Selected MCQ

Current Question
The sodium-potassium pump (Na⁺/K⁺-ATPase) is an example of which type of membrane transport?
  • A. Passive diffusion
  • B. Facilitated diffusion
  • C. Primary active transport
  • D. Secondary active transport
Correct Answer: C
Explanation:
Na⁺/K⁺-ATPase uses ATP directly to pump Na⁺ out and K⁺ in against their gradients, classifying it as primary active transport.
Related Question 1
In Southern blotting, what type of probe is used to detect specific DNA sequences?
  • A. DNA probe labeled with a reporter
  • B. RNA probe labeled with a reporter
  • C. Protein probe labeled with antibody
  • D. Carbohydrate probe
Correct Answer: A
Explanation:
Southern blot uses a labeled single-stranded DNA (or RNA) probe complementary to the target DNA sequence, hybridizing to it on the membrane.
Related Question 2
Down syndrome (trisomy 21) results in how many total chromosomes in a karyotype?
  • A. 45
  • B. 46
  • C. 47
  • D. 48
Correct Answer: C
Explanation:
Down syndrome is caused by an extra copy of chromosome 21. Humans normally have 46 chromosomes; trisomy adds one extra, making 47.
Related Question 3
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 4
Male pattern baldness is dominant in men but recessive in women. This is an example of:
  • A. X-linked inheritance
  • B. Sex-influenced trait
  • C. Codominance
  • D. Autosomal dominance
Correct Answer: B
Explanation:
A sex-influenced trait has different phenotypic dominance in males vs females (due to hormonal differences), as seen with baldness alleles.
Related Question 5
Inheritance of human height, which is influenced by many genes and environmental factors, is an example of:
  • A. Codominance
  • B. Polygenic inheritance
  • C. Pleiotropy
  • D. Autosomal dominance
Correct Answer: B
Explanation:
Height is a quantitative trait determined by multiple genes (polygenes) and the environment, consistent with polygenic inheritance.