PHOTOSYNTHESIS Flashcards
(47 cards)
What are the three basic steps of photosynthesis?
- light-dependent stage
- light-independent stage
- pigment regeneration
These stages include energy capture, carbon fixation, and electron replacement from water splitting.
Where does the light-dependent stage of photosynthesis occur?
thylakoid (membrane)
The thylakoid membrane contains the electron transport chain and ATP synthase.
Where does the light-independent stage (Calvin cycle) take place?
stroma
The stroma is a colorless hydrophilic matrix surrounding the grana within the chloroplast.
What is a pigment?
Any substance that absorbs light
The color of the pigment comes from different wavelengths of light reflected, not absorbed.
What is the absorption spectrum?
Graph showing the absorbance of different wavelengths of light by a pigment
It indicates the best absorption wavelengths for chlorophyll a & b.
What is the action spectrum?
Graph showing the rate of photosynthesis at different wavelengths of light
It demonstrates how the rate of photosynthesis varies with light wavelength.
What is chromatography used for in the context of chloroplast pigments?
To separate and identify chloroplast pigments
It can also be used to compare chloroplast pigments in different plants.
What is photolysis in photosynthesis?
The breakdown of water to release oxygen
It occurs during the light-dependent reactions and is catalyzed by photosystem II.
What is cyclic photophosphorylation?
Involves only photosystem I without reducing NADP
Electrons revert to photosystem I, and ATP is synthesized.
What is non-cyclic photophosphorylation?
Involves both photosystems and reduces NADP
Electrons from photosystem II replace those lost in photosystem I.
What are the three main stages of the Calvin cycle?
- RuBP combines with CO2
- GP is reduced to TP
- Regeneration of RuBP
The Calvin cycle produces carbohydrates and other organic substances.
What is a limiting factor in photosynthesis?
The factor that has the greatest effect in reducing the rate of photosynthesis
Common limiting factors include light intensity, temperature, and CO2 concentration.
Name two features of a dicotyledonous leaf that can affect photosynthesis.
- Stomata number/size
- Chloroplast number/size
Other features include leaf surface area, intracellular air spaces, and rubisco concentration.
What is the purpose of using artificial light in glasshouses?
To allow photosynthesis to continue beyond daylight hours
This can be optimized by using specific wavelengths of light.
Describe the Hill reaction.
Investigates light-dependent reactions using DCPIP as an electron acceptor
DCPIP changes color based on its oxidation state, indicating electron transfer.
What is the independent variable in an experiment investigating light intensity’s effect on photosynthesis?
Light intensity or wavelength
This can be adjusted to observe its impact on the rate of photosynthesis.
How can you measure the rate of photosynthesis in an aquatic plant?
Count the number of bubbles produced
This method is often used with a photosynthometer.
What is the role of rubisco in the Calvin cycle?
Catalyzes the combination of RuBP and CO2
This step is crucial for carbon fixation in photosynthesis.
What is the significance of reduced NADP in photosynthesis?
Used in the synthesis of carbohydrates during the light-independent reactions
It is produced during the light-dependent reactions.
What should be maintained during an experiment on photosynthesis?
the temperature
Use at least five different temperatures (e.g., 10°, 20°, 30°, 40°, 50°)
What is the purpose of acclimatizing shoots in a photosynthesis experiment?
to allow sufficient time for the shoots to acclimatise to the conditions
What is important about the lamp distance in a photosynthesis experiment?
keep the lamp at a fixed distance from the shoots
How can you prevent gases in bubbles from dissolving in water?
aerate the water well before use
This can be done by bubbling air through the water.
What should be done after conducting the photosynthesis experiment?
repeat the experiment twice more and calculate the mean values
