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How does the phospholipid bilayer facilitate diffusion?
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The phospholipid bilayer has polar heads and non-polar tails, allowing substances to move through the membrane following the concentration gradient.
How do membrane pumps differ from basic diffusion mechanisms?
Membrane pumps, such as the sodium-potassium pump, actively move ions against their concentration gradients using energy.
What defines active transport, and why is ATP necessary?
Active transport moves substances against their concentration gradient, from low to high concentration, which requires energy in the form of ATP.
Explain the role of carrier proteins in facilitated diffusion using glucose as an example.
Carrier proteins assist glucose in moving from an area of high concentration to an area of low concentration without energy usage.
Why does facilitated diffusion not require ATP?
Because facilitated diffusion moves substances down their concentration gradient, which does not require energy input.
What is the primary difference between diffusion and facilitated diffusion?
Diffusion does not require assistance, while facilitated diffusion uses channel or carrier proteins to aid the movement of substances.
What are the different types of endocytosis?
Phagocytosis (engulfing solids), pinocytosis (engulfing liquids), and receptor-mediated endocytosis (specific molecules captured by receptors).
In what way does the concentration gradient influence diffusion?
Diffusion allows movement from areas of high concentration to low concentration without energy expenditure.
What structural feature of phospholipids allows for membrane functionality in diffusion?
The phospholipids have hydrophilic polar heads and hydrophobic non-polar tails, which allow diffusion through the membrane.
What are the key processes that cells use to maintain homeostasis?
Diffusion, facilitated diffusion, and active transport.
Describe the function of the sodium-potassium pump in active transport.
The sodium-potassium pump moves Na+ and K+ ions against their concentration gradients with the use of ATP by changing protein shape via phosphate group attachment and detachment.
How do materials move against a concentration gradient during active transport?
With the use of ATP to provide energy, materials are moved from low to high concentration.
How does exocytosis help expel materials from the cell?
Exocytosis involves vesicles merging with the cell membrane to release contents outside the cell.
How does pinocytosis differ from phagocytosis?
Pinocytosis involves engulfing liquid particles, whereas phagocytosis involves engulfing solid particles.
What is an example of a substance transported through receptor-mediated endocytosis?
Specific molecules that are captured by receptor proteins and then taken into the cell.
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