The Phloem

Question 1

What is the phloem?

Answer 1

transports glucose + amino acids, etc.

direction is up and down

living cells - sieve tube cells and companion cells

Question 2

What does the companion cell do?

Answer 2

supports sieve tube cells and provide ATP

Question 3

What do sieve tube cells do?

Answer 3

living but with little cytoplasm
few organelles
hollow

Question 4

What are sieve plates?

Answer 4

thin pores between sieve tube cells

Question 5

What are evidences for translocation / mass flow?

Answer 5

radioactive labling - use radioactive C^14 lable, grow plants in that carbon atmosphere and measure the carbon as it moves down the stem/trunk

ringing experiment - remove bark in a ring from the tree trunk, solutes cant move up or down, buldge forms above the ring, fluid above the ring has more solutes than below, evidence the solutes are moving down

HOWEVER -

this is not fully understood or a perfect theory