chapter 6- exchange

Question 1

how have organisms adapted for large SA:VOL

Answer 1

-a flattened shape so no cell is ever far from the surface e.g flatworm
-lungs in mammals, gills in fish

Question 2

features of specialized exchange surfaces

Answer 2

-selectively permeable
-large SA:VOL
-very thin

Question 3

gas exchange in insects

Answer 3

-during activity, muscle cells around trachea produce lactate
-this lowers water potential
-water moves into cells by osmosis
-this reduces water in the tracheoles so air is drawn further in

Question 4

gas exchange in fish

Answer 4

-concurrent flow
-diffusion from water to blood
-diffusion gradient is maintained across entire width of gill lamellae

Question 5

gas exchange in plants

Answer 5

-short diffusion pathway as leaf is one cell thick (and large SA)
-many stomata so diffusion pathway is short

Question 6

absorption of triglycerides

Answer 6

-when micelles reach the ileum, they break releasing monoglycerides and fatty acids
-non polar so easily diffuse