Photosynthesis Flashcards
2 main stages
light dependent reactions and calvin cycle
where do light dependent reactions occur
in thylakoid membranes of chloroplasts
what happens during photolysis
water is split into oxygen, protons, and electrons using light energy
describe the pathway of electrons in non cyclic photophosphorylation
electrons move from PSII to PSI via the etc, generating ATP and reducing NADP to NADPH
how does cyclic photophosphorylation differ from non cyclic
cyclic only involves PSI, recycling electrons to produce ATP but no NADPH or O2
where does calvin cycle occur
stroma of chloroplast
3 main stages of calvin cycle
carbon fixation - CO2 combines with RuBP to form 2 molecules of GP (glycerate-3-phosphate)
reduction - GP reduced to triose phosphate using ATP and NADPH
regeneration - some TP regenerates RuBP using ATP
what is the role of RuBisCO in calvin cycle
catalyses the fixation of CO2 to RuBP
how are chloroplasts adapted for photosynthesis
thylakoids with large surface area for light absorption
stroma contains enzymes for calvin cycle
double membrane regulates material exchange
3 main limiting factors of photosynthesis
light intensity, carbon dioxide concentration, temperature
how does temperature affect photosynthesis
enzymes like RuBisCO operate optimally within a specific temperature range, extreme temperatures reduce efficiency
what is the compensation point in photosynthesis
the point where the rate of photosynthesis equals the rate of respiration
How are photosynthesis and respiration linked?
Photosynthesis produces glucose and oxygen, which are substrates for respiration. Respiration produces CO₂ and H₂O, substrates for photosynthesis
Which processes involve ATP synthesis via chemiosmosis?
photophosphorylation in photosynthesis
How can you measure the rate of photosynthesis using pondweed (e.g., Elodea)?
Use a photosynthometer to collect and measure the volume of oxygen produced over time.
What factors can you vary in a pondweed experiment to investigate photosynthesis?
Light intensity, carbon dioxide concentration, and wavelength of light.
How is the rate of oxygen production calculated in a pondweed experiment?
Record the volume of oxygen gas produced (e.g., using a gas syringe) over a set time.
How can hydrogen carbonate indicator be used to investigate photosynthesis?
The indicator changes color based on CO₂ concentration:
High CO₂: Yellow
Low CO₂: Purple
Normal CO₂: Red
What does a color change in the hydrogen carbonate indicator show?
Photosynthesis removes CO₂, turning the indicator purple. Respiration increases CO₂, turning it yellow.
How can you investigate the effect of light intensity on photosynthesis?
Place pondweed at varying distances from a light source and measure oxygen production. Use a light meter to quantify light intensity.
How do you control variables in a limiting factor experiment?
Use a water bath to maintain constant temperature and a fixed CO₂ concentration using sodium hydrogen carbonate.
How can chromatography be used to separate photosynthetic pigments?
Extract pigments from leaves, apply to chromatography paper, and use a solvent to separate them based on solubility.
How do you calculate the Rf value for pigments in chromatography?
Rf = Distancetraveledbysolvent / Distancetraveledbypigment
What pigments are commonly identified in a chromatography experiment?
Chlorophyll a, chlorophyll b, carotenoids, and xanthophylls.
How can the compensation point of a plant be determined?
Place a plant in sealed tubes with hydrogen carbonate indicator under varying light intensities. Measure CO₂ levels to identify when photosynthesis equals respiration.
