Biology Unit 3.3 - Respiration & Glycolysis

Question 1

What is glycolysis?

Answer 1

Splitting of sugar that occurs in the cytoplasm, which doesn’t require oxygen, and produces ATP through SLP

Question 2

What occurs during stage 1 of glycolysis?

Answer 2

Glucose is phosphorylated forming hexose phosphate, which splits into triose phosphate

Question 3

What occurs during stage 2 of glycolysis?

Answer 3

Triose phosphate is oxidised forming pyruvate, through dehydrogenation

NAD collects the hydrogen ions forming reduced NAD

2 ATP produced through SLP

Question 4

What occurs during the link reaction?

Answer 4

Pyruvate is converted into acetate through decarboxylation, which combines with coenzyme A to form acetyl CoA

Question 5

What occurs during the Krebs cycle?

Answer 5

Takes place in the mitochondrial matrix, where acetate combines with a 4C molecule to form a 6C molecule

Series of decarboxylation and dehydrogenation forms a 4C molecule from the 6C molecule

NAD and FAD are reduced and carry electrons and protons to the electron transport chain

Question 6

What is the function of 2 CoA?

Answer 6

Are regenerated and returns to the link reaction

Question 7

What is the function of 2 4C molecules?

Answer 7

Are regenerated to allow the Krebs cycle to continue

Question 8

What is the function of 4 CO2?

Answer 8

Waste product that diffuses out of the cell

Question 9

What is the function of 2 ATP?

Answer 9

Produced by SLP

Question 10

What is the function of 6 reduced NAD and 2 reduced FAD?

Answer 10

Pass to the inner membrane of the mitochondria and donate electrons and protons to the electron transport chain

Question 11

How are FAD and NAD similar?

Answer 11

Both contain a pentose sugar

Both have two phosphate groups

Both contain two nitrogenous bases

They are both nucleotides

Question 12

How are FAD and NAD different?

Answer 12

FAD has one ring sugar - NAD has two ring sugars

FAD has one linear and one ring 5C sugar - NAD has two ring 5C sugars

FAD contains flavin - NAD contains nicotinamide

FAD has a three-ring base - NAD has a one ring base

Question 13

What occurs in the electron transport chain?

Answer 13

Excited electron pass along electron carriers, providing electron energy which drives proton pumps

Hydrogen ions are pumped into the inter membrane space via a proton pump mechanism

Hydrogen ions diffuse back into the matrix through stalked particles attached to ATP synthetase

Electrochemical gradient generated provides needed energy for ATP production

Process is known as chemiosmosis

Question 14

What is the role of oxygen in the electron transport chain?

Answer 14

Combines with hydrogen to form water, ensuring the flow of electron energy is maintained

Question 15

How is ATP production in chloroplasts and mitochondria similar?

Answer 15

Involve transport of excited electron from carrier to carrier

Electron energy is released to drive proton pumps

Protons are pumped into the inter membrane space

Protons diffuse down the concentration gradient through stalked particles

Electrochemical gradient provides the energy needed to produce ATP

ATP is produced from ADP and Pi by chemiosmosis

Question 16

How is ATP production in chloroplasts and mitochondria different?

Answer 16

No SLP - SLP present

Electron originate from chlorophyll and water - Electron originate from H atoms

Electrons either return to chlorophyll or are passed to NADP - Oxygen is the final electron acceptor

Chemiosmosis occurs on thylakoid membranes - Chemiosmosis occurs on the inner membrane

H ions accumulate in the thylakoid cavity - H ions accumulate in the inter membrane space

Only 1 proton pump - 3 types of proton pumps

Question 17

What occurs during anaerobic respiration?

Answer 17

Absence of oxygen means reduced NAD and FAD cannot be re-oxidised, so the link reaction and Krebs cycle cannot take place

ATP yield is reduced - 2 molecules

Question 18

Why is oxygen important in ATP production?

Answer 18

Hydrogen atoms combine with oxygen to form water

Without oxygen, hydrogen atoms accumulate, and the process stops

Question 19

How is lactic acid formed in animal cells?

Answer 19

Reduced NAD passes hydrogen to pyruvate, reducing it to lactate

Yields two molecules of ATP

Lactic acid builds up causing cramps

When oxygen is available lactic acid is broken down and converted into glycogen

Question 20

What occurs during fermentation in yeast?

Answer 20

Pyruvate is decarboxylated to produce ethanal

Hydrogen is released and passed on to NAD

Reduced NAD passes the hydrogen to ethanal, reducing it to ethanol

Yields 2 molecules of ATP

Question 21

How is fat used in respiration?

Answer 21

Used when carbohydrate levels are low

Split into glycerol and fatty acids by hydrolysis

Glycerol is converted into a 3C sugar and enters the Krebs cycle via triose phosphate

Long fatty acid chains are split into 2C molecule and enter as acetyl CoA

Large number of ATP molecules are built up

H ions released are picked up by NAD and fed into the electron transport chain

Question 22

How is protein used in respiration?

Answer 22

Used during starvation

Hydrolysed into its constituent amino acids
Amino acids are deaminated in the liver

Amino groups is converted into urea and excreted

Rest of amino acids are converted into acetyl CoA, pyruvate or some other Krebs cycle intermediate

Question 23

How do electrons move from cytochrome to cytochrome?

Answer 23

Cytochromes have complimentary shapes and bind

Cytochrome c receives an electron, changing its tertiary shape

Cytochrome c is now complimentary to cytochrome oxidase

Electron is passed to oxygen, where cytochrome c detaches and returns to cytochrome bc

Question 24

What are the main products of glycolysis?

Answer 24

2 ATP

2 Reduced NAD

2 Pyruvate

Question 25

What are the main products of the Krebs cycle?

Answer 25

2 CoA

2 4C molecules

4 CO2

2 ATP

6 Reduced NAD

2 Reduced FAD

Question 26

What are the main products of the electron transport chain?

Answer 26

ATP

Water

Oxidised NAD

Oxidised FAD