Question

Why is transpiration is called ‘a necessary evil’?

Answer 1

Transpiration is often called a “necessary evil” because, while it leads to water loss from the plant, it also provides essential benefits that are vital for plant survival and function.

1. It causes around 90% of water loss for the plant.
2. The plant expends energy absorbing and transporting water from the roots, only to lose a large portion through transpiration.
3. However, it is necessary for the plant since it causes a suction force known as transpirational pull.
4. This suction force helps transport water up to larger heights in plants against the force of gravity.
5. It also leads to excessive loss of water, sometimes causing the wilting of leaves.
6. Transpiration has a cooling effect, which prevents the plant from overheating under direct sunlight.
7. It creates a pull that helps transport water and dissolved minerals from the roots to the leaves.
8. Thus, transpiration is a “necessary evil” because, while it can cause potentially harmful water loss, it is vital for nutrient transport, cooling, and maintaining structure, all essential for the plant's overall health and survival.