Carrier-mediated transport is necessary when
A) diffusion will not allow adequate amounts of a substance to enter the cell.
B) movement into the cell is against a concentration gradient.
C) the level of nutrients in nature is very low.
D) nutrient concentration is very low in the environment, is higher inside of the cell, or diffusion is not possible.
Bacteria stain as gram-positive or gram-negative because of differences in the cell
A) wall.
B) cytoplasm.
C) nucleus.
D) chromosome.
Nutrient transport requires energy because the nutrients must be transported into the cell against a concentration gradient. The energy required for nutrient transport is supplied by
A) ATP.
B) the proton motive force.
C) phosphoenol pyruvate.
D) ATP, the proton motive force, or phosphoenol pyruvate.
The morphology of a cell influences its
A) motility.
B) metabolism.
C) surface-to-volume ratio.
D) motility and surface-to-volume ratio
Bacteria with type IV pili
A) possess tubular or stalk-like extensions of their cells.
B) likely exhibit twitching motility.
C) have capsules that promote dehydration.
D) live in aquatic environments.
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