Counter Current in Fish
- Water containing oxygen enters the fish thought the mouth and pass out through the gills.
- Each gill is made out of thin plates called gill filaments, they are covered by tiny structures called lamellae, which increase the gas exchange surface area even more.
- Lamellae consists of lots of blood capillaries that carry deoxygenated blood.
- Blood and the water flow in opposite way, this is called the counter current system which maintains a large concentration gradient between water and the blood in capillaries.
Insects use Tracheae to exchange gas
- Insects have air-filled pipes called tracheae.
- Air moves in the tracheae through pores on the surface called spiracles.
- Oxygen travels down the concentration gradient towards the cell.
- Oxygen directly diffuses into respiring cells ( oxygn is not transferred).
- Carbon dioxides are released in the atmosphere through the spiracles.
- They have a rhythmic abdominal movement to move air in and out of the spiracles.
Gas exchange in Plants
- Photosynthesis requires CO2, which produces oxygen as a waste gas. They need oxygen for respiration. which produces CO2 as a waste gas.
- The gas exchange surface of plants are mesophyll cells on the leaf ( they create a large S.A).
- Mesophyll cells are inside the leaf, gas moves in and out of it through pores in the epidermis called stomata.
- The stomata can open to allow exchange of gas, and close if the plant is losing too much water.
- It’s the function of guard cells to open and close the stomata.
- Some plants are specially adapted to for life in warm, dry or windy habitats, where water loss is a problem.
- Stomata **** in pits to trap moist air.
- A layer of "hairs" on the epidermis to trap moist air.
- Curled leaves to trap moist air and protecting it from the wind.
- A reduced number of stomata to reduce water loss.
- Waxy, waterproof layer on the leaf to reduce water evaporation.