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Questions and Answers
Homeostasis is maintained by the cell ______ controlling the movement of things in and out of the cell.
Homeostasis is maintained by the cell ______ controlling the movement of things in and out of the cell.
membrane
Passive Transport requires no extra ______ by the cell because molecules move from high concentration to low concentration.
Passive Transport requires no extra ______ by the cell because molecules move from high concentration to low concentration.
energy
The process of spreading out molecules across a membrane until ______ is reached.
The process of spreading out molecules across a membrane until ______ is reached.
equilibrium
Active Transport requires extra energy (ATP) to move materials from ______ to high concentration against the concentration gradient.
Active Transport requires extra energy (ATP) to move materials from ______ to high concentration against the concentration gradient.
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A ______ is a uniform mixture of two or more substances.
A ______ is a uniform mixture of two or more substances.
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Facilitated diffusion involves a transport ______ that helps molecules pass through the cell membrane.
Facilitated diffusion involves a transport ______ that helps molecules pass through the cell membrane.
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Things that are small, nonpolar, and hydrophobic can easily pass through the cell ______.
Things that are small, nonpolar, and hydrophobic can easily pass through the cell ______.
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Examples of molecules that use facilitated diffusion include ______ and polar molecules like calcium.
Examples of molecules that use facilitated diffusion include ______ and polar molecules like calcium.
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The simple diffusion of water across the cell membrane is known as ______.
The simple diffusion of water across the cell membrane is known as ______.
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Low water concentration means ______ solute concentration.
Low water concentration means ______ solute concentration.
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Study Notes
Cell Transport Concept 2 Notes
- Cell transport is essential for maintaining homeostasis at the cellular level.
- The cell membrane controls what enters and exits the cell.
- The membrane is selectively permeable, meaning it is picky about what passes through.
- Small, nonpolar molecules and water can easily pass through.
- Polar molecules and larger molecules cannot easily pass through.
- Transport of materials across the membrane is either passive or active.
Passive Transport
- Passive transport does not require energy input.
- Molecules move from an area of high concentration to an area of low concentration (down the concentration gradient).
- Includes simple diffusion, facilitated diffusion, and osmosis.
Simple Diffusion
- The movement of small, nonpolar molecules across a membrane.
- Example: Oxygen (O2) and carbon dioxide (CO2).
- Molecules move to equalize concentration across the membrane until equilibrium is reached.
Facilitated Diffusion
- The movement of large molecules or polar molecules with the assistance of protein channels.
- Examples: Glucose (sugar = C6H12O6).
- Larger or polar substances cannot easily pass through the membrane, but proteins aid the movement.
Osmosis
- The diffusion of water across a membrane.
- Water moves from a high water concentration to a low water concentration.
- Water concentration is inversely related to solute concentration. High water means low solute; low water means high solute.
- The movement of water affects the shape and function of cells.
- Solutions can be hypertonic (lower water concentration than the cell), hypotonic (higher water concentration than the cell), or isotonic (equal water concentration to the cell).
- In hypertonic solutions, water moves out of the cell, causing the cell to shrivel.
- In hypotonic solutions, water moves into the cell, causing the cell to swell.
- In isotonic solutions, water movement is balanced, and the cell shape remains unchanged.
Active Transport
- Active transport requires energy input (ATP).
- Molecules move against the concentration gradient (from low to high concentration).
- Includes molecular pumps, exocytosis, and endocytosis.
Molecular Pumps
- Use energy to move molecules across the membrane.
- Examples: Potassium (K+), chlorine (Cl-), and sodium (Na+) ions.
- These ions are usually charged particles.
Exocytosis
- Exporting materials out of a cell.
- Example: Neurotransmitters released by nerve cells.
Endocytosis
- Importing large particles into a cell.
- Example: White blood cells engulfing bacteria.
Additional Information
- Solute is what gets dissolved. A good example is lemonade powder.
- Solvent is what dissolves. A good example is water.
- Solution is a mixture of both.
- Concentration is the amount of solute dissolved in the solvent and indicated by [ ].
- Cells use cell transport to maintain homeostasis.
Classroom Assignments & Activities
- Take cell tests and define terms from section 8.3.
- Complete assignments and activities related to cell transport over several days and weeks that include flashcards, reading, lab work and graphic organizers.
- Work on provided reading guides with related class time.
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Description
Explore the principles of cell transport and membrane dynamics essential for cellular homeostasis. This quiz covers passive transport mechanisms such as simple diffusion and facilitated diffusion, alongside energy-independent movement of molecules. Test your understanding of how substances move in and out of cells.
