Chapter 6: Exchange Flashcards
What affects the rate of exchange of an organism?
the size and metabolic rate
What need to be exchanged between an organism and it environment?
Respiratory gases (oxygen and carbon dioxide); nutrients (glucose, fatty acids, amino acids, vitamins and minerals); excretory products (urea and carbon dioxide); and heat
What are the two types of exchange?
passive, no energy required; and active, that requires metabolic energy.
Why is a large surface area to volume ratio important?
The cells make up most of the volume, the larger the surface area means there is a larger outside surface for gas to diffuse into, so gas doesn’t have to travel as far to reach cells in the middle of the organism.
How have some organisms adapted to increase surface area for gas exchange?
a flattened shape ,so cells closer to surface; specialised exchange surfaces with larger surface area.
What are the features of specialised exchange surfaces?
a large SA:V ; short diffusion distance; selectively permeable membrane; movement of gases; a transport system for internal medium.
What is the equation of the factors of diffusion?
diffusion∝(surface area x difference in concentration)/ length of diffusion path
How do single-celled organisms exchange gases?
by diffusing through their cell surface membrane.
What structures do insects use in gas exchange?
Spiracles, which are tiny pores on the body surface; trachea, an internal network of tubes; tracheoles, a smaller network of tubes that branch from trachea and come to a dead end.
What are the three ways insects use the tracheal system for gas exchange?
A diffusion gradient; mass transport and the ends of tracheoles being filled with water.
How do insects use a diffusion gradient for gas exchange in the tracheoles?
Oxygen in tracheoles is used up by respiring cells so concentration falls creating a diffusion gradient. this causes more oxygen to diffuse into trachea. This is the opposite for waste materials.
How do insects use mass transport for gas exchange?
they contract their muscles enabling the mass movement of air in and out. know as abdominal pumping
How does ends of tracheoles being filled with water benefit gas exchange. in insects?
anaerobic respiration produces lactate which lowers the water potential of muscle cells, the water in the tracheoles osmotically travels into these cells decreasing in volume and decreasing the pressure in the tracheoles , causing more air to diffuse in.
How does gas enter and leave the tracheae?
through the spiracles
How do insects prevent water loss through their spiracles?
they can close them and re-open them
