You do an experiment in which you increase the concentration of phosphate in a solution and measure the uptake by plant cells. You find that once the concentration of phosphate reaches 1 gram per liter adding more phosphate does not increase uptake any further. From this you would conclude that phosphate is taken up by ________.

A. endocytosis.
B. osmosis.
C. exocytosis.
D. facilitated diffusion.
E. active transport.


Answer: D

Biology & Microbiology

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Which statement is false about intact neurons?

a. An action potential can be generated in an input zone only. b. A trigger zone has enough sodium gates to initiate an action potential. c. Each portion of a membrane has its own recovery time. d. The potassium gates open during the recovery period. e. Gated sodium channels are inactivated during the recovery period.

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Ribosomes leave the nucleus as

a. intact 80S ribosomes. b. intact 70S ribosomes. c. 40S and 60S ribosomal subunits. d. 18S and 28S rRNAs.

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Because water _______, it is ideal as the most abundant molecule in cells.

a. has low heat of vaporization b. is a polar molecule that can form hydrogen bonds with itself and with other polar molecules c. dissolves nonpolar molecules d. expands when it freezes

Biology & Microbiology

The first self-replicating molecule was probably ________

Fill in the blank(s) with correct word

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