z z zz Outline the role of xylem and phloem tissue in plants.
Recognise the role played by stomata in the exchange of gases with the atmosphere.
Investigate the response of plants to changes in their environment. Transport in Plants
Plants need water, minerals and food (starch and sugars) to grow and carry out their other processes. These substances are carried around a plant by a transport system.
Transport Tissue Plants have two types of transport tissue: 1. Xylem tissue transports water and minerals.
Leaf Stem
2. Phloem tissue transports food. Phloem tissue and xylem tissue are found together in vascular bundles. These bundles are obvious as the veins on a leaf blade or in a freshly cut celery stem.
Transport of Water and Minerals
Water and minerals taken up by roots
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Fig. 7.2.1 Transpiration
1. Water and minerals are taken in from the soil by the roots.
2. The water and minerals travel up the stem in the xylem tissue.
3. Water is delivered to the leaves for use in photosynthesis.
4. Heat energy from the Sun causes the water in the leaves to evaporate. The loss of water vapour from the surface of a plant is called transpiration.
Observing the transpiration stream
1. Place a freshly cut stem of celery into a solution of food dye and observe it for 48 hours. 2. Remove the celery stem from the dye solution and rinse. Record your observations. 3. Where has the dye collected? Why?
