photosynthesis Flashcards
what is photosynthesis?
the process where energy from light is used to make glucose from H2O and CO2 in a series of reactions (the light energy is converted to chemical energy in the form of glucose)
what is the overall equation for photosynthesis?
6CO2 + 6H20 -> C6H12O6 + 6O2
what is a metabolic pathway?
a series of small reactions controlled by enzymes, e.g. respiration and photosynthesis
what is phosphorylation?
adding phosphate to a molecule, e.g. ADP is phosphorylated to ATP
what is photophosphorylation?
adding phosphate to a molecule using light
what is photolysis?
the splitting of a molecule using light energy
what is photoionisation?
when light energy ‘excites’ electrons in an atom or molecule, giving them more energy and causing them to be released. The release of electrons causes the atom or molecule to become a positively charged ion
what is hydrolysis?
the splitting of a molecule using water
what is a redox reaction?
reactions that involve oxidation and reduction
what is reduction?
gain of electrons, loss of oxygen or gain of hydrogen
what is oxidation?
loss of electrons, gain of oxygen or loss of hydrogen
what is the coenzyme involved in photosynthesis?
NADP
what is the role of NADP?
transfers hydrogen from one molecule to another can reduce or oxidise a molecule
where does photosynthesis occur?
in the chloroplasts
what are chloroplasts?
flattened organelle surrounded by a double membrane found in plant cells
what are thylakoids?
fluid filled sacs stacked up in the chlorophyll into structures called grana linked together by thylakoid membrane called lamellae
what are photosynthetic pigments?
coloured substances that absorb the light energy needed for photosynthesis, found in the thylakoid membranes attached to proteins e.g. chlorophyll a, chlorophyll b, and carotene
what is a photosystem?
the protein and pigment
what are the two photosystems?
photosystem II and photosystem I
what wavelength of light does photosystem I best absorb?
700 nm
what wavelength of light does photosystem II best absorb?
680 nm
what is the stroma?
a gel like substance that is contained within the inner membrane of the chloroplast and surround the thylakoid, contains enzymes, sugars, and organic acids, store carbohydrates produced in photosynthesis that aren’t used straight away as starch grains
what are the two stages of photosynthesis?
the light dependent reaction and the light independent reaction
what is the light dependent reaction?
requires light energy, takes place in the thylakoid membranes, light energy is absorbed by chlorophyll in the photosystems, light energy excites the electrons in the chlorophyll leading to their eventual release from the molecule, the chlorophyll has been photo ionised, some energy released from electrons is used to phosphorylate ADP to ATP, and some is used to reduce NADP to form reduced NADP, ATP transfers energy and reduced NADP transfers hydrogen to the LIDR, during this process H2O is oxidised to O2
what is the light independent reaction?
also called the calvin cycle, does not require light energy but relies on the products of the LDR, takes place in the stroma of the chloroplasts, ATP and reduced NADP supply the energy and hydrogen to make simple sugars from CO2