Estimates of current rates of extinction -triyambak.org

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#Question id: 12576

Estimates of current rates of extinction

#Section 5: Applied Ecology & Evolution

Indicate that we have reached a state of stable equilibrium in which speciation and extinction rates are approximately equal.
Suggest that one-half of all animal and plant species may be gone by the year 2100.
Indicate that rates may be greater than the mass extinctions at the close of the Cretaceous period.
Indicate that only 1% of all of the species that have ever lived on Earth are still alive.

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#Question id: 12960

#Section 5: Applied Ecology & Evolution

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.

Which of the following is most likely correct concerning the gene for resistance to warfarin?

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#Question id: 12579

#Section 5: Applied Ecology & Evolution

Which of the following probably contains the highest concentration of toxic pollutants (biological magnification)?

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#Question id: 12580

#Section 5: Applied Ecology & Evolution

When levels of CO2 are experimentally increased, C3 plants generally respond with a greater increase in productivity than C4 plants. This is because

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#Question id: 12582