Edexcel IAL Biology Topic 7 Respiration and internal environment

Trace energy transfer through the named respiratory stage, show calculation steps with units and connect muscle or internal-environment evidence to the physiological response.

Exam points

Explain ATP production through glycolysis, Krebs reactions and oxidative phosphorylation.
Calculate respiration rate or RQ from gas volumes, time and substrate evidence.
Link muscle and internal-environment data to contraction, recovery or homeostasis.

Covered syllabus points

7.1—Aerobic respiration overview 7.2—Glycolysis in aerobic and anaerobic respiration 7.3—Link reaction and Krebs cycle 7.4—Oxidative phosphorylation 7.5—Lactate after anaerobic respiration 7.6—Respiratory quotient 7.7—Core Practical 15 - respiration in yeast 7.8—Core Practical 16 - respirometer, respiration rate and RQ 7.9—Movement by muscles, tendons, skeleton and ligaments 7.10—Skeletal muscle fibre and twitch types 7.11—Sliding filament theory 7.12—Cardiac muscle electrical activity and ECGs 7.13—Cardiac output, ventilation and control centres 7.14—Adrenaline and fight-or-flight 7.15—Core Practical 17 - exercise and spirometer traces 7.16—Negative and positive feedback 7.17—Homeostasis and thermoregulation 7.18—Mammalian kidney structure 7.19—Urea production and ultrafiltration 7.20—Selective reabsorption and loop of Henle 7.21—ADH and osmoregulation 7.22—Transcription factors and hormone action

[Maximum number: 4]

Aerobic respiration is made up of several stages.

(a)

Which is the correct order of the stages of respiration required for the complete oxidation of glucose? □ A

Table for Question (a) — Edexcel A-Level Biology A2

[ 1 ]

(b)

Write a balanced equation for the complete oxidation of glucose in aerobic respiration.

[ 2 ]

An answer showing the following steps:

- equation (1)

- balanced equation (1)

accept incorrect formula e.g. CO2 accept correct word equation

e.g. $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}+6 \mathrm{O}_{2} \rightarrow 6 \mathrm{CO}_{2}+6 \mathrm{H}_{2} \mathrm{O}$ ignore ATP / ADP

1 mark if equation correct but not balanced

(c)

The equation shows the aerobic respiration of a lipid.

2 \mathrm{C}_{18} \mathrm{H}_{34} \mathrm{O}_{2}+51 \mathrm{O}_{2} \rightarrow 36 \mathrm{CO}_{2}+34 \mathrm{H}_{2} \mathrm{O}

[ 1 ]

(i)

Which is the respiratory quotient when this lipid is used in aerobic respiration? (1) □ A 0.67 □ B 0.71 □ C 1.06 □ D 1.42

[ 1 ]

[Maximum number: 9]

Animals use aerobic and anaerobic respiration to produce ATP.

(a)

Aerobic respiration has three stages where reactions occur between enzymes and substrates.

[ 3 ]

(i)

Which row of the table shows the location of each stage?
□ A
□ B
□ C
□ D

Table for Question (i) — Edexcel A-Level Biology A2

[ 1 ]

(ii)

A student calculated the volume of oxygen used by a cockroach as $1.7 \mathrm{~cm}^{3}$ hour ${ }^{-1}$ . The same cockroach produced $1.3 \mathrm{~cm}^{3}$ hour ${ }^{-1}$ of carbon dioxide in the same time.

What is the respiratory quotient (RQ) of this cockroach?

0.7

0.8

1.3

2.2

[ 1 ]

(iii)

Hydramethylnon is an insecticide that is used to treat termite infestations.

Hydramethylnon inhibits the electron transport chain.
Which row of the table shows the expected changes caused by hydramethylnon?

Table for Question (iii) — Edexcel A-Level Biology A2

[ 1 ]

(b)

*(c) The photograph shows a crocodile (Crocodylus porosus) that lives in saltwater habitats.

Figure for Question (b) — Edexcel A-Level Biology A2

An investigation measured the lactate production rate of these crocodiles when they were active.

The graph shows the results of this investigation.

Lactate production rate $/ \mu \mathrm{mol} \min ^{-1} \mathrm{~g}^{-1}$

Each plotted point on the graph represents a single crocodile.
Discuss the roles of the different types of respiration in these active crocodiles.
Use the information in the graph and your own knowledge to support your answer.

[ 6 ]

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Covered syllabus points

Topic 7 - Respiration, Muscles and the Internal Environment question 1

Question (a)

Question (b)

Question (c)

Question (i)

Topic 7 - Respiration, Muscles and the Internal Environment question 2

Question (a)

Question (i)

Question (ii)

Question (iii)

Question (b)