Topic: Respiration Flashcards
Explain the similarities and differences in anaerobic and aerobic cellular respiration. 8 marks
Answers must include both similarities and differences to receive full marks.
aerobic requires oxygen and anaerobic does not utilize oxygen
similarities: 3 max
both can start with glucose
both use glycolysis
both produce ATP/energy(heat)
both produce pyruvate
carbon dioxide is produced
(both start with glycolysis) aerobic leads to Krebs’ cycle and anaerobic leads to fermentation
differences: 5 max
anaerobic:
(fermentation) produces lactic acid in humans
(fermentation) produces ethanol and CO2 in yeast
occurs in cytoplasm of the cell
recycles NADH (NAD+)
aerobic cellular respiration
pyruvate transported to mitochondria
further oxidized to CO2 and water (in Krebs cycle)
produces a larger amount of ATP (36-38 ATP)/anaerobic produces less ATP (2)
can use other compounds / lipids / amino acids for energy
Compare how pyruvate is used in human cells when oxygen is available and when oxygen is not available. [5]
aerobic cell respiration if oxygen available and anaerobic if unavailable;
pyruvate enters mitochondrion for aerobic respiration;
whereas pyruvate stays in the cytoplasm for processing under anaerobic conditions;
pyruvate converted aerobically into carbon dioxide and water;
whereas pyruvate converted anaerobically to lactate;
large ATP yield when oxygen available/from aerobic cell respiration;
no (further) ATP yield without oxygen;
Outline the process of glycylosis. 5 marks
occurs in cytoplasm;
hexose is phosphorylated using ATP;
hexose phosphate is split into two triose phosphates;
oxidation by removal of hydrogen; (do not accept hydrogen ions/protons)
conversion of NAD to NADH (+H+);
net gain of two ATP / two ATP used and four ATP produced;
pyruvate produced at the end of glycolysis;
Accept glucose/fructose/6C sugar instead of hexose. Accept 3C sugar/glyceraldehyde instead of triose.
Explain how the structure of the mitochondrion allows it to carry out its function efficiently. 8 marks
membranes to compartmentalise / separate from processes in the cytoplasm
small size gives large surface are to volume ratio
large surface area to volume ratio allows rapid uptake / release of materials
matrix contains enzymes of the Krebs cycle / matrix carries out Krebs cycle
inner membrane invaginated / infolded / forms cristae to increase the surface area
large surface area gives more space for electron transport chain / oxidative phosphorylation
inner membrane contains ATP synthase / ATPase / stalked particles that make ATP
(narrow) gap between inner and outer membranes / intermembrane space ( must be stated or labeled)
pH / H+ / proton concentration gradient rapidly established / steeper
chemiosmosis therefore more efficient / chemiosmosis can occur
inner membrane contains the electron transport pathway
DNA present to act as genetic material
ribosomes for protein synthesis
some proteins do not need to be imported
Explain the reactions that occur in the matrix of the mitochondrion that are part of aerobic respiration. 8 marks
pyruvate is decarboxylated/ CO2 removed
link reaction/ pyruvate combined with CoA/ ethanoyl/acetyl CoA formed
pyruvate is oxidized/ hydrogen removed
reduction of NAD/ formation
of NADH + H+
whole conversion called oxidative decarboxylation
Krebs cycle
C2 + C4 —> C6
C6 —> C5 giving off CO2
C5 —> C4 giving off CO2
hydrogen atoms removed collected by hydrogen-carrying molecules (NADH, FADH2)
ATP formed by substrate level phosphorylation
oxygen accepts electrons/ oxygen combines with hydrogen
total yield per turn of Krebs cycle = 2 CO2,, 3 NADH + H+, 1 FADH2, 1 ATP (directly produced)
Explain the process of aerobic respiration. 8 marks
by glycolysis, glucose is broken down into pyruvate (two molecules) in the cytoplasm
with a small yield of ATP/ net yield of 2 ATP
and NADH + H+/ NADH
aerobic respiration in the presence of oxygen
pyruvate converted to acetyl CoA
by oxidative decarboxylation /
NADH and CO2 formed
fatty acids / lipids converted to acetyl CoA
acetyl groups enter the Krebs cycle (accept acetyl CoA)
Krebs cycle yields a small amount of ATP/ one ATP per cycle
and FADH2/ FADH + H+/ NADH /NADH + H+/ reduced compounds/ electron collecting molecules
these molecules pass electrons to electron transport chain (reject donates H+)
oxygen is final electron acceptor/ water produced
electron transport chain linked to creation of an electrochemical gradient
electrochemical gradient/ chemiosmosis powers creation of ATP
through ATPase/synthase/synthetase
Accept any appropriate terminology for NAD and FAD.
Outline the role of oxygen in providing cells with energy. 6 marks
(Award 1 mark for any of the below; up to 6 marks max.)
needed for aerobic (but not anaerobic) resp./simple equation for aerobic resp.
used in oxidative phosphorylation
oxygen accepts electrons at the end of the ETC
also accepts protons to form water / water formed using oxygen
allows more electrons along the ETC
allows NAD to be regenerated / reduced NAD to be oxidised
allows ATP production
allows a high yield of ATP from glucose in respiration / 32-38 instead of 2
Explain how chemiosmosis assists in ATP production during oxidative phosphorylation. 9 marks
occurs during aerobic respiration;
oxidative phosphorylation occurs during the electron transport chain;
hydrogen/electrons are passed between carriers;
releasing energy;
finally join with oxygen (to produce water);
occurs in cristae of mitochondria;
chemiosmosis is the movement of protons/hydrogen ions;
protons move/are moved against their concentration gradient;
into the space between the two membranes;
protons flow back to the matrix;
through the ATP synthase/synthetase (enzyme);
energy is released which produces more ATP/combines ADP and Pi;
Describe the central role of acetyl (ethanoyl) CoA in carbohydrate and fat metabolism. 5 marks
acetyl CoA enters Krebs cycle
glucose / carbohydrates converted to pyruvate in glycolysis
pyruvate enters mitochondria
pyruvate converted to acetyl CoA
by oxidative decarboxylation / hydrogen and CO2 removed
fats enter mitochondria
fats oxidised to acetyl CoA / oxidation of fatty acids / fats converted to acetyl CoA
