CB6a paper 2 Flashcards
Equation for photosynthesis
Carbon dioxide + water -> glucose + oxygen
Reactants Products
Energy is transferred by light
Where does photosynthesis occur?
In the chloroplasts which contains chlorophyll which traps energy transferred by light
Is photosynthesis an exothermic or endothermic reaction
Endothermic
What do glucose molecules form when they link together
A polymer called starch
How long does starch stay the chloroplasts
Until photosynthesis ends
Extra info
The starch is then broken down into simpler substances which are moved into the cytoplasm and used to make sucrose (another type of sugar molecule). Sucrose is then transported around the plant.
Sucrose is transported around the plant and used to make…
Starch
Other molecules for the plant
Glucose for respiration (to release energy)
Where are the palisade cells located
Near the top of the leaves and contain many chloroplasts
Leaf adaptations. Leaves contain microscopic pores called
Stomata (singular =stoma)
What does stomata allow
Carbon dioxide to diffuse into the leaf
Sucrose is transported around the plant and used to make…
Starch
Other molecules for the plant
Glucose for respiration (to release energy)
Where are the palisade cells located
Near the top of the leaves and contain many chloroplasts
Leaf adaptations. Leaves contain microscopic pores called
Stomata (singular =stoma)
What does stomata allow
Carbon dioxide to diffuse into the leaf
What are the stomata opened and closed by
Specialised guard cells
When does the stoma open
In the light when water flows into pairs of guard cells, making them rigid (allowing the stoma to open)
Positive of leaves thickness
They are thin, allowing carbon dioxide to not have to diffuse far into the leaf before reaching the callers that need it
What is a limiting factor
A factor that prevents a rate increasing
State three limiting factors for photosynthesis
Carbon dioxide concentration
Temperature
And light intensity
The water absorbed by plant roots is used for
Carrying dissolved mineral ions
Photosynthesis
Keeping cells rigid
Cooling the leaves
Water passes into the cytoplasm of root hair cells by
Osmosis
Transpiration
The flow of water into a root, up the stem and out of the leaves
Xylem vessels
Tiny continuous pipes leading from plants roots up into its leaves
Water is pulled up the xylem vessels in the stem, as
water evaporates from the xylem vessels in the leaves
Fact
The concentration of water vapour in the air spaces is higher inside than outside. So water molecules diffuse down the concentration gradient out of the leaf. A bigger difference between the gradients makes the gradient steeper, thus increasing the rate of diffusion. So any factor that affects the concentration of water outside the stomata, will increase transpiration. These factors are:
Wind (moves water molecules away from stomata)
Low humidity in air (less water vapour )
