translocation in the phloem Flashcards
plants transport the organic products of photosynthesis, but in what form are they transported
these are transported as soluble sucrose in living tubes called phloem
where are the products of photosynthesis taken to
they are loaded in the leaves and taken to other parts where they are used for energy requiring processes such as growth e.g. atp for active transport
are phloem cells dead
no,they are living
what does thphloem cells being alive allow them to do
this allows them to produce ATP for sucrose transport
what is the general structure of phloem cells
they are long and thin cells joined together to form sieve tube elements
their end cell walls have perforations by the name______
sieve plates
what do pjloem cells not have and what does this result in
phloem cells do no have a nucleus and little cytoplasm which reduces resistance to the flow of substances
what two cell types are phloem cells divided into
sieve tube elements
companion cells
what are sieve tube elements
living cells with no nucleus and just a few organelles so less resistance to flow
what are companion cells
carry out living functions and provide ATP energy from mitochondria for the active transport of solutes
what is step one in translocation in the phloem
source produces glucose (by photosynthesis) which is then converted into sucrose
what is step two in translocation in the phloem
sucrose solution is actively loaded into the phloem
how is the sucrose solution loaded into the phloem
using ATP from the companion cells
what is step three in translocation in the phloem
water potential in the phloem decreases.water moves in from xylem by osmosis
what is step four in translocation in the phloem
hydrostatic pressure builds up,forcing the sucrose solution along the phloem by mass flow to the sink (from a high to low pressure.
