Question

part c: decide whether each statement is true or false.

1. active transport requires atp to move substances against their concentration gradient.
2. the cell membrane is selectively permeable, allowing all molecules to pass through.
3. a hypertonic solution causes water to move into a cell, making it swell.
4. endocytosis is a form of passive transport.
5. facilitated diffusion requires a transport protein to help move molecules across the membrane.
6. in an isotonic solution, the concentration of solutes inside and outside the cell is equal.
7. hypotonic solutions will cause animal cells to lose water and shrink.

part d: answer the following questions using complete sentences.

1. what is the difference between facilitated diffusion and simple diffusion?
2. what molecules can easily diffuse across the cell membrane?
3. what molecules cannot easily diffuse across the cell membrane?
4. why would a dehydrated individual need to receive a saline iv instead of (explain your answer in terms of cell transport and osmosis.)

Explanation:

Part C:

1. Active transport moves substances against the concentration gradient, requiring energy. So, the statement (if it's about moving against gradient) is true.
2. The cell - membrane is selectively permeable, allowing certain substances to pass through while restricting others. True.
3. A hypertonic solution causes water to move out of a cell, causing it to shrink. True.
4. Endocytosis is a form of active transport as it requires energy to engulf substances. So, the statement that it is passive is false.
5. Facilitated diffusion uses transport proteins to move molecules across the membrane. True.
6. In an isotonic solution, the solute concentration inside and outside the cell is equal. True.
7. Hypotonic solutions cause animal cells to take in water and swell, not lose water and shrink. False.

Part D:

1. Simple diffusion is the movement of small, non - polar molecules directly across the lipid bilayer of the cell membrane down their concentration gradient without the help of transport proteins. Facilitated diffusion is the movement of larger, polar or charged molecules across the cell membrane down their concentration gradient with the assistance of transport proteins (either channel proteins or carrier proteins).
2. Small, non - polar molecules such as oxygen ($O_2$), carbon dioxide ($CO_2$), and small lipids can easily diffuse across the cell membrane because they can dissolve in the lipid bilayer.
3. Large, polar molecules (such as glucose), charged ions (such as $Na^+$, $K^+$), and macromolecules (such as proteins and nucleic acids) cannot easily diffuse across the cell membrane due to the hydrophobic nature of the lipid bilayer.
4. A dehydrated individual needs a saline IV because a saline solution is isotonic to the body's cells. If a hypotonic solution were given, water would rush into the cells, potentially causing them to swell and burst. If a hypertonic solution were given, water would be drawn out of the cells, worsening the dehydration. An isotonic saline solution ensures that there is no net movement of water across the cell membranes, maintaining cell integrity while replenishing lost fluids.

Answer:

Part C:

1. True
2. True
3. True
4. False
5. True
6. True
7. False

Part D:

1. Simple diffusion is the movement of small non - polar molecules directly across the lipid bilayer without transport proteins, while facilitated diffusion uses transport proteins to move larger, polar or charged molecules across the membrane.
2. Small non - polar molecules like $O_2$, $CO_2$, and small lipids.
3. Large polar molecules, charged ions, and macromolecules.
4. A saline IV is isotonic, which maintains cell integrity and replenishes lost fluids without causing harmful water movement across cell membranes.