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Genetics - Incomplete Dominance — Biology Questions & Practice

Practise 12 Genetics - Incomplete Dominance questions from Biology for competitive exams such as UPSC, Banking, SSC and Railway. Read the worked questions below, check every answer with an explanation, and track what you get wrong.

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Practice questions on Genetics - Incomplete Dominance — with answers

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1. In four o'clock plants (Mirabilis jalapa), flower/coat color shows incomplete dominance (neither allele is fully dominant). A homozygous red flowers individual is crossed with a homozygous white flowers individual. What phenotype will ALL of the F1 offspring show?

Apink flowers
Bred flowers
Cwhite flowers
Dhalf blend, half red flowers

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Answer: A

Since red flowers and white flowers show incomplete dominance, the heterozygous F1 offspring show an intermediate blended phenotype: pink flowers.

2. In four o'clock plants (Mirabilis jalapa), when two F1 pink flowers individuals (heterozygous, from a red flowers x white flowers cross showing incomplete dominance) are crossed together, what fraction of their offspring is expected to show the red flowers phenotype?

A1
B1/8
C1/2
D1/4

Show answer

Answer: D

Since there is no dominance, the F1 x F1 cross produces a 1:2:1 phenotypic ratio identical to the genotypic ratio: 1/4 red flowers, 1/2 pink flowers, 1/4 white flowers. The fraction showing red flowers is 1/4.

3. In four o'clock plants (Mirabilis jalapa), when two F1 pink flowers individuals (heterozygous, from a red flowers x white flowers cross showing incomplete dominance) are crossed together, what fraction of their offspring is expected to show the pink flowers phenotype?

A1/8
B3/4
C1/2
D1

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Answer: C

4. In four o'clock plants (Mirabilis jalapa), when two F1 pink flowers individuals (heterozygous, from a red flowers x white flowers cross showing incomplete dominance) are crossed together, what fraction of their offspring is expected to show the white flowers phenotype?

A0
B1/4
C1
D3/4

Show answer

Answer: B

5. In snapdragon plants (Antirrhinum), flower/coat color shows incomplete dominance (neither allele is fully dominant). A homozygous red flowers individual is crossed with a homozygous white flowers individual. What phenotype will ALL of the F1 offspring show?

Apink flowers
Bred flowers
Cwhite flowers
Dhalf blend, half red flowers

Show answer

Answer: A

Since red flowers and white flowers show incomplete dominance, the heterozygous F1 offspring show an intermediate blended phenotype: pink flowers.

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Genetics - Incomplete Dominance — Biology Questions & Practice

Practice questions on Genetics - Incomplete Dominance — with answers

1. In four o'clock plants (Mirabilis jalapa), flower/coat color shows incomplete dominance (neither allele is fully dominant). A homozygous red flowers individual is crossed with a homozygous white flowers individual. What phenotype will ALL of the F1 offspring show?

2. In four o'clock plants (Mirabilis jalapa), when two F1 pink flowers individuals (heterozygous, from a red flowers x white flowers cross showing incomplete dominance) are crossed together, what fraction of their offspring is expected to show the red flowers phenotype?

3. In four o'clock plants (Mirabilis jalapa), when two F1 pink flowers individuals (heterozygous, from a red flowers x white flowers cross showing incomplete dominance) are crossed together, what fraction of their offspring is expected to show the pink flowers phenotype?

4. In four o'clock plants (Mirabilis jalapa), when two F1 pink flowers individuals (heterozygous, from a red flowers x white flowers cross showing incomplete dominance) are crossed together, what fraction of their offspring is expected to show the white flowers phenotype?

5. In snapdragon plants (Antirrhinum), flower/coat color shows incomplete dominance (neither allele is fully dominant). A homozygous red flowers individual is crossed with a homozygous white flowers individual. What phenotype will ALL of the F1 offspring show?

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