plants - topic 4

Question 1

Describe translocation in plants (source to sink)

Answer 1

• ** Sucrose** ,made by source cells such as palisade cells, moves from companion cells to sieve tube elements via active transport
• water potential decreases in sieve tube
• water moves into sieve tube from Xylem via osmosis
• hydrostatic pressure increases
• sucrose moves down hydrostatic pressure gradient towards sink cells (eg root hair cells)
• root hair cells use sucrose in respiration
• increasing water potential so water moves via osmosis back to xylem and into sink cell.

Question 2

describe the structure and function of the schlerenchyma

Answer 2

made of dead cells no pits
lignified walls
provide structural support

Question 3

explain the effect of nitrate ions on plant growth

Answer 3

nitrates needed to make amino acid
defficiency means proteins cannot be made
growth stunted

Question 4

explain the effect of Mg ions on growth

Answer 4

used for the production of chlorophyll
provides green colour
defficiency means plant turns brown
photosynthesis cannot occur
lack of growth

Question 5

explain the effect of calcium on plant growth

Answer 5

calcium is important for the formation of the cell wall
defficiency leads to droopyness and lack of growth

Question 6

explain the structural features and function of the xylem

Answer 6

walls made of dead cells and pits
lignified walls
provide structural support
transport H2O and mineral ions

Question 7

describe the structural fetures and function of phloem

Answer 7

made of living cells (sieve tube elements, companion cells)
not lignified
transport of organic molecules (translocation)

Question 8

describe the structure and function of the schlerenchyma

Answer 8

made of dead cells no pits
lignified walls
provide structural support