Practice Questions

TLS Online TPP Program

#Question id: 13142

The Norway rat (Rattus Norvegicus), a widespread pest, was controlled for about a decade by the anticoagulant warfarin. This chemical substance, placed in food pellets, is absorbed by the intestinal tract and inhibits the clotting of blood. After a population decline for about 10 years, rat populations increased and stabilized. In one European population, as illustrated in the graph below, the percentage of rats resistant to warfarin has remained fairly stable over a number of years.
Resistance to warfarin is governed by a dominant autosomal gene, R. More than 15 percent of the resistant animals are heterozygous at this locus (Rr). The table below indicates the response to warfarin and relative reproductive fitness of individuals that are homozygous or heterozygous for the dominant gene (R). The RR individuals have a 20-fold increase in vitamin K requirement over individuals.
Fitness is a measure of the reproductive success of a particular genotype. The highest fitness is 1.00.
There is a substantial number of heterozygotes in the population. Which of the following is the best explanation of this observation?

#Unit 10. Ecological Principles

Heterozygotes (Rr) have a selective advantage over both homozygotes (RR and rr).
The gene for susceptibility (r) is increasing rapidly each generation.
The gene for susceptibility (r) is being lost by chance each generation.
Dominant homozygotes (RR) enjoy a reproductive advantage over heterozygotes

More Questions

#Question id: 7518

#General Aptitude

#Question id: 2971

#Unit 2. Cellular Organization

Which one of the following is the most appropriate match?

Events	Protein	Phases
A. Cohesins are loaded onto chromosomes	I. Mei-S332/Shugoshin	a. G1
B. Cohesins can dissociate from the DNA	II. Polo kinase and Aurora B kinase	b. G2
C. Prevents cohesin phosphorylation, and hence dissociation	III. Scc2-Scc4	c. S
D. Phosphorylation of cohesins	IV. Pds5-Wapl	d. M

#Question id: 24586

#Unit 3. Fundamental Processes

Microsatellite instability is caused by the mutation in

#Question id: 18862

#Unit 13. Methods in Biology

#Question id: 2876

#Unit 2. Cellular Organization

From the following set of statements regarding DNA topology, state whether each of the given statement is either True or False.

A. The two strands of cccDNA can be easily separated without any breakage of bonds.

B. Circular DNA molecules purified from bacteria and eukaryotes are usually negatively supercoiled.

C. Interwound writhe and spiral writhe are topologically different.

D. The organisms that live under extreme temperature conditions have been found to have positively supercoiled DNA.

E. Negative supercoils can be thought of as a store of free energy that aids in processes that require strand separation.