Biology Quiz 3 Flashcards

Cellular Transport Study Guide

Cell membranes act as barriers between the inner contents of the cell and the environment outside the cell. Different materials interact with cell membranes based on their properties.

Nonpolar Substances (Hydrophobic): These can diffuse across the phospholipid bilayer.
Large, Polar Molecules: These require transport proteins to move across the membrane.

The movement of molecules or ions across a cell membrane without the need for energy. Substances move from an area of high concentration to an area of low concentration, which increases the overall entropy of the system.
Entropy: A measure of disorder or randomness in a system.
Examples: Simple diffusion, facilitated diffusion, and osmosis.

The movement of molecules or ions across a cell membrane from an area of lower concentration to an area of higher concentration, against the concentration gradient. This process requires energy, usually in the form of ATP.
Examples: Sodium-Potassium Pump (Na+/K+), Calcium Pump (Ca2+), and Proton Pump (H+).

Diffusion: A form of passive transport through a selectively permeable membrane.
Osmosis: The diffusion of water across a selectively permeable membrane. Water diffuses from a region of lower solute concentration (higher water concentration) to a region of higher solute concentration (lower water concentration) until solute concentrations are equal on both sides of the membrane.

Isotonic: Same solute concentration as another solution.
Hypertonic: A solution that has a greater solute concentration and lower water concentration. Water moves outside of the cell, causing it to shrink.
Hypotonic: A solution that has a lower solute concentration and higher water concentration in comparison to the cell.

Dialysis Experiment:
- Sodium Chloride moved out of the bag, and the sulfate ion moved into the bag.
- Starch and protein molecules were unable to move through the dialysis membrane because large molecules cannot penetrate the bag.
- Water moved through the dialysis membrane because the molecules are small enough.
Plasmolysis: A process that occurs in plant cells when they lose water in a hypertonic solution.
- Water Loss: The plant cell loses water when placed in a solution with a higher solute concentration outside than inside the cell.
- Cell Shrinkage: As water leaves the cell, the cell membrane pulls away from the cell wall, causing the cell to shrink.
- Visible Effect: You can often see the cell contents clumping together in the center, leaving a gap between the cell membrane and the cell wall.
Crenation: A process that happens in animal cells, like red blood cells, when they lose water in a hypertonic solution.
- Water Loss: The cell loses water because the solution outside the cell has a higher concentration of solutes than inside the cell.
- Cell Shrinkage: The cell shrinks and has a wrinkled appearance.
- No Cell Wall: Unlike plant cells, animal cells do not have a cell wall, so they just shrivel up without any membrane pulling away from a wall.

To collect and interpret data to see how osmosis and diffusion occur across a membrane.
Hypothesis: If we place an onion epidermis in a NaCl solution, then the cells will undergo plasmolysis because water will leave the onion cells through osmosis. Precipitate will form, indicating the presence of chloride ions.

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Biology Quiz 3 Flashcards

Cell membranes act as barriers between the inner contents of the cell and the environment outside the cell. Different materials interact with cell membranes based on their properties.

Nonpolar Substances (Hydrophobic): These can diffuse across the phospholipid bilayer.
Large, Polar Molecules: These require transport proteins to move across the membrane.

The movement of molecules or ions across a cell membrane without the need for energy. Substances move from an area of high concentration to an area of low concentration, which increases the overall entropy of the system.
Entropy: A measure of disorder or randomness in a system.
Examples: Simple diffusion, facilitated diffusion, and osmosis.

The movement of molecules or ions across a cell membrane from an area of lower concentration to an area of higher concentration, against the concentration gradient. This process requires energy, usually in the form of ATP.
Examples: Sodium-Potassium Pump (Na+/K+), Calcium Pump (Ca2+), and Proton Pump (H+).

Diffusion: A form of passive transport through a selectively permeable membrane.
Osmosis: The diffusion of water across a selectively permeable membrane. Water diffuses from a region of lower solute concentration (higher water concentration) to a region of higher solute concentration (lower water concentration) until solute concentrations are equal on both sides of the membrane.

Isotonic: Same solute concentration as another solution.
Hypertonic: A solution that has a greater solute concentration and lower water concentration. Water moves outside of the cell, causing it to shrink.
Hypotonic: A solution that has a lower solute concentration and higher water concentration in comparison to the cell.

Dialysis Experiment:
- Sodium Chloride moved out of the bag, and the sulfate ion moved into the bag.
- Starch and protein molecules were unable to move through the dialysis membrane because large molecules cannot penetrate the bag.
- Water moved through the dialysis membrane because the molecules are small enough.
Plasmolysis: A process that occurs in plant cells when they lose water in a hypertonic solution.
- Water Loss: The plant cell loses water when placed in a solution with a higher solute concentration outside than inside the cell.
- Cell Shrinkage: As water leaves the cell, the cell membrane pulls away from the cell wall, causing the cell to shrink.
- Visible Effect: You can often see the cell contents clumping together in the center, leaving a gap between the cell membrane and the cell wall.
Crenation: A process that happens in animal cells, like red blood cells, when they lose water in a hypertonic solution.
- Water Loss: The cell loses water because the solution outside the cell has a higher concentration of solutes than inside the cell.
- Cell Shrinkage: The cell shrinks and has a wrinkled appearance.
- No Cell Wall: Unlike plant cells, animal cells do not have a cell wall, so they just shrivel up without any membrane pulling away from a wall.

To collect and interpret data to see how osmosis and diffusion occur across a membrane.
Hypothesis: If we place an onion epidermis in a NaCl solution, then the cells will undergo plasmolysis because water will leave the onion cells through osmosis. Precipitate will form, indicating the presence of chloride ions.