Chapter 12 Respiration Essay QS Flashcards
(21 cards)
Describe the structure & role of ATP as the energy currency in all living organisms. (8)
- nucleotide
- adenine + ribose sugar
- loss of phosphate leads to energy release/hydrolysis releases 30.5 kJ
- ADP + Pi –> ATP
- small packets of energy
- small/water soluble, so can move around cell
- used by cells as an immediate energy donor
- link between energy yielding & energy requiring reactions
- high turnover
- two examples of use:
- active transport
- muscle contraction
- anabolic reactions
- Calvin cycle
- exocytosis
Describe how organisms make ATP from ADP. (9)
- respiration AND photosynthesis
- ADP + Pi –> ATP
Respiration
- substrate phosphorylation
- in glycolysis/Krebs cycle
- as triose phosphate/TP is converted to pyruvate
- net gain of 2 ATP per molecule of glucose
- (in Kreb’s cycle) 2 ATP per glucose molecule
- oxidative phosphorylation
- in ETC
- hydrogens from reduced NAD
- 3 ATP made per reduced NAD
Photosynthesis
- light-dependent stage; electrons excited
- passed down chain of electron carriers
- once in non-cyclic photophosphorylation / repeatedly in cyclic photophosphorylation
Explain how the energy in ATP is released & used. (6)
- ATP + H2O –> ADP + H3PO4
- energy released = 30.5 kJ/mol
- ATPase
- channel protein
- ref. active transport
- ref. muscle contraction
- needed for initial steps of glycolysis
- needed for light-independent stage of photosynthesis
- for energy in (the reduction of) GP (to TP)
- for phosphate in regenerating RuBP
Using examples, outline the need for energy in living organisms (7).
- organisms need energy for metabolism
- ATP as (universal) energy currency
- light energy for photosynthesis
- light-dependent stage detail
- light-independent stage detail
- chemical energy
-for anabolic reactions - named reaction, e.g. protein synthesis
- activation of glucose in glycolysis
- active transport
- detail; e.g. sodium-potassium pump/movement against a concentration gradient
- mechanical energy/movement
- detail; e.g. muscle contraction
- temperature regulation
- AVP; e.g. bioluminescence
Describe the main stages of glycolysis. (8)
- glucose phosphorylated/activated by ATP
- raises energy level/overcome activation energy
- to hexose (fructose) bisphosphate
- lysis/splitting of, glucose/hexose; R: sugar splitting
- breaks down to 2 TP
- 6C –> 2 x 3C
- dehydrogenation/description
- 2! reduced NAD formed (from each TP to pyruvate formed)
- 4 ATP produced
- pyruvate produced
- reduced NAD –> oxidative phosphorylation/redox
- named enzyme
Describe how a molecule of glucose is converted to pyruvate & then to acetylCoA. (9)
- glycolysis
- glucose phosphorylated by ATP
- to fructose (1,6-)bisphosphate
- lysis to form 2 TP
- (triose phosphate) has hydrogen removed/dehydrogenated
- reduced NAD formed
- 4 ATP produced
- ref. substrate-linked phosphorylation
Pyruvate produced
- enters mitochondrial matrix
- link reaction
- decarboxylated/carbon dioxide removed
- (pyruvate) is dehydrogenated
- combines with coenzyme A
Explain the role of ATP in active transport of ions & in named anabolic reactions. (7)
Active transport or anabolic reactions
- ATP provides energy (linked to either); ignore ref. to energy currency alone active transport
- movement against concentration gradient
- carrier/transport, protein (in membrane); ignore pump
- binds to (specific) ion
- protein changes shape
Anabolic reactions
- synthesis of complex substances from simpler ones
- starch/cellulose/glycogen, from, monosaccharides
- glycosidic bonds
- lipid/triglyceride, from fatty acids & glycerol
- ester bonds
- polypeptides/proteins, from amino acids
- peptide bonds
- other named polymer from suitable monomer
Explain the role of NAD & oxygen in oxidative phosphorylation. (8)
- hydrogen/2H or H
- from Krebs Cycle
- reduced NAD
- transferred to ETC
- results in flow of electrons along ETC
- ref. to energy levels
- creates H+/proton gradient
- ref. to stalked particles/ATPase
- results in synthesis of ATP
- 3 ATP per reduced NAD
- oxygen combines with H+ & electrons
- to form water
- ref. aerobic respiration
Describe the main features of the Krebs Cycle. (9)
- matrix
- of mitochondrion
- acetyl CoA combines with oxaloacetate
- to form citrate
- 4C to 6C
- decarboxylation/produce CO2
- dehydrogenation/oxidation
- 2CO2 released
- reduced NAD produced
- reduced FAD produced
- ATP produced
- series of steps/intermediates
- enzyme catalysed reactions
- oxaloacetate regenerated
Describe how ATP is produced form ADP in the Krebs cycle. (2)
- transfer of phosphate group to ADP/ADP phosphorylated/ADP + Pi –> ATP
- substrate-linked phosphorylation
- enzyme (catalysed reaction)
Explain the role of NAD in aerobic respiration. (6)
- coenzyme
- for dehydrogenase
- reduced
- carries electrons
- & protons/H+/H/hydrogen
- from Krebs cycle
- & from glycolysis
- to ETC
- regenerated
- ATP produced
- 3 molecules of ATP per NADH
Describe the process of oxidative phosphorylation. (9)
- reduced NAD/FAD
- passed to ETC
- hydrogens removed
- split into H+ & electrons
- electrons passed to carriers
- H+ stays in mitochondrial matrix
- oxygen is final electron carrier
- reduces H+
- forms water
- ref. energy levels of carriers
- energy available to convert ADP & Pi to ATP
- occurs 3 times (for each reduced NAD)
- chemiosmosis/ATP synthase
Describe the structure of a mitochondrion & outline its function in a plant cell. (8)
- 0.5 - 1.0 micrometers, diameter
- double membrane
- cristae
- hold, stalked particles/ATP synthase
- site of ETC
- ref. H+ & intermembrane space
- ATP production
- oxidative phosphorylation/ chemiosmosis
- matrix is site of Krebs cycle
- enzymes in matrix
- 70S ribosomes
- (mitochondrial) DNA
Outline the process of anaerobic respiration in both mammal & yeast cells. (8)
General
- reduced NAD produced in glycolysis
- small amount of ATP produced in glycolysis
In yeast cells
- pyruvate converted to ethanal
- carbon dioxide released/decarboxylation
- ethanal, reduced/accepts H+
- by reduced NAD
- ethanol formed
In mammalian cells
- pyruvate converted to lactate
- by reduced NAD
- in, liver/muscle, cells
Explain the roles of NAD in anaerobic respiration in both plants & animals. (6)
In cytoplasm
- NAD, reduced/accepts H+
- during glycolysis
In plants
- pyruvate converted to ethanal
- ethanal reduced
- by reduced NAD
- ethanol formed
In animals
- pyruvate converted to lactate
- by reduced NAD
- in, liver/muscles
- allows glycolysis to continue
Explain the differences between aerobic & anaerobic respiration. (8)
- anaerobic in absence of oxygen, aerobic in presence of oxygen
- anaerobic only uses glycolysis, aerobic uses glycolysis + Krebs cycle + ETC
- anaerobic in cytoplasm only, aerobic involves mitochondria
- anaerobic - reduced NAD recycled to allow making of more pyruvate
- aerobic - oxygen required as final hydrogen acceptor
- anaerobic - only 2 ATP from each glucose, aerobic - 36/38 ATP from each glucose
- aerobic equation in symbols or words
- yeast anaerobic equation, glucose –> ethanol + CO2
- muscle anaerobic equation, glucose –> lactate/lactic acid
- anaerobic can use only glucose, aerobic can use other substrates
Explain how rice is adapted to grow with its roots submerged in water. (6)
- aerenchyma
- in stem AND roots
- helps oxygen to diffuse to roots
- shallow roots
- air (film) trapped on underwater leaves
- fast internode growth
- (modified) growth regulated by, gibberellin/ethene
- anaerobic respiration, underwater/when submerged
- tolerant to high ethanol concentration/high tolerance to ethanol
- ethanol dehydrogenase (switched on in anaerobic conditions)
Describe how you would carry out an investigation on the effect of temperature on the rate of respiration of yeast in anaerobic conditions using a redox indicator, such as methylene blue. (9)
- methylene blue/DCPIP, is a hydrogen acceptor (dye)
- becomes colourless when reduced
- use yeast suspension (in tube)
- add named sugar (solution) AND, methylene blue, DCPIP
- put thin layer of oil on/put bung on, to prevent oxygen reaching yeast
- ref. to water bath (at set temperature)
- time how long it takes (for methylene blue/DCPIP) to go colourless
- use colorimeter
- ref. to 5 different temperatures
- repeat (whole) experiment at least twice more
- calculate mean values
- method to calculate rate of respiration; e.g. graph or 1/T
- plot graph of rate of respiration against temperature
State the meaning of the term respiratory quotient (RQ) & describe how the RQ could be measured for a sample of germinating seeds. (7)
RQ
- (ratio of ) CO2 given out divided by O2 taken in
- ref. volume/moles; R amount
- per unit time
any eight from:
Investigation
- use respirometer
- seeds placed on, mesh/gauze
- KOH/NaOH/sodalime, to absorb CO2
- manometer/capillary tube/syringe
- movement of fluid (in manometer/capillary tube/syringe) = uptake of oxygen
- keep, temperature/air pressure, constant
- measure oxygen uptake after certain time
- repeat without KOH/NaOH/sodalime
- difference in manometer readings due to carbon dioxide given out
Explain the principles of operation of a test strip for glucose & suggest advantages for a person with type 2 diabetes of using a biosensor instead of a test strip.
any 4 from:
- strip contains glucose oxidase & peroxidase
- strip dipped into urine
- glucose (& oxygen) react with glucose oxidase to produce H2O2
- H2O2 reacts with peroxidase to produce a colour change
- colour is matched with a colour chart to give estimate of glucose concentration
any 3 from:
- quicker
- accurate
- gives immediate reading
- results can be stored electronically
- quantitative
- reusable
Explain how a lack of oxygen affects oxidative phosphorylation. (4)
Oxidative phosphorylation stops because:
- oxygen is the final electron acceptor
- no / fewer, electrons move along ETC
- no / fewer, H+ pumped into intermembrane space OR no / less steep, proton gradient
- no / less, chemiosmosis
- reduced NAD & reduced FAD not oxidised
- no / less, ATP produced
- no / less, pyruvate enters mitochondrion
