Photosynthesis Flashcards
ATP is useful in many biological processes. Explain why (5)
- Releases energy in small amounts
- Broken down in one step / single bond broken
- Immediate energy compound
- Phosphorylates
- Makes more reactive / lowers Ea
- Can be reformed / made again
Contrast the structures of ATP and a nucleotide found in DNA to give two differences (2)
- ATP has ribose sugar whereas DNA nucleotides have deoxyribose sugar
- ATP has 3 phosphate groups whereas DNA nucleotides have only 1 phosphate groups
- ATP nitrogen-containing base is always adenine whereas DNA nucleotide base can differ (adenine, thymine, guanine, cytosine)
Give two ways in which the hydrolysis of ATP is used in cells (2)
- Active transport of Na+
- Phosphorylates other compound making them more reactive
- Releases small amounts of energy for protein synthesis
- DNA replication
- Secretion of enzyme / hormones
Where does the light-dependent reaction occur? (1)
Granum
Where does the light - independent reaction occur? (1)
Stroma
Name the two products of the light - dependent reaction that are required in the light - independent reaction? (2)
- ATP
- NADPH
What are the reactants and products of the light - dependent reaction? (2)
- REACTANTS - Light, Water
- PRODUCTS - Oxygen, ATP, NADPH
What are the reactants and products of the light - independent reaction? (2)
- REACTANTS - NADPH, ATP, Carbon Dioxide
- PRODUCTS - Glucose
What does a co-enzyme do? Give an example (1)
Co-operates with an enzyme
Example - NADPH
What is meant by the photo-ionisation of chlorophyll? (1)
Oxidation of Chlorophyll when hit by light
What is meant by photo-lysis of water? (1)
Splitting of water to produce 2 electrons, 2 protons and half O2
What is meant by the photo-phosphorylation of ADP? (1)
making ATP (from ADP + Pi) using energy from light
Describe the light dependent reaction (6)
- Chlorophyll absorbs light energy and excites electrons
- Electrons removed (Oxidation of chlorophyll) via photo-ionisation
- Electrons move along carriers/electron transport chain releasing energy
- Energy released (by electrons) used to form proton gradient
- H+ ions move through ATP synthase
- Providing energy to join ADP and Pi to form ATP
- Photolysis of water produces 2 protons, 2 electrons and ½ Oxygen
- NADP reduced by electrons and protons / H+
Describe the light independent reaction. (6)
- Carbon dioxide combines with RuBP
- Produces two GP with enzyme RuBisCo
- GP reduced to triose phosphate
- Using NADPH
- Using energy from ATP
- Triose phosphate converted to glucose or RuBP
Where precisely is RuBisCo found in a cell? (1)
Stroma
Explain why plants that have more chlorophyll will grow faster than plants with less chlorophyll. (4)
- Have faster production of ATP and NADPH
- So faster light independent reaction
- So produce more sugars that can be used in respiration
- So have more energy for growth
- Have faster synthesis of new organic materials
ATP is produced in the light dependent reaction, suggest why this is not their (plants) only source of ATP (4)
- Plants don’t photosynthesis in the dark
- Not all the parts of the plants photosynthesise
- Plants require more ATP than is produced in the light dependant reaction
- ATP used in Active Transport (accept other named processes)
Describe what happens during photo-ionisation in the light dependent reaction (2)
- Chlorophyll absorbs light
OR - Light excites electrons in chlorophyll
- Electrons are lost
OR - Chlorophyll becomes positively charged
OR - Electrons go to electron transport
When producing a chromatogram, explain why the origin is marked using a pencil rather than ink (1)
Ink and leaf pigment would mix
OR
Origin line in pen would be in a different position
OR
Origin line in pencil would be in same position
OR
Pencil origin line would still be visible
While making a chromatogram, describe the method used to separate the pigments after the solution of pigment had been applied to the origin (2)
- Level of solvent below origin line
- Remove/stop before solvent reaches top
Suggest and explain the advantage to plants of having different colour pigments in leaves. (1)
Absorbs more wavelengths of light for photosynthesis
Explain the role of chlorophyll in photo-lysis (2)
- Absorbs light energy
- Loses electrons and is oxidised
Explain why scientists measure the rate of production of oxygen in this investigation (2)
- Oxygen produced in the light independent reaction
- Faster oxygen is produced, the faster the light dependent reaction
Describe the effect of introducing a herbicide/inhibitor on the electron transport chain. (4)
- Reduced transfer of protons across thylakoid membrane
- Less ATP produced
- Less NADPH produced
- Light independent reaction slows down
OR
Less reduction of GP to triose phosphate
Explain the relationship between the stomatal opening and photosynthesis (2)
- Stomata allow uptake of carbon dioxide
- Carbon dioxide used in photosynthesis
