for vestigial wings (n). What is the genotypic ratio of the offspring of a cross between two Nn parents?

    1. Option A: 3 NN : 1 nn
    2. Option B: 1 NN : 1 nn
    3. Option C: 1 NN : 2 Nn : 1 nn
    4. Option D: 2 NN : 1 Nn : 1 nn
    Show the answer to question 4

    Answer: C, 1 NN : 2 Nn : 1 nn

    Nn × Nn gives NN, Nn, Nn, and nn: a 1 : 2 : 1 genotypic ratio.

  5. Question 5

    Classification

    From the list below, select the animal that is a fish.

    1. Option A: duck
    2. Option B: lizard
    3. Option C: frog
    4. Option D: shark
    Show the answer to question 5

    Answer: D, shark

    The shark is a fish (class Pisces).

  6. Question 6

    Genetics

    In humans, the allele for normal pigmentation (A) is dominant over the allele for albinism (a). What is the expected phenotypic ratio of the offspring of a cross between AA and aa parents?

    1. Option A: 3 normal pigmentation : 1 albinism
    2. Option B: 1 normal pigmentation : 1 albinism
    3. Option C: All albinism
    4. Option D: All normal pigmentation
    Show the answer to question 6

    Answer: D, All normal pigmentation

    AA × aa gives only Aa offspring, all showing normal pigmentation.

  7. Question 7

    Transport

    Which blood group is the universal donor?

    1. Option A: AB
    2. Option B: O
    3. Option C: A
    4. Option D: B
    Show the answer to question 7

    Answer: B, O

    Group O red cells carry no A or B antigens.

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