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#Question id: 12958


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.

The strong dependence of RR individuals on large quantities of vitamin K probably is responsible for

#Unit 10. Ecological Principles
  1. Their lowered fitness
  2. Their susceptibility to warfarin
  3. Their superiority to heterozygotes (Rr)
  4. Their increasing numbers in the population each generation
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#Question id: 4820

#Unit 8. Inheritance Biology

Which of the following gametes are produced in grater proportional by an individual of genotype Ab/aB if the genes are in the same chromosome with some recombination between them?

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#Question id: 4821

#Unit 8. Inheritance Biology

What are frequency of recombination  if one cell carry out cross over every 50 cell undergoes meiosis ?

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#Question id: 4822

#Unit 8. Inheritance Biology

In a particular species of mammal black hair (B) is dominant to green hair (b) and red eyes (R) are dominant to white eyes (r). If a BbRr individual is mated with a bbrrindividual the expected phenotypic ratio of the offspring is 1 black-red : 1 black-white: 1 green-red : 1 green-white. However, when you mate these individuals you find that the phenotypic ratio of the offspring is 6 black-red :1 black-white : 1 green-red : 6 green-white. What could account for this difference?

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#Question id: 4823

#Unit 8. Inheritance Biology

Which one of the following DNA markers can be used to distinguish between a homozygote and heterozygote ?

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#Question id: 4824

#Unit 8. Inheritance Biology

If plant with genotype AaBb is test cross where A and B are link at 10 map unit  in trance configuration then the probability of getting AaBB and AaBb genotype respectively?

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#Question id: 4825

#Unit 8. Inheritance Biology

How many genetically different gametes can be made by an individual of genotype AaBbCcDd if gene A, B are completely link and other are unlink?