2.9 & 8.3 Flashcards
what is photosynthesis?
conversion of light energy into chemical energy (ATP)
what is the electromagnetic spectrum?
the range of all possible frequencies of electromagnetic radiation
what is Chlorophyll?
Chlorophyll is a green pigment found in photosynthetic organisms that is responsible for light absorption
what does chlorophyll do?
When chlorophyll absorbs light, it releases electrons which are used to synthesise ATP (chemical energy)
what color does chlorophyll absorbs?
Blue and red
what color does chlorophyll reflect?
green
what does The absorption spectrum show?
indicates the wavelengths of light absorbed by each pigment
what does The action spectrum show?
indicates the overall rate of photosynthesis at each wavelength of light
Both display two main peaks, what the colors they peak at and what is their number?
a larger peak at the blue region (~450 nm) and a smaller peak at the red region (~670 nm)
what are the 2 steps of photosynthesis?
The light dependent reactions and The light independent reactions
what does The light independent reactions do?
use the chemical energy to synthesise organic compounds
what does The light dependent reactions do?
convert light energy from the Sun into chemical energy (ATP)
what comes first light dependent of light independent reactions?
Light Dependent Reactions comes first.
what happens in the the Light Dependent Reactions?
1) Light is absorbed by chlorophyll, which results in the production of ATP (chemical energy)
2) Light is also absorbed by water, which is split (photolysis) to produce oxygen and hydrogen
3) The hydrogen and ATP are used in the light independent reactions, the oxygen is released from stomata as a waste product
what happens in the the Light Independent Reactions?
1) ATP and hydrogen (carried by NADPH) are transferred to the site of the light independent reactions
2) The hydrogen is combined with carbon dioxide to form complex organic compounds (e.g. carbohydrates, amino acids, etc.)
3) The ATP provides the required energy to power these anabolic reactions and fix the carbon molecules together
what is photolysis?
chemical process by which molecules are broken down into smaller units through the absorption of light
name 3 pigments
chlorophylls, xanthophyll and carotenes
what is Chromatography?
Chromatography is an experimental technique by which mixtures can be separated
what are the 3 limiting factors on the rate of photosynthesis?
temperature, light intensity and CO2 concentration
how is temperature a limiting factor?
- Photosynthesis is controlled by enzymes, which are sensitive to temperature fluctuations
- As temperature increases reaction rate will increase
how is light intensity a limiting factor?
- Light is absorbed by chlorophyll, which convert the radiant energy into chemical energy (ATP)
- As light intensity increases reaction rate will increase
how is CO2 concentration a limiting factor?
- Carbon dioxide is involved in the fixation of carbon atoms to form organic molecules
- As carbon dioxide concentration increases reaction rate will increase
where do Light Dependent Reactions occur?
discs within the chloroplast called thylakoids
what are the 3 steps of the Light Dependent Reactions?
1) Excitation of photosystems by light energy
2) Production of ATP via an electron transport chain
3) Reduction of NADP+ and the photolysis of water
what is Cyclic Photophosphorylation?
Cyclic photophosphorylation involves the use of only one photosystem (PS I) and does not involve the reduction of NADP+
what is Non-Cyclic Photophosphorylation?
Non-cyclic photophosphorylation involves two photosystems (PS I and PS II) and does involve the reduction of NADP+
where does The light independent reactions occur?
fluid-filled space of the chloroplast called the stroma
what is the light independent reactions also known as?
the calvin cycle
what are the 3 main steps of the calvin cycle?
1) Carbon Fixation
2) Reduction of Glycerate-3-Phosphate
3) Regeneration of RuBP
what happens in carbon fixation?
An enzyme, RuBP carboxylase (or Rubisco), catalyses the attachment of a CO2 molecule to RuBP
what happens in Reduction of Glycerate-3-Phosphate?
Reduction by NADPH transfers hydrogen atoms to the compound, while the hydrolysis of ATP provides energy
what happens in Regeneration of RuBP (Rubisco)?
Of the six molecules of TP produced per cycle, one TP molecule may be used to form half a sugar molecule
Name 5 structure of the chloroplast
Thylakoids Grana Photosystems Stroma Lamellae
what does the stroma do?
central cavity that contains appropriate enzymes and a suitable pH for the Calvin cycle to occur
