Question

1. in diffusion, molecules move across a cell membrane from an area of high concentration to an area of low concentration. 3. what is the difference between simple diffusion and facilitated diffusion? 4. if an animal cell is placed in a hypertonic solution, what is the result? the cell will shrink. 5. in active transport, what is necessary to transport substances across the cell membrane? 6. what is the difference between endocytosis and exocytosis?

Explanation:

1. In diffusion, molecules move down a concentration gradient. Simple diffusion occurs without the help of transport proteins, while facilitated diffusion uses transport proteins (channels or carriers) to move molecules across the cell membrane.
2. Active transport requires energy (usually ATP) to move substances against their concentration gradient across the cell membrane.
3. In a hypertonic solution, the solute concentration outside the animal cell is higher than inside. Water moves out of the cell by osmosis, causing the cell to shrink.
4. Endocytosis is the process of taking substances into the cell by engulfing them with the cell - membrane to form a vesicle. Exocytosis is the opposite, where vesicles fuse with the cell - membrane to release substances outside the cell.

Answer:

1. Simple diffusion doesn't require transport proteins; facilitated diffusion does.
2. Energy (ATP) is required for active transport to move substances against the concentration gradient.
3. The cell will shrink as water moves out due to osmosis.
4. Endocytosis takes substances into the cell, exocytosis releases substances out of the cell.
5. Endocytosis involves taking substances into the cell by forming a vesicle from the cell - membrane. Exocytosis involves the fusion of vesicles with the cell - membrane to release substances outside the cell.