Respiration

Question 1

What is respiraton

Answer 1

A set of metabolic reactions that take place in organisms and break down respiratory substances, such as glucose, into smaller inorganic molecules like water and carbon dioxide
Linked to the synthesis of ATP

Question 2

Why is respiration described as a catabolic process

Answer 2

Complex molecules( respiratory substances) are broken down into smaller simpler molecules

Question 3

Why do organisms need to respire

Answer 3

Produces chemical energy in ATP for a variety of processes include active transport, metabolic reactions and muscles contractions
Releases heat energy for thermoregulation

Question 4

Define aerobic respiration

Answer 4

A form of cellular respiration that takes place in the presence of oxygen and produces carbon dioxide, water and ATP

Question 5

Name the four main stages of aerobic respiration and state where they occur

Answer 5

Glycolysis - cytoplasm
Link reaction - mitochondrial matrix
Kreb cycle- mitochondrial matrix
Electron transport chain- inner mitochondrial membrane

Question 6

Outline the stages of glycolysis

Answer 6

1. Glucose ( hexose sugar) in phosphorylated to hexose bisohosphate by 2x ATP
2. Hexose bisphosphate splits into 2x triose phosphate (TP)
3. 2 molecules of TP oxidised to 2x pyruvate
   Net gain of 2x reduced NAD(NADH) and 2x ATP per glucose

Question 7

Equation to summarise glycolysis

Question 8

How does pyruvate from glycolysis enter the mitochondria

Answer 8

Via active transport

Question 9

Outline the link reaction

Question 10

Write an equation to summarise the link reaction

Question 11

What is the kreb cycle

Answer 11

A series of oxidation reduction reactions in the matrix of the mitochondria in which acetyl coenzyme A is oxidised generating reduced NAD, reduced FAD, ATP and carbon dioxide

Question 12

Outline the stages of kreb cycle

Question 13

What is the function of the kerbs cycle

Answer 13

It is a means of releasing energy from carbon bonds to provide ATP, reduced NAD and reduced FAD( with the release of CO2)

Question 14

How many reduced NAD and reduced FAD does the complete oxidation of one glucose molecule yield

Answer 14

10 reduced NAD
2 reduced FAD

Question 15

What is the electron transport chain

Answer 15

A series of electron carrier proteins that transfer electron in a chain of oxidation reduction reactions releasing energy

Question 16

How does chemiosmosis produce ATP during aerobic respiration

Answer 16

Protons flow down their conc gradient from the inter membrane space into the mitochondrial matrix via ATP synthase
ATP synthase phosphorylates ADP to form ATP as protons flow through it

Question 17

State the role of oxygen in the electron transport chain

Answer 17

Final electron acceptor

Question 18

How many ATP are produced per oxidised NAD in aerobic respiration

Answer 18

3 ATP

Question 19

How many ATP are produced per oxidised FAD in aerobic respiration

Answer 19

2 ATP

Question 20

Define anerobic respiration

Answer 20

A form of cellular respiration that takes place in the absence of oxygen. Less ATP is formed than in aerobic respiration

Question 21

State the product of anerobic respiration in animals

Answer 21

Lactic acid

Question 22

Outline anerobic respiration in animals

Answer 22

Only glycolysis continues
Reduced NAD ( product of glycolysis) transfers H to pyruvate, forming lactic acid

Question 23

State the products or anerobic respiration in plants and microorganisms

Answer 23

Ethanol and carbon dioxide

Question 24

Outline anerobic respiration in plants and microorganisms

Answer 24

Only glycolysis continues
Pyruvate is decarboxylated to form ethanal
Ethanal is reduced to ethanol used reduced NAD, producing oxidised NAD for further glycolysis

Question 25

Why is the maximum yield of ATP in aerobic oxygen in respiration never achieved

Answer 25

ATP lost due to leaky membranes
Energy required to move pyruvate and ADP into the mitochondrial matrix

Question 26

Name two types of molecules that can be used as an alternative respiratory substrates

Answer 26

Amino acids from proteins
Glycerol and fatty acids from lipid

Question 27

Explain how lipid are used in respiration

Answer 27

Hydrolysed to glycerol and fatty acids
Glycerol converted to a 3C sugar and enters glycolysis
Fatty acids broken down into 2C acetate fragments which enter the Krebs cycle as acetyl coenzyme A

Question 28

Explain how proteins are used in respiration

Answer 28

Hydrolysed to amino acids
Amino acids deaminated in the liver forming keto acids and ammonia
Keto acids enter glycolysis and the Krebs cycle