Photosynthesis Flashcards
What is an organic compound?
A compound containing carbon
What is an inorganic compound?
A compound that does not contain carbon
What is REDOX?
- Reduction is the gain of electrons or hydrogen - Oxidation is the loss of electrons or hydrogen
What is a Co-enzyme?
A non protein molecule that aids enzymes by transferring smaller molecules around
What is phosphorylation?
The process of adding a phosphate group to something
What is photophosphorylation?
Using light energy to phosphorylate something
What is photolysis?
Using light energy to split a molecule
What is the electron transport chain?
The flow of electrons through proteins (electron carriers) in a membrane
What is a proton?
A H+ ion
What happens in the light dependent reaction?
- Light energy is absorbed and used to make ATP and NADPH- Takes place in the thylakoid membrane
What happens in the light independent reaction?
- Products from the light dependent reaction (ATP and NADPH) are used to convert CO2 into useful organic compounds such as amino acids, lipids and glucose - Takes place in the stroma
What is the function of the chloroplast?
It absorbs light energy which Is used in photosynthesis to make useful organic compounds
What is the structure of a chloroplast?
- Stroma - Grana- Tylakoid- Lamellae - Starch grain - Chloroplast DNA
What is the grana?
A stack of thylakoids
What is a thylakoid?
Small disks with high surface area that contain the photosynthetic pigments required for photosynthesis, they are the site of the light dependent reaction
What is the stroma?
The site of the light independent reaction
What happens to electrons in the light dependent reaction?
- Light energy is absorbed by photosynthetic pigments which excites an electron in photosystem 2, this electron gains energy and leaves PS2 travelling down the electron transport chain into PS1 - Light energy is absorbed by photosynthetic pigments which excites an electron in photosystem 1 which leaves PS1 - Energy given off from the electron moving down the ETC is used to join ADP to Pi and Move H+ ions from the stroma into the thylakoid - Electron that leaves PS2 is replaced by electrons from the photolysis of water
What happens to hydrogen in the light dependent reaction?
- H+ is released from the photolysis of water (inner thylakoid)- H+ is moved into the thylakoid using energy from the ETC - H+ inside the thylakoid moves along ATP synthase channels out of the thylakoid into the stroma by chemiosmosis where its combined with NADP to form NADPH
What are the products of the light independent reaction?
NADPH and ATP
What is NADP?
A co-enzyme
What happens in the Calvin cycle?
Products of the light dependent reaction (NADPH and ATP) are used to convert CO2 into useful organic compounds
What are the stages of the Calvin cycle?
- CO2 is combined with ribulose bisphosphate (catalysed by the enzyme rubisco) to form 2 molecules of glycerate-3-phosphate - Each molecule of G3P is reduced to form 2 triose phosphate molecules using 2 NADPH and 2 ATP- Some TP is used to regenerate RUBP and some is converted into useful organic products
What are the 3 limiting factors of photosynthesis?
- Light intensity - Carbon dioxide concentration - Heat
How is light intensity a limiting factor?
- The greater the light intensity, the greater the energy available for photosynthesis- Light has to be a certain wavelength (blue or red)- Different photosynthetic pigments absorb different wavelengths of light
How can you prevent light being a limiting factor of photosynthesis?
- Keep plants in direct sunlight - Use lighting at night
How is carbon dioxide concentration a limiting factor?
- Optimum CO2 level for plants is 0.4% and only 0.04% is available - CO2 is a continuous limiting factor in the day time - Above 0.4% CO2 has a negative effect on photosynthesis
How can you prevent carbon dioxide concentration being a limiting factor of photosynthesis?
- Burn a fossil fuel e.g. propane in a green house
How is temperature a limiting factor?
- Photosynthesis is controlled by enzymes - Beyond optimum temp enzymes begin to denture and photosynthesis will stop - High temps can cause guard cells to close the stomata reducing CO2
How can you prevent temperature being a limiting factor of photosynthesis?
Regular heating/cooling to maintain the optimum temperature
