Match the values in the table to the problems the environment poses. Then write claim, evidence and reason in that order.
This lesson is part of plant adaptations in SPM Biology. It brings together the three types from the earlier lessons.
What is the claim-evidence-reason frame?
Claim: state the plant type. Evidence: quote at least two values from the table. Reason: explain how each value helps the plant in its environment.
The frame stops you from writing a claim with no support.
Worked example: three plants in one table
An original table:
| Plant | Cuticle thickness (µm) | Stomata per mm² | Air space in leaf (% of volume) | Salt glands |
|---|---|---|---|---|
| P | 12 | 40, in pits | 5 | None |
| Q | 2 | 300, upper surface | 55 | None |
| R | 6 | 120 | 10 | Present |
Plant P. Claim: a xerophyte. Evidence: the cuticle is 12 µm, the thickest, and there are only 40 stomata per mm², in pits. Reason: the thick cuticle reduces evaporation, and stomata in pits trap humid air and reduce water loss.
Plant Q. Claim: a hydrophyte with floating leaves. Evidence: 55% air space and stomata on the upper surface. Reason: air spaces give buoyancy and stomata on the upper surface exchange gases with the air.
Plant R. Claim: a halophyte. Evidence: salt glands are present. Reason: the glands excrete excess salt.
Why is one value not enough?
Plant Q’s thin cuticle (2 µm) alone could fit any plant that does not lose much water. The high air space and the position of stomata together point to floating leaves.
Plant R has a cuticle of 6 µm and 120 stomata, which fit an ordinary land plant. Only the salt glands identify it.
The mistake that weakens the answer
A student writes “Plant P is a xerophyte because it has few stomata” and stops. It gives only one value and no reason.
The improved version adds a second value, the 12 µm cuticle, and explains what each does to water loss.
A self-check question
Plant S has a cuticle of 14 µm, 35 stomata per mm² in pits, leaves that are rolled and a fleshy stem. Write a claim, evidence and reason.
Answer
Claim: S is a xerophyte. Evidence: a thick cuticle of 14 µm, few stomata (35 per mm²) in pits, rolled leaves and a fleshy stem. Reason: the thick cuticle reduces evaporation, pits and rolled leaves trap humid air so less water vapour escapes, and the fleshy stem stores water.
The claim evidence revision desk gives more practice in this frame, and the mistake log tool tracks slips. Then try the practice set.
If table questions keep stalling, SPM Biology one-to-one tuition lets a teacher rehearse the frame on fresh tables.