CAPF AC 2021 Q7: Science & Technology – Biology
Which one of the following plant tissues has large air spaces?
- (a) Sclerenchyma
- (b) Meristem
- (c) Collenchyma
- (d) Aerenchyma
Answer: (d) Aerenchyma
Explanation
Plant tissue with large air spaces
How to think: the name gives it away.
Aer means air.
Aerenchyma is the tissue with air cavities.
What it is: a type of parenchyma found in aquatic plants such as lotus and water hyacinth.
Its large air cavities help the plant float (buoyancy) and carry oxygen to the submerged parts.
| Tissue | Cells | Spaces between cells | Job |
|---|---|---|---|
| Meristem | Living, dividing | None | Growth |
| Parenchyma | Living, thin walls | Present | Storage |
| Aerenchyma | Living, thin walls | Large air cavities | Buoyancy in water plants |
| Collenchyma | Living, thick at the corners | Very little | Flexibility |
| Sclerenchyma | Dead, thick lignin walls | None | Strength and hardness |
Answer: (d) Aerenchyma.
Why each option is right or wrong
- (a) Incorrect. Sclerenchyma has dead cells with thick lignin walls and no spaces between them.
- (b) Incorrect. Meristem cells are tightly packed dividing cells with no spaces between them.
- (c) Incorrect. Collenchyma has very little space between cells; it gives flexibility.
- (d) CORRECT. Aerenchyma is parenchyma with large air cavities, found in aquatic plants.
Key point
Aerenchyma = parenchyma with large air cavities, in aquatic plants, gives buoyancy. Chlorenchyma = parenchyma with chlorophyll, does photosynthesis.
Remember
Aerenchyma: air cavities, aquatic plants, floating.
Common mistakes
- Confusing aerenchyma with chlorenchyma, the parenchyma that has chlorophyll.
- Choosing collenchyma, which has very little intercellular space.
- Forgetting that aerenchyma is only a special kind of parenchyma.
Exam tip
Educated guess: look for the word root. Aer means air, as in aeroplane and aerobic.
Sources
- NCERT Class IX Science — Tissues (plant tissues)
- NCERT Exemplar Class IX Science — Tissues