Transpiration Flashcards
What is transpiration?
Transpiration is the loss of water vapor from the surface of leaves.
Explain the process of transpiration. (3)
- Water is pulled up the xylem in the stem from the roots to the leaves.
- The water is used for photosynthesis and to stop the plant from wilting
- Water evaporates from the leaves into the air.
As water is used up or lost from the leaves more is sucked up from the ______ vessels. It’s a bit like sucking up water up a straw. So there is a continuous flow of water from the _____ to the ______. This movement of water up the xylem is called the _______ ________.
Xylem
Roots
Leaves
Transpiration stream
Explain transpiration within the mesophyll layer?
- Water first evaporates from the spongy cells into the air spaces.
- The air space become full of water vapor.
- Water vapor diffuses through the stomata into the air.
- The water lost from the spongy cells is replaced by more water from the xylem.
Why does more transpiration take place during the day than at night?
Stomata are open during the day but close at night.
Stomata May also close in very _____ conditions. This is because the water lost in ________ is not being replaced by water from the soil. The stomata close to _____ transpiration.
Dry
Transpiration
Reduce
What happens if the plant doesn’t get enough water?
It will start to wilt. It’s cells have lost so much water that they are no longer turgid or full of water.
Turgid cells are ____ and give the plant support.
Firm
What happens when cells become flaccid?
The plant becomes soft and the stem is no longer upright and the leaves droop.
What are the environmental factors which affect transpiration?(4)
Wind
Humidity
Temperature
Light
How do windy conditions affect the rate of transpiration?
Transpiration increases the rate of transpiration. Water molecules are blown away from the lead surface, so more diffuse out of the stomata.
How does humidity affect transpiration?
They decrease the rate of transpiration. The air contains a lot of water already.
How does temperature affect temperature?
Warm conditions increase the rate of transpiration. The air can hold more water vapor.
How does light affect transpiration?
Light causes the stomata to open. This increases the rate of transpiration.
How do you measure the rate of water uptake?
Using a potometer
Why is the amount of water lost actually less than the amount of water taken in by the roots?
Most of the water is used up in photosynthesis.
How does transpiration help with the pulling of water ?
As water evaporates through the stomata in the leaves, it creates a negative pressure (tension or suction) in th leaves and tissues of the xylem. The negative pressure exerts a pulling force on the water in the plant’s xylem and draws the water upward.
How does cohesion help with drawing water?
When water molecules stick to one another through cohesion, they fill the column in the xylem and act as a single molecule of water.
Capillary action is the movement of a liquid across the surface of a solid caused by _____ between the two. When you place a tube in water, water ________ moves up the sides of the tube because of adhesion, even before you apply sucking force.
Adhesion
Automatically
