Principles of Inheritance and Variation Chapter-Wise Test 8

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following genetic disorders follows a Y-linked inheritance pattern?

Color blindness
Hemophilia
Hypertrichosis (hairy ears)
Sickle-cell anemia
3

Hypertrichosis (hairy ears) follows a Y-linked inheritance pattern, as the gene is located on the Y chromosome and is only passed from father to son.

What is the function of a Barr body in female cells?

Activates all X chromosomes
Prevents expression of autosomal genes
Inactivates one X chromosome
Determines the sex of the individual
3

A Barr body is an inactivated X chromosome in female cells, ensuring dosage compensation.

Which of the following explains why some traits disappear in the F1 generation but reappear in the F2 generation?

Incomplete dominance
Co-dominance
Law of Dominance
Law of Segregation
4

The Law of Segregation explains that recessive traits can be masked in the F1 generation and reappear in the F2 generation.

Which of the following is an incorrect statement about co-dominance?

Both alleles are expressed in the heterozygous state.
AB blood group is an example of co-dominance.
One allele completely suppresses the other in co-dominance.
Co-dominance differs from incomplete dominance.
3

In co-dominance, both alleles are equally expressed rather than one suppressing the other.

What is the role of the Y-chromosome in human sex determination?

It determines female characteristics
It triggers male development
It carries genes for blood type
It is inherited only from the mother
2

The Y-chromosome carries the SRY gene, which triggers male development in humans.

Which type of sex determination system is seen in birds?

XY system
XO system
ZW system
Haplodiploidy
3

In birds, the ZW system determines sex, where males are ZZ and females are ZW.

What is the primary cause of Down’s syndrome?

Mutation in the hemoglobin gene
Trisomy of chromosome 21
Deletion of chromosome 18
Loss of the Y chromosome
2

Down’s syndrome is caused by trisomy of chromosome 21, leading to developmental and cognitive impairments.

Which of the following conditions results from monosomy of the X chromosome?

Klinefelter’s syndrome
Turner’s syndrome
Down’s syndrome
Edward’s syndrome
2

Turner’s syndrome is caused by monosomy of the X chromosome (45, XO), leading to sterility and other developmental issues.

Which of the following correctly describes pleiotropy?

One gene affects multiple traits.
Multiple genes affect a single trait.
One gene determines only one phenotype.
Traits are inherited through mitochondrial DNA.
1

Pleiotropy occurs when a single gene influences multiple phenotypic traits, as seen in sickle-cell anemia.

Which of the following statements about genetic variation is correct?

Mutation is the only source of genetic variation.
Genetic variation can result from recombination.
All mutations lead to harmful effects.
Genetic drift does not contribute to variation.
2

Recombination during meiosis is a major source of genetic variation along with mutation and gene flow.

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