To evaluate, give a claim, back it with data, state a limit of that evidence, and end with a judgement. This order of claim, evidence, limit and judgement suits most evaluate questions.
This lesson follows distinguishing applications from limitations and belongs to the genetic technology lessons in SPM Biology.
Worked example: an invented field trial
These are invented values for practice. A modified crop and an ordinary crop were grown in neighbouring plots in one season at one site.
| Measure | Ordinary crop | Modified crop |
|---|---|---|
| Yield (tonnes per hectare) | 3.2 | 4.1 |
| Pesticide sprays applied | 6 | 2 |
Yield change = 4.1 − 3.2 = 0.9 tonnes, and 0.9 ÷ 3.2 × 100 = 28% higher. Sprays fell from 6 to 2, which is 4 fewer.
How do I write the evaluation?
Use four short sentences.
- Claim: the modified crop gave a higher yield with fewer sprays.
- Evidence: yield rose from 3.2 to 4.1 tonnes per hectare, about 28%, and sprays fell from 6 to 2.
- Limit: the data comes from one site and one season, and they show nothing about effects on other organisms.
- Judgement: the benefit looks real in this trial, but more seasons and sites are needed before a firm conclusion.
The mistake that costs marks
The common slip is to list only benefits. A student writes that the crop has a higher yield, uses fewer sprays and is better for farmers, with no figures and no limit.
| Answer | Marks lost |
|---|---|
| “The modified crop is better.” | No evidence, no limit, no judgement |
| “Yield is higher and sprays are lower.” | Benefits only, no figures |
| Correct: claim, figures, a limit and a judgement | Covers all four |
Also avoid absolute words such as always and proves. One trial supports a claim but does not prove it.
Check yourself
Name two extra pieces of evidence that would strengthen the conclusion of the trial above.
Answer
Results from more seasons and from more sites would show whether the higher yield is consistent. Data on the effect on other organisms in and around the plots would address the main risk.
What to study next
Continue with interpreting a genetic-technology diagram and then the practice set. The claim evidence revision desk helps you improve your own written answers.
If you want a teacher to go through your evaluations, see online one-to-one Biology tuition.