Respiration

Question 1

What is the equation for respiration

Answer 1

glucose + oxygen → carbon dioxide + water + energy

C6H1206 + 6 O2 → 6 CO2 + 6 H20 + 2870kJ

Question 2

What are the 4 stages of aerobic respiration

Answer 2

-glycolysis
-the link reaction
-kerbs cycle
-electron transport chain

Question 3

If no oxygen is available what will occur

Answer 3

Anaerobic respiration and NAD is regenerated by reduction of pyruvate to either lactic acid or ethanol

Question 4

How is are mitochondria adapted for respiration

Answer 4

The structure of mitochondria makes them well adapted to their function
They have a large surface area due to the presence of cristae (inner folds) which enables the membrane to hold many electron transport chain proteins and ATP synthase enzymes
More active cell types can have larger mitochondria with longer and more tightly packed cristae to enable the synthesis of more ATP because they have a larger surface area
The number of mitochondria in each cell can vary depending on cell activity
Muscle cells are more active and have more mitochondria per cell than fat cells

Question 5

Where in the mitochondria does the link reaction take place

Answer 5

Matrix

Question 6

Where in the mitochondria does krebs take place

Answer 6

Matrix

Question 7

Where does electron transport take place

Answer 7

On the cristae

Question 8

Give the similarities of chloroplasts and mitochondria

Answer 8

-both have a double membrane
-large internal membrane structure
-both fluid filled
-both contain DNA and ribosomes

Question 9

Give the differences between the chloroplasts and the mitochondria

Answer 9

-chloroplasts have grana whereas mito have cristae
-chloroplasts have stroma and mitochondria have matrix
-choloroplasts contain chlorophyll and mito don’t

Question 10

Give the process of glycolysis

Answer 10

-activation of glucose - glucose is phosphorylated using phosphate from 2 ATP - fructose 1,6-diphosphate is produced - this has a lower Ea
- fructose 1,6-diphosphate molecules splits into 2 TP
-TP is oxidised by 2 NAD which is reduced to 2 NADH
-TP is also dephosphorylated by removing phosphates and producing ATP
-this then produces pyruvate

-net gain of ATP
-NAD reduced

Question 11

Where does glycolysis take place

Answer 11

Cytoplasm of the cell

Question 12

What is the net yield of glycolysis per glucose is

Answer 12

2 ATP
+2 NADH
2 pyruvate

Question 13

What is the link reaction

Answer 13

Pyruvate undergoes oxidative decarboxylation - oxygen and carbon removed
- electrons and hydrogen from NAD become reduced to NADH
-removal of carbon dioxide coverts the pyruvate into acetate
-the acetate then combines with CoenzymeA to form acetylCoenzymeA

Question 14

What is the net yield of the link reaction per glucose

Answer 14

2 acetyl CoenzymeA
2 NADH
2 Carbon dioxide

Question 15

where does the krebs cycle take place

Answer 15

• matrix of the mitochondria

Question 16

what is the krebs cycle

Answer 16

-cycle of enzyme-controlled reactions
-main goal is to provide a continuous supply of reduced electron carriers - to be fed into the final stage of respiration

Question 17

describe the process of the krebs cycle

Answer 17

-acetylCoA (2C) combines with Oxaloacetate (4C) to produce a 6 carbon ompound called citric acid
-cirtic acid then undergoes
-a series of oxidative decarboxylation reactions - produce 5C and then 4C
this removes hydrogen ions and electrons - picked up by NAD and is reduced to NADH

-after a 4C compound is produced it undergoes oxidation and substrate level phosphorylation
where FAD is reduced to FADH - gain H+
phosphate is removed from the intermediate to produce ATP when combined with ADP

-the next 4C compound then undergoes oxidation to regenerate the oxaloacetate
NAD reduced to NADH

Question 18

what are oxidative decarboxylation reactions

Answer 18

where the compound looses a molecule of CO2
and a H+ ion by reducing either NAD to NADH or FAD to FADH

Question 19

how many times does the Krebs cycle happen per molecule of glucose

Answer 19

twice as 2 pyruvates are used in glycolysis
and so 2 acetylCoA is used in krebs

Question 20

what is the net products of the krebs cycle per glucose

Answer 20

• 4 Carbon dioxide
• 2 FADH
• 6 NADH
• 2 ATP

Question 21

what is the 4th stage of aerobic respiration

Answer 21

electron transport chain

Question 22

where does the ETC take place

Answer 22

cristae of the mitochondria

Question 23

where do the electrons come from in ETC

Answer 23

the NADH and FADH produced in the previous reactions

Question 24

how is the cristae adapted for the ETC

Answer 24

-cristae/inner membrane is folded - giving a large SA

Question 25

describe the process of the ETC

Answer 25

-within the membrane there are a series of electron carrier protein complexes arranged in descending energy levels -as electrons pass through the carrier protiens the energy released is used to move hydrogen ions from the matrix into the intermembrane space -this movements sets up a large H+ ion conc gradient for the movement of H+ back into the matrix -when the ETC reaches a enzyme ATP synthase the H+ ions are removed via facilitated diffusion -each time a H+ ion passes through the enzyme it attaches a phosphate to an ADP thus producing ATP -when the electrons reach the end of the ETC they are picked up by oxygen - terminal electron acceptor -each oxygen atom picks up 2H+ and 2e- to produce a molecule of H20 2H+ + 2e- + 1/2 O2 = H2O -this process is known as oxidative phosphorylation - because ATP is made and oxygen is used up -chemiosmaotic theory

Question 26

how many ATP is produced for every NADH

Answer 26

3ATP

Question 27

how many ATP is produced per FADH

Answer 27

2 ATP

Question 28

what are the overall amounts of NADH and how many ATP does this produce

Answer 28

-2 in glycolysis -2 in link -6 in krebs 10 overall = 30 ATP

Question 29

what is ther overall amount of FADH and how many ATP does it produce

Answer 29

-2 in krebs -4 ATP

Question 30

explain why the coloured liquid in the tubing moved towards tube B

Answer 30

-oxygen taken up or used by thing in question -CO2 given out is abosorbed by KOH -volume or pressure in other tube decreases -if diagram open to atmos - then say pressure in tube decreases below atmos -if with another tube - then say decreases below pressure in the other tube

Question 31

what happens if oxygen is not available for respiaration

Answer 31

-anaerobic resp occurs -ETC cannot operate -cells initial supply of NAD runs out

Question 32

how is NAD regenerated in anaerobic respiration

Answer 32

-pyruvate from glycolysis is reduced -which uses up the NADH -oxidise NADH to NAD -ATP continued to be made

Question 33

what is pyruvate converted to in animal cells in anaerobic respiration

Answer 33

-lactic acid

Question 34

what is the net yeild for ATP in anaerobic respiration

Answer 34

2 ATP compared to 38 in aerobic

Question 35

in plants and microbes what s the pyruvate converted to in anaerobic resp

Answer 35

-ethanol - by removing CO2 and adding NADH/ reduce -carbon dioxide

Question 36

GW1516 is a performance-enhancing drug. GW1516 activates AMPK and develops slow muscle fibres at rest. Use diagram above to justify why professional athletes are not allowed to take GW1516. Do not include details of chemiosmotic theory in your answer.

Answer 36

1. More acetylcoenzyme A would enter the Krebs cycle; 2. (So) the Krebs cycle generates (more) reduced coenzymes OR (So more) reduced coenzymes pass their electrons to the electron transfer chain; 3. (So more) ATP would be produced; idea for more is required once 4. Athletes could build (slow) muscle (fibres) without exercising; Ignore ‘develop (slow) muscle (fibres) at rest’ as in stem of question Accept description of not exercising, eg without training 5. (Having more) slow muscle (fibres) would increase endurance; Accept descriptions of endurance in terms of delayed onset of anaerobic respiration

Question 37

Humans synthesise more than their body mass of ATP each day. Explain why it is necessary for them to synthesise such a large amount of ATP.

Answer 37

1. ATP cannot be stored / is an immediate source of energy; 2. ATP only releases a small amount of energy at a time;

Question 38

what are 4 uses of ATP by the body

Answer 38

-active transport -DNA synthesis -movement of organelles within cells -maintaining body temp / thermoregulation

Question 39

where are fatty acids used in respiration

Answer 39

-the krebs cycle

Question 40

describe the process of chemiosmosis

Answer 40

-The model states that energy from electrons passed through a chain of proteins in the membrane (the electron transport chain) is used to pump protons up their concentration gradient into the intermembrane space -The H+ ions are then transported by facilitated diffusion, from the inter-membrane space, through a channel in ATP synthase into the matrix -The energy of the H+ ions flowing down their concentration gradient is harnessed resulting in the phosphorylation of ADP into ATP by ATP synthase