Exocytosis and endocytosis are ways that cells ________ take in and release materials.

• A. actively
• B. randomly
• C. chemically
• D. passively

Answer: (A)

Verified step by step guidance

1. Understand the key terms: Exocytosis and endocytosis are processes used by cells to transport materials across the cell membrane. These processes involve the movement of large molecules or particles that cannot pass through the membrane by simple diffusion or facilitated diffusion.
2. Recognize the type of transport: Both exocytosis and endocytosis require energy in the form of ATP because they involve the movement of materials against concentration gradients or the rearrangement of the cell membrane. This makes them forms of active transport.
3. Eliminate incorrect options: 'Randomly' is incorrect because these processes are highly regulated and specific. 'Chemically' is incorrect because the processes are physical rather than chemical. 'Passively' is incorrect because passive transport does not require energy, unlike exocytosis and endocytosis.
4. Identify the correct answer: Since these processes require energy, they are classified as 'actively' transporting materials.
5. Conclude: The correct answer is 'actively,' as exocytosis and endocytosis are energy-dependent processes that allow cells to take in and release materials.