Movement of a molecule against a concentration
gradient is
a. simple diffusion.
b. facilitated diffusion.
c. osmosis.
d. active transport.
e. bulk flow.
Answer: d
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Nerve impulses travel along the neurons by the opening of channels that allow sodium ions to flow inward, followed by an outward flow of potassium ions. In order to ensure that the impulse may be produced at any time, sodium is actively transported out of the cell, and potassium is transported into the cell by the sodium/potassium pump. Which of the following types of work is performed by the
sodium/potassium pump? A) mechanical B) electrical C) concentration D) synthetic E) bioluminescent
After transcription and before translation, eukaryotic mRNA is modified by adding
A) tRNAs and amino acids. B) amino acids and a poly-A tail. C) a cap of modified nucleotides and a poly-A tail. D) an AUG at one end and a poly-U tail at the other.
Chemical messengers in the cell that control the amounts of enzyme produced is/are
A. DNA. B. gene regulator proteins. C. inhibitors. D. coenzymes.
_____ have 46 chromosomes, whereas _____ have 23
Fill in the blank(s) with the appropriate word(s).