respiration

Question 1

what is the equation for respiration

Answer 1

C6 H12 06 + 602 ——- 6 C02 + 6H20

Question 2

why is ATP useful

Answer 2

• releases energy in small amounts
• broken down in one step
• makes energy available rapidly
• phosphorylates other molecules
• lowers activation energy
• can be made again

Question 3

where does the main process of respiration occur

Answer 3

in the mitochondria

Question 4

what is in the mitochondria

Answer 4

• outer and inner membrane
• intermembrane space
• crista
• matrix
• 70s ribosomes
• DNA ( like prokaryotic cells )

Question 5

what are the four main stages in aerobic respiration and where do they occur

Answer 5

• glycolysis ( cytoplasm of the cell )
• link reaction ( matrix of the mitochondria )
• krebs cycle ( matrix of the mitochondria )
• electron transport chain ( mitochondrial membranes )

Question 6

what is substrate level phosphorylation

Answer 6

ATP generated directly through respiration
directly donates phosphate from another phosphate group
- only occurs in glycolysis and krebs

Question 7

what is oxidative phosphorylation

Answer 7

ATP generated from the chemical energy released when a hydrogen carrier or co enzyme has been reduced
- only at electron transfer chain

Question 8

what is the advantage of the mitochondria in the muscles containing lots of cristae

Answer 8

• larger SA for electron carrier system/ oxidative phosphorylation
• provide ATP / energy for contraction

Question 9

what is dehydrogenase

Answer 9

an enzyme that removes hydrogen from its substrate
catalyses the reduction of NAD

Question 10

what is the process of glycolysis

Answer 10

1) glucose is activated by phosphorylation - requires hydrolysis of ATP to ADP
2) phosphorylated glucose splits into two triose phosphates, using energy provided by phosphorylation
3) each triose phosphates are oxidised to pyruvate, dehydrogenase reduces co enzyme and NAD to NADH
4) ATP is produced through substrate level phosphorylation

Question 11

what are the yields of glycolysis ( what are the products )

Answer 11

• 2 ATP
• 2 NADH
• 2 pyruvate

Question 12

what is the process of the link reaction

Answer 12

• pyruvate is actively transported into the mitochondrial matrix
• pyruvate is oxidised to acetate
• H is lost and reduces NAD
• a molecule of co2 is produced ( decarboxylation )
• coenzyme A combines with acetate to form acetyl coenzyme A

Question 13

what are the yields of the link reaction

Answer 13

• NADH
• acetyl coenzyme A ( 2C compound )
• co2 ( waste )

Question 14

what is the process in the krebs cycle

Answer 14

1) 2C acetyl coenzyme A combines with a 4C molecule to form 6C
2) 6c loses co2 and hydrogen via dehydrogenase to reduce NAD
3) 5c loses co2 and H via dehydrogenase to reduce 2NAD and FAD producing a 4C compound and 1x ATP

Question 15

what are the yields of the krebs cycle

Answer 15

• 2 co2
• 1 atp
• 3 NADH
• FADH
• per term

each molecule of glucose contains 2 molecules of acetyl coenzyme A so krebs will occur twice

Question 16

what is the process in the electron transport chain

Answer 16

• NADH, FADH produced in glycolysis, link reaction and krebs are required at the etc to produce ATP via oxidative phosphorylation
  1) NADH and FADH are oxidised losing H via dehydrogenase
  2) electrons from H pass down a series of electron carriers on the mitochondrial membrane in a series of redox reactions
  3) as electrons pass along the etc they lose energy, which is used to move H+ or protons through the inner membrane into the intermembrane space
  4) some of the energy is lost to heat
  5) H+ pass back through the inner membrane via ATP synthase
  6) energy is released to from ATP from ADP+Pi
  7) electrons and H+ combine with o2 to form water
  8) o2 is the final electron acceptor

Question 17

what is the process of lipids being hydrolysed into glycerol and fatty acids

Answer 17

• glycerol is phosphorylated and converted to triose phosphate which enters glycolysis and krebs
• fatty acids are broken down into 2C fragments and converted into acetyl coA
• oxidation of fatty acids yields many H+ and reduces many NADs which can be used to produce ATP

Question 18

what is the process of proteins being hydrolysed into amino acids

Answer 18

• amino groups are removed ( deamination )
• enter the respiratory pathway at different stages depending on the number of carbon atoms they contain

Question 19

what happens when oxygen is not available ( anaerobic respiration )

Answer 19

• no o2 to act as final electron acceptor
• the link reaction, krebs and ETC stop
• glycolysis does not require o2 so can continue however NAD must still be generated
• the H from NADH is now accepted by pyruvate rather than passing through the ETC

Question 20

what happens to pyruvate in animals during anaerobic respiration

Answer 20

reduced to lactic acid, oxidising NAD to allow glycolysis to continue
in muscles lactate causes muscle fatigue and cramps
when o2 becomes available again, lactate is converted back into pyruvate and respiration continues

Question 21

what happens to pyruvate in plants and yeast during anaerobic respiration

Answer 21

pyruvate is reduced to ethanol and co2 is produced, oxidising NADH

Question 22

what is the comparison of energy released in aerobic and anaerobic respiration

Answer 22

aerobic = net 38 molecules of ATP per molecule of glucose
anaerobic = yeilds 2 molecules of ATP per molecule of glucose

Question 23

how is rate of respiration measured

Answer 23

volume of co2 produced per unit area or mass per unit time

Question 24

what is the required practical for respiration

Answer 24

methyl blue and respiration in yeast

Question 25

what occurs in the required prac for respiration

Answer 25

- yeast can respire both aerobically and anaerobically - during aerobic, the transport of electrons is linked to the synthesis of ATP - these electrons are accepted by methyl blue, this changes the colour from blue to colourless - faster the rate of respiration, faster the solution will decolourise

Question 26

what happens in a respirometer when an animal or plant respires aerobically

Answer 26

- o2 used for respiration - reduces amount of 02 in the chamber - reduces pressure - solution potassium hydroxide absorbs co2 released by organism - ink in the connecting tubes moves from high to low pressure, ink moves left - measure time taken to obtain rate

Question 27

what happens in a respirometer when an animal or plant respires anaerobically

Answer 27

- using same volume of yeast in both tubes - one tube of yeast has a layer of oil - syringe in the top of the tube to allow for repeat experiments without changing the apparatus - give time before the experiment begins to allow time for organisms respiration to level - pressure will increase, moving the ink right

Question 28

how do you calculate the rate of respiration in a respirometer

Answer 28

1) measure distance ink bubble moves 2) divide this by the fixed time period