Year 7 Science · Unit 1 · Lesson 7
Apply Worksheet
Learning Goals
Match each part to its job
Write the letter of the correct job next to each part. Each letter is used once.
| Part | Letter | Job |
|---|---|---|
| Cell wall | A. Absorbs sunlight and makes glucose | |
| Plasma membrane | B. Rigid cellulose layer that holds the cell’s shape | |
| Nucleus | C. Stores water and keeps the cell plump | |
| Chloroplast | D. Releases energy from glucose (respiration) | |
| Large vacuole | E. Thin layer that controls what enters and leaves | |
| Mitochondria | F. Control centre that stores DNA |
1. What is chlorophyll, and in which part of the cell is it found?
Order the steps
Number the steps from 1 to 6 to show how to prepare and view an onion-skin slide. 1 = what you do first.
| Step number | Step |
|---|---|
| Look through the microscope on the lowest magnification (×40) and find a clear area of cells. | |
| Lay the onion skin flat on a glass slide. | |
| Gently lower a coverslip onto the stained onion skin, avoiding air bubbles. | |
| Switch to a higher magnification to see the nucleus and cell wall more clearly. | |
| Peel a thin, see-through layer from the inside of an onion. | |
| Add one drop of iodine solution to stain the onion skin. |
Cause and effect
Complete the chain for a leaf cell in sunlight. Each box explains what happens next.
Read the data
Scenario: the drooping basil
A basil plant on a hot windowsill has drooped. A student waters it and measures the height of its top leaf above the soil every few minutes.
| Time after watering (min) | 0 | 5 | 10 | 15 | 20 | 30 |
|---|---|---|---|---|---|---|
| Height of top leaf (cm) | 9 | 11 | 15 | 19 | 21 | 21 |
Source: sample class results.
2. Plot the data from Table 1 as a line graph. Label both axes with units.
3. Describe the trend. After about how many minutes was the plant fully upright again?
4. The drooping plant had not lost a single cell wall. Use the vacuole and the cell wall to explain why it drooped, and why watering made it stand up again.
5. A student says: “Plant cells don’t need mitochondria because they have chloroplasts to make energy.” Do you agree or disagree? Use evidence from the lesson to support your answer.
Match each part to its job
Cell wall → B; Plasma membrane → E; Nucleus → F; Chloroplast → A; Large vacuole → C; Mitochondria → D.
Question 1
The green pigment that absorbs sunlight (1), found inside chloroplasts (1). [2 marks]
Order the steps
Reading down the table as printed, the correct step numbers are 5, 2, 4, 6, 1, 3. In order: peel a thin layer of onion; lay it flat on a slide; add iodine; lower a coverslip; view at ×40; switch to higher magnification.
Cause and effect
Box 2: chlorophyll in the chloroplasts absorbs the light (1). Box 3: the chloroplast turns carbon dioxide and water into glucose (1). [2 marks]
Question 2
Axes: time (min) and height (cm), with units (1); even scales (1); six points plotted and joined (1). [3 marks]
Question 3
Rises quickly from 9 cm to 21 cm, then levels off (1). Upright after about 20 minutes (1). [2 marks]
Question 4
Short of water, the vacuoles shrank, so nothing pushed on the walls and the cells went soft (1). The walls stayed just as strong but need something pressing on them (1). Watering refilled the vacuoles, which pressed on the walls, so the cells became firm (turgid) (1). [3 marks]
Question 5
Marking guide: 1 position (disagree); 1 chloroplasts make glucose; 1 mitochondria release energy from glucose (respiration); 1 different jobs, so one cannot replace the other; 1 a cell with no chloroplasts that needs energy (root); 1 conclusion: both. [6 marks]
Model answer: I disagree. Chloroplasts make glucose; mitochondria release its energy by respiration. Root cells have no chloroplasts but still need energy from their mitochondria. So plant cells have both.
Common error: thinking chloroplasts “make energy”. They make glucose; mitochondria release its energy.