Questions and Answers
What is the main factor that affects the rate of diffusion?
Facilitated diffusion requires energy to move substances across the cell membrane.
False
What is the term for the movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane?
osmosis
The cell membrane is partially _______________.
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What happens to an animal cell when it is placed in a dilute solution?
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Active transport requires energy to move substances against their concentration gradient.
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Match the following types of diffusion with their descriptions:
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What is the term for the measure of the tendency of water to move from one place to another?
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What happens to a cell placed in a solution with higher water potential than its cytoplasm?
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When a plant cell is placed in a concentrated sugar solution, it becomes turgid.
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What is the term for the process of water entering a plant cell, causing it to swell?
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When a cell is placed in a solution with lower water potential than its cytoplasm, it undergoes ______________________.
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Match the following solutions with the effect on a cell:
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Study Notes
Diffusion
- Movement of particles from a region of higher concentration to a region of lower concentration
- Factors affecting diffusion:
- Concentration gradient
- Temperature
- Surface area
- Distance
- Types of diffusion:
- Simple diffusion: movement through a partially permeable membrane without assistance
- Facilitated diffusion: movement via protein channels or carriers in the membrane
- Examples in living organisms:
- Gas exchange in the lungs and tissues
- Nutrient absorption in the intestines
Osmosis
- Movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane
- Water potential: measure of the tendency of water to move from one place to another
- Key concepts:
- Higher water potential (dilute solution) vs. lower water potential (concentrated solution)
- Effects on cells:
- Animal cells:
- In a dilute solution: cell swells and may burst (lysis)
- In a concentrated solution: cell shrinks (crenation)
- Plant cells:
- In a dilute solution: cell becomes turgid
- In a concentrated solution: cell undergoes plasmolysis
- Animal cells:
Transport Across Cell Membrane
- Methods:
- Passive transport: diffusion, facilitated diffusion, osmosis
- Active transport: requires energy (ATP) to move substances against their concentration gradient
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Description
Understand the concept of diffusion, its factors, types and examples in living organisms. Test your knowledge on simple and facilitated diffusion, concentration gradients and more.