Respiratory organs and gas exchange
Answers are for parents and teachers.
1
Write the mechanism of inhalation and exhalation in 5 steps.
Inhalation: impulse from centre → intercostals and diaphragm contract → chest widens → air enters. Exhalation: muscles relax → chest shrinks → air leaves.
2
Show gas exchange for lungs and tissues in separate diagrams.
Lungs: O₂ alveolus→blood, CO₂ blood→alveolus. Tissue: O₂ blood→cell, CO₂ cell→blood.
3
Count breaths per minute at rest three times and write the average.
Results differ by person; for teenagers usually around 15–20.
4
Write 3 rules to prevent carbon monoxide poisoning at home.
Adults check stove and chimney; ventilate rooms; do not leave gas appliances running unattended; make sure there are no embers before sleeping.
5
Why should the classroom be aired at every break?
Carbon dioxide falls, oxygen rises, spread of germs is reduced and attention improves.