1. How does gas exchange associated with photosynthesis affect transpiration rat
ID: 146103 • Letter: 1
Question
1. How does gas exchange associated with photosynthesis affect transpiration rates?
2. If a mutation caused the stomata of a plant to stay permanently open, how would the rate of transpiration and photosynthesis would be affected? Would this be a beneficial trait? Explain.
3. Describe three adaptations that make it possible for desert plants to survive with very little water.
4. The introductory material described the role cohesion plays in water transport in plants. Describe here how adhesion is important for transpiration in plants.
Explanation / Answer
1. Transpiration - It is a process of water movement through a plant and its evaporation from aerial parts such as leaves, stems and flowers. Stomata are the pores in the leaves that allow gas exchange where water vapour leaves the plant and carbondioxide enters. A leaf needs carbondioxide and water to perform photosynthesis. If the stomata on the surface of leaf opens then the carbondioxide can enter so as we know the transpiration brings the water from roots to the leaf, it is important that plant must not lose excess water. When stomata open it facilitates the gas exchange between the atmosphere and the leaf and the transpiration rate increases. If the stomata is closed then the transpiration rate decreases.
2. Stomata are the pores in the leaves that allow gas exchange where water vapour leaves the plant and carbondioxide enters. Stomata have special cells called guard cells which control the opening and closing of the stomata. This is not a beneficial trait. Due to this mutation if the stomata is opened permanently, then too much transpiration takes place and the leaves would dry out leading to dehydration. As a result the plant wilts, leaf drop and eventually the plant dies.
3. The desert plants have adaptations that make them possible to survive in the hot conditions. Many of the plants like cacti, aloes etc.,. store excess water in the leaves, stems and roots.
They have thick waxy coating, which helps in the storing of moisture.
They also have extensive and shallow root systems so that taht they can absorb lot of water quickly.
Inorder to prevent the excess loss of water due to transpiration, most of the desert plants open stomata durning the night time and take the carbondioxide to store the following day.
4. Adhesion - It is a process of attaching one thing to the other due to attractive forces between them. When coming to plants both Cohesion and adhesion forces help in the transport of water from roots to leaves. In plants, During the night time, when the stomata close and transpiration stops, the water is held in the stem and leaf by the adhesion of water to the cell walls of the xylem vessels and tracheids.water molecules form hydrogen bonds with each other to give them a sticky quality allowing them to form drops, these adhesive forces helps to stick to the organic tissues. Likewise these water molecules cling to the xylem tissues and provide the force to pull water up the sides of the tube in the xylem.
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