AP Biology Campbell Chapter 8

Which of the following statements about diffusion is true?

• It is very rapid of long distances.

• It requires an expenditure of energy by the cell.

• It is an active process in which molecules move from a region of lower concentration to a region of higher concentration.

• It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

Which cell is in a hypertonic environment?

• A

• B

• C

• None of them are hypertonic

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NGSS.HS-LS1-3

_______ regulates what enters and leaves a cell.  

• Cell Membrane

• Nucleus

• Mitochondria

• Cytoplasm

Assuming that the purple molecules are too large to pass through the membrane, what would happen to the water level as a result of osmosis?

• The water level would rise on the A side

• The water level would rise on the B side

• The water level would remain constant

• The water level would drop on the A side.

Which of the following factors would tend to increase membrane fluidity?

• a greater proportion of unsaturated phospholipids

• a greater proportion of saturated phospholipids

• a lower temperature

• a relatively high protein content in the membrane

According to the fluid mosaic model of cell membranes, phospholipids___________________.

• can shift laterally along the plane of the membranee

• frequently flip-flop from one side of the membrane to the other

• occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane

• have hydrophilic tails in the interior of the membrane

Which of the following types of molecules are hydrophilic and therefore excluded from the hydrophobic portion of the phospholipid bilayer?

• transmembrane proteins

• integral membrane proteins

• peripheral proteins

• cholesterol

In what way do the membranes of a eukaryotic cell vary?

• Phospholipids are found only in certain membranes

• Certain proteins are unique to each membrane

• Only certain membranes of the cell are selectively permeable

• Some membranes have hydrophobic surfaces exposed to the cytoplasm while others have hydrophilic surfaces facing the cytoplasm.

Which of the following statements describes a characteristic feature of a carrier protein in a plasma membrane?

• It exhibits specificity for a particular type of molecule

• It requires the expenditure of cellular energy to function.

• It works against diffusion.

• It has not hydrophobic regions.

Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly?

• sucrose.

• an amino acid.

• O₂.

• Na⁺.