Transpiration
Transpiration is the evaporation of water from the Leaf cells that have few chloroplasts and a large surface area to increase the diffusion of carbon dioxide and oxygen cells followed by the The random movement of a substance from a region of high concentration to a region of low concentration of water through the air spaces and out of the Tiny holes in the epidermis (skin) of a leaf. They control gas exchange by opening and closing and are involved in loss of water from leaves. Singular is stoma..
Most of the water that enters a plant will exit the leaf into the atmosphere.
This provides a continuous stream of water which is known as the transpiration stream.
The transpiration stream is important because:
- It provides leaves with a continuous supply of water (for A chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Algae subsumed within plants and some bacteria are also photosynthetic.).
- It continually transports minerals from the roots to the leaves and other parts of the plant.
- It provides plant cells with support from turgor.
- It provides water for transpiration.
If water availability is limited, plants will need to reduce transpiration.
In order to do this, the stomata (mainly found on the underside of the leaf) close.
Factors affecting transpiration
| Factor | Effect on transpiration | How to change this factor experimentally |
| Surface area (not an environmental factor) | Smaller leaves will contain less stomata causing a decrease in transpiration. | Remove leaves. |
| Wind speed | A higher wind speed will increase the rate of evaporation causing an increase in transpiration. | Use a fan. |
| Temperature | A higher temperature will increase the rate of evaporation causing an increase in transpiration. | Use a heater. |
| Humidity | A higher humidity level will reduce the rate of evaporation causing a decrease in transpiration. | Place a clear, plastic bag over the plant shoot. |
| Light intensity | Darkness will cause the stomata to close causing a decrease in transpiration. | Use a lamp. |
| Factor | Surface area (not an environmental factor) |
|---|---|
| Effect on transpiration | Smaller leaves will contain less stomata causing a decrease in transpiration. |
| How to change this factor experimentally | Remove leaves. |
| Factor | Wind speed |
|---|---|
| Effect on transpiration | A higher wind speed will increase the rate of evaporation causing an increase in transpiration. |
| How to change this factor experimentally | Use a fan. |
| Factor | Temperature |
|---|---|
| Effect on transpiration | A higher temperature will increase the rate of evaporation causing an increase in transpiration. |
| How to change this factor experimentally | Use a heater. |
| Factor | Humidity |
|---|---|
| Effect on transpiration | A higher humidity level will reduce the rate of evaporation causing a decrease in transpiration. |
| How to change this factor experimentally | Place a clear, plastic bag over the plant shoot. |
| Factor | Light intensity |
|---|---|
| Effect on transpiration | Darkness will cause the stomata to close causing a decrease in transpiration. |
| How to change this factor experimentally | Use a lamp. |
If less water is being lost through transpiration the plant will absorb less water at the roots.