Adaptations For Gas Exchange

Question 1

what is counter current flow?

Answer 1

Blood flows in the opposite direction to the water that flows over the fish’s gills

Question 2

why is counter current flow good?

Answer 2

it maintains a steep concentration gradient - water is always richer in oxygen than in the blood

Question 3

how do humans ventilate their lungs?

Answer 3

negative pressure breathing

Question 4

how is water loss prevented in insects?

Answer 4

they have an impermeable cuticle to reduce evaporation.
and tiny hairs surrounding spiracles to maintain humidity.

Question 5

how are insects adapted for efficient gas exchange?

Answer 5

spiracles on thorax - lead to tracheae and tracheoles -tracheoles enter cells and are site of GE

Question 6

evaluate adaptations for GE in earth worms

Answer 6

conc. gradient - maintained by GE surface being exposed to air
high SA - worms cylindrical shape
short D path - gas exchange surface is skin but blood capillaries are required to get O2 to inner cells
moisture - behaviour (stays in moist soil) slimy mucus produced by epithelial cells

Question 7

evaluate adaptations for GE in flat worms

Answer 7

only difference is there is no blood capillaries in flat worm unlike earthworms.

Question 8

evaluate adaptations for GE in mammals

Answer 8

high conc. gradient - ventilation of lungs by negative pressure breathing
high SA - millions of alveoli
short D path - alveoli are one cell thick (one squamous epithelial cell)
moisture - lungs are moist/ alveoli are lined with surfactant

Question 9

evaluate adaptations for GE in insects

Answer 9

large SA - large amount of tracheoles
short D path - tracheoles stretch down into the cells of the insect
high conc. gradient - contractions of abdominal muscles compress air sacs increasing ventilation during vigorous activity such as flying
moisture - tracheal fluid in tracheoles