Organisms And Their Environment Flashcards
What must organisms do to survive?
Transfer materials between the two environments.
What does transfer of materials between two environments involve?
Always involves crossing cell plasma membranes.
What’s tissue fluid?
The environment around the cells of multicellular organisms is called tissue fluid.
What effects the amount of each material that is exchanged?
The size and metabolic rate of an organism.
Excluding heat how do exchanges take place? (Two ways)
Passively - no metabolic energy is required - by diffusion and osmosis.
Actively (metabolic energy is required) by active transport.
What must the SA:V ratio be like for exchange to be effective?
The exchange surface(s) of the organism must be large compared with its volume.
How may an animal’s be adapted to have a large SA:V ?
A flatter bed shape so no cell is ever far from the surface
Specialised exchange surfaces with large areas to increase, e.g. lungs and gills
