Why do plants need water?

A few days ago we noticed that one of our little pumpkin plants on the window sill had wilted.  The soil looked dry so we watered the plant and after a few hours it was standing lovely and straight again, which got us wondering why do plants need water.

Why do plants need water

Plants need water to germinate.

We saw this with our bean in a jar. Water is needed to activate the process of germination, it also softens the seed making it easier for the plant to break through.

Photosynthesis

Photosynthesis is the process by which plants make energy to grow. Photosynthesis requires sunlight, water and carbon dioxide. We demonstrated what happens when a plant cannot photosynthesise when we made our cress caterpillar.

Nutrient transfer

Plants need water to absorb nutrients from the soil.

Transpiration

Transpiration is the process by which water moves up the stem of a plant from root to leaf when water is lost from the plant due to evaporation occurring at the leaves. This continual flow of water and nutrients  keeps the plant’s cells firm, if the cells become short of water they lose firmness and the plant starts to wilt.

We can demonstrate transpiration by placing white flowers in coloured water, the water travels up the stem to the petals which become coloured like the water.

Transpiration

Have you ever noticed your plants wilting? Did they revive after you watered them?

 

Suitable for Key Stage 1 – Living things and their habitats

 

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