Biology test 2

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

CO2

Which of the following is true of osmosis?

In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

the fluid mosaic model describes the plasma membrane as consisting of

Individual proteins and phospholipids that can drift in a phospholipid bilayer.

Which of the following most accurately describes selective permeability?

Only certain molecules can cross a cell membrane.

Which of the following processes can move a solute against its concentration gradient?

active transport

Which of the following allows water to move much faster across cell membranes?

aquaporins

Singer and Nicolson's fluid mosaic model of the membrane proposed that membranes

consist of protein molecules embedded in a fluid bilayer of phospholipids

The sodium-potassium pump is called an electrogenic pump because it _____.

contributes to the membrane potential

Osmosis can be defined as

diffusion of water

Diffusion

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

A cell that neither gains nor loses water when it is immersed in a solution is

isotonic to its environment.

Oxygen crosses a plasma membrane by

passive transport

Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of

passive transport.

White blood cells engulf bacteria using _____.

phagocytosis

The difference between pinocytosis and receptor-mediated endocytosis is that _____.

pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.

Most of the functions of a cell membrane are performed by

proteins

The force driving simple diffusion is _____, while the energy source for active transport is _____.

the concentration gradient; ATP

Plasma membranes are selectively permeable. This means that

the plasma membrane allows some substances to enter or leave a cell more easily than others.