Gas Exchange Extra

Question 0

Why does the tracheal system limit the size of the insect?

Answer 0

Because it relies on diffusion to bring oxygen to the respiring tissues. If insects were too large it would take too long for oxygen to reach tissues

Question 1

How do insects prevent excessive water loss from their tracheal system?

Answer 1

Gases enter/leave the trachea through spiracles. Insects have valves that can open/close these. When closed water can’t evaporate out.

Question 2

Other than valves, what causes the spiracles to open?

Answer 2

Rising levels of CO2

Question 3

How do bony fish ventilate their gills?

Answer 3

Using muscular contractions which cause water to move through the mouth, over the gills and out of the open opercula valve

If ram ventilators are stationary and water flow insufficient to extract the required amount of oxygen they will drown e.g. When they get caught in fishing nets

Question 4

How are leaves adapted for gas exchange?

Answer 4

Thin and flat - large surface area

No living cell is far from external air

Numerous interconnecting air spaces throughout the mesophyll

Many small pores - stomata (mostly in lower epidermis)