exhange and transport systems (surface area)

Question 1

what type of ratio do smaller organisms have?

Answer 1

large surface area to volume ratio

Question 2

why do organisms need to exchange substances with their environment?

Answer 2

take in oxygen and nutrients
excrete waste products
need to stay at the same temperature

Question 3

how do single celled organisms exchange substances?

Answer 3

substances diffuses across the cell surface membrane

Question 4

why is diffusion too slow for gas exchange in multicellular organisms?

Answer 4

some cells are deep within the body- big distance between them and the outside environment
have a low surface area to volume ratio- hard to exchange via a small outer surface

Question 5

what is lost as the surface area to volume ratio increases?

Answer 5

heat, so organisms need a higher metabolic rate

Question 6

what are adaptations to maximise gas exchange?

Answer 6

large surface area to volume ratio 
thin so a short diffusion distance 
selectively permeable 
movement of environmental medium 
transport system to move medium

Question 7

what is Fick’s law?

Answer 7

diffusion is proportional to (surface area x concentration)/ length of diffusion path