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memb. struct. permea
bio exam 2-chapter 7 membrane structure selective permeability
| Question | Answer |
|---|---|
| What is selective permeability? | A property of cell membranes that allows them to regulate the passage of substances. |
| What molecules can pass freely through the cell membrane? | Small nonpolar molecules and small uncharged polar molecules |
| What molecules cannot pass freely through the cell membrane? | Large polar molecules, ions, large molecules |
| Why is the membrane being selectively permeable in relation to the molecules that make it up | Primarily because of composition and structure, phospholipid bilayer, proteins, cholesterol, and carbohydrates |
| What are differences between active transport and passive transport? | Active transport requires energy to move substances against their concentration gradient, while passive transport does not require energy and moves substances down their concentration gradient. |
| What are three examples of passive transport? | Diffusion (or simple diffusion), osmosis, and facilitated diffusion |
| What does diffusion mean? | The process in which molecules move from higher concentration to lower concentration, driven by kinetic energy, until they are evenly distributed |
| What are substances that can freely diffuse through the cell membrane by simple diffusion? | Oxygen, carbon dioxide, water, ethanol, fat-soluble vitamins (A, D, E, K) |
| What is the relationship between the diffusion of different substances across a membrane? | Influenced by their concentration gradients, size, polarity, and the presence of specific transport proteins |
| What is osmosis? | The process in which water molecules move through a semipermeable membrane from an area of lower to higher solute concentration, aiming to equalize the concentrations of both sides of the membrane |
| What molecule moves through a selectively permeable membrane? | Water molecules |
| What molecule does not generally move through a selectively permeable membrane? | Solute molecules (salts, sugars, proteins) |
| What three terms describe a solution's tonicity? | Hypertonic, hypotonic, isotonic |
| What kind of movement does isotonic solutions have? | They move water in and out of the cell at equal rates, resulting in no net change in the cell's volume |
| What kind of movement does hypertonic solutions have? | They move water out of the cell, causing it to lose water and shrink |
| What kind of movement does hypotonic solutions have | They move water into the cell, causing it to swell and burst |
| How do single celled freshwater organisms have adapted to living in their hypotonic environment? | Single-celled freshwater organisms use contractile vacuoles to expel excess water, preventing them from swelling and bursting in their hypotonic environment. |
| What is facilitated diffusion? | The passive movement of molecules across a cell membrane through specific transport proteins, without the use of energy. |
| What is the difference between facilitated diffusion and simple diffusion? | Simple diffusion involves molecules moving directly through the cell membrane without assistance, facilitated diffusion requires transport proteins to help move molecules across the membrane. |
| What are examples of substances that diffuse across the membrane via facilitated diffusion? | Glucose, amino acids, and ions like chloride and bicarbonate |
Created by:
josie_d
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