Which endocrine gland is the main center for
control of the internal environment?
a. pineal and thymus
b. hypothalamus
c. thyroid and parathyroids
d. adrenal cortex and adrenal medulla
e. pancreas and gonads
B
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Phosphofructokinase is regulated by a number of factors, including high levels of ATP. Why is this enzyme regulated by ATP levels?
A. If ATP levels are high, this provides a mechanism to directly inhibit the Krebs cycle, thus preventing further generation of NADH, FADH2 and ATP molecules that are not needed. B. If ATP levels are high, it is important to directly inhibit the reaction that commits the substrate to glycolysis to allow the substrate to be available for other reactions, since the cell has ample energy. C. If ATP levels are high, it is important to inhibit ATP synthase, and phosphofructokinase directly inhibits ATP synthase. D. If ATP levels are high, this provides a mechanism to directly inhibit the electron transport chain, thus preventing the formation of a proton gradient in the intermembrane space of mitochondria.
Gregor Mendel's pioneering genetic experiments with pea plants occurred before the discovery of the structure and function of chromosomes. Which of the following observations about inheritance in pea plants could be explained only after the discovery that genes may be linked on a chromosome?
(A) Pea color and pea shape display independent inheritance patterns. (B) Offspring of a given cross show all possible combinations of traits in equal proportions. (C) Most offspring of a given cross have a combination of traits that is identical to that of either one parent or the other. (D) Recessive phenotypes can skip a generation, showing up only in the parental and F2 generations.
The molecule that traps the sun's energy is
A. ATP. B. glyceraldehyde-3-phosphate. C. chloroplast. D. chlorophyll.
Which of the following is the best feature that allows moray eels to be successful hunters?
a. Their ability to swallow items larger than their heads. b. Their ability to fit into small holes in spite of their large body. c. Their habit to ambush when they hunt. d. Their jaw arrangement.