nutrition Flashcards
The process of photosynthesis is..
light energy is absorbed by chlorophyll - a green substance found in chloroplasts in the palisade cells in the leaf. Absorbed light energy is used to convert carbon dioxide (from the air) and water (from the soil) into a sugar called glucose. Finally, oxygen is released as a by-product
How does varying carbon dioxide concentration affect the rate of photosynthesis?
As carbon dioxide concentrations increase, so too does the rate of photosynthesis until a certain point. At lower carbon dioxide concentrations carbon dioxide is the limiting factor because an increase in carbon dioxide causes an increase in photosynthesis.
How does light intensity affect the rate of photosynthesis?
Increasing the light intensity increases the rate of photosynthesis, until some other factor – a limiting factor – becomes in short supply. At very high light intensities, photosynthesis is slowed and then inhibited, but these light intensities do not occur in nature.
How does temperature affect the rate of photosynthesis?
As temperature increases the number of collisions increases, therefore the rate of photosynthesis increases. However, at high temperatures, enzymes are denatured and this will decrease the rate of photosynthesis.
Structure of a leaf
The leaf has a waxy cuticle to stop it losing water and drying out. The epidermis is a protective layer of cells and contains no chloroplasts. The palisade layer contains the most chloroplasts as it is near the top of the leaf. The chloroplasts contain the pigment chlorophyll.
How is the structure of a leaf adapted to photosynthesis?
They are adapted for photosynthesis by having a large surface area, and contain openings, called stomata to allow carbon dioxide into the leaf and oxygen out.
Why are magnesium ions needed for chlorophyll?
Magnesium is needed to make the green pigment chlorophyll inside chloroplasts. Without enough magnesium, plants cannot synthesise chlorophyll so won’t be able to carry out photosynthesis. Their leaves will turn yellow and start to die.
Why are nitrate ions important?
A lack of nitrate ions means that less DNA and protein is synthesised.
