2.81 Photo tropism

• Phototropism= Light Growth Response
• Positive= Growth towards light
• Stem grows upwards
• But if light comes from the side the plant stem bends towards the light
• Plant hormone causes this

2.80 Geotropism

• Geotropic= Gravity growth response
• Root growing downwards= Positive Geotropism
• Root going upwards= Negative Geotropism

2.79 Plants and Stimuli

• Plants respond to stimuli
• Changes in the environment E.g. Temperature or Light
• Plants have receptors that detect stimuli and respond
• Response are growth (Tropism)
• Light= Phototropism Gravity=Geotropism

2.54 Transpiration

·        -Evaporation  of water from the surface of a plant

·         -Heat provided by sunlight

·         -Evaporation from the stomatole pores

·         -Phase change occurs in air space in the spongy layer

·         -Water vapor diffuses down the diffusion gradient and through the stomatole pore

How Water is absorbed

Breaching Surface
Root hairs (very small roots)
Epidermal Root
Active Transport
Osmosis