photosynthesis - SB6 Flashcards
what is the symbol equation for photosynthesis?
carbon dioxide + water –(energy transfered by light)–> glucose + oxygen
how does photosynthesis provide energy for plants?
plants can trap energy transferred by light from the sun. This energy is then transferred to molecules of glucose via photosynthesis and stored as energy
how does photosynthesis provide energy for the whole food chain?
when animals eat plants that photosynthesis, their cells break down and take on the energy the plant stored.
where does photosynthesis occur?
in choloroplasts
what do chloroplasts contain that traps light?
chlorophyll
what kind of reaction is photosynthesis? why?
endothermic - heat energy is being absorbed from the sun
what happens to glucose once formed from photosynthesis?
the molecules link together to form thepolymer starch which stays in the choloroplasts until photosynthesis stops
what happens to starch after stored in the chloroplasts?
starch is broken down into simpler substances which are moved into the cytoplasm and used to make sucrose
after sucrose is made in the cytoplasm
it is transported around the plant and can be used to make starch, glucose + others (cellulose, lipids or proteins)
how is a leaf adapted for photosynthesis?
- large surface area
- palisade cells near the top of the leaf with lots of choloroplasts to absorb lots of light
- leaves contain pores called stomata allowing C02 to diffuse into the leaf
- guard cells - control stomata by opening them during the day (rigid with water)- closing during night
- Leaves are thin so CO2 doesnt have far to diffuse before reaching the cells that need it
- Stomata allows gas exchange
what factors effect photosynthesis
- concentration of air molecules (lower = decreased rate)
- Temperature
- Cabon dioxide concentration
- Light intensisty
what is the maximum rate of photosynthesis is controlled by?
the factor in shortest supply
how do you calculate light intensity when the distance of a light source changes?
new intensity = original light intensity x (distance of light source)2 / (new distance)2
how can we investigate the effect of light intensity on photosynthesis rate?
using balls of algae in tubes of water with hydrogen carbonate indicator - you can vary light intensity by altering the distance between lamp and algae. The indicator will change the pH depending on how much o2 is produced (how much it photosynthesises)
what equation can be used relating pH change and time to measure rate of photosynthesis?
change in pH/ hour
