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S1 Science: Microscope Skills and Cell Observation (Paper 3: challenge)
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S1 Science: Microscope Skills and Cell Observation (Paper 3: challenge)
This paper is all reverse work and comparison: magnification from image and real size, real area from image dimensions, and real size compared between two cells. Convert units first, then write one equation.
Direct answers Write either image / magnification = real, or image / real = magnification, before touching the numbers; choosing the right direction prevents upside-down work.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S1 Science: Microscope Skills and Cell Observation |
| Level | S1 Science |
02 Questions (10 items)
- FoundationWith a 10x eyepiece and 4x, 10x and 40x objectives, what are the three total magnifications?
- FoundationWhat are the three basic rules of a biological drawing?
- FoundationWhat is the core of the cell theory?
- IntermediateA cell is 0.15 mm long. What total magnification makes its image 60 mm long?
- IntermediateA cell image is 45 mm long while the cell is really 75 micrometres. What is the total magnification?
- IntermediateAt 400x a rectangular cell image is 24 mm by 16 mm. What is the real area in square micrometres?
- ChallengeAt 400x the field diameter is 0.5 mm and cells average 25 micrometres across. How many cells fit across the diameter?
- ChallengeAn onion epidermal cell image is 30 mm at 400x, while a cheek cell is really 60 micrometres long. Which is larger in reality?
- ChallengeTotal magnification drops from 400x to 100x. By what factor does the image area of the same specimen change?
- Error redoWhat is wrong with saying a higher magnification gives a bigger, clearer field?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 40x, 100x and 400x | 10 x 4 = 40, 10 x 10 = 100 and 10 x 40 = 400. |
| 2 | Use a pencil, keep outlines clean with no shading, and add parallel label lines with the magnification written beside the drawing. | A drawing records what was seen, so accuracy of outline, proportion and labelling matters more than neatness. |
| 3 | All living things are made of cells, and the cell is the basic unit of life. | That is why observing cells means observing the most basic unit of life, and why the microscope matters so much in biology. |
| 4 | 400x | 60 / 0.15 = 400, since magnification is image size divided by real size. |
| 5 | 600x | 75 micrometres = 0.075 mm and 45 / 0.075 = 600. |
| 6 | 2 400 square micrometres | 24 / 400 = 0.06 mm (60 micrometres) and 16 / 400 = 0.04 mm (40 micrometres), so 60 x 40 = 2 400 square micrometres. |
| 7 | 20 cells | 0.5 mm = 500 micrometres and 500 / 25 = 20. |
| 8 | The onion cell, at 75 micrometres, which is 15 micrometres longer. | 30 / 400 = 0.075 mm = 75 micrometres, and 75 – 60 = 15 micrometres. |
| 9 | 16 times larger | Magnification becomes one quarter, so area becomes one sixteenth of the old value, that is 16 times larger than before. |
| 10 | A higher magnification gives a smaller and darker field, and resolution is limited by the lenses, so beyond that point the image only blurs. | Magnification and resolution are different things: past the limit of the lenses, enlarging only enlarges the blur. |
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.
Challenge questions usually work backwards: find magnification from image and real size, or compare two cells through their images. Put both sides in the same unit first, then cross multiply.Tutor Registration →
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.