Introduction
Deforestation is a common topic in PSLE Science, especially in questions related to photosynthesis, gases in the environment, and human impact on nature.
In this question, students are tested on whether they understand what happens when trees are cut down or burnt.
The Question
What is one effect of deforestation?
Options included:
- More types of plants and animals
- Increase in carbon dioxide
- Increase in oxygen
- Lower temperature
Step-by-Step Explanation (Following Teacher’s Working)
1. Trees are cut down or burnt
The teacher highlights:
- “trees cut off”
- “burnt”
When trees are destroyed, there are fewer plants available.
2. Fewer trees for photosynthesis
The teacher writes:
- “fewer trees for photosynthesis”
Since photosynthesis removes carbon dioxide, fewer trees means…
3. Less carbon dioxide is removed from the air
With fewer plants absorbing carbon dioxide, the gas remains in the atmosphere.
4. Burning trees releases more carbon dioxide
Burning produces carbon dioxide, further increasing its amount.
✅ Final Answer
(2) Increase in carbon dioxide
Key Concepts
| Concept | Why It Matters |
| Photosynthesis | Removes carbon dioxide and releases oxygen |
| Deforestation | Reduces the number of plants that carry out photosynthesis |
| Burning of trees | Produces carbon dioxide |
| Environmental impact | Affects climate and living organisms |
Tips for Students
✔ Link deforestation to photosynthesis.
✔ Remember: Less photosynthesis = more carbon dioxide.
✔ Burning trees also adds carbon dioxide.
✔ Eliminate wrong options using logic (e.g., fewer trees ≠ more oxygen).
For Parents
This question tests foundational understanding of:
- Environmental science
- Photosynthesis
- Human impact on ecosystems
Students often memorise without understanding. We focus on concept-based learning so that children can apply knowledge confidently in real PSLE scenarios.