2.3.2 - Plant Organ System

What is translocation?

The movement of dissolved sugars from the leaves to other parts of the plant

What is transpiration?

The evaporation of water vapor from the surface of a plant

How does transpiration work?

• Water evaporates from the leaf surface via the stomata

• Water molecules cohere together - more water is pulled up the xylem in an unbroken column

• More water is taken up from the soil - creating a continuous transpiration stream

How does temperature affect the rate of transpiration?

Increasing the temperature results in a higher rate of evaporation and diffusion of water - therefore rate of transpiration is increased

How does humidity affect the rate of transpiration?

High relative humidity will reduce the water vapor concentration gradient. The rate of evaporation will decrease, and so will the rate of transpiration

How does wind speed affect the rate of transpiration?

Increased air movement lowers water vapor concentration outside of the leaf. This increases the water vapor concentration gradient, thereby increasing the rate of evaporation and transpiration.

How does light intensity affect the rate of transpiration?

Increasing the light intensity means the rate of photosynthesis increases, so more stomata open. This allows the rate of evaporation to increase, increasing the rate of transpiration