insects and fish

Question 1

what are the 3 things which increase the efficiency of gas exchange:

Answer 1

1) high surface area
2) short diffusion distance
3) high concentration gradient

Question 2

describe how insects use gas exchange to breathe

how do insects maintain a high concentration gradient for oxygen?

Answer 2

> air enters through spiracles
oxygen diffuses along trachea down its concentration gradient
trachea surrounded by cells
oxygen diffuses into cells

ventilation maintains a high concentration gradient

Question 3

how do insects reduce water loss?

Answer 3

> waxy cuticle covers body, reducing evaporation

> spiracles can be closed

Question 4

how are gills adapted for efficient diffusion?

Answer 4

> filaments and lamellae have high surface area

> thin epithelium = short diffusion pathway

Question 5

describe and explain the advantage of the counter current principle

Answer 5

• water and blood flow in opposite directions
• so water is always next to blood with a lower concentration of oxygen meaning a high concentration gradient is maintained
• this means diffusion can occur along the length of the gill