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

#Question id: 19814

#Unit 12. Applied Biology

Ribozyme/ RNaseP approach is one of the strategies for producing virus resistant transgenic plants. How this provides protection?
TLS Online TPP Program

#Question id: 24165

#Unit 1. Molecules and their Interaction Relevant to Biology

When winding an old clock, it is important not to overwind it. Overwinding occurs when the mainspring is almost fully wound, but the operator continues to turn the winding key. This causes the main spring to coil too tightly, and might even break it.

This paragraph best supports the statement that
TLS Online TPP Program

#Question id: 11343

#Unit 2. Cellular Organization

In the liver, which type of GLUT transports glucose out of hepatocytes when liver glycogen is broken down to replenish blood glucose?
TLS Online TPP Program

#Question id: 27389

#Unit 1. Molecules and their Interaction Relevant to Biology

The of the tendency of an atom to attract a bonding pair of electrons is known as
TLS Online TPP Program

#Question id: 9227

#Unit 9. Diversity of Life Forms

A land developer and several ecologists are discussing how a parcel of private land should be developed with housing while saving 20 hectares as natural habitat. The land developer suggests that the 20 hectares be divided into 20 separate 1-hectare areas, spread out across the area. The ecologists suggest that it would be better to have one intact parcel of 20 hectares on one side of the larger area. What is the significance of these different arrangements of the 20 hectares?