Review Questions

For each question, choose the ONE BEST answer or completion.

1. Biological membranes

A. contain phospholipid.

B. contain protein.

C. are relatively impermeable to ionic solutes.

D. are relatively permeable to small uncharged solutes.

E. all of the above.

2. The extracellular matrix

A. can contain collagen.

B. can contain phospholipid.

C. can contain RNA.

D. is relatively impermeable to ionic solutes.

E. all of the above.

3. Which of the following statements about gap junctions is incorrect?

A. They are formed from six subunits.

B. They are found in both plants and animals.

C. They allow small solute molecules to pass between the cytosol of one cell and the cytosol of its neighbor.

D. They allow electrical current to pass between the cytosol of one cell and the cytosol of its neighbor.

E. They can switch (gate) to a closed state.

4. A cell with a high density of nuclear pores is likely to be

A. digesting and destroying other cells.

B. using lots of the energy currency ATP.

C. synthesizing lots of protein.

D. communicating electrically with its neighbors.

E. undergoing or soon to enter mitosis.

5. In diffusing from the mitochondrial matrix of one animal cell to the interior of the Golgi apparatus of another cell 50 ^m away in the same animal a molecule of CO2 would cross a minimum of

A. two membranes.

B. three membranes.

C. four membranes.

D. five membranes.

E. six membranes.

6. One organelle often found at the cell center is the

A. nucleus.

B. peroxisome.

C. endoplasmic reticulum.

D. Golgi apparatus.

E. lysosome.

7. A stimulated cell will often release calcium ions from its

A. nucleus.

B. endoplasmic reticulum.

C. mitochondria.

D. lysosomes.

E. peroxisomes.

8. In addition to being found free in the cytoplasm, ribosomes are found on the outer surface of the

A. nucleus.

B. smooth endoplasmic reticulum.

C. mitochondrion.

D. chloroplast.

E. plasma membrane.

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