Biology
Which one of the following favours the fastest transpiration rate?
- A cool, humid, windy day,
- A hot, humid, windy day,
- A hot, humid, still day,
- A hot, dry, windy day.
Answer
A hot, dry, windy day.
Reason — Transpiration is mainly affected by the temperature, humidity, and wind speed. On a hot, dry, windy day transpiration increases.
Cool temperature reduces evaporation, and high humidity reduces the diffusion of water vapour, resulting in slower transpiration. Hot temperature and wind increase transpiration, but high humidity slows it down by reducing the concentration gradient. Still air and high humidity greatly reduce transpiration, resulting in a very slow rate.
Related Questions
The root hairs are suited for absorbing water from the soil because:
- They have a large surface area
- They have a semi-permeable membrane
- They contain a solution of higher concentration than the surrounding water.
- All the three.
Transpiration is defined as:
- the rise of water up to the stem of a plant.
- the elimination of water with dissolved water products.
- the loss of water as water vapour from the aerial parts of a plant.
- the loss of water as water vapour from the roots as well as the leaves of the plant.
Vinay has kept a small herbaceous plant in a test tube containing water. The surface of the water is covered by a layer of oil. After three hours, he observed that the level of water in the test tube has decreased. This is due to:
- Absorption
- Transpiration
- Wilting
- Both (1) and (2)
Root hairs are the epidermal outgrowths of the outermost layer of roots. They are well-suited for absorption of water from soil due to which of the following features ?
P. Large surface area.
Q. Lower concentration of cell sap.
R. Semi permeable nature of the cell membrane.- Only P
- Only Q
- Only P and Q
- Only P and R