The table shows the percentage of some gases in four samples of air. Which sample is expired air?

True or False: The structure labelled X is a trachea.

State the function of the cell labelled X.

The graphs show the changes in the volume of air in the lungs of the same person, measured at different levels of activities. Based on the graph, which letter represents the person at rest?

Which is the septum?

This experiment was left for days. Predict what you'll observed with the limewater, explain your answer.

Using the letters provided, in which order does blood pass through the chambers as it returns from the lungs during a complete circuit?

State the equation of the aerobic respiration:

Sodul was frightened by the sudden loud noise. What do you think happened to his heart rate and pupil when he's frightened?