Science (086) — CBSE Class 10 board question

Transpiration is called a "necessary evil" because:

1. Evil (harmful): Plants lose large amounts of water through stomata during transpiration, which can cause wilting and water stress, especially in dry conditions.

1. Necessary (useful): It creates a suction pull that helps in the upward transport of water and minerals from roots to leaves through xylem. It also helps in cooling the plant.

The phrase "necessary evil" means something harmful but unavoidable because it also brings benefits. Examiners expect one reason why it is harmful and one reason why it is beneficial. The key benefit is the transpiration pull driving water transport through xylem. Note: this topic is from Chapter 6 (Life Processes — Transport in Plants), which is in your syllabus even though the provided passages don't explicitly cover transpiration; these are standard NCERT-expected points.