Transport in plants

Question 1

Function of the xylem?

Answer 1

> carry water up the plant

> carry minerals

Question 2

Xylem vessels

Answer 2

> lignin impregnates the walls of the cells
end walls and contents of cells decay leaving a long column of dead cells
lignin strengthens the walls/preventing collapsing
xylem is flexible
lignification has gaps allowing water to travel across vessels

Question 3

Adaptions of xylem?

Answer 3

> made of dead cells to form a column
tubes are narrow so column of water doesn’t break
bordered pits allow water to move sideways
lignin deposited in spirals allow stem to flex

Question 4

Phloem

Answer 4

> tissue transporting sucrose and amino acids around the plant
sucrose is dissolved in water to form sap
contain sieve tube elements and companion cells

Question 5

Sieve tube elements

Answer 5

> contain no nucleus and little cytoplasm
> leave space for mass flow of sap
> sieve tube plates at the end 
> holes allow sap to move next tube
> thin walls/5 or 6 sides

Question 6

Companion cells

Answer 6

> in between sieve tubes
large nucleus and dense cytoplasm
lots of mitochondria to produce ATP for active processes
carry out metabolic processes needed to load assimilates into sieve tubes