[Unit 6.2] | Gas Exchange In Unicellular Organisms & Insects

Question 1

How does gas exchange occur in unicellular organisms?

Answer 1

Due to their high SA:V ratio, gas exchange can occur via simple diffusion across the body surface.

Question 2

What is the path that gas takes to enter the cells of an insect?

Answer 2

1. Enters Spiracles
2. Enters Tracheae
3. Enters Tracheoles
4. Passes through fluid
5. Enters cell

Question 3

What is a spiracle?

Answer 3

• A pore in the surface of an insect where gas exchange occurs.

Question 4

What are the tracheae?

Answer 4

• (Plural of trachea)

• A network of tubes reinforced by chitin rings where air can flow through.

Question 5

What are tracheoles?

Answer 5

• Subdivisions of the tracheae that extend through the tissue/cells of an insect.

• Offers a short diffusion pathway between itself and the insect’s cells.

Question 6

How do insects increase the rate of exchange?

Answer 6

When moving, muscle contractions may squeeze the tracheae which enables mass movements of air in & out.