Respiration

Question 1

Glucose

Answer 1

• Hexose sugar produced during photosynthesis

- Contains energy absorbed from sunlight with C-H Bonds

Question 2

Carbon framework of glucose

Answer 2

The C-H bonds and glucose is broken down

-Energy is released and used for the synthesis of ATP by chemiosmosis

Question 3

Respiration

Answer 3

Complex multi step pathway

Question 4

Eukaryotic cells

Answer 4

Takes place in the mitochondria of cells

Question 5

Prokaryotic cells

Answer 5

Do not have a mitochondria so many reactions take place in the cell membrane

Question 6

What is the first stage of respiration?

Answer 6

Glycolysis

Question 7

Glycolysis

Question 8

Glycolysis - Step 1: Phosphorylation

Answer 8

Phosphorylation: Two phosphates released from the 2 ATP molecules are attached to a glucose molecule forming hexose bi-phosphate

Question 9

Glycolysis - Step 2: Lysis

Answer 9

Lysis: This destabilises the molecule causing it to split into 2 triose phosphate molecules

Question 10

Glycolysis - Step 3: Phosphorylation

Answer 10

Phosphorylation: Another phosphate group is added to each triose phosphate forming 2 bi phosphate molecules.
-These phosphate groups come from free inorganic phosphate ions present in the cytoplasm

Question 11

Glycolysis - Step 4: Dehydrogenation + Formation of ATP

Answer 11

Dehydrogenation + Formation of ATP: 2 triose bi-phosphate molecules are the oxidised by the removal of hydrogen atoms (dehydrogenation) to form 2 pyruvate molecules.
-NAD co-enzymes accept the removed hydrogen’s (which are reduced) forming NADH

Question 12

Substrate level phosphorylation

Answer 12

formation of ATP without an electron transport chain.

-ATP is formed by the transfer of a phosphate group from triose bi phosphate to ADP

Question 13

Overall Net ATP yield

Answer 13

Two ATP molecules are used at the beginning and 4 ATP molecules are produced so 2 is produced overall

Question 14

Cristae

Answer 14

Projections of the inner membrane which increase SA available for oxidative phosphorylation

Question 15

Inner mitochondrial membrane

Answer 15

Contains electron transport chains and ATP Synthase

Question 16

Outer mitochondrial membrane

Answer 16

Separates the contents of the mitochondrion from the rest of the cell, creating a cellular compartment with ideal conditions for aerobic respiration

Question 17

Matrix

Answer 17

Contains enzymes for the Krebs cycle and the link reaction. It also contains mitochondrial DNA

Question 18

Inter membrane Space

Answer 18

Proteins are pumped into the space by the electron transport chain. The space is small so the concentration builds up quickly

Question 19

The link reaction (oxidative decarboxylation)

Answer 19

This is the first step in anaerobic respiration. This is referred to as the link reaction because it links anaerobic glycolysis occurring in the cytoplasm, to the aerobic steps of respiration in the mitochondria

Question 20

Link Reaction - Step 1: Movement

Answer 20

(Eukaryotic cells): Pyruvate enters the mitochondria matrix by active transport via specific carrier proteins

Question 21

Link Reaction - Step 2: Removal

Answer 21

Pyruvate then undergoes the link reaction and CO2 is removed (decarboxylation),along with hydrogen (oxidation).

Question 22

Link Reaction - Step 3: Hydrogen

Answer 22

Hydrogen atoms which are removed are accepted by NAD. NAD is reduced to form NADH

Question 23

Link Reaction: Step 4: Acetyl

Answer 23

2 carbon acetyl group is formed and binds to an coenzyme A which results in acetyl COA

Question 24

Link Reaction: Step 5: Delivery

Answer 24

The acetyl coa is delivered to the krebs cycle.

Question 25

What is the reduced NAD used for?

Answer 25

Oxidative phosphoryalation to synthesise ATP

Question 26

Explain why the removal of carbon dioxide in the link reaction is oxidative (2 marks)

Answer 26

Hydrogen is also removed (1); removal of hydrogen oxidises pyruvate (1).

Question 27

Name one organic compound and one organic compound and one inorganic compound produced in the link reaction? (2 marks)

Answer 27

Acetyl group (1); carbon dioxide (1)

Question 28

Suggest why glcolysis occurs in the cytoplasm but not the mitochondrial matrix (4 marks)

Answer 28

Enzymes required are in cytoplasm/ORA (1); glucose molecule too large to move into
mitochondrion (1); no transport proteins for pyruvate (1); mitochondria not originally present in
(eukaryotic) cells (1).

Question 29

Where does the Krebs cycle take place?

Answer 29

The mitochondrial matrix where each complete cycle results in the breakdown of an acetyl group

Question 30

Krebs Cycle: Step 1: Entrance

Answer 30

Acetyl Coenzyme A brings the Acetyl group into the krebs cycle. The two carbon acetyl group combines with 4 carbon oxaloacetate to form citrate

Question 31

Krebs Cycle: Step 2: Decarboxylation + Dehydration

Answer 31

The citrate molecule molecule undergoes decarboxylation and dehydration producing one reduced NAD and CO2. A five carbon molecule is formed

Question 32

Krebs Cycle: Step 3: Further Decarboxylation + Dehydration

Answer 32

The five carbon compound undergoes further decarboxylation and dehydration , eventually regenerating oxaloacetate.

Question 33

Krebs Cycle: Step 4: Cycle continues

Answer 33

The cycle continues so more CO2 and 2 more reduced NADs and one reduced FAD are produced. ATP is also produced by substrate- level phosphorylation