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TLS Online TPP Program

#Question id: 7100

If cells from the animal pole of a frog blastula (animal cap cells) are placed into contact with cells from the vegetal hemisphere, after removing the cells fated to form mesoderm, what is the result?

#Unit 5. Developmental Biology
  1. Animal cap cells are induced to form mesodermal derivatives.
  2. Vegetal hemisphere cells are induced by the animal cap cells to form mesodermal derivatives.
  3. An embryo forms with only ectodermal and endodermal derivatives.
  4. Animal cap cells are induced to form endodermal derivatives.
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TLS Online TPP Program

#Question id: 12954

#Unit 7. System Physiology – Animal

A 55-year-old male patient with hypertension has had his blood pressure reasonably well controlled by administration of a thiazide diuretic. During his last visit (6 months ago) his blood pressure was 130/75 mm Hg and his serum creatinine was 1 mg/100 ml. He has been exercising regularly for the past 2 years, but recently has complained of knee pain and began taking large amounts of a nonsteroidal anti-inflammatory drug. When he arrives at your office, his blood pressure is 155/85 and his serum creatinine is now 2.5 mg/100 ml. Which of the following best explains his increased serum creatinine?
TLS Online TPP Program

#Question id: 12955

#Unit 7. System Physiology – Animal

Which of the following would tend to decrease GFR by more than 10% in a normal kidney?
TLS Online TPP Program

#Question id: 12956

#Unit 10. Ecological Principles

For  nearly 200  years, biogeographers have  noted that  the  tropics  have  more terrestrial species than  temperate regions. Which of the following is NOT a plausible explanation for this pattern?
TLS Online TPP Program

#Question id: 12957

#Unit 10. Ecological Principles

Dichlorodiphenyltrichloroethane is related to the phenomenon of:
TLS Online TPP Program

#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
TLS Online TPP Program

#Question id: 12959

#Unit 10. Ecological Principles

Ozone layer depletion, since the 1970s, is primarily