Advanced Science Primary 5 Systems

Which of the following correctly compares the air we breathe in and the air we breathe out?

A Breathed-out air has no oxygen.
B Breathed-in air has more carbon dioxide than breathed-out air.
C Breathed-out air has more water vapour and is warmer.
D Breathed-in air has no carbon dioxide.
Show Worked Solution

Worked Solution

Step 1: Compare inhaled and exhaled air. Step [2-9]: Cells produce heat and water vapour as by-products of respiration. Step [2-9]: This moisture and heat are transferred to the air in the lungs before exhalation.

Correct answer: Breathed-out air has more water vapour and is warmer.

Want more questions like this? Superholic Lab has 10,000+ MOE-aligned questions with full worked solutions.

Start Free Trial — 7 Days Free