Selected MCQ

Current Question
Which characteristic is common to Type II restriction endonucleases?
  • A. They require ATP to cut DNA
  • B. They recognize and cut at specific palindromic DNA sequences
  • C. They cut single-stranded RNA
  • D. They are not used in DNA cloning
Correct Answer: B
Explanation:
Type II restriction enzymes recognize specific palindromic DNA sequences and cleave double-stranded DNA at those sites, without requiring ATP.
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
Why is fetal bovine serum commonly added to cell culture media?
  • A. To buffer the pH
  • B. To provide growth factors and nutrients
  • C. To increase osmolarity
  • D. To act as an antibiotic
Correct Answer: B
Explanation:
Fetal bovine serum supplies a mix of growth factors, hormones, and nutrients that support cell growth and viability in culture.
Related Question 3
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 4
A female exhibits an X-linked recessive trait. What must be true of her parents’ genotypes?
  • A. Her father must have the trait, and her mother must be at least a carrier
  • B. Both parents must be affected
  • C. Only her mother is affected
  • D. Either parent could have the trait independently
Correct Answer: A
Explanation:
For a daughter to be homozygous for an X-linked recessive allele, her father must have the allele (so he is affected) and her mother must carry at least one mutant X.
Related Question 5
What is the genotype of a person with blood type O in the ABO system?
  • A. IᴬIᴬ or Iᴬi
  • B. IᴮIᴮ or Iᴮi
  • C. ii
  • D. IᴬIᴮ
Correct Answer: C
Explanation:
Type O blood has no A or B antigen and is genotypically ii (both alleles are the recessive i).