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Class 10 Science Chapter 8: Heredity MCQs with answers

10 multiple-choice questions on Heredity, each with its answer and the reason, written from the NCERT chapter. Open a question's solution to check your working; then take the free test to find your next chapter.

Question 1
Which of the following is a pair of contrasting visible characters that Mendel studied in garden peas?
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Answer: (b) round or wrinkled seeds

Mendel worked with contrasting visible characters of garden peas such as round or wrinkled seeds, tall or short plants and white or violet flowers. The other pairs are not among them.

Question 2
A pea plant carries one T factor and one t factor for height. The plant will be
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Answer: (a) tall

A single copy of T is enough to make the plant tall; both copies must be t for it to be short. Tt is therefore tall, with no halfway height.

Question 3
A section of cellular DNA that provides the information for making one protein is called
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Answer: (b) a gene

DNA is the information source for making proteins, and the section of DNA that carries the information for one protein is the gene for that protein. A chromosome is a whole piece of DNA carrying many genes.

Question 4
The pair of sex chromosomes present in the body cells of a man is
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Answer: (b) XY

Men have a mismatched pair: one normal-sized X and one short Y. Women have a perfect pair, XX.

Question 5
In a few reptiles, whether a hatchling is male or female is decided by
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Answer: (b) the temperature at which the fertilised egg is kept

In some reptiles the temperature at which the fertilised eggs are kept determines whether the young developing in them will be male or female; this is an environmental cue, not a chromosome.

Question 6
An individual garden snail is found to have changed from male to female during its life. This shows that in snails
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Answer: (b) sex is not genetically determined

Individuals that can change sex cannot have a sex fixed by their genes; the chapter takes this to show that sex in snails is not genetically determined.

Question 7
In which of the following will the offspring show the greatest variation among themselves?
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Answer: (c) kids born to a pair of goats

Sexual reproduction generates greater diversity than asexual reproduction. The goat kids come from sexual reproduction; the other three come from a single parent asexually and are very similar.

Question 8
Ritu's earlobes hang free below the point where they join the head, while her friend Anjali's earlobes are closely attached to the side of the head. These two forms are
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Answer: (a) variants of one inherited trait found in human populations

Free and attached earlobes are two variants found in human populations. Seeing which form is common does not show which is dominant; that needs crosses of pure contrasting parents.

Question 9
A breeder crosses pure-breeding pea plants that bear round seeds with pure-breeding plants that bear wrinkled seeds. The F1 seeds will be
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Answer: (a) all round

Round seed is the dominant trait, and the F1 of pure contrasting parents shows only one parental trait with no halfway form, so every F1 seed is round.

Question 10
Meena and Arjun have a son. The chromosome that made the child a boy came from
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Answer: (b) Arjun, who gave a Y

Every child gets an X from the mother, boy or girl. A boy is XY, so the deciding chromosome is the Y he received from his father.

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