Gas exchange in fish, insects and plants Flashcards
Why is gas exchange in fish hard?
There is a lower concentration of oxygen in water than in the air
Explain the process of gas exchange in fish
Water, containing oxygen, enters the fish through the mouth and passes out through the gills. Gills are made of gill filaments which are covered in lamella which increase the surface area. The lamella are also surrounded by lots of blood capillaries and have a thin surface layer which speeds up diffusion. Blood and water flow in opposite directions.
Explain the counter current system
Blood flows through lamella in one direction and water flows over lamella in opposite direction.
How does a counter current system allow gas exchange?
It maintains a large concentration gradient between water and blood. The concentraion of oxygen in water is always higher than in the blood so as much oxygen diffuses from water into the blood
What do insects use for gas exchange?
Trachea (microscopic air filled pipes)
Explain the process of gas exchange in insects?
Air moves into the trachea through pores on the surface could spiracle. Oxygen travels down the concentration gradient towards the cells. Trachea branches off into tracheoles which have think permeable walls. Oxygen diffuses directly into respiring cells. Carbon dioxide from cells moves down its concentration gradient towards spiracles. Rhythmic abdominal movements move air in and out of spiracles.
Explain adaptations of spiracles
Muscles can close spiracles to reduce water loss
Waxy and waterproof body
Where are gases exchanged in plants?
Surface of mesophyll cells
Which gases are needed and produced from photosynthesis?
Need carbon dioxide and produce oxygen
Which gases are needed and produced from respiration?
Need oxygen and produce carbon dioxide
Explain gas exchange in plants
Mesophyll cells are inside leaves. Gases move in and out through special pores in the epidermis called stomata. The stomata can open to allow the exchange of gases and close to reduce water loss.
What controls the opening and closing of stomata?
Guard cells
Explain xerophytic adaptaions
Stomata sunken in pits = trap moist air and decrease the concentration gradient of water between air and leaf. Decreases amount of evaporation and diffusion of water.
Layer of hair on epidermis = trap moist air
Curled leaves with stomata inside = protection from wind
Reduced number of stomata = Fewer places for water to escape
Waxy, waterproof cuticle = less evaporation
