Incomplete Dominance

Description: Test your understanding of Incomplete Dominance, a fascinating genetic phenomenon where neither allele is dominant over the other.
Number of Questions: 14
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Tags: genetics incomplete dominance biology
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In incomplete dominance, the heterozygous genotype results in:

  1. A blend of the two phenotypes

  2. An intermediate phenotype

  3. A dominant phenotype

  4. A recessive phenotype


Correct Option: A
Explanation:

Incomplete dominance occurs when neither allele is dominant over the other, resulting in a heterozygous individual expressing a phenotype that is a blend of the two homozygous phenotypes.

Which of these is an example of incomplete dominance in plants?

  1. Red and white flowers producing pink flowers

  2. Tall and short plants producing medium-height plants

  3. Round and wrinkled seeds producing oval seeds

  4. Brown and black fur in dogs producing spotted fur


Correct Option: A
Explanation:

In the case of red and white flowers, the heterozygous genotype produces pink flowers, which is a blend of the two homozygous phenotypes.

What is the genotypic ratio of a cross between two heterozygous individuals in incomplete dominance?

  1. 1:2:1

  2. 3:1

  3. 1:1

  4. 9:3:3:1


Correct Option: A
Explanation:

In a cross between two heterozygous individuals, the genotypic ratio is 1:2:1, where 1 represents homozygous dominant, 2 represents heterozygous, and 1 represents homozygous recessive.

Incomplete dominance is also known as:

  1. Partial dominance

  2. Codominance

  3. Blended inheritance

  4. All of the above


Correct Option: D
Explanation:

Incomplete dominance is also referred to as partial dominance, codominance, and blended inheritance, as it involves a blend of the phenotypes of the two homozygous genotypes.

Which of these is NOT an example of incomplete dominance?

  1. Andalusian horses with a roan coat color

  2. Red and white carnations producing pink carnations

  3. Black and white chickens producing gray chickens

  4. Brown-eyed and blue-eyed parents having green-eyed children


Correct Option: D
Explanation:

Green-eyed children from brown-eyed and blue-eyed parents is an example of polygenic inheritance, not incomplete dominance.

In incomplete dominance, the heterozygous phenotype is:

  1. Identical to the dominant phenotype

  2. Identical to the recessive phenotype

  3. A blend of the two phenotypes

  4. None of the above


Correct Option: C
Explanation:

In incomplete dominance, the heterozygous phenotype is a blend of the two phenotypes expressed by the homozygous dominant and recessive genotypes.

What is the phenotypic ratio of a cross between two heterozygous individuals in incomplete dominance?

  1. 3:1

  2. 1:2:1

  3. 9:3:3:1

  4. 1:1


Correct Option: B
Explanation:

In a cross between two heterozygous individuals, the phenotypic ratio is 1:2:1, where 1 represents the homozygous dominant phenotype, 2 represents the heterozygous phenotype, and 1 represents the homozygous recessive phenotype.

Which of these is an example of incomplete dominance in animals?

  1. Andalusian horses with a roan coat color

  2. Red and white carnations producing pink carnations

  3. Black and white chickens producing gray chickens

  4. Brown-eyed and blue-eyed parents having green-eyed children


Correct Option: A
Explanation:

Andalusian horses with a roan coat color are an example of incomplete dominance in animals, where the heterozygous genotype produces a coat color that is a blend of red and white.

Incomplete dominance is observed in:

  1. Homozygous dominant individuals

  2. Heterozygous individuals

  3. Homozygous recessive individuals

  4. All of the above


Correct Option: B
Explanation:

Incomplete dominance is observed in heterozygous individuals, where the two different alleles of a gene are expressed simultaneously, resulting in a phenotype that is a blend of the two homozygous phenotypes.

Which of these is NOT a characteristic of incomplete dominance?

  1. The heterozygous phenotype is intermediate between the homozygous phenotypes

  2. The heterozygous phenotype is identical to one of the homozygous phenotypes

  3. The heterozygous phenotype is a blend of the two homozygous phenotypes

  4. The heterozygous genotype has equal contributions from both alleles


Correct Option: B
Explanation:

In incomplete dominance, the heterozygous phenotype is a blend of the two homozygous phenotypes, not identical to one of them.

In incomplete dominance, the heterozygous genotype is:

  1. RR

  2. Rr

  3. rr

  4. None of the above


Correct Option: B
Explanation:

In incomplete dominance, the heterozygous genotype is Rr, where R represents the dominant allele and r represents the recessive allele.

What is the probability of obtaining a heterozygous offspring from a cross between two heterozygous individuals in incomplete dominance?

  1. 1/4

  2. 1/2

  3. 3/4

  4. 1


Correct Option: B
Explanation:

In a cross between two heterozygous individuals, the probability of obtaining a heterozygous offspring is 1/2, as there is a 50% chance that the offspring will inherit one dominant allele and one recessive allele from each parent.

Which of these is an example of incomplete dominance in humans?

  1. ABO blood group system

  2. Cystic fibrosis

  3. Sickle cell anemia

  4. Huntington's disease


Correct Option: A
Explanation:

The ABO blood group system in humans is an example of incomplete dominance, where the alleles A and B are codominant, resulting in blood types A, B, AB, and O.

Which of these is NOT a consequence of incomplete dominance?

  1. Increased genetic diversity

  2. Production of new phenotypes

  3. Masking of recessive alleles

  4. Reduced fitness of heterozygous individuals


Correct Option: D
Explanation:

Incomplete dominance typically does not result in reduced fitness of heterozygous individuals, as the heterozygous phenotype is often intermediate between the homozygous phenotypes.

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