|The ability to do work
|Why are the units of energy?
|What does the body need energy for?
|Metabolism Movement Active transport Maintenance, repair, division Production of substances (enzymes etc.) Maintainance of body themperature
|How does energy flow through living systems?
|Light energy converted by plants to chemical energy (glucose) by photosynthesis Chemical energy is converted into ATP during respiration ATP used to do work
|Word equation for then hydrolysis of ATP
|Adenine triphosphate + water = Andenine disphosphate + inorganic phosphate (+ energy)
|Decribe how ATP is converted into ADP and ADP is converted into ATP
|ATP is hydrolysed into ADP and inorganic phosphate, the ADP is then condensened (phosphorylated) into ATP
|Name the three types of phosphorylation
|Photophosphorylation Oxidative phosphorylation Substrate level phosphorylation
|How are leaves adapted for photosynthesis
|Large surface area Thin (short diffusion pathway) Transparent cuticle Long upper mesophyll with lots of chloroplasts Stomta (gas exchange) Xylem (transport water to leaf)
|General equation for photosynthesis
|6carbon dioxide + 6water = Glucose + 6oxygen
|How are the chloroplasts structured?
|Grana = stacks of discs called thylakoids, connecting tubular extensions = lamellae. Stroma = fluid filled matrix, contain starch grains
|What occurs when chlorophyll absorb light?
|Elections are excited to higher energy level, these electrons leave the molecule and are taken up by an electron carrier
|When the chlorophyll loses electrons is it oxidised or reduced?
|How does the excitation of chlorophyll lead to ATP production?
|Electrons pass along a number of electron carriers, in a series or redox reactions, each carrier is at a lower energy level so the electrons lose energy at each stage this energy is used to synthesis ATP
|How is reduced NADP produced in the light dependent reaction?
|The photolysis of water produces the electrons needed to replace those lost in the chlorophyll, this also produces hydrogen ions which reduce NADP
|Equation for the photolysis of water:
|2Water (+light) = 4Hydrogen ions + 4Electrons + Oxygen
|Why is the photolysis of water needed during the light dependant reaction?
|To produce the electrons needed to replace those lost by the chlorophyll, also produces hydrogen ions to reduce NADP and oxygen
|Where does the light dependant reaction take place?
|Grana/Thylakoids of the chloroplasts
|How are the thylakoids adapted for their function (light dependant reaction)?
|Large surface area - for the attachment of chlorophyll, electron carriers and enzymes. Network of proteins, to hold chlorophyll in a way to maximise light absorption. Granal membranes contain enzymes for ATP synthesis. DNA and ribosomes - so chloroplasts can manufacture proteins needed
|How does carbon dioxide enter the chloroplast?
|Through the stomata of the leaf then into the stroma the chloroplast
|How is carbon dioxide used to produce organic molecules (glucose) and regereratec RuBP in the calvin cycle
|Carbon dioxide combines with a 5 carbon compound called RuBP producing two 3 carbon molecules; ATP and reduced NADP are used to produce GP and TP; NADP is reformed and returns to the light dependent reaction; some TP is converted to organic substances most is regenerated RuBP using ATP
|Where does the light independent reaction take place?
|In the stroma of the chloroplast
|Why does the light independent reaction not take place in the absence of light?
|The light independent reaction uses the products of the light dependent reaction
|What is the law of limiting factors?
|At any given moment the rate of a physiological process is limited by the factor that is at its least favourable value
|What are two ways of measuring the rate of photosynthesis?
|Measuring the volume of oxygen released by the plant; Or the volume of carbon dioxide taken up by the plant
|If light intensity is the limiting factor how is it related to the rate of photosynthesis?
|Rate of photosynthesis is directly proportional to intensity of light
|What is the compensation point?
|The point where the volume of oxygen produced and volume of carbon dioxide used by the plant is exactly balanced; no net production or loss of gas
|How does carbon dioxide concentration affect the rate of photosynthesis?
|Carbon dioxide concentration affects the enzyme activity thus increasing rate of photosynthesis
|How does temperature affect the rate of photosynthesis?
|Plants have an optimum temperature above this rate will decrease as the enzymes will become denatured
|How and why is glucose phosphorylated?
|Glucose is phosphorylated to make it more reactive the phosphate comes from the hydrolysis of ATP
|How does phosphorylated glucose two molecules of pyruvate?
|Phosphorylated glucose is split into two 3 carbon molecules of triose phosphate; the 2 triose phosphate molecules are oxidised; hydrogen ions are removed and transferred to a hydrogen ion carrier NAD; enzymes convert triose phosphate pyruvate producing 2 atp molecules
|How are two molecules of reduced NAD produced?
|Two molecules of triose phosphate are oxidised producing two hydrogen ions which can reduce two molecules NAD
|Why is the overall ATP yield of glycolysis only two?
|Two molecules of ATP are required to phosphorylate glucose, only four molecules of ATP are produced when two molecules of triose phosphate are converted into two molecules of pyruvate
|Where does glycolysis take place?
|In the cytoplasm of the cell
|Why is glycolysis the only source of ATP in the absence of oxygen (anaerobic conditions)?
|Glycolysis does not require oxygen to occur whilst all the other stages of respiration do require oxygen
|Give the equation for the link reaction
|Pyruvate + NAD + coenzyme A = acetyl coenzyme A + reduced NAD + carbon dioxide
|Explain how the link reaction produces 2 molecules of carbon dioxide
|First pyruvate is oxidised; two hydrogen ions are accepted by NAD; the resulting acetyl group combines with coenzyme a to produce acetyl coenzyme a; and one carbon dioxide molecule
|How does the krebs cycle produce two reduced hydrogen carriers and ATP?
|Acetyl coenzyme a combines with a four carbon molecule to produce a 6 carbon molecule; this 6 carbon molecule loses carbon dioxide and hydrogen to give the 4 carbon molecule these hydrogen ions are used to produce reduced hydrogen carriers, ATP is formed by substrate level phosphorylation
|what is the overall yield for the link reaction and krebs cycle for one molecule of glucose
|two reduced NAD molecules, two reduced FAD molecules, two ATP molecules and 6 carbon dioxide molecules
|explain the significance of the krebs cycle
|breaks down macromolecules into smaller ones produces hydrogen ions letter carried to the electron transport chain by oxidative phosphorylation leading to ATP production regenerate the 4 carbon molecule that combines with acetyl coenzyme a and isa source of intermediate compounds used by cells in the manufacture of other substances
|why are hydrogen acceptors oxidised where do the protons and electrons
|hydrogen atoms are released from the hydrogen carriers the atom split in two protons and electrons the electrons move along the electron transport chain
|how is the energy lost at each electron acceptor used
|To pump electrons from the matrix intuothe inter membrane space
|how is an electrochemical gradient established
|the concentration of protons in the intermembrane space is higher in the matrix
|how does protons moving back into the matrix produce atp
|protons move down at the electrochemical gradient back into the matrix via atp synthase this drive theory synthesis of atp from adp and inorganic phosphate
|what is the name of the process which generates atp
|how is water produced in the electron transport chain
|in a matrix at the end of the electron transport chain the protons and electrons and oxygen combine to form water
|why is oxygen described as the final proton accepter in the electron transport chain
|oxygen combines with the protons to form water
|what process can occur in anaerobic conditions
|what is the equation for anaerobic respiration in plants and some microbe?
|Pyruvate + reduced NAD = ethanol + carbon dioxide + NAD
|how is ethanol produced from pyruvate in plants and some microbes
|Pyruvate loses carbon dioxide and accepts hydrogen from reduced NAD to produce ethanol
|What is the equation for anaerobic respiration in animals?
|Pyruvate + reduced NAD = lactate + NAD
|How is lactate produced from pyruvate in animals?
|Pyruvate takes up two hydrogen atoms from the reduced NAD forming lactate
|Why is lactate build up bad in humans?
|Lactate is harmful,causes muscle cramps and fatigue
|What is the energy yield from aerobic respiration?
|Two molecules of ATP from every one molecule of glucose