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TLS Online TPP Program

#Question id: 12085

In bottom sediments of lakes and streams, organic matter is broken down by heterotrophic microorganisms and ammonia is released. Under aerobic conditions, specialized bacteria convert ammonia to nitrate (nitrification). This nitrate, together with nitrate from other sources, diffuses into the deeper sediments, where it may undergo anaerobic conversion to nitrogen gas (denitrification). These sediments typically contain oligochaete worms that live with their heads buried and their tails waving back and forth in the overlying water. Plastic columns were packed with freshly collected  stream  sediments  and  then  covered  with  layers  of  nitrate enriched  water.  A  similar  set  of  columns  was packed with sediment that had been sterilized and then covered with either nitrate-enriched water or distilled water. Oligochaete  worms  were  collected  and  acclimated  to  20°(C)Following  acclimation,  worms  were  rinsed  in  distilled water and then added to three sediment columns. The columns were incubated in the dark at 20°C and monitored every three days for changes in the concentration of nitrate in the overlying water. Nitrate concentrations in each of the experimental treatments were plotted against time, as shown in the graph below.

Which of the following explains why the columns were incubated in the dark?

#Unit 10. Ecological Principles
  1. Oligochaete worms are nocturnal. 8
  2. Microbial nitrification is inhibited by light.
  3. Microbial denitrification is inhibited by light.

  4. Photosynthetic organisms might compete with sed4iment microorganisms for nitrate in the light.

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TLS Online TPP Program

#Question id: 20282

#Unit 7. System Physiology – Animal

Growth hormone secretion is regulated by negative feedback, three feedback loops including both long and short loops are involved,
a.  GHRH inhibits its own secretion from the hypothalamus via an ultrashort-loop feedback.
b. Somatomedins, which are by-products of the growth hormone action on target tissues, inhibit secretion of growth hormone by the anterior pituitary.
c. Both growth hormone and somatomedins stimulate the secretion of somatostatin by the hypothalamus.
d. SRIF is also secreted by the hypothalmus and acts on the somatotrophs to stimulate growth hormone secretion.
Which one of the following represents all correct statements?
TLS Online TPP Program

#Question id: 20283

#Unit 7. System Physiology – Animal

The following statements regarding to the pancreas and its function.
a. The pancreas is composed of two major types of tissues, (1) the acini, which secrete digestive juices into the duodenum, and (2) the islets of Langerhans, which secrete insulin and glucagon directly into the blood.
b. The islets contain three major types of cells, alpha, beta, and delta cells
c. The beta cells, constituting about 25 percent of all the cells of the islets, lie mainly in the middle of each islet and secrete insulin and amylin.
d. The alpha cells, about 60 percent of the total, secrete glucagon and the delta cells, about 10 percent of the total, secrete somatostatin.
TLS Online TPP Program

#Question id: 20284

#Unit 7. System Physiology – Animal

What is the importance of C-peptide in proinsulin?
TLS Online TPP Program

#Question id: 20285

#Unit 7. System Physiology – Animal

Which of the following is CORRECT?
TLS Online TPP Program

#Question id: 20286

#Unit 7. System Physiology – Animal

Except for that portion of the insulin that combines with receptors in the target cells, the remainder is degraded by the enzyme _____?
TLS Online TPP Program

#Question id: 20287

#Unit 7. System Physiology – Animal

Match the medications to their main action:

1. Thiazolidinedionesa. to control plasma glucose
2. Metforminb. cause additional release of insulin by the pancreas
3. Sulfonylureasc. suppress liver glucose production
4. Insulind. increase insulin sensitivity