specialised surfaces Flashcards
why do cells need glucose and oxygen
aerobic respiration
what waste products do organisms need to excrete
carbon dioxide and urea
do small animals have a large SA:V or a small SA:V
large SA:V
why do unicellular organisms not require specialised surfaces
smaller diffusion pathway
what are the three reasons why diffusion is too slow in multicellular organisms
some cells are deep within the body so diffusion distance is too large
low SA:V difficult to exchange as much substances
high metabolic rate using up oxygen rapidly
what are the features of an efficient exchange system
large surface area
thin
good ventilation
how do root hair cells have a large SA
millions of microscopic hairs branching into the soil to increase surface area
why do root hair cells need a large surface area
helps to increase the rate of absorption of water by osmosis and mineral ions by active transport
how is the alveoli thin
made from a single layer of epithelial cells
what does the thin alveoli layer allow for
decrease distance in which oxygen and carbon dioxide diffuse increasing diffusion rate
how does the alveoli have good ventilation
surrounded by a large capillary network constantly delivering oxygen and removing CO2
why does the alveoli need a good blood supply
maintain concentration gradients of oxygen and carbon dioxide
how do fish gills have good ventilation
large network of capillaries keeping them supplied with blood with fresh water constantly flowing
why do fish need good ventilation
maintain concentration gradients of oxygen and carbon dioxide
