Question

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

Explanation:

1. In diffusion, molecules move from high - concentration to low - concentration areas without the help of transport proteins. In facilitated diffusion, molecules also move from high - to low - concentration but require transport proteins (channels or carriers) to cross the cell membrane.
2. Endocytosis is the process by which a cell takes in substances by engulfing them with its cell membrane, forming a vesicle inside the cell. Exocytosis is the opposite, where vesicles inside the cell fuse with the cell membrane to release substances outside the cell.
3. When an animal cell is placed in a hypertonic solution, water will move out of the cell by osmosis. This causes the cell to shrink or crenate.
4. Active transport requires energy (usually in the form of ATP) to move substances across the cell membrane against their concentration gradient (from low - to high - concentration).

Answer:

1. In diffusion, molecules move without transport proteins from high to low concentration. In facilitated diffusion, transport proteins are involved in the high - to - low concentration movement of molecules.
2. Endocytosis is taking substances into the cell by membrane engulfment. Exocytosis is releasing substances out of the cell by vesicle - membrane fusion.
3. The animal cell will shrink (crenate) as water moves out due to osmosis.
4. Energy (ATP) is necessary to move substances against their concentration gradient.