中文（繁體）
中文（简体）
English
S1 Science: Microscope Skills and Cell Observation (Paper 1: basics)
← Back to the Secondary Science chapter index
S1 Science: Microscope Skills and Cell Observation (Paper 1: basics)
This first paper drills three lines only: multiply the magnifications, convert between millimetres and micrometres, and divide image size by magnification to get real size. Master these before attempting the reverse questions.
Direct answers Write both magnifications beside every question; once that becomes a habit you will not drop a factor in the exam.
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)
- FoundationHow is the total magnification of a microscope calculated?
- FoundationThe eyepiece is 10x and the objective is 40x. What is the total magnification?
- FoundationHow many micrometres are there in 1 mm?
- IntermediateWith a 15x eyepiece and a 10x objective, what is the total magnification for a 0.2 mm specimen?
- IntermediateAt 400x an image of a cell measures 40 mm across. What is the real diameter of the cell?
- IntermediateWhich three structures are found in plant cells but not in animal cells?
- ChallengeAt low power the field diameter is 2 mm. Switching to a high power lens of four times that magnification, what is the new field diameter?
- ChallengeThe image sits at the upper right of the field. Which way should the slide be moved to bring it to the centre?
- ChallengeEight similar onion epidermal cells lie in a row across a field 1.6 mm wide. What is the average width of one cell in micrometres?
- Error redoWhat is wrong with saying total magnification is the eyepiece plus the objective? Use 10x and 40x.
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | Total magnification = eyepiece magnification x objective magnification. | Each lens magnifies once, so the image is magnified twice and the two values are multiplied, not added. |
| 2 | 400x | 10 x 40 = 400, written as 400 times. |
| 3 | 1 000 micrometres | 1 mm = 1 000 micrometres, so multiply by a thousand when going from mm to micrometres. |
| 4 | 150x | 15 x 10 = 150; magnification depends only on the two lenses, not on specimen length. |
| 5 | 0.1 mm, which is 100 micrometres | Real size = image size / total magnification = 40 / 400 = 0.1 mm, and 0.1 mm is 100 micrometres. |
| 6 | A cell wall, chloroplasts and a large vacuole. | Animal cells have a cell membrane only: no cell wall, no chloroplasts and no large vacuole. |
| 7 | 0.5 mm | Field diameter is inversely proportional to magnification, so 2 / 4 = 0.5 mm. |
| 8 | Towards the upper right. | The microscope image is inverted in both directions, so the slide is pushed towards the side where the image appears. |
| 9 | 200 micrometres | 1.6 / 8 = 0.2 mm and 0.2 x 1 000 = 200 micrometres. |
| 10 | Adding gives only 50x; the correct total is 10 x 40 = 400x. | The image is magnified twice in succession, so the values multiply; adding badly underestimates the magnification. |
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.
Three basics: total magnification is eyepiece times objective, 1 mm equals 1 000 micrometres, and real cell size is image size divided by total magnification. Write both magnifications first, then 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.