M5 C17: Energy for Biological Processes Flashcards
what is the law of energy?
energy cant be created or destroyed
where does energy come from for metabolic reactions in producers?
radiation from the sun is converted into chemical energy
what is the respiration equation?
C6H12O6 + 6O2 → 6CO2 + 6H2O
what is the photosynthesis equation?
6CO2 + 6H20 → C6H12O6 + 6O2
What is the purpose of photosynthesis?
to make glucose by converting inorganic substances to organic substances
what is the purpose of respiration?
to produce atp for metabolic processes
converts organic substances to inorganic
when is energy released?
when bonds are formed
when is energy absorbed?
when bonds are broken
what is an exothermic reaction?
overall reaction releases more energy (more bonds made)
what is an endothermic reaction?
overall reaction absorbs more energy (more bonds broken)
autotrpohic?
organism that can produce own food using inorganic materials
heterotrophic?
cant make its own food rely on other organisms
photosynthesis?
where plants make glucose out of CO2 and light
chlorophyll?
makes a plant green captures light in photosynthgesis
choloplast?
site of photodynthesis
what is a pigment?
natural coloring matter of animals or plant tissue absorb wavelengths of light. Molecules that absorb specific wavelengths of light.
where does the light dependent reaction occur in the chloroplast?
occurs in the thylakoid membranes and the thylakoid spaces (the spaces inside the thylakoids)
photosystems
Protein complexes involved in the absorption of light and electron transfers in photosynthesis.
Non-cyclic photophosphorylation
The synthesis of ATP and reduced NADP involving photosystems I and II.
Cyclic photophosphorylation
The synthesis of ATP involving only photosystem I.
No reduced NADP produced .
what do photosystems contain?
Location of other pigments such as chlorophyll b, xanthophylls and carotenoids. Also called a light harvesting system
reaction centre
what pigment is in the reaction system?
Location of chlorophyll a
what is another name for the pigments not in the reaction centre?
(in the light harevesting system)
accessory pigments
antenna pigments
what wavelength of light does chlorophyll absorb?
mainly blue and red light and reflects green (why plants appear green).
Different combinations of pigments are the reason for different shades and colours of leaves.
what happens in the light dependent reaction?
(briefly)
energy from sunlight is absorbed and is used to form ATP. Hydrogen from water is used to reduce coenzyme NADP to reduced NADP.
what is the first step of the light dependent reaction
light absorbed by PSII excites electrons that are released from the reaction centre of the photosystem.
ATP is then produced by chemiosmosis.
what is chemisosmosis?
diffusion of protons from a region of high concentration to a region of low concentration through a partially permeable membrane due to energy from electrons moving down electron carriers.
protons then move back through atp synthase to releases energy to attach an inorganic phosphate to ADP as they do, forming ATP.
what happens after chemiosmosis in PSII?
ligh excited electrons which are then released from the reaction centre at PSI these are passed to another electron transport chain, again producing ATP by chemiosmosis.
Electrons leaving this electron transport chain are accepted by the coenzyme NADP along with a hydrogen ion to form reduced NADP.
how are electrons replaced in PSII
replaced by the splitting of water into hydrogen ions, electrons andoxygen molecules using energy from the sun-photolysis.
how are electrons replaced in PSI?
replaced by electrons that have just travelled along the first electron transport chain after being released from PSII.
what is a waste product of the light dependent reaction?
O2
what substances from the light dependent reactions reduce NADP?
excited electrons from PSI and hydrogen ions from photolysis of water combine to reduce NADP
what happens in the light independent stage?
takes place in the stroma and uses carbon dioxide and the products from the light-dependent stage (ATP and reduced NADP).
what does carbon dioxide do when entering the calvin cycle?
CO2 and RuBP (5C) join together making an unstable intermediate 6C compound
what catalyses the reaction between CO2 and RuBP?
RuBisCO (ribulose bisphosphate carboxylase)
what happens after the unstable intermediate has been formed in the calvin cycle?
This breaks down to form X2 3C molecules called GP
what happens once GP is formed in the calvin cycle?
GP is turned into TP, using energy from NADPH and ATP
What is TP used for?
1 TP is used to make glucose; 5 TPs are recycled to regenerate RuBP, which requires ATP
what happens in carbon fixation/
carbon is ‘fixed’ to RuBP from carbon dioxide
what happens in reduction?
GP is reduced to form TP due to ATP and NADPH
what happens in regeneration?
5/6 of the TP molecules are used to regenerate RuBP which requires ATP releasing energy
what are some examples of biological molecules TP can syntheise/
glucose
sucrose
amino accids
when does photorespiration happen?
Photorespiration occurs when carbon dioxide levels fall and oxygen levels increase.
what is photorespiration?
when plants consume oxygen and release carbon dioxide during photosynthesis, resulting in a decrease in photosynthetic output.
caused by the enzyme RuBisCO adding oxygen to a sugar instead of carbon dioxide during normal photosynthesis reducing efficiency
how does light intensity affect photosynthesis?
light is needed as an energy source
as it increases ATP and NADPH is produced quicker therefore it can be used in calvin cycle
less light= less atp and nadph so more GP
how does carbon dioxide concentration affect photosynthesis?
increase in CO2 means carbon fixation can happen faster and more GP can be produced? TP
What effect does temperature have on photosynthesis?
increases rate of enzyme activity until they denature. this can include carbon fixation
what is a negative effect of high temperatures?
when plants undergo dry spells, closure of stomata stops CO2 coming in, so carbon fixation can’t occur
