TRANSLOCATION

Question 1

describe phloem

Answer 1

alive but few organelles
rely on companion cells (carry out respiration) to keep them alive
have ends that form sieve plates where cytoplasm can pass
no lignin in walls so walls are permeable to water and solutes

Question 2

what is translocation

Answer 2

process where organic and some inorganic ions are transported from one part of a plant to another
sugars (formed during photosynthesis) at a source need to be transported to be used or stored at a sink

Question 3

describe the mass flow theory

Answer 3

1. sucrose are actively transported from source cells to companion cells to sieve tubes
2. this lowers the water potential so water moves into the sieve tubes via osmosis
3. a high pressure is created in sieve tubes near source cells
4. since solutes are used in respiration / stored in sink cells a pressure gradient is created
   water and solutes move down the pressure gradient

Question 4

what three evidences are there for the mass flow theory

Answer 4

ringing experiment
radioactive tracers
aphids