Question

a primary active transport process is one in which ______.

an intracellular vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid

molecules move across the plasma membrane without an input of energy

molecules pass directly through the phospholipid bilayer of the plasma membrane

the plasma membrane folds inward to form a vesicle containing extracellular material

molecules move through transport proteins that have been activated by atp

Explanation:

1. Analyze each option:

• Option 1: Describes exocytosis, not primary active transport.
• Option 2: Movement without energy input is passive transport, not active.
• Option 3: Direct passage through phospholipid bilayer is simple diffusion (passive), not active transport.
• Option 4: Describes endocytosis, not primary active transport.
• Option 5: Primary active transport uses ATP to activate transport proteins for molecule movement against concentration gradient.

Answer:

molecules move through transport proteins that have been activated by ATP