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S1 Science: Plants and Photosynthesis (Paper 2 (intermediate))
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Tutor Prep Guide · Photosynthesis inputs and outputs, leaf structure, stomata and transpiration, and the iodine starch test
S1 Science: Plants and Photosynthesis (Paper 2 (intermediate))
This paper links leaf structure with stomata and transpiration, and gives the reason for every step of the iodine test.
Direct answers Root hairs absorb water, the xylem carries it upward and stomata control water vapour, which is the main line of transport and transpiration.
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: Plants and Photosynthesis |
| Level | S1 |
02 Questions (10 items)
- FoundationWhat is the main function of root hairs?
- FoundationWhich tissue carries water and minerals, and in which direction?
- FoundationWhich cells control the opening and closing of stomata?
- IntermediateWhich layer of a leaf cross section holds the most chloroplasts?
- IntermediatePart of a leaf is covered with black paper, the leaf is lit for hours and then tested with iodine. What colour is the covered part and what does it show?
- IntermediateWhy is the leaf boiled in alcohol over a water bath before the starch test?
- ChallengeA plant releases 8 cm3 of oxygen each hour. How much in 3.5 hours?
- ChallengeA leaf area of 40 cm2 releases 2 cm3 per 10 cm2 each hour. How much in 5 hours?
- ChallengeWhere does the water lost in transpiration leave the plant, and what is the benefit?
- Error redoA student sees the blue black colour and answers that glucose is present. What is the correct answer?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | To increase surface area so that water and minerals are absorbed faster | Root hairs are long and thin, which greatly increases the absorbing surface. |
| 2 | The xylem, upward from the root to the stem and leaves | Xylem vessels run from the root right up into the leaf veins. |
| 3 | The guard cells | Guard cells swell when they take in water and the stoma opens, then close as they lose water. |
| 4 | The palisade layer, the tightly packed cells just below the upper epidermis | The palisade layer sits near the upper surface and is packed with chloroplasts. |
| 5 | It stays brownish yellow, showing that no starch is made without light | Only the lit part turns blue black, which proves that light is needed. |
| 6 | To remove chlorophyll so that the colour change with iodine can be seen clearly | Alcohol dissolves chlorophyll, and the blue black colour only shows once the leaf is pale. |
| 7 | 28 cm3 | Multiplying 8 by 3.5 gives 28 cm3. |
| 8 | 40 cm3 | Each hour gives 8 cm3, and five hours give 40 cm3. |
| 9 | Mainly through the stomata as water vapour, which pulls water up from the root and cools the leaf | Transpiration creates the pull that draws water from the root to the leaf. |
| 10 | It shows that starch is present in the leaf | Iodine tests for starch, not glucose, and this is a very common lost mark. |
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.
For photosynthesis questions ask three things: whether all inputs are present (light, carbon dioxide, water), what the outputs are, and which condition the experiment changed.Tutor Registration →
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