12 respiration

Question 1

4 reasons why krebs cycle is important

Answer 1

• breaks down macromolecules into smaller ones (pyruvate to CO2)
• produces hydrogen atoms that provide energy for oxidative phosphorylation
• regenerates 4-carbon molecule that combines with acetylCoA
• a source of immediate compounds used by cells

Question 2

stages of oxidative phosphorylation

Answer 2

• FADH and NADH donate electrons of hydrogen atoms to electron transfer chain
• energy released from electrons causes the active transport of protons across the inner mitochondrial membrane
• creates high conc of protons in inter-membral space, protons pass through ATP synthase, catalyse reaction of ATP synthesis
• at the end of the chain electrons combine with protons and oxygen to form water, oxygen is the terminal acceptor of electrons

Question 3

what is the role of oxygen in respiration?

Answer 3

terminal electron acceptor (combines with protons and electrons to form water)

Question 4

products of link reaction and Krebs cycle for one molecule of pyruvate

Answer 4

• reduced coenzymes FADH and NADH
• 1 molecule of ATP
• 3 molecules of CO2

Question 5

stages of the Krebs cycle

Answer 5

• 2-carbon acetylCoA combines with 4-carbon molecule to form 6-carbon molecule
• 6-carbon molecule loses 1 CO2 and H which reduces NAD to NADH to become a 5-carbon molecule
• 5-carbon molecule loses 1 CO2 and h which reduces NAD to NADH and 1 molecule of ATP is produces as a result of substrate-level phosphorylation
• the 4-carbon molecule begins the cycle again

Question 6

stages of the link reaction

Answer 6

• pyruvate is oxidised to acetate (2-carbon), pyruvate loses a CO2 molecule and 2 hyrdogens which are accepted by NAD to form NADH (hydrogenation)
• acetate combine with coenzyme A to form acetlycoenzyme A (2-carbon)

Question 7

overall yield of one glucose molecule undergone glycolysis

Answer 7

• 2 ATP
• 2 NADH
• 2 pyruvate

Question 8

stages of glycolysis

Answer 8

• phosphorylation of glucose (6-carbon), addition of 2 phosphate molecules to glucose making it more reactive and lowering activation energy (phosphate from hydrolysis of ATP)
• each glucose phosphate molecule is split into 2 triose phosphates (3-carbon)
• hydrogen removed from triode phosphates forming NADH
• enzyme-controlled reactions convert triode phosphate to pyruvate (3-carbon), 2 ATP formed

Question 9

location of Krebs cycle

Answer 9

mitochondrial matrix

Question 10

what is triose phosphate used for?

Answer 10

regeneration of RuBP and making useful organic molecules within the plant

Question 11

location of link-reaction

Answer 11

mitochondrial matrix

Question 12

4 stages of aerobic respiration

Answer 12

• glycolysis
• link reaction
• Krebs cycle
• oxidative phosphorylation

Question 13

location of glycolysis

Answer 13

cytoplasm

Question 14

what is dehydrogenation?

Answer 14

removal of hydrogen

Question 15

what is decarboxylation?

Answer 15

removal of carbon dioxide

Question 16

what is the role of the Krebs cycle?

Answer 16

• generate NADH and FADH which transfer hydrogen ions to the electron transfer chain
• produce 1 molecule of ATP

Question 17

what are example of other respiratory substrate that enter the Krebs cycle?

Answer 17

lipids and amino acids

Question 18

what is the role of oxygen in aerobic respiration?

Answer 18

terminal electron acceptor

Question 19

word equation for anaerobic respiration in plants and some micro-organisms
(bacteria and fungi)

Answer 19

pyruvate + NADH -> ethanol + carbon dioxide + oxidised NAD

Question 20

how is ethanol produced in plants and some micro-organisms

Answer 20

pyruvate loses 1 CO2 and accepts hydrogen from NADH to produce ethanol

Question 21

word equation for anaerobic respiration in animals

Answer 21

pyruvate + NADH -> lactate + oxidised NAD

Question 22

what is the oxidised NAD produced in anaerobic respiration used for?

Answer 22

it can be reused in glycolysis