Which of the following statements about the evolution of life histories is correct?

a.Unstable environments with unlimited resources favor r-selected populations.

b.K-selected populations are most often found in environments where density-independent factors are important regulators of population size.

c.Most populations have both r- and K-selected characteristics that vary under different environmental conditions.

d.The reproductive efforts of r-selected populations are directed at producing just a few offspring with good competitive abilities.

#Question id: 10612

#Unit 10. Ecological Principles

dN/dt = rN (K-N/K )

The logistic equation above is used to describe therate of change of a population, N, with time, t, Where r is the intrinsic rate of increase and K is the carrying capacity. Which of the following value of N showing maximum growth rate?

  ( K= 420, r =.05)

#Question id: 12958

#Unit 10. Ecological Principles

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

#Question id: 5030

#Unit 11. Evolution and Behavior

There is evidence that ray-finned fishes originally evolved

#Question id: 5843

#Unit 8. Inheritance Biology

 In homologous recombination in E. coli, the protein that assembles into long, helical filaments that coat a region of DNA is:

#Question id: 1300

#Unit 4. Cell Communication and Cell Signaling

Which of these is NOT a component of plant cell walls?