Topic 3 - A: Exchange and transport systems

Question 1

What do gas exchange surfaces generally have in common

Answer 1

large surface area
thin

Question 2

Structure of gills

Answer 2

water enters through mouth and exits through gills
gill is made of thin plates called gill filaments providing large SA
Gill filaments covered in holes called lamellae which also increase SA
lamellae have capillaries and thin surface

Question 3

counter current current system

Answer 3

blood flows through lamellae in one direction and water flows over them in the opposite direction
this means the water with high oxygen concentration always flow next to blood with lower O concentration
this means steep concentration gradient is kept, so as much oxygen diffuses from water into blood

Question 4

gas exchange in insects

Answer 4

air move into tracheae through spiracles
oxygen goes down concentration gradient towards
tracheae branch into tracheoles which are thin
carbon dioxide does opposite and is released through the spiracles

Question 5

How is water loss controlled

Answer 5

sunken stomata
hairs
curled leaves
reduced number of stomata
waxy waterproof cuticle