Summary Pearson Edexcel Biology Paper 5 Processes: Pt 1

BIOLOGY PAPER 5 PROCESSES: PART 1

CONTENTS:

- Topic 7

- 7A: Glycolysis in the Cytoplasm 3

- 7A: Link Reaction in the Mitochondrial Matrix 3-4

- 7A: The Krebs Cycle in the Mitochondrial Matrix 4

- 7A: The Electron Transport Chain in the Inner Mitochondrial Membranes 5

- 7A: Number of ATP Molecules Produced During Aerobic Respiration Per
Glucose Molecule 5

- 7A: Anaerobic Respiration in Mammals 6

- 7A: Anaerobic Respiration in Plants & Fungi 6

- 7B: Actin-Myosin Interactions: Ratchet Mechanisms 7

- 7B: Stages in the Cardiac Cycle 7

- 7B: Using ECG’s 8

- 7B: The ECG of a Healthy Heart 8

- 7B: Calculating Cardiac Output 8-9

- 7B: Negative Feedback Steps 9

- 7B: How Heart Rate Adjusts 9

- 7B: Role of Baroreceptors 9-10

- 7B: Role of Chemoreceptors in the Aorta 10

- 7B: Hormonal Control of the Heart Using Adrenaline 10

- 7B: Control & Regulation of Breathing 10-11

- 7B: Effect of Exercise on Breathing 11

- 7C: Releasing A Second Messenger: Ways Hormones Have Their Effects 12

- 7C: The Hormone Enters The Cell: Ways Hormones Have Their Effects 12

,- 7C: The Liver & The Deamination Process 12

- 7C: Ultrafiltration: A Passive Process 13

- 7C: Selective Reabsorption 13-14

- 7C: Mechanism of ADH Action Through The Blood 14

- 7C: ADH Action: During A Water Shortage 14-15

- 7C: ADH Action: During Water Loading 15

- 7C: How Animals’ Body Temperature RISES 15

- 7C: How Animals’ Body Temperature LOWERS 15

- 7C: Cooling Mechanisms 15-16

- 7C: Warming Mechanisms: (MAINLY HEAT RETENTION METHODS) 16-17

,TOPIC 7:

7A: Glycolysis in the Cytoplasm:

1. PHOSPHORYLATION OF GLUCOSE (6 CARBONS):
- Glucose is phosphorylated using 2 x ATP
- Produces:
- 2 x triose phosphate
- 2 x ADP

2. OXIDATION OF TRIOSE PHOSPHATE:
- After triose phosphate loses hydrogen, it forms 2 x pyruvate
- Hydrogen ions are collected by NAD⁻ which reduces the coenzyme
- Forms 2 x NADH

3. PRODUCTS OF GLYCOLYSIS:
- 2 x pyruvate
- Moves into the mitochondrial matrix for the link reaction

- 2 x ATP
- Total of 4 is made but 2 were used to phosphorylate glucose
- Leaves 2

- 2 x NADH
- Used during oxidative phosphorylation


7A: Link Reaction in the Mitochondrial Matrix:

1. 2 x pyruvate goes from the cytoplasm and into the mitochondria through the
mitochondrial matrix
2. C & O₂ is removed from the pyruvate through decarboxylation
- Results in the formation of CO₂ & a 2 Carbon compound

3. The 2 Carbon compound joins with coenzyme A to form acetyl coenzyme A
- Pyruvate is oxidised
- Loses a hydrogen ion to NAD⁻ & forms NADH through
dehydrogenation

4. Decarboxylases removes CO₂; Dehydrogenases remove Hydrogen
5. PRODUCTS OF THE LINK REACTION:
- Every molecule of glucose produces 2 x pyruvate, so the cycle occurs twice
per glucose molecule
- SO, THE PRODUCTS ARE:

, - 2 x acetyl CoA
- Energy from here is used in the Krebs Cycle

- 2 x CO₂
- 2 x NADH
- Used in the Electron Transport Chain to produce ATP


7A: The Krebs Cycle in the Mitochondrial Matrix:

1. Acetyl group (3 Carbons) from acetyl coenzyme A combines with a 4 Carbon
compound to form a 6 Carbon compound
2. The 6 Carbon compound is highly unstable so it breaks down to form a 4 Carbon
compound
- 2 x CO₂ is removed in the process & is released as a waste product through
decarboxylation

3. The 4 Carbon compound combines with an acetyl group (2 Carbons) from acetyl
coenzyme A
- Produces another 6 Carbon compound
- Steps 2 & 3 are repeated on a cycle

4. The 6 Carbon compound releases Hydrogen atoms that reduces NAD⁻ & FADH⁻²
to 3 x NADH & 1 x FADH₂
5. A phosphate is transferred from one of the intermediates in the substrate level
phosphorylation to ADP
- Forms 1 x ATP

6. PRODUCTS OF KREBS CYCLE:
- Every molecule of glucose produces 2 x acetyl coenzyme A molecules, so
the cycle occurs twice per glucose molecule
- SO, THE PRODUCTS ARE:
- 2 x ATP
- 6 x NADH
- Used in oxidative phosphorylation

- 2 X FADH₂
- Used in oxidative phosphorylation

- 4 x CO₂