Selected MCQ

Current Question
Huntington’s disease, characterized by neurodegeneration and anticipation, is inherited in which manner?
  • A. Autosomal recessive
  • B. Autosomal dominant
  • C. X-linked recessive
  • D. Mitochondrial
Correct Answer: B
Explanation:
Huntington’s disease is autosomal dominant (one mutant allele is sufficient) and shows anticipation due to CAG repeat expansion, but inheritance is strictly dominant.
Related Question 1
Phenylketonuria (PKU) is inherited as an autosomal recessive trait. If two carriers have a child, what is the probability the child will be unaffected (no mutant alleles)?
  • A. 100%
  • B. 75%
  • C. 50%
  • D. 25%
Correct Answer: B
Explanation:
For two carriers (Aa × Aa), the offspring genotype ratio is 1 AA: 2 Aa: 1 aa. 75% (AA + Aa) are unaffected (though 50% are carriers).
Related Question 2
Which term describes genes that are located on the same chromosome and inherited together more often than by chance?
  • A. Linked genes
  • B. Epistatic genes
  • C. Polygenic genes
  • D. Independent genes
Correct Answer: A
Explanation:
Linked genes are near each other on the same chromosome. They tend to be inherited together, and their recombination frequency is less than 50%.
Related Question 3
Pluripotent stem cells are characterized by their ability to:
  • A. Differentiate into all cell types, including extraembryonic membranes
  • B. Differentiate into any cell type of the body (but not extraembryonic tissues)
  • C. Self-renew indefinitely but only become one cell type
  • D. Be harvested from adult muscle tissue
Correct Answer: B
Explanation:
Pluripotent stem cells (like embryonic stem cells) can form any body cell type (endoderm, mesoderm, ectoderm) but cannot form an entire organism (unlike totipotent zygotes).
Related Question 4
In genomic imprinting, the expression of a gene depends on its parental origin. For example, only the paternally inherited allele of a certain gene is expressed. This is known as:
  • A. Epigenetic modification
  • B. Loss of heterozygosity
  • C. Imprinting
  • D. Mendelian inheritance
Correct Answer: C
Explanation:
Genomic imprinting is an epigenetic phenomenon where only one allele (maternal or paternal) is expressed, depending on the parent of origin, while the other is silenced.
Related Question 5
A man has an X-linked recessive disease and marries an unaffected woman who is not a carrier. What is the outcome for their children?
  • A. All daughters will be carriers; none of the sons will be affected
  • B. All daughters will be affected, sons unaffected
  • C. All sons will be affected; no daughters will be carriers
  • D. None of their children will inherit the disease allele
Correct Answer: A
Explanation:
The father passes his mutant X to all daughters, making them carriers (but not affected). He passes his Y to his sons, so no son is affected or a carrier.