Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 9264
TLS Online TPP Program

#Question id: 12482

The Rb protein has been called the “master brake” of the cell cycle. How the Rb protein acts as a cell cycle brake?

#Unit 2. Cellular Organization
  1. Rb bound to E2F and function as transcriptional repressors because Rb recruits chromatin-modifying enzymes that promote deacetylation and methylation of specific histone lysines, causing chromatin to assume a condensed, transcriptionally inactive form.
  2. S phase CDKs and mitotic CDKs maintain Rb protein in the phosphorylated state throughout the S, G2, and early M phases.
  3. Rb bound to E2F and promotes ubiquitinylation of E2F and inhibits chromosomal segregation.
  4. Rb bound to E2F and promotes acetylation which prevents unloading of cohesins.
More Questions
TLS Online TPP Program

#Question id: 26372

#Unit 3. Fundamental Processes

Dam (Dam-) mutants accumulates
TLS Online TPP Program

#Question id: 206

#Unit 1. Molecules and their Interaction Relevant to Biology

The reactive center of coenzyme A is
TLS Online TPP Program

#Question id: 5661

#Unit 5. Developmental Biology

Following statements regarding to the embryogenesis in A. thaliana.

A. The first zygotic division is unequal, with the basal cell larger than the apical cell. The basal cell divides to give rise to the suspensor. The apical cell divides vertically to form a two-celled proembryo, which will give rise to the rest of the embryo.

B. The top most suspensor cell is recruited into the embryo, where it is known as the hypophysis, and contributes to the embryonic root meristem and root cap.

C. The next two divisions produce an eight-cell octant-stage embryo, which develops into a heart-stage embryo of around 32 cells

D. The embryo elongates and the cotyledons start to develop as wing-like structures at one end, while an embryonic root forms at the other. This stage is known as the globular stage.

Which of the following statements are correct?
TLS Online TPP Program

#Question id: 20328

#Unit 4. Cell Communication and Cell Signaling

Acyl-homomserine lactones (AHLs) are auto-inducers used by Gram-negative bacteria to communicate. Which statements are about that Quorum sensing signaling in bacteria. 
a. transcription is activated at low cell density
b. transcription is not activated at low cell density
c. transcription is activated at high cell density
d. transcription is not activated at high cell density
e. Upon reaching a threshold concentration, AHL can bind to its receptor LuxR.
f. Upon reaching a threshold concentration, AHL can bind to Lux box.