Class 10/Specimen Paper
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
BioNotesBioNotesCreated by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Online
ICSE Suggested Specimen Paper Based Preparation Guide
Why is it better to water plants in the morning or evening rather than in the middle of a hot, sunny day?
A plant with broad leaves is likely to transpire more than a plant with needle-like leaves. Explain why.
Odd One Out: Transpiration, Guttation, Bleeding, Photosynthesis.
Scenario: A Ganong's potometer is used to measure the rate of water uptake by a shoot. If the experiment is conducted in a dark, humid room, how would the movement of the air bubble compare to an experiment conducted in a bright, windy room? Explain your reasoning.
Xerophytes: Masters of Water Conservation
Xerophytes are plants adapted to survive in arid environments like deserts, where water is scarce and transpiration rates are potentially very high. Cacti are a prime example. They exhibit a range of adaptations to minimize water loss. Their leaves are reduced to spines, which drastically lowers the surface area for transpiration. Photosynthesis is carried out by their fleshy, green stems, which are covered by a thick, waxy cuticle. Their stomata are often sunken in pits and, in many cases, they use a special type of photosynthesis (CAM) where they only open their stomata at night to take in CO2. This case study perfectly illustrates how plant structure and function can be modified through evolution to overcome the environmental challenge of water scarcity.
Assertion (A): Guttation occurs most readily during the night or early morning. Reason (R): During the night, transpiration is low, and root pressure builds up, forcing water out through hydathodes.
(a) Both (A) and (R) are true and (R) is the correct explanation of (A). (b) Both (A) and (R) are true but (R) is not the correct explanation of (A). (c) (A) is true but (R) is false. (d) (A) is false but (R) is true.
While transpiration is often described as a "necessary evil" because of the significant water loss, it is also vital for the plant's survival. Imagine a hypothetical plant that has completely impermeable leaves and loses no water to transpiration. What would be the major physiological drawback of this adaptation?