BIOA02H3 Lecture Notes - Lecture 10: Leaf, Hair Cell, Phloem
27 Apr 2018
School
Department
Course
Professor
BIO A02 – Module 1 Notes Hassan Alibhai
Plant Form and Function Page 44
Transport in Plants
•We know that the process begins in the soil, with root hairs.
◦The question begins when we examine how the entire process occurs
Basic Plant Needs
•Glucose
◦CO2
◦Light
◦H20
•H20
•O2
•Minerals
Water Transport through the Xylem
•Three hypotheses of water transport (the three mechanisms that help water travel to the top)
Capillary Action Root Osmotic Push Transpiration
•Blood rises up “magic”
•Cohesion => ties together
same molecules of liquid
•Adhesion => liquid rises
up a given capillary
◦The narrower the
capillary is, the
higher the water
moves
•Trees are
much taller, so
this doesn’t
explain it
•Water moves through a
semi-permeable
membrane, but salts and
nutrients can’t
•Water evens out
concentrations by water
moving until salt
concentrations equate
•Net rise in the water
◦Osmotic push
▪Water easily taken
up through the
root hairs
•Plant actively pumps ions
into root hair cells, influx
•Most important, dictates
how far up water can
flow (others barely do
anything)
•Sun heats up leaves
•Water evaporates and is
lost in the xylem
•Cohesion between water
molecules pulls up
“continuous strings” of
water
◦Xylem to mesophyll
LIMIT => 1 meter (not enough
to contribute to tree height)
LIMIT => 3 meters (still not
enough to contribute)
LIMIT => 130 meters (majority
of the contribution to growth)
Remember: water is
always transported only in
the “xylem of the year”,
just across the vascular
cambium from the phloem.
43
BIOA02H3 Full Course Notes
Verified Note
43 documents
Document Summary
Page 44: we know that the process begins in the soil, with root hairs, the question begins when we examine how the entire process occurs. Basic plant needs: glucose, co2, light, h20, h20, o2, minerals. Remember: water is always transported only in the xylem of the year , just across the vascular cambium from the phloem. Water transport through the xylem: three hypotheses of water transport (the three mechanisms that help water travel to the top) Plant actively pumps ions into root hair cells, influx how far up water can flow (others barely do anything) Sun heats up leaves: water evaporates and is lost in the xylem, cohesion between water molecules pulls up. Continuous strings of water: xylem to mesophyll. Limit => 1 meter (not enough to contribute to tree height) Limit => 3 meters (still not enough to contribute) Limit => 130 meters (majority of the contribution to growth) Water transport summary => root hair to xylem.
