C5 - PHOTOSYNTHESIS AND RESPIRATION Flashcards
photosynthesis, respiration, energy transfer and nutrient cycles
why is energy important
- plants and animals need energy for biological processes to occur
- plants need energy for photosynthesis, active transport, DNA replication, cell division and protein synthesis
- animals need energy for muscle contraction, maintaining body temperature, active transport, DNA
what is the process of photosynthesis
- the process where ENERGY from LIGHT is used to make GLUCOSE from WATER and CARBON DIOXIDE
- the LIGHT ENERGY is converted to CHEMICAL ENERGY in the form of GLUCOSE (c6h12o6)
- ENERGY is stored in the GLUCOSE until the PLANTS release it by RESPIRATION
- ANIMALS obtain GLUCOSE by eating PLANTS (or by eating other animals, which have eaten plants), then RESPIRE the GLUCOSE to RELEASE ENERGY
what is the chemical equation for photosynthesis
6CO2 + 6H2O + energy -> C6H12O6 + 6O2
what is photosynthesis an example of
a metabolic pathway, the process occurs in a series of small reactions controlled by enzymes
how do plants and animal cells release energy from glucose
respiration
what is the energy from respiration used for
- used to power all the biological processes in a cell
what would happen to these biological processes (ex, photosynthesis and respiration) if there was no energy
they would stop and the plant/animal would die
what are the 2 types of respiration
aerobic and anaerobic respiration
what is the difference between aerobic and anaerobic respiration
aerobic respiration uses oxygen
what is aerobic respiration
respiration using oxygen
what is anaerobic respiration
respiration without oxygen
what is the chemical equation for aerobic respiration
C6H12O6 + 6O2 -> 6CO2 + 6H20 + energy
what is the purpose of anaerobic respiration
- in plants and yeast -> produces ethanol and carbon dioxide and releases energy
- in humans -> produces lactate and releases energy
what are aerobic and anaerobic respiration both an example of
metabolic pathways
what is the name of any organism that carries out photosynthesis
- photoautotroph (an organism that can make its own food using light energy)
- the process of photosynthesis is the SAME in ALL photoautotrophs -> suggests that they all evolved from a COMMON ANCESTOR
is energy created, destroyed or neither?
- energy is never created or destroyed
- energy is always converted from one form to another
- ex, (in photosynthesis) light energy is converted to chemical energy (glucose) and this energy is used to fuel biological processes
what is ATP
- adenosine triphosphate
- the immediate source of energy in a cell
what is the purpose of ATP
- a cell cant get its energy directly from glucose, so in RESPIRATION the energy released from GLUCOSE is used to make ATP
- it carries energy AROUND the cell to where its needed
what is ATP made of
- nucleotide base ADENINE
- RIBOSE sugar (pentose sugar)
- 3 phosphate groups
how is ATP formed
- ATP is SYNTHESISED via a CONDENSATION REACTION between ADP and Pi, using energy from an energy-releasing reaction (like the breakdown of glucose in respiration)
- the energy is stored as CHEMICAL ENERGY in a PHOSPHATE BOND
- the enzyme which catalyses this ^ reaction is ATP SYNTHASE (synthase = synthesise = joins)
what is phosphorylation
- ADDING phosphate to a molecule
- ex, ADP is PHOSPHORYLATED to ATP
- ATP then diffuses to the part of the cell that NEEDS energy
- CHEMICAL ENERGY is RELEASED from the PHOSPHATE BOND and USED by the CELL
- the enzyme which CATALYSES this ^ reaction is ATP HYDROLASE (hydrolase = hydrolyse = break)
describe the properties of ATP
- stores/releases only a SMALL, manageable amount of energy at a time, so NO energy is WASTED as HEAT
- its a SMALL and SOLUBLE molecule, so it can be EASILY TRANSPORTED around the cell
- EASILY BROKEN DOWN = energy can be released INSTANTLY
- it can be quickly REMADE
- it can make other molecules more REACTIVE through transferring one of its Pi groups to them (PHOSPHORYLATION)
- ATP can’t pass out of the cell = cell always has an IMMEDIATE supply of ENERGY
what processes do plants both carry out
photosynthesis and respiration
how do the plants carry out both processes
- can occur at the same time
- can occur at different rates
the rate of photosynthesis is partly dependent on?
the LIGHT INTENSITY of the ENVIRONMENT the plant is in
what is the compensation point for light intensity
the particular level of LIGHT INTENSITY at which the rate of photosynthesis exactly MATCHES the rate of respiration
how can the compensation point for a plant be worked out
- to measure the rate at which OXYGEN is PRODUCED and USED by a plant at DIFFERENT LIGHT INTENSITIES
- because photosynthesis PRODUCES O2 and RESPIRATION USES O2, the compensation point is the light intensity at which oxygen is being USED as quickly as it is PRODUCED
- the rate of CO2 production and use could also be measured because photosynthesis USES CO2 and respiration PRODUCES it
where does photosynthesis take place
the chloroplasts
what is the first reaction that takes place in photosynthesis
the light dependent reaction/LDR
describe the structure of chloroplasts
- small + flattened organelles
- surrounded by a double membrane
- thylakoids (fluid filled sacs) are stacked up -> forms grana
- a single grana = granum
- the grana are linked together by lamellae (bits of thylakoid membrane)
- a single lamellae = lamella
- photosystems are contained within the inner membrane of the chloroplast
- stroma ( a gel like substance) surrounds the thylakoids
- stroma contains enzymes, sugars and organic acids
- carbohydrates that are produced by photosynthesis, but not used immediately, are stored as STARCH GRAINS in the stroma
what do chloroplasts contain which absorb the light energy needed for photosynthesis
- photosynthetic pigments
what photosynthetic pigments do chloroplasts contain and what is their purpose
- chlorophyll a
- chlorophyll b
- carotene
- they are coloured substances that absorb the light energy needed for photosynthesis
- the pigments are found in THYLAKOID MEMBRANES
- they are attached to proteins = protein and pigment is called a PHOTOSYSTEM
- there are 2 photosystems used by plants to capture light energy, PSI and PSII
- PSI = photosystem I
- absorbs light best at a wavelength of 700 nm
- PSII = photosystem II
- absorbs light best at a wavelength of 680 nm
what are redox reactions
- reactions that involve OXIDATION and REDUCTION
- they occur in photosynthesis and respiration
- if something is REDUCED, it has GAINED ELECTRONS and may have GAINED HYDROGEN or LOST OXYGEN
- if something is OXIDISED, it has LOST ELECTRONS and may have LOST HYDROGEN or GAINED OXYGEN
- oxidation of one molecule ALWAYS involved the reduction of another molecule
what are coenzymes
- coenzyme = a molecule that aids the function of an enzyme
- work by transferring a chemical group from one molecule to another
- a coenzyme used in PHOTOSYNTHESIS = NADP
- NADP transfers HYDROGEN from one molecule, to another = it can REDUCE (give H to) or OXIDISE (take H from) a molecule
what are the 2 stages which make up photosynthesis
- the light dependent reaction/LDR
- the light independent reaction/LIR
what happens in the light dependent reaction
- reaction NEEDS light energy
- takes place in the thylakoid membranes of the chloroplasts
- light energy is absorbed by chlorophyll, and other photosynthetic pigments, in the photosystems
- the light energy excites the ELECTRONS in the chlorophyll, giving them MORE ENERGY = eventually causes the, to LEAVE the chlorophyll molecule
- ^ this process is PHOTOIONISATION
- chlorophyll is now a POSITIVELY CHARGED molecule
- some of the energy from the RELEASED ELECTRONS is used to add a Pi to ADP, forming ATP
- some of the energy from the RELEASED ELECTRONS is used to reduce NADP, forming reduced NADP/NADPH
- ATP transfers energy and NADPH transfers hydrogen to the LIR
- during the process, H2O is OXIDISED to O2
the energy resulting from the photoionisation of chlorophyll, in the LDR, is used for what?
- making ATP from ADP and Pi, called photopohsphorylation (process of adding phosphate to a molecule using light)
- making NADPH from NADP
- splitting water into protons (H+ ions/hydrogen ions), electrons and oxygen
- this is called photolysis (splitting of a molecule using light energy)
what are the products of the LDR
- ATP
- NADPH/ reduced NADP
- H ions
- oxygen
what are the 2 types of photophosphorylation that take place in the LDR
- non cyclic photophosphorylation
- cyclic photophosphorylation
describe the process of non-cyclic photophosphorylation
basics
- produces ATP, NADPH and O2
- photosystems are linked by ELECTRON CARRIERS (proteins that transfer electrons)
- photosystems and electron carriers form an ELECTRON TRANSPORT CHAIN (a chain of proteins through which excited electrons flow)
- multiple processes going on simultaneously in non-cyclic photophosphorylation
light energy excited electrons in chlorophyll
- light energy absorbed by PSII
- light energy excited electrons in chlorophyll
- the electrons move to a HIGHER energy level (have MORE energy)
- these high energy electrons are RELEASED from the chlorophyll, they then move down the ETC to PSI
photolysis of water produces protons, electrons and oxygen
- because the excited electrons leave the chlorophyll (and go to PII via the ETC), they must be replaced
- light energy splits water into protons (H+ ions), electrons and oxygen = PHOTOLYSIS
- equation = H2O -> 2H + 1/2 O2
- the electrons from photolysis ^ here, replace the electrons lost in photoionisation
energy from the excited electrons makes ATP
- the excited electrons LOSE energy as they move DOWN the ETC and this energy is used to transport protons (H+ ions) into the THYLAKOID (so the thylakoid has a HIGHER CONC of PROTONS than the STROMA)
- ^ this forms a proton gradient across the THYLAKOID MEMBRANE
- protons move DOWN their conc gradient, into the stroma, via enzyme ATP SYNTHASE (which is embedded in the thylakoid membrane)
- the energy from this movement combined ADP and Pi, forming ATP
energy from the excited electrons generates NADPH
- light energy is absorbed by PSI, which excites the electrons again to an even HIGHER energy level
- finally, the electrons are transferred to NADP along with a proton (H+/hydrogen ion) from the STROMA to form NADPH
describe chemiosmotic theory
- chemoiosmosis = the process of electrons flowing DOWN the ETC and creating a PROTON GRADIENT across the membrane to drive ATP synthesis
- ^ this process is described by the chemiosmotic theory
describe the process of cyclic photophosphorylation
- produces ATP
- only uses PSI
- called ‘cylic’ because the electrons from the chlorophyll molecule aren’t passed onto NADP, instead they are passed back to PSI via electron carriers
- ^ this means the electrons are RECYCLED flow through PSI
- this process doesn’t produce any NADPH or O2
- only produces small amounts of ATP
how is ATP formed in non-cyclic and cyclic photophosphorylation
by the movement of protons across the thylakoid membrane
describe the light independent reaction/the calvin cycle
- this reaction does NOT use light energy directly
- it DOES rely on the products of the LDR
- takes place in the stroma
- the ATP and NADPH from the LDR supplies the energy and hydrgogen to make GLUCOSE from CO2
describe the basics of the calvin cycle/light independent reaction
- takes place in the stroma
- makes triose phosphate (TP), from CO2 and ribulose bisphosphate (5 carbon compound)
- TP can be used to make glucose and other useful organic substances
- few steps in the cycle
- needs H+ ions to keep it going
- RuBP is regenerated
describe what takes place in the calvin cycle/LIR in detail
formation of glycerate 3-phosphate
- CO2 enters the leaf through the stomata and diffuses into the stomata of the chloroplast
- it is combined with RuBP, this reaction is catalysed by rubisco (enzyme)
- ^ this produces a 6 carbon compound
- the unstable 6 C compound quickly breaks down into 2 molecules of a 3 C compound, called GLYCERATE PHOSPHATE (GP, has 3 C each)
formation of triose phosphate
- the hydrolysis of ATP (from the LDR) provides energy to reduce GP to TP, which is a different 3C compound
- ^ this reaction also requires H+ ions (reduction reaction), which come from NADPH (from the LDR)
- NADPH is recycled to NADP
- some TP is converted into useful organic compounds, like GLUCOSE, and some continues in the calvin cycle to REGENERATE RuBP
regeneration of RuBP
- 5/6 molecules of TP in the cycle are used to regenerate RuBP, instead of making useful organic compounds
- regenerating RuBP uses the rest of the ATP produces by the LDR
what are hexose sugars
- simple 6 carbon sugars, like glucose
- one hexose sugar is made by joining 2 MOLECULES OF TP
- hexose sugars can be used to make larger carbohydrates
how many times does the cycle have to turn to produce a molecule of glucose
- 6 times
- ^ this is because, 3 turns of the cycle produces 6 molecules of TP (2 molecules of TP are made for every 1 molecule of CO2 molecule used)
- 5/6 of TP molecules are used to REGENERATE RuBP
- ^ this means that for 3 turns of the cycle, only 1 TP molecule is produced that is USED TO MAKE A HEXOSE SUGAR
- a HEXose sugar has 6 carbons, so 2 TP molecules are needed to form 1 hexose sugar
- the cycle must turn 6 times to produce 2 molecules of TP, that can be used to make 1 hexose sugar
- 6 turns of the cycle require = 18 ATP molecules and 12 NADPH molecules from the LDR
- ^ this may seem inefficient, however it allows the cycle to continue and also ensures that there’s always enough RuBP ready to combine with CO2, taken in from the atmosphere
how is TP and GP used to make carbohydrates
- hexose sugars are made from 2 TP molecules
- larger carbohydrates (sucrose, starch, cellulose) are made by joining hexose sugars together in different ways
how is TP and GP used to make lipids
- these are made using glycerol, which is SYNTHESISED from TP
- fatty acids are SYNTHESISED from GP
how is TP and GP used to make amino acids
some amino acids are made from GP
summarise the calvin cycle into inputs and outputs
inputs
- CO2
- ATP
- NADPH
outputs
- organic substances (ex, glucose)
- RuBP
list the limiting factors in photosynthesis
- light intensity
- temperature
- CO2 concentration
- water
how is high light intensity of a certain wavelength an optimum condition for photosynthesis
- light is needed to provide the energy for LDR
- the higher the intensity of the light, the more energy it provides
- only CERTAIN wavelengths of light are used for photosynthesis
- the photosynthetic pigments chlorophyll a, chlorophyll b and carotene only absorb the RED and BLUE light in sunlight
how is a temperature of around 25 degrees celsius an optimum condition for photosynthesis
- photosynthesis involved enzymes, ATP synthase and rubisco
- if the temp falls BELOW 10 degree cel, the enzymes may become INACTIVE
- if the temp goes above 45 degrees cel, the enzymes may start to DENATURE
how is a CO2 level of 0.4% an optimum condition for photosynthesis
- CO2 makes up 0.04% of the gases in the atmosphere
- increasing this to 0.4% gives a higher rate of photosynthesis
- any higher than this rate will cause the stomata to start to close
how is a constant water supply an optimum condition for photosynthesis
- plants need a constant water supply
- too little water = photosynthesis
- too much water = soil becomes WATERLOGGED, which reduces the uptake of minerals like magnesium, which is needed to make chlorophyll a
list and explain the limiting factors of photosynthesis
- light
- temperature
- carbon dioxide
- if any one of these ^ factors are too low or high, it will LIMIT photosynthesis, even if the other 2 factors are at the optimum level
how agricultural growers, like farmers, create an environment which has the right amount of everything needed
- the right amount of everything increases growth, and therefore increases yield
- growers create optimum conditions in GLASSHOUSES
CO2 CONCENTRATION
- carbon dioxide is added to the air
- ex - by burning a small amount of PROPANE in a CO2 generator
LIGHT
- light can get in through the glass
- at night time, lamps provide light
TEMPERATURE
- glasshouses trap heat energy from sunlight, which warms the air
- heaters and cooling systems can also be used to keep a CONSTANT OPTIMUM TEMP
- air circulation systems ensure the temp us even throughout the glasshouse
what is the purpose of respiration
it is the process which allows cells to produce ATP from glucose
what are the 2 types of respiration
- aerobic respiration (with oxygen)
- anaerobic respiration (without oxygen)
compare aerobic respiration and anaerobic respiration
- respiration can be done with O2 (aerobic), and without O2 (anaerobic)
- both types of respiration produce ATP, but anaerobic respiration produces LESS ATP
- both start with glycolysis, however the stages after glycolysis differ
what is the structure of the mitochondria and how does this relate to respiration
- the reactions in aerobic respiration take place in the mitochondria
- the CRISTAE in the inner membrane (the folds) = provide a LARGE SA = MAXIMISES RESPIRATION
what are coenzymes and what are the coenzymes in respiration and what is their purpose
- a coenzyme = a molecule that aids the function of an enzyme, by transferring a chemical group from one molecule to another
- the coenzymes in respiration = NAD, coenzyme A and FAD
- NAD + FAD = can reduce or oxidise a molecule
- coenzyme A = transfers ACETATE between molecules
what are the 4 stages in aerobic respiration
- glycolysis
- the link reaction
- the krebs cycle
- oxidative phosphorylation
summarise the roles of each stage in aerobic respiration
- the first 3 stages are a SERIES OF REACTIONS
- the products from these ^ reactions are used in the final stage
- the first stage, glycolysis, happens in the CYTOPLASM of cells
- the other 3 stages take place in the MITOCHONDRIA
what does respiration produce and how are these products used
- GLUCOSE can be used as a RESPIRATORY SUBSTRATE in BOTH aerobic and anaerobic respiration
- glucose isn’t the only respiratory substrate that can be used in aerobic respiration
- some products resulting from the breakdown of other molecules, like fatty acids from lipids and amino acids from proteins, can be CONVERTED INTO MOLECULES WHICH CAN ENTER THE KREBS CYCLE, usually acetyl CoA
what steps are in anaerobic respiration
- doesn’t involve the link reaction, krebs cycle or oxidative phosphorylation
- the products of glycolysis are converted to ETHANOL or LACTATE instead
what happens in glycolysis - basics
- glycolysis makes PYRUVATE from GLUCOSE
- glycolysis involves splitting ONE molecule of GLUCOSE (6C) into TWO smaller molecules of PYRUVATE (3C)
- process takes place in the cytoplasm of cells
- glycolysis is the first stage of BOTH aerobic and anaerobic respiration
- doesn’t need O2 to take place, therefore it is an ANAEROBIC PROCESS
- the 2 stages in glycolysis are phosphorylation and oxidation
describe what happens in glycolysis - in detail
PHOSPHORYLATION
- glucose is phosphorylated using a phosphate molecule from ATP
- this ^ creates 1 molecule of GLUCOSE PHOSPHATE + 1 molecule of ADP
- ATP is then used to add ANOTHER Pi, forming HEXOSE BIPHOSPHATE
- hexose biphosphate is then split into 2 molecules of TRIOSE PHOSPHATE
OXIDATION
- TP is oxidised (loses hydrogen), this forms 2 molecules of PYRUVATE
- NAD collects the H+ ions, forming 2 NADH/reduced NAD
- 4 ATP are produced, but 2 ATP were used in stage 1 (phosphorylation), therefore there is a NET GAIN of 2 ATP
name all the products of glycolysis and where they go to (in aerobic respiration)
- 2 NADH/reduced NAD = to OXIDATIVE PHOSPHORYLATION
- 2 pyruvate = actively transported into the mitochondrial matrix for use in the link reaction
- 2 ATP (net gain) = used for energy
why does glycolysis take place in the cytoplasm
- glucose cant cross the outer mitochondrial membrane
- pyruvate can cross this membrane, so the rest of the aerobic respiration occur within the mitochondria
what are the products of glycolysis in anaerobic respiration
- in anaerobic respiration, the PYRUVATE produced in glycolysis is converted into ethanol (alcoholic fermentation) or lactate (lactate fermentation) using NADH
ALCOHOLIC FERMENTATION
- this occurs in PLANTS and YEAST
- pyruvate is DECARBOXYLATED, which forms ETHANAL
- ethanal is REDUCED by NADH, which becomes NAD, and this forms ETHANOL
LACTATE FERMENTATION
- this occurs in animal cells and some bacteria
- pyruvate is reduced, to form lactate/lactic acid
- it is reduced by NADH, so it also forms NAD
- the production of lactate or ethanol regenerates oxidised NAD
- this ^ means glycolysis can CONTINUE even when there isn’t much oxygen around, so a small amount of ATP can still be produced to keep some biological processes going
what happens in the link reaction
- the link reaction converts the pyruvate (produced in glycolysis) to ACETYL COENZYME A
- pyruvate DECARBOXYLATED, so one carbon atom is removed from the PYRUVATE in the form of CO2
- at the same time, pyruvate is OXIDISED to form ACETATE and NAD is reduced to form NADH
- acetate is combined with CoA to form ACETYL COEZYME A
- NO ATP IS FORMED IN THIS REACTION
how many times does the link reaction need to occur per glucose molecule
- 2 pyruvate molecules are made per glucose molecule which enters glycolysis
- link reaction and the krebs cycle happen TWICE for every glucose molecule
what are the products of a single link reaction, and of 2 link reactions (which is for every glucose molecule) and where to they go
1 link reaction
- 1 acetyl CoA
- 1 CO2
- 1 NADH
2 link reactions, per glucose mol
- 2 acetyl CoA
- 2 CO2
- 2 NADH
- the 2 acetyl CoA go to the KREBS CYCLE
- the 2 CO2 are released as a waste product
- the 2 NADH go to the oxidative phosphorylation
what is the krebs cycle - basics
- produces reduced coenzymes and ATP
- involves a series of oxidation-reduction/redox reactions, which take place in the MATRIX
- cycle happens ONCE for every pyruvate molecule
what happens in the krebs cycle - detailed
FORMATION OF A 6C COMPOUND
- acetyl coA (from the link reaction) combined with a 4C molecule (oxaloacetate) to form a 6C compound (citrate)
- CoA goes back to the link reaction to be used again
FORMATION OF A 5C COMPOUND
- the 6C compound is converted to 5C
- DECARBOXYLATION occurs, where CO2 is removed
- DEHYDROGENATION also occurs, the H is used to produce NADH from NAD
REGENERATION OF OXALOACETATE
- the 5C molecule is converted to a 4C molecule
- decarboxylation and dehydrogenation occur = this produces 1 molecule of FADH + 2 molecules of NADH
- ATP is produced by the direct transfer of a phosphate group from an INTERMEDIATE COMPOUND to ADP
- when a phosphate group is directly transferred from one molecule to another, its called SUBSTRATE-LEVEL PHOSPHORYLATION
- citrate has now been converted to oxaloacetate
how many krebs cycles take place per glucose molecule
2
how many products per 1 krebs cycle and where do they go
- 1 CoA -> reused in the next link reaction
- oxaloacetate -> regenerated for use in the next krebs cycle
- 2 CO2 -> released as a waste product
- 1 ATP -> used for energy
- 3 NADH -> to oxidative phosphorylation
- 1 FADH -> to oxidative phosphorylation
what is oxidative phosphorylation - basics
- the process where the energy carried by electrons, from reduced coenzymes (NADH and FADH), is used to MAKE ATP
- the whole point of the previous stages stages is to make NADH and FADH for the final stage
- oxidative phosphorylation involves the electron transport chain and chemiosmosis
describe the process of oxidative phosphorylation
STEP 1
- hydrogen atoms are released from NADH and FADH as they are oxidised to NAD and FAD
- the H atoms are split into protons (H+) and electrons (e-)
STEP 2
- the electrons move DOWN the ETC (made of electron carriers), LOSING ENERGY at each carrier
STEP 3
- this energy is used by the electron carriers to pump protons from the MITOCHONDRIAL MATRIX into the INTERMEMBRANE SPACE (the space between the inner and outer mitochondrial membranes)
STEP 4
- the concentration of protons is now HIGHER in the INTERMEMBRANE space than in the MITOCHONDRIAL MATRIX - this forms an ELECTROCHEMICAL GRADIENT (a conc gradient of ions)
STEP 5
- protons then move down the electrochemical gradient, back across the inner mitochondrial matrix, via ATP synthase (which is embedded in the inner mitochondrial membrane)
- this movement drives the synthesis of ATP from ADP and Pi
STEP 6
- this process of ATP production driven by movement of H+ ions across a membrane (due to electrons moving down an ETC) is called CHEMIOSMOSIS
STEP 7
- in the mitochondrial matrix, at the end of the ETC, the protons (H+), electrons and oxygen (from the blood) combine to form WATER
- oxygen is said to be the FINAL ELECTRON ACCEPTOR
how much ATP is made from each NADH and each FADH
- 2.5 ATP are made from each NADH
- 1.5 ATP are made from each FADH
how many molecules of ATP are made from 1 molecule of glucose in aerobic respiration in a cell
32 ATP
name the stage of respiration, molecules produced and number of ATP molecules a cell can make from 1 mol of glucose in AEROBIC RESPIRATION
- glycolysis, 2 ATP mols produced , 2 ATP mols produced
- glycolysis, 2 NADH mols produced, 5 ATP mols produced
- link reaction x2, 2 NADH mols produced, 5 ATP mols produced
- krebs cycle x2, 2 ATP mols produced (net)
- krebs cycle x2, 6 NADH mols produced, 15 ATP mols produced
- krebs cycle x2, 2 FADH mols produced, 3 ATP mols produced
- total ATP produced per glucose mol = 32 ATP mols
summarise aerobic respiration
- glycolysis, link reaction and the krebs cycle are basically a series of reactions which produce ATP, NADH, FADH and CO2
- the reduced coenzymes, NADH and FADH, are then used in oxidative phosphorylation, to produce more ATP
what are mitochondrial diseases
- ATP production can be affected by mitochondrial diseases
- mitochondrial diseases affect the functioning of mitochondria
- they can affect how proteins involved in oxidative phosphorylation or the krebs cycle function, reducing ATP production
- this may cause anaerobic respiration to increase, to try and make up some of the ATP shortage
- this results in lots of lactate being produced, which can cause muscle fatigue and weakness
- some lactate will also diffuse into the bloodstream, leading to high lactate concentration in the blood
what are the basics of ecosystems
- an ecosystem includes all the ORGANISMS in a particular area and all the ABIOTIC (non-living) CONDITIONS
- in all ecosystems, there are PRODUCERS (organisms which make their own food)
- ex, in land based ecosystems, plants (like trees) produce their own food through PHOTOSYNTHESIS
- during photosynthesis, plants use ENERGY, from sunlight, and CO2, from the atmosphere in land based ecosystems/dissolved in water in aquatic ecosystems, to make GLUCOSE and OTHER SUGARS
- some of the sugars produced during photosynthesis are used in RESPIRATION, to release energy for growth
- the rest of the glucose is used to make OTHER BIOLOGICAL MOLECULES, like CELLULOSE (a component of plant cell walls)
- these biological molecules make up the plants BIOMASS (the mass of living material, can be thought of as the chemical energy stored in the plant)
- energy is transferred through the living organisms of an ecosystem when organisms eat other organisms (think of this as an energy passing system)
- ex, producers are eaten by PRIMARY CONSUMERS, who are eaten by SECONDARY CONSUMERS and they are consumed by TERTIARY CONSUMERS (this is a FOOD CHAIN)
how is biomass measured
- biomass can be measured in terms of the MASS OF CARBON than an organism contains or the dry mass of its tissue per unit area
- dry mass is the mass of the organism with the WATER REMOVED
- the water content of living tissue varies, so dry mass is used as a measure of biomass, instead of wet mass
- to measure the dry mass, a sample of the organism is DRIED, often in an oven at a low temp
- the sample if then weighed at regular intervals (everyday for ex)
- once the mass becomes constant, you can be sure all the water has been removed
- the mass of carbon present is usually 50% of the dry mass
- once the dry mass of the sample has been measured, it can be scaled up to give the biomass/dry mass of the total population or area being investigated
- typical units may be kg,m-2
what is a calorimetry and what is its purpose
- you can estimate the amount of CHEMICAL ENERGY stored in BIOMASS by BURNING THE BIOMASS IN A CALORIMETER
- the amount of heat given off tells you how much energy is in it
- energy is measured in joules or kilojoules
- a sample of dry biomass is burnt and the energy released is used to heat a known volume of water
- the change in temperature of the water is used to calculate the chemical energy of the dry biomass
what is primary production and its formula
- gross primary production is the TOTAL AMOUNT OF CHEMICAL ENERGY CONVERTED FROM LIGHT ENERGY BY PLANTS, IN A GIVEN AREA
- around 50% of the GPP is LOST TO THE ENVIRONMENT AS HEAT, when the plants respire : RESPIRATORY LOSS (R)
- the remaining chemical energy is called the NET PRIMARY PRODUCTION (NPP)
FORMULA
- NPP = GPP - R
- often, primary production is expressed as a rate (the total amount of chemical energy/biomass in a given area, in a given time
- typical units may be kJ ha-1 yr-1 (kilojoules per hectare per year) OR kj m-2 yr-1 (kilojoules per square metre per year)
- when primary production is expressed as a rate, it is called PRIMARY PRODUCTIVITY
- the NPP is the energy available to the plant for growth and reproduction, the energy stored in the plants biomass
- it is also the energy available to the organisms at the next stage in the food chain (the next trophic level), these include herbivores and decomposers
what is net production in consumers
- consumers also store chemical energy in their biomass
- consumers get energy by INGESTING PLANT MATERIAL or ANIMALS THAT HAVE EATEN PLANT MATERIAL
- however, not all the chemical energy stored in the consumers food is transferred to the next trophic level, around 90% of available energy is LOST in various ways
- not all food is eaten (ex, bones) so the energy it contains is NOT taken in
- for all the parts that ARE ingested, some are indigestible and egested as faeces and the chemical energy stored in these parts is lost to the environment
AND some energy is lost to the env through RESPIRATION to EXCRETION OF URINE - the energy thats left after all this is stored in the consumers biomass and IS available to the next trophic level, this energy is the consumers NET PRODUCTION
FORMULA
- N = I - (F+R)
- N = net production
- I = chemical energy in ingested food
- F = chemical energy lost in faeces and urine
- R = energy lost through respiration
- the net production of consumers can also be called SECONDARY PRODUCTION or SECONDARY PRODUCTIVITY when expressed as a RATE
what is the efficiency of energy transfer
FORMULA
- % efficiency of energy transfer = (net production of trophic level / net production of previous trophic level) x100
- as you move UP a food chain (producers ->consumers_
