Which of the following can lead to loss-of-heterozygosity in a tumor-suppressor gene?

a. deletion of the normal copy                       

b. non dysjunction during mitosis

c. somatic mutation of the normal copy

d. mitotic recombination between a wild-type and mutant allele

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#Question id: 9607

#Unit 9. Diversity of Life Forms

The common housefly belongs to all of the following taxa. Assuming you had access to textbooks or other scientific literature, knowing which of the following should provide you with the most specific information about the common housefly?

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#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?

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#Question id: 12246

#Unit 10. Ecological Principles

The graphs below show that the relationship between atmospheric CO2 and mean global temperature is

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#Question id: 3405

#Unit 11. Evolution and Behavior

Phylogenies can be used to test whether speciation has been sympatric or allopatric. Following figure shown a new species arises by allopatric speciation, its nearest relative will usually live in a different geographic area, such as in a nearby lake. Which of the following phylogenetic tree is correct?

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#Question id: 22962

#Unit 7. System Physiology – Animal

What is the relationship between calcium and PTH? 

a. When extracellular Ca2+ is decreased àCa2+ binding to the receptor àinhibits PTH secretion

b. When extracellular Ca2+ concentration is increased à Ca2+ binds to the receptor à activates phospholipase C àinhibits PTH secretion

c. When extracellular Ca2+ is decreased à Ca2+ doesn’t binds to the receptor àstimulates PTH secretion

d. When extracellular Ca2+ concentration is increased à Ca2+ binds to the receptor à activates phospholipase C àstimulates PTH secretion.