Factors Affecting the Rate of Water Uptake Flashcards

All 6 cards in this deck

What effect does increasing light intensity have on the rate of transpiration?

It increases it, because the stomata open wider in the light so more water vapour is lost.

What effect does air movement (wind) have on the rate of transpiration?

It increases it, because water vapour is blown away from the leaf, keeping a steep concentration gradient.

What effect does increasing temperature have on the rate of transpiration?

It increases it, because water evaporates and diffuses out of the leaf faster.

True or false? A plant in very humid air loses water faster than the same plant in dry air.

False. High humidity reduces the concentration gradient of water vapour, so transpiration is slower.

What are the steps to measure the rate of water uptake using a potometer?
e.g. testing the effect of air movement using a fan

1. Cut a leafy shoot and seal it into the potometer under water so no air leaks in.
2. Measure how far the air bubble moves along the capillary tube in a set time.
3. Repeat with the fan on, keeping temperature, light intensity and humidity the same.

What are the steps to calculate the rate of water uptake from potometer readings?
e.g. the air bubble moves 36 mm in 12 minutes

1. Find the distance moved: 36 mm.
2. Find the time taken: 12 min.
3. Rate = distance $\div$ time = 3 mm/min.