exam questions Flashcards
explain when an organism needs a transport system (2)
- if they have a small surface area to volume ratio
- because diffusion alone is too slow / inefficient to keep up with metabolic rate
give 2 differences of the circulatory systems of animals and fish (2)
- animals have a double circulatory system and fish have a single circulatory system
- animal hearts have a septum which separates oxygenated & deoxygenated blood and fish do not have a septum so oxygenated & deoxygenated blood is not separated
explain why animals need well developed transport systems (3)
- diffusion alone is too slow
- to keep up with high metabolic demands
- requires a large oxygen supply to maintain a steep concentration gradient which maximises rate of diffusion
- of O2 and waste products like CO2
how is surface area to volume ratio calculated?
surface area = side squared x total sides
volume = side cubed
surface area divided by volume : 1
compare the circulatory systems of mammals and fish (6)
mammals
- double closed
- blood goes through 2 sets of capillaries
- heart has 4 chambers: 2 ventricles and 2 atria
- septum to separate oxygenated & deoxygenated blood
- high blood pressure
- high oxygen demand
fish
- single closed
- blood goes through 1 set of capillaries
- heart has 2 chambers: 1 ventricle and 1 atria
- no septum to separate deoxygenated & oxygenated blood
- low blood pressure
- low oxygen demand
describe how an artery is adapted to its function (4)
- large smooth muscle layer for vasoconstriction & vasodilation
- large elastic layer to allow continuous blood flow
- narrow lumen to increase blood pressure
- collagen to maintain shape and volume
describe how a vein is adapted to its function (4)
- small smooth muscle layer
- wide lumen for large reservoir of blood
- lots of collagen to maintain shape and volume for a large amount of blood
- valves prevent back flow
describe how a capillary is adapted to its function (4)
- 1 red blood cell thick
- short diffusion distance
- large SA
- thin walls
