Question

which of the following describes a form of active transport?
a oxygen transfers into red blood cells through small gaps in the cell membrane from oxygen-rich environment surround the cells.
b large molecules are brought into the cell by wrapping the cell membrane around the molecules to form a vesicle.
c water moves across the cell membrane from the side with high osmotic pressure towards the side with low osmotic pressure.
d membrane proteins provide a pathway for larger particles to move across the cell membrane and bring the cell and environment closer to equilibrium.

Explanation:

• Option A: Oxygen transfer through small gaps in the cell membrane is a form of passive transport (simple diffusion).
• Option B: Bringing large molecules into the cell by wrapping the cell membrane around them to form a vesicle is endocytosis, which is an active - transport process as it requires energy.
• Option C: Water movement across the cell membrane from high to low osmotic pressure is osmosis, a passive - transport process.
• Option D: Membrane proteins providing a pathway for larger particles to move across the membrane to reach equilibrium is facilitated diffusion, a passive - transport process.

Answer:

B. Large molecules are brought into the cell by wrapping the cell membrane around the molecules to form a vesicle.