Transport Across Cell Membranes

What is the primary difference between active and passive transport across a cell membrane?

• Active transport moves molecules with their concentration gradient, while passive transport moves them against it.

• Active transport requires energy (ATP), while passive transport does not.

• Passive transport uses proteins, while active transport does not.

• Passive transport moves large particles, while active transport moves small molecules.

Which statement accurately describes the process of diffusion?

• Molecules move from an area of lower concentration to an area of higher concentration, requiring energy.

• Molecules move randomly until they are evenly distributed, requiring no energy.

• Water molecules move across a semi-permeable membrane to equalize solute concentration.

• Proteins facilitate the movement of specific molecules across the membrane against their gradient.

How do oxygen and carbon dioxide move between the alveoli and capillary beds in the lungs?

• Through active transport, utilizing ATP.

• Via facilitated diffusion, requiring specific protein channels.

• By osmosis, driven by water potential differences.

• Through simple diffusion, following their concentration gradients.

A red blood cell is placed in a solution with a higher solute concentration than its cytoplasm. What will be the most likely outcome for the cell?

• The cell will swell and potentially burst.

• The cell will remain unchanged in size and shape.

• The cell will shrink and become crenated.

• The cell will actively transport water out to maintain equilibrium.

Which statement accurately describes facilitated diffusion?

• It requires ATP to move molecules against their concentration gradient.

• It allows small, nonpolar molecules to pass directly through the lipid bilayer.

• It utilizes protein channels or carriers to move molecules down their concentration gradient without energy input.

• It involves the engulfment of large particles by the cell membrane.

What is a key characteristic of active transport mechanisms like the sodium-potassium pump?

• They move substances down their concentration gradient.

• They do not require cellular energy.

• They maintain concentration gradients by moving substances against them.

• They are only used for the transport of large molecules.

How do cells typically import large quantities of external substances, such as bacteria, into their cytoplasm?

• Through simple diffusion across the cell membrane.

• Via facilitated diffusion using specific protein channels.

• By active transport pumps that directly bind and move the substances.

• Through endocytosis, where the cell membrane engulfs the substances.