Gaseous Exchange in Plants & Transporting Systems

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There are two types of Transporting Systems in a Plant

·         Xylem tubes transport water and mineral salts from the roots up to the shoot to the leaves in the transpiration stream

·         Phloem tubes transports food, like sugars, amino acids from where they're made in the leaves to other parts of the plant.

Root Hairs Take in Water 

The cells on plant roots grow into long "hair" which stick out into the soil. This goves the plant a big surface area for absorbing water from the soil.

Transpiration

It is caused by Evapouration and diffusion. The evaporation creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the Xylem vessels to replace it. This means more water is drawn up from the roots and so there's a contant transpiration stream of water through the plant.

Because there is more water in the plant than the air, it diffuses out of the stomata.

·         Light Intensity- the brighter the light, the greater the transpiration rate. Due to little water escaping in the dark as there is no light but in daylight the whole day it opens the Stomata to photosysthesis.

·         Temperature- the warmer the air, the faster

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