Biology
Name the factors that affect the rate of transpiration. State their role in each case.
Answer
The following main factors affect the rate of transpiration —
- Sunlight — During daytime, the rate of transpiration is faster. This is because the stomata remain open to allow the inward diffusion of carbon dioxide for photosynthesis. During night time, the stomata are closed, and hence transpiration hardly occurs.
- Temperature — Plants transpire more rapidly at higher temperatures because water evaporates more rapidly as the temperature rises.
- Humidity — Transpiration is reduced if the air is humid. Air cannot hold any water molecules when it is already laden with moisture (humidity).
- Wind — Transpiration is more when the wind is blowing faster as water vapour moves away faster from the surface of leaves.
Related Questions
Briefly explain, how transpiration helps in the upward conduction of water in plants?
How does temperature, light intensity and wind affect transpiration?
Draw a magnified view of the root hair and label all its parts neatly. From the parts labelled by you, name the parts matching the description given below:
(a) Outermost layer of the root
(b) Unicellular outgrowth
(c) Part that is freely permeable
(d) Part that is semi-permeable
After playing outside on a hot sunny afternoon, Aarav came home sweating and drank a lot of water. Later in the evening, he noticed that the plant on his study table looked dull and droopy. Wondering if plants also "get hot" in summer, he asked his mother what was wrong. She told him that just like humans sweat to cool down, plants also lose water through a process that helps them stay cool. But when too much water is lost, the plant starts to droop.
(a) What is the process by which plants lose water through their leaves?
(b) Through which part of the leaf does this water loss mainly happen?
(c) Besides cooling the plant, how else does transpiration help the plant?
(d) In transpiration, water is lost from the plant in the form of ………… (water vapour /water droplets).
(e) Draw a simple flow chart showing water movement from roots to leaves and then out of the plant.
(f) Aarav's mother said that once he waters the plant, it will look fresh again. What is the process by which roots absorb water from the soil?