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IB Biology: Cells and Membrane Transport – Practice Paper 2 (10 Questions)
IB Biology: Cells and Membrane Transport – Practice Paper 2 (10 Questions)
Paper two compares the four transport routes of simple diffusion, facilitated diffusion, osmosis and active transport, converts image sizes with magnification, explains carrier saturation and plasmolysis, then covers endocytosis and haemolysis.
Quick answer Total magnification is eyepiece times objective, and actual size is image size divided by that total.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 questions |
| Suggested time | 25 minutes |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: IB Biology: Cells and Membrane Transport – Tutor Lesson Plan |
| Level | IB SL |
02 Questions (10 items)
- FoundationHow does simple diffusion differ from facilitated diffusion?
- FoundationDefine osmosis.
- FoundationState three features of active transport.
- FoundationWhat happens to a red blood cell placed in pure water, and why?
- IntermediateWith a ten times eyepiece and a forty times objective, a cell measures eight millimetres in the image. What is its actual length?
- IntermediateA cell is fifty micrometres long. How long is its image at four hundred times magnification, in millimetres?
- IntermediateWhy does the rate of facilitated diffusion level off at high concentration?
- ChallengeOnion epidermal cells are placed in one molar sucrose solution and in pure water. What happens in each case?
- ChallengeWhy do large molecules such as proteins enter by endocytosis rather than diffusion?
- Error redoA student writes that active transport moves substances from high to low concentration. What is wrong?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | facilitated diffusion needs membrane proteins while simple diffusion passes the bilayer; both run down the gradient without ATP | Size and charge decide which route is open, so large or charged particles need proteins. |
| 2 | water crossing a partially permeable membrane from higher to lower water potential | Only water moves, and the direction follows the water potential gradient. |
| 3 | it moves against the gradient, needs ATP and needs carrier proteins | Energy changes the carrier shape so particles are pumped from low to high concentration. |
| 4 | water enters and the cell bursts, which is haemolysis | Pure water has the highest water potential and an animal cell has no wall to resist entry. |
| 5 | twenty micrometres | Total magnification is four hundred, so eight thousand micrometres divide to twenty. |
| 6 | twenty millimetres | Fifty micrometres times four hundred is twenty thousand micrometres, or twenty millimetres. |
| 7 | the number of carrier proteins is limited, so they become saturated | As with enzymes, extra substrate cannot raise the rate once carriers are full. |
| 8 | in sucrose they lose water and plasmolyse; in pure water they swell but the wall prevents bursting | The sucrose solution has the lower water potential, while in pure water the wall provides support. |
| 9 | they are far too large for membrane channels, so the membrane engulfs them in a vesicle | Endocytosis needs ATP to reshape the membrane, so it is an active process. |
| 10 | active transport works against the gradient, from low to high, and uses ATP | Downhill movement is passive and needs no energy. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.
