Frequently Asked Questions: Plant Physiology

Q. How do plants get water from the roots up to the leaves?
A. There are several processes - transpiration or water loss through the leaves helps to draw water upwards, capillary action or the attraction between the chemical called water and the fine tubes carrying water inside the stem, and lastly the root pressure of the water that has been absorbed by the root from the soil.

Q. Why do many Australian plants have small leaves?
A. In Australia's dry environment the small leaves help to reduce transpiration or water loss from the leaves.

Q. Which way do shoots and roots grow in zero gravity?
A. On earth, shoots grow upwards and roots grow downwards due to gravity. However in space where there is little gravity, it is not known how this will affect plant growth. Probably, the shoots and roots will grow in any direction.

Q. What coloured wavelengths of light must be absorbed by green plants in photosynthesis?
A. White light is a mixture of coloured lights - red, orange, yellow, green, blue, indigo and violet. A green plant appears green because it reflects green light and doesn't use it but absorbs the other colours of light. The main lights absorbed by a plant for photosynthesis are red and blue.

Q. What are carnivorous plants?
A. Carnivorous plants such as the Sundew, the Venus Flytrap and the Pitcher Plant, have chlorophyll and photosynthesise but also have mechanisms for trapping and digesting insects. They live in soils, usually swampy soils, which lack nitrogen so they extract their needed nitrogen from the muscle protein of insects.