:*
companion cell
Mechanism of Translocation
with nucleus
÷÷÷÷÷ . sieve tube
element
The of fast
rate is be explained by diffusion
'
movement too to
.
cytoplasm
The flow
theory
this
mass explains mechanism
-
.
I Transfer of sucrose into sieve elements from photosynthesis ing tissue
a) Sucrose is manufactured from of
the
products photosynthesis in cells with chloroplasts
b) Sucrose diffuses by facilitated diffusion from photosynthesis ing cells into
companion cells
ions ( Ht ) ATP
c)
Hydrogen are
actively transported from
companion cells into the spaces within cell walls
using .
d) LH
"
) then diffuse down through tube
Hydrogen ions a concentration gradient carrier proteins into sieve elements .
e) Sucrose molecules transported Ht
by transport
are
along ions co -
.
2 Mass flow of sucrose through sieve tube elements
a) When sieve tubes tubes have potential 4
sucrose enters the ,
the sieve a more
negative water .
from ( with into
b) Water moves the
xylem a less
negative water potential ) the sieve tubes
by osmosis ,
creating a
high
hydrostatic pressure within them .
c) At sinks, sucrose is used
up during respiration or converted to search for
storage .
d) These cells have low content from
a so sucrose is
actively transported into them the tubes
lowering their water
'
. . sucrose sieve
potential .
e) Water into these cells from the tubes
by osmosis , the hydrostatic of
lowering
i. pressure
moves
respiring sieve
the sieve tubes .
i.
High hydrostatic pressure at source and low
hydrostatic pressure
at sink .
i. Mass flow of sucrose solution is caused
by hydrostatic pressure down the sieve tubes .
3 Transfer of from the tube elements into sink cells
sucrose sieve
storage or
The is
sucrose
actively transported by companion cells out of the sieve tubes and into the sink cells
-
.
,
?⃝
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller talhaahmed360. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $9.67. You're not tied to anything after your purchase.