B1.4: Photosynthesis Flashcards
What is photosynthesis?
The process by which a cell captures energy in sunlight and uses it to make food
Is photosynthesis endothermic or exothermic?
Endothermic
Where does photosyntesis occur?
Chloroplasts
What is the word equation of photosynthesis?
Carbon dioxide + water —> glucose + oxygen
What is the balanced symbol equation of photosynthesis?
6CO2 + 6H2O —> C6H12O6 + 6O2
How do plants take in carbon dioxide?
Diffuses from the air into plant through the stomata
How do plants take in water?
Through roots, osmosis
What is stage 1 of photosynthesis?
Light energy used to split water. Releases oxygen gas and hydrogen ions
What is stage 2 of photosynthesis?
Carbon dioxide gas combines with hydrogen and oxygen in the atmosphere to produce glucose
How can plants be tested for starch in photosynthesis experiments?
- add iodine solution to a leaf
- make sure leaf is fully coated
- if after a few minutes a blueish black colour develops, starch is present
What are variegated leaves?
Leaves that have chlorophyll only in some parts of the leaf. Only some parts are green
Hwo to prove oxygen is given off in photosynthesis?
Glowing splint will relight in oxygen
How to prove chlorophyll is needed for photosynthesis
Place a destarched variegated leaves in sunlight for several hours then testing a leaf for the presence of starch
How to prove light is needed for photosynthesis?
Take a destarched plant and cover part with black card or tin foil, so light cannot reach that area
Place the plant in the sunlight for several hours then remove the card and test the leaf for starch
What is the formula for the rate of photosynthesis?
1/t
Units: mm-1
What are the 3 main factors affecting photosynthesis?
Temperature
Light intensity
CO2 concentration
How does light intensity affect the rate of photosynthesis?
Higher light intensity means more light energy can be converted into chemical energy, increases rate. But eventually, reaches maximum rate and curve plateaus
How does temperature affect the rate of photosynthesis?
Increased temperature will increase the rate of photosynthesis until a maximum temperature is reached. Decreased temperatures will decrease the rare of photosynthesis. If temperature becomes too high, enzymes will denature
What is the optimum temperature for photosynthesis?
30 degrees C
How does CO2 concentration affect the rate of photosynthesis?
Increasing CO2 conc increases the rate as CO2 is required to make glucose
When does the curve plataeu for the carbon dioxide graph affecting photosynthesis?
0.04%
What is the inverse square law?
Light intensity = 1 / (d)^2
