2.81 Phototropism

• The word phototropism means light growth, suggesting that the growth is towards the light.
• The light comes in all directions meaning that the light will grow forward. 
• If light comes into the plant sideways that means that the plant will grow in the direction the light is coming in. 
• The light on one side causes the plant to move to the opposite side. 
• Auxin causes more growth to the plant which makes the plant grow in the other direction an also causes the plant to bend. 
• Cell division is called mitosis which means that the cells multiply.

2.80 Geotropism

• Geo of Geotropism stands for gravity and tropism stands for growth response. 
• The embryonic roots grown downwards and it's called positive geotropism. 
• Where the embryonic roots grow upwards it is negative geotropism. 
• Plants commonly exist in a state of "anisotropic growth," where roots grow downward and shoots grow upward. 
• No matter what you do to a plant within Earth's atmosphere, it will still grow roots down, stem up. 

2.79 Plants and Stimuli

• Stimuli is the changes in the environment such as temperature or light changes. 
• The plant has receptors that can detect stimuli and turn that into a response, usually the responses make them grow called tropism. 
• Tropism involves light is called phototropism, gravity, geotropism. 
• The connection between the receptors and response usually take to place plant hormones, such as auxin. 
• Auxins are a class of plant growth substances its role in the plant is usually structure and growth. 

2.55 Rate of Transpiration

• Transpiration is the loss of water through a leaf.  
• Absorption of sunlight through the leaf transforms water into heat. 
• For evaporation to happen the liquid has to turn into a gas through diffusion through the stomatal pore.
• The concentration gradient for water if there is a big difference there would be a high rate of transpiration. 
• If the humidity was low that would make the rate of transpiration slow, with high temperature you would get more evaporation. 

2.17 Photosynthesis

• The source of light energy is the sun. 
• The plants need carbon hydrogen, and oxygen through the stems. 
• The water molecules come out at the xylem into the palisade layer. 
• Photosynthesis occurs in the palisade layer. 
•  The phloem stores the minerals and food.

2.53 Uptake of Water

• Water is collected from the roots of the plants and travels up the stem. 
• The root has a big surface area so the root can absorb a lot of water. 
• Water enters through the epidermis of the roots. 
• Even though there is no water, minerals enter freely. 
• In the plant through osmosis water moves from a dilute to a concentrated region.

2.54 Transpiration

• For water to turn into gas it requires heat. 
• Heat is supplied by sunlight as it is absorbed by the plant structure. 
• Evaporation happens through the stomatal pore. 
• Water is delivered into the leaf by the xylem. 
• Water vapor diffuses down the diffusion gradient and through the stomatole pore.