performed by C) phospholipids. D) cholesterol 15) Plasma membranes are selective
ID: 209132 • Letter: P
Question
performed by C) phospholipids. D) cholesterol 15) Plasma membranes are selectively permeable. This means that rane is intact and the cell is healthy to enter or leave a ceill more easily tham others. B) the plasma C) glucose cannot enter the cell. D) plasma membranes mast be very thick. allows some 16) Small, nonpolar, hydrophobic molecules such as fatty acids A) easily pass B) very slowly diffuse through a membrane's lipid bilayer C) require D) are actively transported across cell membranes. proteins to pass through a membrane's lipid bilayer 17) Which of the following sabstances would have the most trouble crossing a biological A) 02 B) CO2 C) Nat D) a small, nonpolar molecule such as butane (C4AH10) 18) Oxygen crosses a plasma membrane by A) osmosis. C) pinocytosis. and moves a 19) Facilitated diffusion across a biological membrane requires its concentration gradient. A) energy and transport proteins; down B) transport proteins; down C) energy and transport proteins; against against 20) When an enzyme catalyzes a reaction A) it lowers the activation energy of the reaction B) it raises the activation energy of the reaction C) it acts as a D) it is used once and discarded. 21) The molecules responsible for membrane transport are A) steroids. B) phospholipids D) proteinsExplanation / Answer
15) Plasma membranes are selectively permeable. This means that the plasma membrane allows some substances to enter or leave a cell more easily than others.
16) Small, nonpolar, hydrophobic molecules such as fatty acids easily pass through a membrane's lipid bilayer.
17) Na+ would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer.
18) Oxygen crosses a plasma membrane by passive transport.
19) Facilitated diffusion across a biological membrane requires transport proteins and moves a substance down its concentration gradient.
20) When an enzyme catalyzes a reaction it lowers the activation energy of the reaction.
21) The molecules responsible for membrane transport are proteins.
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