Question

1. describe how molecules enter and leave a cell without the use of the cell’s energy. 2. describe the two major types of active transport. critical thinking 3. sep construct an explanation water molecules diffuse through the cell membrane through aquaporins. how are these proteins helpful in osmosis?

Explanation:

1. Molecules enter and leave a cell without using cell - energy through passive transport mechanisms like diffusion (movement from high to low concentration), facilitated diffusion (uses transport proteins for larger or polar molecules), and osmosis (diffusion of water across a semi - permeable membrane).
2. The two major types of active transport are primary active transport (uses ATP directly, e.g., sodium - potassium pump) and secondary active transport (uses an electrochemical gradient established by primary active transport to move other substances, e.g., co - transport).
3. Aquaporins are helpful in osmosis as they are specialized channel proteins that allow water molecules to pass through the cell membrane more rapidly. They increase the rate of water diffusion across the membrane, facilitating the movement of water in response to osmotic gradients.

Answer:

1. Molecules enter and leave a cell without using cell energy through passive transport such as diffusion, facilitated diffusion, and osmosis.
2. The two major types of active transport are primary active transport (using ATP directly) and secondary active transport (using an established electrochemical gradient).
3. Aquaporins are helpful in osmosis as they increase the rate of water diffusion across the cell membrane by providing a specialized pathway for water molecules.