Which sentence best describes exocytosis?

• A. A cell engulfs large particles by wrapping its plasma membrane around them.
• B. A cell transports materials out of the cell by fusing vesicles with the plasma membrane.
• C. A cell digests materials within lysosomes after endocytosis.
• D. A cell imports small molecules through protein channels in the plasma membrane.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of exocytosis. Exocytosis is a cellular process where materials are transported out of the cell. This involves vesicles within the cell fusing with the plasma membrane to release their contents into the extracellular space.
2. Step 2: Analyze the options provided in the question. Each option describes a different cellular process, and you need to identify which one aligns with the definition of exocytosis.
3. Step 3: Eliminate incorrect options. For example, 'A cell engulfs large particles by wrapping its plasma membrane around them' describes endocytosis, not exocytosis. Similarly, 'A cell digests materials within lysosomes after endocytosis' refers to intracellular digestion, and 'A cell imports small molecules through protein channels in the plasma membrane' describes facilitated diffusion or active transport.
4. Step 4: Focus on the correct option. The sentence 'A cell transports materials out of the cell by fusing vesicles with the plasma membrane' accurately describes exocytosis, as it involves the outward transport of materials via vesicle fusion.
5. Step 5: Confirm your understanding by reviewing the definition of exocytosis and ensuring it matches the correct option. This process is essential for functions like neurotransmitter release and secretion of hormones.