Non human gas exchange

Question 1

How does gas exchange work in fish?

Answer 1

• Lower conc of oxygen in water than in air
• Water passes through the fish’s mouth and passes through the gills
• Each gill is made of thin plates called gill filaments which increase SA.
• The gill filaments are covered in lamellae which further increase SA.
• Lamellae have lots of capillaries and a thin surface layer to speed up diffusion.

Question 2

How does the counter current system work in fish?

Answer 2

Blood and water move in opposite directions through the lamellae which maintains a concentration gradient between the water and the blood. The conc of oxygen in water is always higher than blood so oxygen diffuses into the blood.

Question 3

What is the insects gas exchange system like?

Answer 3

• Microscopic air filled pipes called tracheae.
• Air moves into tracheae through pores called spiracles.
• Oxygen travels down the concentration gradient towards cells.
• Tracheae branch off into tracheoles which have thin, permeable walls and go directly to respiring cells.
• Rhythmic abdominal movements move air in and out of the spiracles.

Question 4

How is carbon dioxide released from insects?

Answer 4

CO2 moves down its own conc grad toward spiracles to be released into the atmosphere.

Question 5

How do plants do gas exchange?

Answer 5

• Gas exchange surface is the mesophyll cells in the leaf. They have a large SA.
• Gases move in and out through special pores in the epidermis called stomata.
• Guard cells control the opening and closing of stomata.

Question 6

How can plants prevent water loss?

Answer 6

• Guard cells lose water and become flaccid which closes the pore.
• Some plants have layers of hair which trap moisture.
• Some plants have waxy, waterproof cuticles.

Question 7

How do insects reduce water loss?

Answer 7

• Waxy cuticle and tiny hairs around the spiracles.

- They use their muscles to close their spiracles.