The gene that codes for the repressor protein of the E. coli lac operon is constitutive; therefore, the lac operon is
typically:a.
turned off.
b. turned on.
c. unaffected by the repressor protein.
d. constitutive.
e. activated by the repressor protein..
a
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For water fleas of the genus Daphnia, switching from a pattern of asexual reproduction to sexual reproduction coincides with _____
A) environmental conditions becoming more favorable for offspring B) greater abundance of food resources for offspring C) periods of temperature or food stresses on adults D) completion of puberty E) exhaustion of an individual's supply of eggs
Which of the following statements about the control of blood volume and blood pressure is false?
A. Angiotensin II stimulates the release of antidiuretic hormone, which increases salt and water uptake by the distal convoluted tubule. B. A drop in blood pressure stimulates the cells of the juxtaglomerular apparatus to release renin. C. Inactive angiotensinogen is converted to angiotensin II by an enzyme released from the lungs. D. Angiotensin II causes the smooth muscle in the walls of the arterioles to contract. E. Blood pressure and volume are monitored by baroreceptors in the aorta and carotid bodies.
Dandelions, Taraxacum officinale, are plants that produce fruitlike propagules that are actually produced asexually. Sexual reproduction is very rare in this organism. Which species concept would be least useful in defining dandelions as a species?
A. Phylogenetic species concept. B. Biological species concept. C. Evolutionary species concept. D. Ecological species concept. E. Both the evolutionary and ecological species concepts.
The quantity of available nutrients _____ from the lower levels of the energy pyramid to the higher ones.
a) increases b) decreases c) remains stable d) cycles