Summary Plants

1. Define respiratory quotient (RQ)
​ ​ ​ ​ ​ ​ ​[1]
- RQ = volume of carbon dioxide give off / volume of oxygen taken up
(Eg: C18H36O2 + 26 O2 --> 18 H2O + 18 CO2)
(RQ = = 0.7 --> substrate = fat)


2. State how the RQ is calculated. [2]
- volume of carbon dioxide produced divided by volume of oxygen consumed
- number of moles


3. Why carbohydrates release half as much energy per unit mass as fats and oils
​[2]
-1 -1
(energy density of carbohydrate = 15.8kJg ; lipids = 39.4kJg )
- less C-C bonds
- less C-H bonds (more H for ETC)
- more oxygen


4. Explain the relative energy values of carbohydrate and lipid as respiratory
[3] substrates
- carbohydrates have less C-H bonds for ETC
- less energy is produced per unit mass
- so carbohydrates has lower energy density


5. Explain the significance of different values that may be obtained of RQ values
​ [2]
- the RQ value is depends on the substrate
- the RQ value for carbohydrate is 1, protein is 0.9 and fat is 0.7 in aerobic respiration
- the RQ value is greater than 1 in some anaerobic respiration


6. State a circumstance under which the RQ value would rise to over 1.0
- anaerobic respiration


7. Matrix --> Krebs cycle (substrate level phosphorylation)
Matrix --> link reaction (pyruvate --> acetyl CoA ; need deH and deCo2)
Cytoplasm (in glycolysis) --> substrate level phosphorylation

,8. Cristae / inner mitochondrial membrane --> oxidative phosphorylation

9. Structure of mitochondrion that adapted to carry process in KC and
OP ​ ​ [3]
- matrix contains enzyme required for Krebs cycle
- cristae is folded to increase surface area for electron transfer / ETC
- inner mitochondrial membrane has stalked particles with enzyme ATP synthase (to
synthesize ATP)


10. Role of NAD in respiration
​ ​ ​ ​ ​ ​ ​[3]
- carries hydrogen ions and electrons to ETC
- act as a coenzyme
- used in dehydrogenation during glycolysis
+
(remove H from triose phosphate by accepting it and become reduced NAD)


11. How photophosphorylation differs from oxidative phosphorylation
​ ​[3]
* for photophosphorylation
- occurs in chloroplasts, on thylakoid membrane / grana
- light is involved
- there is photolysis of water to produce oxygen
- 2 types : cyclic and non-cyclic

* for oxidative phosphorylation
- occurs in cristae of mitochondria
- light is not involved
- oxygen is the final electron acceptor


12. Importance of ATP in cells and
examples ​ ​ ​ ​ ​ ​[3]
- provide energy ​ ​ -​ DNA replication
- muscle contraction ​ ​ -​ cell movement
- protein synthesis ​ ​ ​- active transport

13. Compare ATP produced by substrate level phosphorylation and oxidative ​
[2]
phosphorylation
​ ​ ​ ​ ​ ​ ​ ​ ​
- oxidative phosphorylation (cristae) more than substrate level phosphorylation

, - oxidative phosphorylation produces 28 of ATP per glucose while substrate-level
phosphorylation (cytoplasm in glycolysis / matrix in Krebs cycle) produces 4-6 of
ATP per glucose


14. ATP is described as having a universal role as the energy currency in all living
organisms. Explain why ​ ​ ​ ​ ​ ​ ​ ​
[4]
- it is easily to hydrolyse to release energy, which is 30.5kJ
- it is small and water-soluble so it is easily transported around cells
- it is found in all organisms
- rapid turnover
- it links catabolic and metabolic reactions ; links between energy yielding and energy
requiring reactions


15. Places where ATP is synthesized in cells ​ ​ ​ ​ ​
[2]
- cristae (oxidative phosphorylation)
- grana / thylakoids (photophosphorylation in plants)
- cytoplasm (glycolysis)
- mitochondria matrix (Krebs cycle)


16. Substrate level phosphorylation CAN without oxygen, oxidative
phosphorylation
CAN’T. Why? ​ ​ ​ ​ ​ ​ ​ ​ ​
[3]
Why NAD cannot be regenerated from reduced NAD in mito in absence of O2
[3]
- requires proton gradient produced by ETC
- without oxygen, ETC does not occur
- NAD cannot be reformed
- oxygen combines with oxygen final acceptor in ETC


17. How lack of oxygen affect respiratory process in mitochondria
​ ​ ​ [3]
- no proton gradient produced by ETC
- no ATP synthesized / oxidative phosphorylation does not occur (ETC does not
occur)
- NADH cannot be oxidised / NAD cannot be reformed
- stops Krebs cycle


18. NAD is reduced in
- cytoplasm (in glycolysis)
- matrix of mitochondria (in Krebs cycle)