Exchange System In Plants Flashcards
What increase the surface are of root and leaves?
It is increased by root hair cells
and
the surface area of laves is increased by the flattened shape and intern air spaces
What does stomata in plants do?
Plants have stomata to obtain CO2 from the atmosphere and to remove oxygen produced by photosynthesis
Where do plants mainly lose water vapour?
Through their leaves. Most of the loss of water vapour takes place through the stomata
When does evaporation of water vapour in plants take place quicker?
Evaporation is more rapid in hot, dry and windy conditions
What happens if plants lose water faster than it is replaces by the roots?
If plants lose water faster than it is replaces by the roots, the stomata can close to prevent wilting
What controls the size of stomata?
Guard cells, which surround them
Why do leaves have stomata?
To allow gases to diffuse in and out of the leaf
What is taken in by plants and how?
CO2 enters leaves by diffusion
Most of huge water and mineral ions are absorbed by roots
What does the cuticle do?
The thin, waxy cuticle prevents water loss but still allows sunlight in
Why do leaves have thin leaves?
To minimise the diffusion distance of gases
How is CO2 allowed into the leaf?
Through the stomata and air spaces
What are the conditions which affect water loss?
Light - transpiration increases in bright light - the stomata open wider to allow more carbon dioxide into the leaf for photosynthesis. More water is therefore able to evaporate.
Temperature - transpiration is faster in higher temperature - evaporation and diffusion are faster at higher temperatures.
Wind - transpiration is faster in windy conditions - water vapour is removed quickly by air movement, speeding up diffusion of more water vapour out of the leaf.
Humidity - transpiration is slower in humid conditions - diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air.
What is transpiration?
Transpiration explains how water moves up the plant against gravity in tubes made of dead xylem cells without the use of a pump.
Water on the surface of spongy and palisade cells (inside the leaf) evaporates and then diffuses out of the leaf. This is called transpiration. More water is drawn out of the xylem cells inside the leaf to replace what’s lost. As the xylem cells make a continuous tube from the leaf, down the stem to the roots, this acts like a drinking straw, producing a flow of water and dissolved minerals from roots to leaves.
