Which nitrogenous base pairs with adenine in a DNA molecule?
A) cytosine
B) thymine
C) uracil
D) guanine
B
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Select the endocrine gland whose secretory function is under direct control of the sympathetic nervous system
a. pancreas b. thyroid c. adrenal medulla d. parathyroid e. posterior pituitary
The substance that an enzyme combines with is
a. another enzyme. b. a product. c. an active site. d. the substrate.
Gram positive cells:
a) are able to exclude crystal violet during the Gram stain. b) have a thinner layer of peptidoglycan than Gram negative cells have c) have lipoteichoic acids to connect the cell wall to the plasma membrane d) possess an outer membrane
The main effect of burning peat, wood, coal, and petroleum on the Earth's climate is
A. the fires release back into the atmosphere carbon dioxide that was once taken from the atmosphere by plants and stored in their own tissues; the increased carbon dioxide holds in solar heat and causes a rise in temperature. B. the rising heat from fires produces wind that cools the surface of the Earth. C. the fires significantly heat the air and cause a rise in global temperature. D. the smoke blocks sunlight from reaching the Earth and causes a significant lowering of the Earth's temperature. E. the fires use up oxygen that would otherwise block penetration of ultraviolet light from reaching the Earth; the increased ultraviolet radiation heats the Earth.