b3 -3

Question	Answer
State 2 areas where materials are exchanged in plants?	■ carbon dioxide enters leaves by diffusion ■ most of the water and mineral ions are absorbed by roots.
How is surface area in plants increased to help with the exchange of materials ?	The surface area of the roots is increased by root hairs and the surface area of leaves is increased by the flattened shape and internal air spaces.
What is the function of stomata ?	Plants have stomata to obtain carbon dioxide from the atmosphere and to remove oxygen produced in respiration
Plants mainly lose water vapour from their leaves. Most of the loss of water vapour takes place through the stomata. What can increase the rate of water loss and how can this be reduced ?	■ Evaporation is more rapid in hot, dry and windy conditions. ■ If plants lose water faster than it is replaced by the roots, the stomata can close to prevent wilting.
What controls the size of the stomata ?	The size of stomata is controlled by guard cells, which surround them.
Describe the structures in flowering plants that allow for the transport of substances	■ xylem tissue transports water and mineral ions from the roots to the stem and leaves ■ the movement of water from the roots through the xylem and out of the leaves is called the transpiration stream ■ phloem tissue carries dissolved sugars from the leaves to the rest of the plant, including the growing regions and the storage organs.

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	Created by david doran about 7 years ago