Life on Earth - Photosynthesis Flashcards
Describe Photosynthesis
- The process by which green plants and other organisms use sunlight to synthesize nutrients from carbon dioxide and water.
- Takes place inside the chloroplasts.
- Two stage process
Name and describe the 1st stage of Photosynthesis
1. LIGHT REACTIONS
* Light energy from the sun is trapped by the chlorophyll in chloroplasts
* Light energy is converted into chemical energy used to make ATP.
* Water splits to produce hydrogen and oxygen
* Oxygen diffuses out of cell.
* Hydrogen and ATP → passed to Carbon Fixation
(ALL IN CHRONOLOGICAL ORDER)
Name and describe the 2nd stage of Photosynthesis
2. CARBON FIXATION
* Series of enzyme-controlled reactions
* The ATP is broken down to release energy which is used to combine hydrogen (from light reactions) with carbon dioxide to produce sugar.
Hydrogen + Carbon dioxide → sugar
(ALL IN CHRONOLOGICAL ORDER)
Photosynthesis word equation?
carbon dioxide + water → sugar + oxygen
(assisted by Light energy and Chlorophyll)
List 4 fates (uses) of sugar
- Energy source - used in respiration
- Plant energy storage - can be made into glucose, then into starch
- Plant building material - can be made into glucose, then into cellulose
- Production of other types of food - sugar is a carb
Plants can combine sugar with nitrates to produce amino acids for proteins
Define the term ‘Limiting factor’, applying it to photosynthesis and list the 3 limiting factors of photosynthesis
- Anything in short supply that prevents photosynthesis occurring at its maximum rate.
- Light intensity, Temperature, Carbon dioxide
Describe the impact carbon dioxide concentration has on photosynthesis
- Required to make sugar during carbon fixation.
- No CO2? → No sugar
Describe the impact light intensity has on photosynthesis
- Required to provide light for the light reactions.
- No light/low light intensity? → No ATP or Hydrogen for Carbon Fixation
Describe the impact temperature has on photosynthesis
- Affects the rate the enzymes catalysing the reactions in both stages can occur.
- Temperature not at enzyme optimum? → Rate of photosynthesis declines.
How is the rate of photosynthesis and the rate of plant growth linked?
Provides the energy plants need to grow and develop