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#Question id: 12218

The control of gastric acid secretion in response to a meal involves several events that take place over a 4- or 5-hr period following the meal. These events include
(1) a decrease in the pH of the gastric contents,
(2) an increase in the rate of acid secretion,
(3) a decrease in the rate of acid secretion, and
(4) an increase in the pH of the gastric contents. Which of the following best describes
the correct temporal order of events over a 4- or 5-hr period following a meal?

#Unit 7. System Physiology – Animal

4, 3, 2, 1
3, 1, 4, 2
3, 4, 1, 2
4, 2, 1, 3

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TLS Online TPP Program

#Question id: 13142

#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.

There is a substantial number of heterozygotes in the population. Which of the following is the best explanation of this observation?

TLS Online TPP Program

#Question id: 13141

#Unit 10. Ecological Principles

Five similar populations of a herbaceous annual plant are monitored for three years; then, the numbers of individuals in populations I-IV are increased by an experimenter. Subsequent changes in the sizes of all the populations are shown in the graph below.

If size distributions of individuals do not vary among these populations, which of the following relationships best illustrates the occurrence of population regulation?

TLS Online TPP Program

#Question id: 13140

#Unit 10. Ecological Principles

One summer the moose population on Island was unusually high, and park naturalists noticed signs of malnutrition among the adults. The wolf population was fairly low, near 20. That winter, for the first time in many years, a substantial number of seemingly healthy adult moose as well as calves and crippled animals were killed and eaten by wolves. This description is part of a general situation in which the wolf and moose populations

TLS Online TPP Program

#Question id: 13139

#Unit 10. Ecological Principles

The logistic equation above is used to describe the rate 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 statements is true for this equation?

TLS Online TPP Program

#Question id: 13138

#Unit 10. Ecological Principles

Life-history characteristics associated with K-selected ordgtanisms include K