2(g) GAS EXCHANGE · RECALL

2.50 Breathing in humans

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012.50Pearson Edexcel focus

Brief CORMMSS for exercise intensity and breathing rate.

Reveal answer

C: 4–5 step-up rates; O: same age/fitness; R: several people, mean; M1: breaths counted; M2: for 1 min straight after exercise; S1: same duration; S2: rest to resting rate between tests.

Key words: step-up · breaths

022.50Pearson Edexcel focus

How do you measure breathing rate accurately?

Reveal answer

Count chest rises for a full minute (not 15 s × 4), without the person knowing, and repeat for a mean.

Key words: minute · mean

032.50Pearson Edexcel focus

Why does breathing stay fast after exercise?

Reveal answer

Oxygen debt → lactic acid must be broken down → extra oxygen needed → rate falls gradually.

Key words: oxygen debt

042.50Lesson

What is meant by the term breathing rate?

Reveal answer

Number of complete breaths per minute.

Key words: breathing rate

052.50Lesson

What is meant by the term recovery time?

Reveal answer

Time for a measured variable to return toward its baseline.

Key words: recovery time

062.50Lesson

What is meant by the term repeated-measures design?

Reveal answer

A design comparing the same participant across conditions.

Key words: repeated-measures design

072.50Lesson

What is meant by the term anti-suckback trap?

Reveal answer

A safety arrangement preventing test liquid reaching the mouth.

Key words: anti-suckback trap

082.50Lesson

Measurements and limitations, Indicator/limewater. What it shows? Limitation?

Reveal answer

What it shows: Exhaled air contains more CO₂ than room air. Limitation: Often qualitative and airflow-dependent.

Key words: Indicator/limewater

092.50Lesson

Measurements and limitations, Breathing rate. What it shows? Limitation?

Reveal answer

What it shows: Breaths per minute. Limitation: Does not show breath depth.

Key words: Breathing rate

102.50Lesson

Measurements and limitations, Tidal volume. What it shows? Limitation?

Reveal answer

What it shows: Air volume per breath. Limitation: Needs calibrated equipment and hygiene measures.

Key words: Tidal volume

112.50Lesson

Measurements and limitations, Minute ventilation. What it shows? Limitation?

Reveal answer

What it shows: Rate × tidal volume. Limitation: More informative but inherits both measurement uncertainties.

Key words: Minute ventilation

122.50Lesson

Measurements and limitations, Recovery curve. What it shows? Limitation?

Reveal answer

What it shows: Return toward baseline over time. Limitation: Affected by intensity, stress, temperature and individual variation.

Key words: Recovery curve

132.50Lesson

True or false, and why? “A high breathing rate proves someone is unfit.”

Reveal answer

False. Rate depends on intensity, stress, temperature, technique and individual physiology; this practical is not diagnostic.

142.50Lesson

True or false, and why? “Counting for 15 seconds is always precise.”

Reveal answer

False. Multiplication magnifies a one-breath counting error; longer counts improve resolution but may miss rapid change.

152.50Lesson

True or false, and why? “Participants should breathe in through limewater.”

Reveal answer

False. Only exhale through a protected one-way setup; inhalation risks suckback.

162.50Lesson

True or false, and why? “Elevated breathing after exercise only removes lactate.”

Reveal answer

False. Recovery involves multiple metabolic, thermal and acid–base processes.

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