5.2.2 Respiration

Question 1

cellular respiration

Answer 1

the breakdown of glucose molecules to produce ATP

Question 2

ways to make ATP

Answer 2

phosphorylation - cyclic or non-cyclic
substrate level phosphorylation
oxidative phosphorylation

Question 3

cyclic/non-cyclic phosphorylation

Answer 3

produces ATP to convert GP to TP and TP to RuBP in the Calvin Cycle

Question 4

substrate level phosphorylation

Answer 4

occurs in glycolysis/ Krebs cycle
purpose of ATP is to allow movement of respiratory intermediates around cell

Question 5

oxidative phosphorylation

Answer 5

occurs in mitochondria
oxygen acts as final e- acceptor
large number of ATP produced due to chemiosmosis

Question 6

uses of ATP in a plant

Answer 6

H+ pumps in companion cells - active loading of sucrose
GP to TP, TP to RuBP
active transport of minerals into root hair cells
pumping of ions in/out of guard cells
NA+/K+ pump
protein synthesis, DNA replication, mitosis

Question 7

chemiosmosis

Answer 7

flow of protons down their electrochemical gradient, across a cell membrane through a channel associated with ATP synthase, resulting in the formation of ATP

Question 8

where do the high-energy electrons come from in respiration?

Answer 8

reduced NAD
reduced FAD

Question 9

where is the location of the electron transport chain

Answer 9

inner mitochondrial membrane

Question 10

folded inner membrane

Answer 10

increase surface area for ATP synthase

Question 11

four stages of aerobic respiration

Answer 11

glycolysis
link reaction
krebs cycle
oxidative phosphorylation

Question 12

glycolysis

Answer 12

occurs in cytoplasm
splits glucose
forms 2 molecules of pyruvate

Question 13

substrate-level phosphorylation

Answer 13

phosphate group is removed from a phosphorylated compound and added to a molecule of ADP to form ATP
occurs in glycolysis & Krebs cycle

Question 14

the link reaction
oxidative decarboxylation

Answer 14

occurs in mitochondrial matirx
produces acetyl coenzyme A from pyruvate
produces CO2, reduced NAD
uses coenzyme A

Question 15

how do pyruvate and reduced NAD from glycolysis reach the link reaction?

Answer 15

“mitochondrial shunt mechanism”
active transport of pyruvate and NADH from cytoplasm into matrix
req. ATP

Question 16

Krebs cycle

Answer 16

coenzyme A carries acetyl group to cycle and is then recycled to link reaction

Question 17

oxidative phosphorylation

Answer 17

reduced NAD (& FAD)= dehydrogenated @ complex 1 (2)
H atoms split = H+ and e-
e- move into e- transport chain
as e- lose energy, H+ actively pumped across inner mito. memb. into intermemb. space (high proton concentration)
protons flow by chemiosmosis and proton motive force through ATP synthase - ATP produced
oxygen acts as final e- acceptor

Question 18

theoretical yield of ATP in aerobic respiration

Answer 18

36

Question 19

why is the theoretical yield not always achieved

Answer 19

H+ ions leak through outer membrane into the cytoplasm - reduced steepness of H+ gradient = less chemiosmosis, less ATP produced

ATP is used to actively transport pyruvate & NADH from cytoplasm into mitochondria

Question 20

when do eukaryotes respire anaerobically?

Answer 20

when there is not enough oxygen to act as the final electron acceptor
only glycolysis and fermentation occur

Question 21

if oxygen is absent:

Answer 21

protons moving through ATP synthase by chemiosmosis cannot be accepted by oxygen
proton conc increases in mitochondrial matrix
no H+ gradient, no chemiosmosis, oxidative phosphorylation stops
accumulation of reduced NAD/FAD - cannot be oxidised
Krebs cycle stops
link reaction stops - no NAD/FAD to accept hydrogen atoms

Question 22

ethanol fermentation

Answer 22

occurs in plants and fungi
2 step process: ethanAL as the intermediate
ethanAL is reduced to ethanOL by NADH
allows NAD to return to glycolysis & accept H atoms in the conversion of TP to pyruvate

Question 23

lactate fermentation

Answer 23

occurs in animals
lactic acid is produced when pyruvate is reduced
NADH donates H atoms to pyruvate
NAD returns to glycolysis
cell can keep producing net 2 ATP molecules per glucose

Question 24

respiratory substrates

Answer 24

molecules other than glucose can be used as respiratory substrates

Question 25

respiratory quoteint (RQ)

Answer 25

CO2 produced / O2 absorbed

Question 26

RQ values of respiratory substrates

Answer 26

carbohydrates = 1
lipids = 0.7
proteins = 0.9

Question 27

RQ value for respiration

Answer 27

anaerobic = infinity
mixture of anaerobic and aerobic = more than 1
purely aerobic = 1 or less