Year 8 Science · Unit 1 · Lesson 17
Apply Worksheet
Learning Goals
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
1. Copying the numbers from a table is the same as interpreting them.
Correct it:
2. A labelled diagram is decoration only, so it cannot be used as evidence.
Correct it:
3. A case study can show what happens to a whole living system when one part is disrupted.
Correct it:
4. Interpreting evidence means adding facts that are not in the data, to make the answer sound better.
Correct it:
5. A statement said very confidently counts as scientific evidence.
Correct it:
Classify and give a reason
Is each piece of evidence a table, a diagram or a case study? Then say what it would help you explain.
| Evidence | Table, diagram or case study? | What it would help explain |
|---|---|---|
| A report on one farmer’s orange trees, which dropped their fruit after their roots sat in floodwater for a week | ||
| The resting pulse of 30 students, listed with how many hours of sport each plays a week | ||
| A drawing of a leaf cut in half, with the stomata, xylem and phloem labelled |
Cause and effect: aphids on a rose bush
Case study: a gardener’s rose bush
Aphids are tiny insects. They push their mouthparts into the phloem of young stems and suck out the sugary sap. A rose bush covered in aphids for several weeks grew very few new shoots, and its flower buds stayed small.
1. Name the structure in this case study, and state its role in a healthy plant.
Complete the chain. Each box is caused by the box before it.
Read the data
Investigation: sealing leaf surfaces
A class picked four similar leaves from one plant. They spread petroleum jelly on some leaf surfaces. The jelly forms a seal that water vapour cannot pass through. They weighed each leaf, hung all four in the same room for three days, then weighed them again. Any mass lost is water that escaped from the leaf.
| Leaf | Surface covered in jelly | Mass at start (g) | Mass after 3 days (g) | Mass lost (g) |
|---|---|---|---|---|
| A | neither | 4.2 | 2.8 | 1.4 |
| B | upper surface only | 4.0 | 2.8 | |
| C | lower surface only | 4.1 | 3.8 | |
| D | both surfaces | 4.3 | 4.2 | 0.1 |
Source: sample class results.
2. Complete the last column for leaves B and C. Then calculate leaf C’s water loss as a percentage of leaf A’s water loss.
Answer %
3. Sort these three statements about Table 1. Label each one copies, interprets or goes beyond the evidence, and explain your label for the last one.
(a) “All plants have stomata only on the lower surface of their leaves.”
(b) “Leaf C lost 0.3 g.”
(c) “Sealing the lower surface cut water loss far more than sealing the upper surface.”
4. Answer the question “Through which surface does this leaf lose most of its water?” Write a claim, use evidence from at least three leaves in Table 1, and explain the result by naming the leaf structure involved and what it does.
True or false
1. False: copying repeats the numbers; interpreting explains what they suggest about the living system. 2. False: diagrams show structures and labels that help explain role and function. 3. True. 4. False: interpreting means explaining what the evidence suggests, without making up facts that are not in it. 5. False: evidence must come from data, diagrams or case studies that can be observed and checked.
Classify and give a reason
Orange trees: case study; the effect of one disruption (waterlogged roots) on the whole plant. Pulse and sport: table; a pattern or comparison between sport and resting pulse. Leaf drawing: diagram; where structures are and what their roles are.
Cause and effect: aphids on a rose bush
1. Phloem. It carries sugar (food made in the leaves) to other parts of the plant, such as growing shoots, buds and roots. [2 marks]
Box 2: less sugar (food) is carried from the leaves to the growing shoots and buds. Box 3: cells in the new shoots and buds get too little food to grow.
Read the data
2. B: 4.0 − 2.8 = 1.2 g. C: 4.1 − 3.8 = 0.3 g. 0.3 ÷ 1.4 × 100 = 21% (about one fifth). [3 marks: 1 each loss, 1 percentage]
3. (a) goes beyond the evidence: only one kind of plant was tested and stomata were not looked at, and B still lost some water. (b) copies. (c) interprets. [3 marks: 1 labels, 2 explanation]
Show What You Know
4. Marking guide: 1 claim; 2 evidence (numbers compared across at least three leaves); 1 reasoning names stomata and their role (pores that let water vapour and gases in and out); 1 effect linked and stays within the evidence. Model answer: This leaf loses most of its water through its lower surface. Sealing the lower surface (C) cut the loss from 1.4 g to 0.3 g, but sealing only the upper surface (B) barely changed it (1.2 g). Water escapes through stomata, the pores in the leaf surface, so the lower surface probably has more stomata. Sealing them stops water vapour escaping, so the leaf loses less mass. This was one test on one kind of plant. [5 marks]
Common error to watch for: reading “upper surface only” as the surface that was left open. The jelly is on the surface named, so leaf B could still lose water through its lower surface.