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3b Study Stack
| Question | Answer |
|---|---|
| What is osmosis? | Osmosis is the movement of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. |
| Does osmosis require energy? | No, osmosis is a type of passive transport and does not require ATP. |
| Why is osmosis important to cells? | It helps regulate water balance and maintain homeostasis within cells. |
| What is a selectively permeable membrane? | A membrane that allows certain molecules (like water) to pass through while blocking others (like solutes). |
| What is a concentration gradient? | The difference in the concentration of a substance between two areas. |
| What is equilibrium? | When the concentration of molecules is equal on both sides of the membrane. |
| How do concentration gradient and equilibrium differ? | A concentration gradient exists when there is a difference in concentration; equilibrium occurs when concentrations are balanced. |
| What is passive transport? | The movement of molecules across the membrane without using energy (ATP). |
| Give examples of passive transport. | Osmosis, simple diffusion, facilitated diffusion. |
| What is simple diffusion? | The movement of molecules directly through the phospholipid bilayer without assistance. |
| Which molecules can move by simple diffusion? | Small, nonpolar molecules like oxygen (O₂) and carbon dioxide (CO₂). |
| What is facilitated diffusion? | The movement of molecules across the membrane with the help of special proteins, without using energy. |
| Which molecules move via facilitated diffusion? | Large or charged molecules like glucose and ions. |
| How do channel proteins and carrier proteins differ? | Channel proteins create a direct open passage, while carrier proteins change shape to transport molecules. |
| What is a hypertonic solution? | A solution with a higher solute concentration than the cell's cytoplasm. |
| What happens to a cell in a hypertonic solution? | Water leaves the cell; animal cells shrink (crenation), and plant cells undergo plasmolysis. |
| What is a hypotonic solution? | A solution with a lower solute concentration than the cell's cytoplasm. |
| What happens to a cell in a hypotonic solution? | Water enters the cell; animal cells may burst (lysis), and plant cells become turgid (swollen). |
| What is an isotonic solution? | A solution with the same solute concentration as the cell's cytoplasm. |
| What happens to a cell in an isotonic solution? | Water moves equally in and out, so there is no net change. Animal cells remain normal; plant cells are flaccid. |
| If a cell has 92% water and 8% salt, and the surrounding solution has 85% water and 15% salt, which way will water move? Why? | Water will move out of the cell because the surrounding environment is hypertonic. |
| Does water move toward a hypertonic or hypotonic environment? | Water moves toward a hypertonic environment. |
| What is active transport? | The movement of molecules against their concentration gradient using energy (ATP). |
| What proteins are involved in active transport? | Carrier proteins (e.g., sodium-potassium pump). |
| Compare exocytosis and endocytosis. | Both require energy (ATP) and vesicles. Exocytosis moves materials out of the cell, while endocytosis brings materials into the cell. |
| What are the three types of endocytosis? | 1. Phagocytosis – Engulfs large particles (e.g., bacteria). 2. Pinocytosis – Takes in small dissolved substances and fluids. 3. Receptor-Mediated Endocytosis – Uses receptors to absorb specific molecules (e.g., hormones, cholesterol). |
| Compare passive and active transport (2 similarities, 2 differences). | Similarities: Both move molecules across the membrane, both help maintain homeostasis. Differences: Passive transport does not require energy, while active transport does. Passive transport moves with the concentration gradient, while active transport mo |
| What is the sodium-potassium pump? | A protein that pumps sodium out and potassium into the cell using ATP. |
| Why is the sodium-potassium pump important for nerve cells? | It helps establish a charge difference needed for nerve impulses. |
| What happens if human cells are surrounded by ocean water (96% water, 4% salt)? | The surrounding solution is hypertonic, so water will leave the cells, causing them to shrink. |
| What type of solution is pool water relative to body cells? | Hypotonic, because water moves into the cells. |
| Why must blood plasma be isotonic to red blood cells? | To prevent cells from swelling or shrinking, ensuring normal function. |
| If a plant cell is 99% water, what surrounding water concentration is best? | 100% water, so water moves into the cell and maintains turgor pressure. |
| How does a paramecium survive in a hypotonic environment? | It uses a contractile vacuole to expel excess water. |
| For oxygen to diffuse into a cell and carbon dioxide to diffuse out, where must their concentrations be higher? | For oxygen to diffuse into a cell and carbon dioxide to diffuse out, where must their concentrations be higher? |
| What is passive transport? | Movement of molecules from higher concentration to lower concentration without energy use (ATP). Examples: diffusion, osmosis, facilitated diffusion. |
| What is diffusion? | The movement of molecules from high to low concentration until equilibrium is reached. Example: Sugar dissolving in water. |
| What is osmosis? | A type of diffusion involving water molecules across a selectively permeable membrane. |
| What is active transport? | Movement of molecules from low to high concentration, requiring energy (ATP). Example: Sodium-potassium pump. |
| What is an isotonic solution? | A solution with the same solute concentration as inside the cell. No net water movement; the cell stays the same. |
| What is a hypotonic solution? | A solution with a higher solute concentration than inside the cell. Water exits the cell, causing it to shrink (crenation). |
| Why does a cell burst in a hypotonic solution? | Water enters the cell, causing it to expand and potentially burst (lysis). |
| Why does a cell shrink in a hypertonic solution? | Water exits the cell, causing it to shrink (crenation). |
| What are carrier proteins? | Proteins that transport molecules by changing shape. They are selective and involved in both facilitated diffusion and active transport. Example: Glucose transporter proteins. |
| What are channel proteins? | Proteins that form open pores allowing specific molecules or ions to pass through. They are faster than carrier proteins and used in passive transport. Example: Ion channels for sodium or potassium ions. |
| How are cell membranes similar to national borders? | Both regulate the movement of substances. Just as borders control what enters and leaves a country, cell membranes control what enters and leaves the cell. |
| What are key features of active transport? | Requires ATP to move substances against their concentration gradient (low to high) and uses specific transport proteins (pumps). |
| What is the sodium-potassium pump? | A transport protein that moves 3 Na⁺ out and 2 K⁺ into the cell, against their concentration gradients, using ATP. |
| What is primary active transport? | Direct use of ATP to transport molecules (e.g., sodium-potassium pump). |
| What is secondary active transport? | Uses the gradient created by primary active transport to move other substances (e.g., glucose symport with sodium). |
| What is endocytosis? | The process of bringing materials into the cell via vesicles. |
| What are the types of endocytosis? | Phagocytosis: "Cell eating" – Engulfing large particles, like bacteria. Pinocytosis: "Cell drinking" – Engulfing extracellular fluid and solutes. Receptor-Mediated Endocytosis: Internalizing specific molecules via receptors (e.g., LDL cholesterol uptake). |
| What is exocytosis? | Constitutive Exocytosis: Continuous release of materials like lipids. Regulated Exocytosis: Triggered by specific signals (e.g., hormone or neurotransmitter release). |
| What are the types of exocytosis? | Water enters the cell, which may cause it to burst (lysis). |
| What happens if a cell is placed in a hypotonic solution? | Water leaves the cell, causing it to shrink (crenation). |
| What happens if active transport is inhibited? | Cells would have difficulty maintaining the correct balance of ions, leading to disrupted homeostasis. |
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samjg
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