Photosynthesis Flashcards
What is photosynthesis?
An endothermic reaction that uses light energy to react carbon dioxide and water to produce glucose and oxygen
Photosynthesis is an endothermic reaction.
What does this mean?
Energy is taken in during the reaction
List two types of photosynthetic organisms.
- Green plants
- Algae
What is the photosynthesis equation?
(Exam-style question)
(Exam-style question)
Explain why photosynthesis is important for the majority of life on Earth.
- Energy stored in biomass of photosynthetic organisms is transferred along food chains
- Animals eat these organisms and each other
- This means many organisms rely on photosynthesis as a source of energy
(Exam-style question)
(Exam-style question)
- Put light source at a specific distance from the pondweed
- Measure the volume of oxygen with a gas syringe / count number of bubbles in a set time
- Repeat with the light at different distances
How would you calculate the rate of oxygen production at each distance?
Volume produced ÷ time taken
List some variables and describe how you should control them when investigating the effect of light intensity on the rate of photosynthesis.
Variables and how to control them:
Light
- Use the same light source at each distance
Temperature (of water)
- Use a heat shield, or put the flask in a water bath
Carbon dioxide concentration (in water)
- Add a set amount of sodium hydrogencarbonate to the set volume of water
Amount of pondweed
- Use the same pondweed each time
Suggest an explanation why sodium hydrogencarbonate is used when investigating the effect of light intensity on the rate of photosynthesis.
It releases carbon dioxide in solution, therefore it can be used to ensure the plant has enough carbon dioxide
State how carbon dioxide would affect a solution’s pH.
It would decrease a solution’s pH because it is acidic
