JAMB and WAEC Biology questions

791 questions with answers and explanations. Tap an option to check yourself.

All topics Cell structure and organisation · 56 Cellular activities · 56 Co-ordination and control · 58 Ecology · 71 Evolution · 45 Excretion · 52 Growth · 45 Heredity and variation · 60 Nutrition · 64 Reproduction · 62 Respiration · 55 Support and movement · 50 Transport · 57 Variety of organisms · 60

Question 421· Heredity and variation· WAEC
Which of these is an example of discontinuous variation?
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Answer: A. ABO blood groups
Explanation and discussion
Question 422· Heredity and variation· WAEC
A characteristic that shows in the offspring whenever its gene is present is
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Answer: B. dominant
Explanation and discussion
Question 423· Heredity and variation· JAMB
Two parents both have the genotype AS. What is the probability that their child will have the genotype SS?
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Answer: A. ¼
Explanation and discussion
Question 424· Heredity and variation· WAEC
Crossing two heterozygous tall plants (Tt × Tt) gives a phenotypic ratio of
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Answer: B. 3 tall : 1 short
Explanation and discussion
Question 425· Heredity and variation· JAMB
A person who carries the sickle-cell gene but does not suffer from the disease has the genotype
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Answer: C. AS
Explanation and discussion
Question 426· Heredity and variation· WAEC
The ABO blood groups are an example of
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Answer: B. discontinuous variation
Explanation and discussion
Question 427· Heredity and variation· WAEC
A cross between two heterozygous tall pea plants (Tt × Tt) produces offspring in the ratio
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Answer: B. 3 tall : 1 dwarf
Explanation and discussion
Question 428· Heredity and variation· JAMB
Haemophilia is more common in men than in women because it is
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Answer: C. a sex-linked recessive trait carried on the X chromosome
Explanation and discussion
Question 429· Heredity and variation· JAMB
In the cross shown, T (tall) is dominant over t (dwarf). What percentage of the offspring are dwarf?
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Answer: C. 50%
Explanation and discussion
Question 430· Heredity and variation· JAMB
If a heterozygous tall plant (Tt) is crossed with a dwarf plant (tt), the ratio of tall to dwarf offspring is:
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Answer: B. 1 : 1
Explanation and discussion
Question 431· Heredity and variation· JAMB
A scar on the skin is an example of
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Answer: D. an acquired characteristic
Explanation and discussion
Question 432· Heredity and variation· JAMB
Down's syndrome is caused by
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Answer: A. an extra copy of chromosome 21
Explanation and discussion
Question 433· Heredity and variation· JAMB
In a dihybrid cross between two double heterozygotes (AaBb × AaBb), the expected phenotypic ratio is
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Answer: C. 9 : 3 : 3 : 1
Explanation and discussion
Question 434· Heredity and variation· JAMB
A mother is a carrier of haemophilia and the father is normal. What is the probability that a son of theirs has haemophilia?
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Answer: B. 1/2
Explanation and discussion
Question 435· Heredity and variation· WAEC
A person with sickle cell trait has the genotype
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Answer: C. HbAS
Explanation and discussion
Question 436· Heredity and variation· WAEC
The scientist known as the father of genetics is
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Answer: B. Gregor Mendel
Explanation and discussion
Question 437· Heredity and variation· JAMB
A test cross is used to find out whether an organism showing a dominant trait is
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Answer: D. homozygous or heterozygous
Explanation and discussion
Question 438· Heredity and variation· JAMB
Genes are located on
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Answer: D. chromosomes
Explanation and discussion
Question 439· Heredity and variation· WAEC
Two heterozygous tall pea plants (Tt × Tt) are crossed. What is the phenotypic ratio of the offspring?
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Answer: A. 3 tall : 1 short
Explanation and discussion
Question 440· Heredity and variation· JAMB
Which of the following is an example of continuous variation?
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Answer: B. height
Explanation and discussion

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JAMB and WAEC Biology questions

Which of these is an example of discontinuous variation?

A characteristic that shows in the offspring whenever its gene is present is

Two parents both have the genotype AS. What is the probability that their child will have the genotype SS?

Crossing two heterozygous tall plants (Tt × Tt) gives a phenotypic ratio of

A person who carries the sickle-cell gene but does not suffer from the disease has the genotype

The ABO blood groups are an example of

A cross between two heterozygous tall pea plants (Tt × Tt) produces offspring in the ratio

Haemophilia is more common in men than in women because it is

In the cross shown, T (tall) is dominant over t (dwarf). What percentage of the offspring are dwarf?

If a heterozygous tall plant (Tt) is crossed with a dwarf plant (tt), the ratio of tall to dwarf offspring is:

A scar on the skin is an example of

Down's syndrome is caused by

In a dihybrid cross between two double heterozygotes (AaBb × AaBb), the expected phenotypic ratio is

A mother is a carrier of haemophilia and the father is normal. What is the probability that a son of theirs has haemophilia?

A person with sickle cell trait has the genotype

The scientist known as the father of genetics is

A test cross is used to find out whether an organism showing a dominant trait is

Genes are located on

Two heterozygous tall pea plants (Tt × Tt) are crossed. What is the phenotypic ratio of the offspring?

Which of the following is an example of continuous variation?