respiration

Question 1

describe the process of dehydrogenation and phosphorylation in glycolysis

Answer 1

removal of H from triose phosphate molecules to form pyruvate and reduced NAD

Question 2

explain how NAD acts as a coenzyme in glycolyisis

Answer 2

NAD accepts H and is reduced
during the formation of pyruvate
supplies H to enzyme involved in later stage of respiration

Question 3

substrate level phosphorylation

Answer 3

addition of phosphate group

to ADP/ formation of ATP (using phosphate) from another molecule

Question 4

outline the importance of dehydrogenation and phosphorylation in glycolysis

Answer 4

H removed in BD of glucose
H req at later stage 
addition of phosphate groups destabilises large molecules/glucose
leads to BD of glucose 
and synth of ATP

Question 5

link reaction equation

Answer 5

pyruvate+CoA+NAD->acetyl CoA+CO2+reduced NAD

Question 6

explain why the removal of CO2 in the link reaction is called oxidation

Answer 6

H also removed

removal of H oxidises pyruvate

Question 7

name one organic compound and one inorganic compound produced in the link reaction

Answer 7

CO2

acetyl group

Question 8

suggest why glycolysis occurs in the cytoplasm but not in the mitochondrial matrix

Answer 8

enz req in cytoplasm
glucose mols to large to move into mito
no transport proteins for pyruvate
mito not originally present in eukaryotic cells

Question 9

compare the structures of ATP and NAD

Answer 9

ATP
3 phosphate groups
one ribose
one nitrogenous base
NAD
2 phosphate
2 riboses
3 nitrogenous bases

Question 10

ATP can be described as a coenzyme explain why

Answer 10

used to link reactions

e released as a result of the activity one enz and used by another

Question 11

number of ATP mol prod by substrate-level phosphorylation after 2 rounds of the krebs cycle

Answer 11

1 per turn

2 in total

Question 12

draw a simple diagram summarising the BD of glucose to CO2 and reduced coenzymes

Answer 12

glucose to triose phosphate (1); triose phosphate to

pyruvate (1); addition of two ATP (1); production of four ATP and two reduced NAD

Question 13

sugg why krebs termed as aerobic despite not using oxygen at any point

Answer 13

H needs to be removed for cycle to continue
H removed using NAD/FAD and
reduced
then NAD/FAD are oxidised at ETC oxygen required for electron transport

Question 14

suggest the reason for the involvement of FAD rather than NAD in only one specific step of the krebs cycle

Answer 14

enz are specific 
active site complim to substrates
diff steps req diff enz
diff enz req diff conzeymes
only one step in cyle has enz which req FAD coenz

Question 15

explain why H have to be acivley pumped across mem form matrix and return to the matrix by diffusion through ATP synthase

Answer 15

Actively pumped to increase concentration gradient (1); energy required as moving from low to high
concentration (1); membrane impermeable to ions so ions diffuse down concentration gradient (1);
ATP synthase provides hydrophilic channel (1).

Question 16

explain why the e rel from re FAD lead to the synth of less ATP that the e rel form red NAD

Answer 16

2 Reduced NAD releases electrons to carriers at the start of the ETC (1); reduced FAD releases
electrons to carriers after the start of the ETC (1); with FAD electrons transported a shorter distance
(1); so fewer protons are actively transported (1).

Question 17

suggest an expl for the toxicity of cyanide

Answer 17

1); so fewer protons are actively transported (1).
3 Stops flow of electrons (1); stops active transport of protons (1); proton gradient not formed (1);
(less) ATP synthesised; so less energy available for (vital) metabolic processes

Question 18

discuss-
ATPase is not actually part of ETC
O2 req 4 transfer of e alng ETC
H ions return to matrix by f, diff

Answer 18

ATP synthase is not actually part of the electron transport chain – agree (1); not an electron carrier
(1).
Oxygen is required for the transfer of electrons along the electron transport chain – agree (1); oxygen
is final electron acceptor, required for electron transport (1) Hydrogen ions return to the matrix by
facilitated diffusion – agree (1); diffuse through hydrophilic channels (of ATP synthase) (1).