How it works
This plasma membrane worksheet has 36 questions: phospholipids, cholesterol and proteins in the fluid mosaic model, diffusion and osmosis with cells in hypotonic, isotonic and hypertonic solutions, and pumps, endocytosis and exocytosis.
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Three sets
Membrane structure covers the bilayer, cholesterol, proteins and carbohydrates. Diffusion and osmosis asks which way water moves and what happens to red blood cells and plant cells. Active and bulk transport covers ATP pumps, co-transport and moving big things.
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Practice brings a missed question back until you get it right. The sheet on screen is what prints: remove a question, add more up to all 36, and tick With answer key.
- In osmosis, water moves towards the side with more dissolved solute.
- Hypotonic outside: the cell swells. Hypertonic outside: it shrinks.
- Down the gradient is passive; up the gradient needs energy, usually from ATP.
Questions and answers
What is the plasma membrane made of?
A double layer of phospholipids with hydrophilic heads facing out and hydrophobic tails inside, plus cholesterol, proteins that carry, channel or receive, and carbohydrate chains on the outer surface.
What is the difference between hypotonic and hypertonic?
A hypotonic solution has fewer solutes than the cell, so water moves in. A hypertonic solution has more, so water moves out. In an isotonic solution there is no net movement.
What is the difference between active and passive transport?
Passive transport (diffusion, osmosis, facilitated diffusion) moves substances down their concentration gradient with no energy from the cell. Active transport moves them against it and needs energy, usually ATP.