Principles of Inheritance and Variation Chapter-Wise Test 14

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following correctly describes codominance?

Both alleles are fully expressed in heterozygous individuals.
One allele completely dominates the other.
The phenotype is a blend of both parental traits.
Only recessive alleles are expressed.
1

In codominance, both alleles contribute equally to the phenotype, as seen in the AB blood group.

Which genetic principle states that allele frequencies remain constant in a population under ideal conditions?

Law of Segregation
Law of Independent Assortment
Hardy-Weinberg Principle
Pleiotropy
3

The Hardy-Weinberg Principle states that allele frequencies remain constant unless affected by evolutionary forces.

Which of the following correctly describes a recessive allele?

It is always expressed in the phenotype.
It is expressed only in the heterozygous condition.
It is expressed only in the homozygous recessive condition.
It is dominant over other alleles.
3

A recessive allele is expressed only in individuals who are homozygous recessive (aa).

Which of the following disorders is incorrectly matched with its cause?

Sickle-cell anemia - Mutation in the β-globin gene.
Hemophilia - X-linked recessive disorder.
Turner’s syndrome - Presence of an extra Y chromosome.
Down’s syndrome - Trisomy of chromosome 21.
3

Turner’s syndrome results from the absence of one X chromosome (45, XO), not the presence of an extra Y chromosome.

Which of the following correctly describes pleiotropy?

One gene affects multiple traits.
Multiple genes influence a single trait.
Traits are inherited through mitochondrial DNA.
It occurs only in plants.
1

Pleiotropy occurs when a single gene influences multiple phenotypic traits, such as in Marfan syndrome.

What is the primary role of the XIST gene in female mammals?

Determines male characteristics
Initiates X chromosome inactivation
Controls blood clotting
Regulates eye color
2

The XIST gene is responsible for X chromosome inactivation in female mammals.

Which of the following is an example of epistasis?

Blood group inheritance
Albinism suppressing skin color genes
Incomplete dominance in flower color
Co-dominance in sickle-cell anemia
2

Epistasis occurs when one gene suppresses the expression of another, as seen in albinism.

Which of the following correctly describes multiple allelism?

Each individual inherits more than two alleles for a gene.
A gene has more than two alleles in a population.
A single allele controls multiple traits.
Multiple genes influence a single trait.
2

In multiple allelism, a gene has more than two possible alleles in a population, but each individual inherits only two.

What is the primary reason why Mendel chose the pea plant (Pisum sativum) for his experiments?

It grows only in warm climates
It has a short life cycle and distinct traits
It has large-sized flowers
It produces a single type of seed
2

Mendel chose pea plants because they have a short life cycle and well-defined contrasting traits.

Which of the following is an example of sex-linked inheritance?

Sickle-cell anemia
Thalassemia
Hemophilia
Cystic fibrosis
3

Hemophilia is a sex-linked recessive disorder carried on the X chromosome.

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