The evolution of similar insulating skin coverings such as fur, hair, and feathers in mammals and birds is a result of _____
A) shared ancestry
B) convergent evolution
C) homology
D) evolutionary divergence
B
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Four of the five answers listed below are true
about specific hormones and their effects. Select the EXCEPTION.
a. Thymosin helps T-cells mature. b. Calcitonin lowers blood level calcium. c. Pancreas secretes insulin and glucagons for blood sugar regulation. d. Cortisol affects the immune response. e. Pituitary gland secretes hormones that control the hypothalamus
About twelve to twenty-four hours after the previous
meal, a person’s blood-sugar level normally varies from 60 to 90 milligrams per 100 milliliters of blood, though it may rise to 130 mg/100 ml after meals high in carbohydrates. That the blood-sugar level is maintained within a fairly narrow range despite uneven intake of sugar is due to the body’s ability to carry out a. adaptation. b. inheritance. c. metabolism. d. homeostasis. e. all of these.
Which of the following sequences correctly represents the phytochrome signal transduction pathway?
a. red light ? PIF3 activation ? PIF3 into nucleus ? light-responsive gene switched off b. red light ? Pfr to Pr ? Pr into nucleus ? Pr-PIF3 complex ? light-responsive gene regulation c. UV light ? PIF3 into nucleus ? light responsive gene produces phytochrome ? Pr to Pfr d. blue light ? Pfr into nucleus ? Pfr-PIF3 complex ? light-responsive gene regulation e. red light ? Pr to Pfr ? Pfr into nucleus ? Pfr-PIF3 complex ? light-responsive gene regulation
Messenger RNAs that contain no stop codons are eliminated by
A) nonstop decay. B) directed RNase activity. C) nonsense-mediated decay. D) error-mediated repair. E) none of these mechanisms.