gas exchange

Question 1

What are the features of gas exchange?

Answer 1

• large surface area
• thin/short distance
• steep concentration gradient

Question 2

Why can’t insects use their bodies as an exchange surface?

Answer 2

They have a waterproof chitin exoskeleton and a small surface area to volume ratio to conserve water.

Question 3

What are the main features of an insect gas transport system?

Answer 3

spiracles, tracheae, tracheoles

Question 4

What are spiracles?

Answer 4

Holes on the body’s surface that may be opened or closed by a valve for gas or water exchange.

Question 5

What is a tracheae?

Answer 5

Large tubes extend through all body tissues, supported by rings to prevent collapse.

Question 6

What are tracheoles?

Answer 6

smaller branches dividing off the tracheae

Question 7

What is the process of gas exchange in insects?

Answer 7

• Gases move in and out of the tracheae through the spiracles.
• A diffusion gradient allows oxygen to diffuse into the body tissue while waste co2 diffuses out.
• contraction of muscles in the tracheae allows mass movement of air in and out.

Question 8

What is the gross structure of the human gas exchange.

Answer 8

Trachea, bronchi, bronchioles, capillary network, alveoli.

Question 9

Explain how humans breathing in.

Answer 9

Inspiration ( breathing out):
1. Diaphragm muscles contract, flatten.
2. External interocastal muscles contract, internal intercoastal muscles relx.
3. Increasing volume and decreasing pressure in thoraic only.
4. Air moves into lungs down the concentration gradient.

Question 10

Explain how do human breathe out?

Answer 10

1. Diaphragm relaxes - moves upwards.
2. Extternal intercoastal muscles relax, internal intercoastal muscles contract – ribcage moves down.
3. Decreasing volume and increasing pressure in thoraic.
   Air moves out of the ling down the concentration gradient.

Question 11

3 ways an insects tracheal system is adapted for gas exchange.

Answer 11

Tracheoles have thin walls, so short diffusion distance to cells.
Tracheae provides tubes full of air, so fast diffusion.
High numbers of highly branched tracheoles, so short diffusion to cells.

Question 12

Explain in two ways how a fish’s gills are adapted for gas exchange.

Answer 12

Gills made of many filaments covered with many lamellae - increased surface area for diffusion.
Thin lamellae wall - so short diffusion distance between water.