photosynthesis Flashcards
overall chemical reaction for photosynthesis
6CO2 + 6H2O -> C6H12O6 + 6O2
overall chemical reaction for respiration
C6H12O6 + 6O2 -> 6CO2 + 6H2O
describe the relationship between photosynthesis and respiration
they are the reverse of eachother
explain the importance of photsynthesis for consumers as well as producers
important for consumers as well as producers because it traps the energy from the sun to be transferred through the food chain
what is bond energy?
the idea that bonds require energy to be broken but release energy when they form. small inorganic molecules release a lot of energy when formed. large organic molecules release little energy.
explain photosynthesis in terms of bond energy
a lot of energy is needed to break the bonds in CO2 and H2O but little is given out when glucose forms
explain respiration in terms of bond energy
requires little energy to break bonds in glucose but lots given out when CO2 and H2O form.
name the two stages of photosynthesis and state where each occurs.
1) light dependent stage within thykaloid membranes
2) light independent stage in the stroma
define photosynthetic pigment
a pigment that absorbs light energy
definelight harvesting system
a group of protein and chlorophyll molecules
antennae complex
another name for light harvesting system
define reaction centre
complex of proteins, pigments and cofactors
define photosystem
collevtive name for light harvesting system and reaction centre
name the photosynthetic pigment in the reaction centre of a photosystem
chlorophyll a
name 3 types of photosynthetic pigments found in antennae complex
chlorophyll b, xanthophylls and carotenoids
why is it useful for photosynthetic organisms to have many different photosynthetic pigments?
to absorb different wavelengths of light to maximise energy transferred to the reaction centre.
absorption spectrum graph
graph to show what wavelengths the different pigments absorb
e.g chlorophyll absorbs red and blue but reflects green wavelengths
what is the purpose of chromatography?
used to separate and identify substances
describe the method of thin layer chromatography to separate and identify photosynthetic pigments.
mobile phase is solution containing mixture of pigments. stationary phase is a thin layer of silica gel applied to glass
what does “Rf” stand for in “Rf value”
retention factor
how to calculate the Rf value
the distance the pigment travelled / distance of the solvent front
how to use Rf values to identify molecules present in a solution
Rf values compared to a table of known values to identify components
what determines how far a particular molecule travels in chromatography?
different solubilities and interactions with the stationary phase lead to different distances travelled