Photosynthesis Flashcards
What occurs in the light-dependent stage?
Sunlight is absorbed by chlorophyll and converted into chemical energy where it splits water molecules into H+ ions and Oxygen gas.
What occurs in the light-independent stage?
CO2 from air is combined with H+ ions to form sugars in a series of reactions known as Calvin cycle.
What are the inputs and outputs for the light-dependent stage?
Inputs: H20, NADP, light energy, ADP + Pi
Outputs: NADPH (H+ ions), oxygen, ATP
What are the inputs and outputs for the light-independent stage?
Inputs: CO2, NADPH, ATP
Outputs: glucose, H2O, NADP, ADP + Pi
Where would stage 1 of photosynthesis occur?
In the grana of the chloroplast: the thylakoid membrane where chlorophyll absorbs the sunlight
What type of DNA do chloroplasts contain?
Circular, double-stranded DNA
Evidence of endosymbiotic theory for chloroplasts?
- contain double membrane: one of the prokaryote and one of the host
- contain DNA: capable of self-replication
- contain ribosomes: indicates they can make their own chloroplasts
What are the source of the energy-carrying molecules; ATP and NADPH?
- light dependent stage: splitting of water
- electron transport chain of photosynthesis
- light dependent stage: NADPH produced
Low levels of CO2 mean RuBisCo catalyzes O2 creating H2O2.
Why should CO2 levels remain high?
- increases the rate of photosynthesis, therefore increasing the production of glucose/ growth
- avoids the production of H2O2 which is toxic to the plant and could harm them.
What does it mean on a graph when CO2 or O2 have a concentration of zero?
The rate of CO2 produced by respiration equals the rate of CO2 consumed by photosynthesis, known as compensation point.
What does it mean on a graph when light intensity is increased and concentration of CO2 plateaus?
- lack of water present
- lack of enzymes present
- inability of chlorophyll to absorb any more light
- lack of co2 present
What is the purpose of additional pigments in chloroplasts?
Allows plant to absorb different wavelengths of lights, maximising absorption of radiant energy.
Where is the location of the calvin cycle?
In the stroma of the chloroplast.
What factors increase the rate of photosynthesis?
- light intensity
- [CO2]
- [H20]
- temperature
What is the equation for photosynthesis?
6CO2 + 6H20 = C6H12O6 + 6O2
What is chlorophyll a?
The main pigment found in chlorophyll.
It absorbs red and blue lights.
What is in the stroma?
The fluid part of the chloroplast which contains the enzymes controlling the carbon fixation reactions.
What happens to the hydrogen after is split by the energy from light?
Hydrogen is transferred to the hydrogen acceptor. NADP becomes reduced to form NADPH2.
What is chemosythesis?
The process of using energy released from oxidation of inorganic chemicals to build organic molecules. Chemosynthetic organisms are still autotrophs but do not require sunlight.
What is a heterotroph?
An organism that requires pre-formed organic molecules. Animals and fungi cannot make their own organic molecules. They get their chemical energy from feeding.
What is an autotroph?
Synthesise their own organic molecules from inorganic molecules. Plants and algae’s are autotrophs.
Why does sunlight need to be converted?
Sunlight cannot be stored and at night there is no sunlight so the plant would have no energy available to perform cellular activities.
How can the energy of glucose be released?
The chemical energy of glucose is released in a series of oxidation reactions called cellular respiration. One molecule of glucose can produce 36 ATP molecules.
Where do the reactants of photosynthesis come from?
Light energy: sun
Water: soil via roots transported by xylem
CO2: air via stomata
