#2: Gas Exchange in Single-Celled + Insects

These flashcards cover key concepts related to gas exchange in single-celled organisms and insects as outlined in the lecture notes.

How do single-celled organisms exchange gases?

They absorb oxygen and release carbon dioxide by diffusion across their body surface.

What is the role of tracheae in insects?

Tracheae are internal tubes that allow for gas exchange by bringing atmospheric air directly to respiring tissues.

What is a diffusion gradient?

A difference in concentration that causes gases, such as oxygen and carbon dioxide, to move from areas of higher concentration to areas of lower concentration.

What are spiracles in insects?

Tiny pores on the body surface that allow gases to enter and leave the tracheal system.

What happens to the concentration of oxygen in the tracheae when spiracles are closed?

The concentration of oxygen decreases when the spiracles are closed.

Why do terrestrial insects need to conserve water during gas exchange?

Increased surface area for gas exchange can lead to higher rates of water evaporation.

How does the contraction of muscles in insects aid gas exchange?

Muscle contractions squeeze the trachea, enabling mass movements of air which increases the speed of gas exchange.

How does anaerobic respiration affect gas exchange in insects?

It produces lactate, lowering water potential in muscle cells, causing water to move into cells and increasing the volume of air that can be drawn into tracheoles.

Why are insects limited in size by their tracheal system?

The effectiveness of diffusion decreases with longer pathways, limiting how large insects can grow.

What is the conflict faced by terrestrial insects in regards to gas exchange?

The need for gas exchange conflict with the need to conserve water.