Selected MCQ

Current Question
In flow cytometry, cells are labeled with fluorescent antibodies and passed in a stream through a laser. This technique primarily measures:
  • A. Cell size and internal complexity
  • B. DNA sequence variants
  • C. Protein structure by X-ray diffraction
  • D. Glycolytic activity
Correct Answer: A
Explanation:
Flow cytometry measures light scattering (size and granularity) and fluorescence from labeled markers, allowing rapid analysis of cell populations (size, complexity, marker expression).
Related Question 1
Monoclonal antibodies differ from polyclonal antibodies in that monoclonals:
  • A. Are produced by multiple B cell clones
  • B. Recognize multiple epitopes on the same antigen
  • C. Are derived from a single B cell clone and recognize a single epitope
  • D. Are less specific than polyclonals
Correct Answer: C
Explanation:
Monoclonal antibodies come from one B-cell clone, so they are identical and recognize one epitope. Polyclonal antibodies are produced by many B cells and recognize multiple epitopes on the antigen.
Related Question 2
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 3
In Northern blotting, the labeled probe hybridizes to:
  • A. DNA immobilized on a membrane
  • B. RNA immobilized on a membrane
  • C. Protein immobilized on a membrane
  • D. Any membrane-bound molecules
Correct Answer: B
Explanation:
A Northern blot is used to detect RNA. A labeled DNA or RNA probe hybridizes to the target RNA on the membrane.
Related Question 4
The technique for producing monoclonal antibodies involves fusing a specific antibody-producing B cell with a myeloma cell (a cancer cell). This hybrid cell line is called a:
  • A. Bacteriophage
  • B. Hybridoma
  • C. Plasmid
  • D. Complement
Correct Answer: B
Explanation:
A hybridoma results from fusing a single B lymphocyte (which produces one antibody) with a myeloma cell, creating an immortal cell line that produces identical (monoclonal) antibodies.
Related Question 5
Which method uses an electrical pulse to introduce DNA into cells?
  • A. Microinjection
  • B. Electroporation
  • C. Lipofection
  • D. Ultracentrifugation
Correct Answer: B
Explanation:
Electroporation applies a brief high-voltage pulse to permeabilize cell membranes, transiently allowing DNA uptake.