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AP Biology Botany 3Plant Nutrition and Transport
Water and minerals in the soil are absorbed by
the ________________________.
________________________, the loss of water from
leaves (mostly through __________________), creates
a force within leaves that pulls xylem sap upward.
Transpiration
Getting Water Into The Xylem Of The Root
Generation of Transpirational Pull
In addition to apoplastic and
symplastic movement, there are newly
discovered channels called
________________________
that allow only water to move across
the ___________________________. Water movement through aquaporins is quicker
since no_________________ are involved.
Movement of Minerals Into The Root
Plants need minerals to _______________________
organic compounds such as _________________________,
proteinsand lipids.
Plants obtain these minerals from the soil and are _________________________ by
various transport ________________________.
Macro- and Micro- Nutrients
_______________________________ are required by plants in relatively large amounts
and compose much of the plant’s ____________________. (C, N, O, P, S, H, K, Ca, Mg, Si, etc. )
______________________________ are needed in very small quantities. Typically
function as ___________________________.
Mycorrhizae: A Mutualistic Relationship
Gas exchange occurs through the _________________________________.
__________ is required for photosynthesis and ______ is released into the atmosphere.
____________ exchange gases with the air spaces in the ______, taking in ______ and
releasing ___________.
___________________ are produced by photosynthesis in the ___________.
____________________ sap(green arrows) can flow both ways.
__________________ sap(blue arrows) transport water and minerals upward from roots
to _____________________________.
Water Is In The Root, So Now What?
______________________ is caused by active distribution of mineral nutrient ions into
the root ______________.
Without _____________________ to carry the ions up the ______________, they
accumulate in the root xylem and ____________________ the water potential.
At night in some plants, ___________________________causes guttation or exudation of
drops of __________________ sap from the tips or
edges of leaves as pictured here.
Water then ________________________ from the soil into the root xylem due to
____________________.
Root pressure is caused by this ________________________of water in the xylem pushing
on the _______________ cells.
Root pressure provides a_____________, which pushes water up the ____________, but it
is not enough to account for the ________________________
of water to leaves at the top of the tallest trees.
Let’s Apply Some TACT To The Situation!
A more likely scenario involves the Cohesion-Tension Theory
(also known as _____________________________________________________________________________
or TACT Theory)
__________________: Water is a _____________ molecule.
When two water molecules approach one another they form
an ______________________________ attraction called
________________________________________
This attractive force, along with other intermolecular forces,
is one of the principal factors responsible for the occurrence of
_____________________________________ in liquid water.
It also allows plants to draw water from _______________
through the __________________ to the leaf.
__________________________ occurs when water
forms hydrogen bonds with xylem cell walls.
___________________________ occurs when water
molecules hydrogen bond with each other.
Transpiration: Water is constantly lost by transpiration in the leaf.
When one water molecule is __________ another is pulled
along by the processes of
__________________________________________________.
Transpiration pull, utilizing ______________________________
and the inherent ___________________________ of water, is the
______________________ mechanism of water movement in plants.
Ode To The Hydrogen Bond
Water Potential
Water potential quantifies the tendency of free (________________________________)
water to move from one area to another due to ___________________, gravity,
_________________________________ pressure, or _______________ effects such as
surface tension.
Water potential has proved especially useful in understanding water movement within plants, animals, and soil.
Water potential is typically expressed in potential energy per unit volume and very often is represented by the Greek letter psi, . (pronounced as “sigh” )
Water Potential
The addition of solutes to water _______________________ the water's potential (makes
it more _________________________), just as the increase in pressure
__________________ its potential (makes it more positive).
Pure water is usually defined as having an _________________________ () of zero, and
in this case, _______________________ potential can never be positive.
Free water moves from regions of _____________________ water potential to regions of
________________water potential if there is no barrier to its flow.
The word “potential” refers to water’s ________________________________________
which is water’s capacity to perform work when it moves from a region of higher
water potential to a region of lower water potential.
The water potential equation is = S + P where is the water potential, S is the
______________________________________ (directly proportional to its molarity and
sometimes called ____________________________________ and the S of pure water is
zero) and P is the ________________________________________.
Water Potential
P is the physical pressure exerted on a _____________________________.
It can be either positive or negative relative to the _________________________ pressure.
Water in a nonliving hollow xylem cells is under a _______________________ potential
(tension) of less than −2 MPa.
BUT the water in a living cell is usually under _____________________ pressure due to
the osmotic uptake of water.
Solutes have a negative effect on by bindingwater molecules.
Pure water at equilibrium
H2O
Adding solutes to theright arm makes lowerthere, resulting in netmovement of water tothe right arm:
Pure water
Positive pressure has a positive effect on by pushing water.
Pure water at equilibrium
H2O
Positivepressure
Applying positivepressure to the right armmakes higher there,resulting in net movementof water to the left arm:
Solutes and positivepressure have opposingeffects on watermovement.Pure water at equilibrium
H2O
Positivepressure
In this example, the effectof adding solutes isoffset by positivepressure, resulting in nonet movement of water:
Negative pressure(tension) has a negativeeffect on by pullingwater.Pure water at equilibrium
H2O
Negativepressure
Applying negativepressure to the right armmakes lower there,resulting in net movementof water to the right arm:
Water Potential vs. Tonicity
Water Potential and Plant Vocabulary
The green arrows indicate water moving _____________ of the cell.
The yellow arrows indicate water moving ______________ the cell.
Once More With Feeling!
Initial conditions: cellular greater than environmental
Last Time, I Promise!
Initial conditions: cellular less than environmental
0.4 M sucrose solution:
Initial flaccid cell:
Plasmolyzed cellat osmotic equilibriumwith its surroundings
P = 0
S = −0.7
P = 0
S = − 0.9
P = 0
S = − 0.9
= − 0.9 MPa
= − 0.7 MPa
= − 0.9 MPa
Distilled water:
Initial flaccid cell:
Turgid cellat osmotic equilibriumwith its surroundings
P = 0
S = − 0.7
P = 0
S = 0
P = 0.7
S = − 0.7
= − 0.7 MPa
= 0 MPa
= − 0 MPa
Wilting
________________ loss in plants causes wilting
o Which can be __________________________
when the plant is watered
Stomata Regulate Transpiration Rate
When water moves into ___________________ cells from
neighboring cells by osmosis, they become more ____________.
The structure of the guard cells’ wall causes them to
____________ outward in response to the _________________ water.
This bowing increases the size of the pore (___________________________)
between the guard cells allowing for an increase in ______________________________.
Homeostasis and Water Regulation
By contrast, when the guard cells _____________ water and become _________________, they become less
bowed , and the pore (stomata) __________________.
This _____________________ gas exchange.
Role Of Potassium Ion In Stomatal Opening And Closing
The transport of __________ (potassium ions, symbolized here as red dots) across the
plasma membrane and vacuolar membrane causes the ________________changes of
guard cells.
H2OH2O
H2OH2O
H2O
K+
H2O H2O
H2O
H2OH2O
Homeostasis and Water Balance
Trees that experience a prolonged ___________________
may compensate by losing part of their crown as a
consequence of leaves ________________ and being shed.
_________________________s may be reallocated so that more _____________________ is
expended for root growth in the “____________________” for additional water.
Natural Selection and Arid Environments
Plants that have adapted to arid environments have the following leaf adaptations:
o Leaves that are ____________________ with ________ stomata placed only on the
underside of the leaf
o Leaves covered with ____________________ (hairs) which reflect more light thus
_____________________ the rate of transpiration
o Leaves with stomata located in surface pits which increases
_________________________________ and reduces the rate of transpiration
o Leaves that are spine-like with stems that carry out _____________________
(cacti) and store water.
Natural Selection and Flooding
Plants that experience prolonged ____________________ will have problems.
Roots underwater cannot obtain the _____________________ needed for
_________________________________ and _________ synthesis.
As a result, leaves may __________ out causing the plant to die.
Additionally, production of ____________________ that promote root synthesis are
suppressed.
Adaptations to Water Environments
Plants that have adapted to __________ environments have the following adaptations:
o Formation of large lenticels (____________) on the stem.
o Formation of adventitious roots above the water that ____________ gas exchange.
o Formation of stomata only on the _______________ of the leaf (water lilies).
o Formation of a layer of air-filled channels called ____________________ for gas
exchange which moves gases between the plant above the water and the ____________________________ tissues.
Bulk Flow of Photosynthetic Products
Vessel(xylem)
H2O H2O
Sieve tube(phloem)
Source cell(leaf)
Sucrose1
Loading of sugar (green dots) into the sieve tube at the source reduces water potential inside the sieve-tube members. This causes the tube to take up water by osmosis. 2
1
2 This uptake of water generates a positive pressure that forces the sap to flow along the tube.
Tra
nspi
ratio
n st
ream
Pres
sure
flow
Nutritional Adaptations in Plants
________________________- grow on other plants, but do not harm their host
________________________-absorb water, minerals, and sugars from their host
_________________________-photosynthetic but supplement their mineral diet with
insects and small animals; found in nitrogen poor soils
Halophytes
Adaptations of Plants: Saline Environments
Soil ______________________ around the world is increasing.
Many plants are killed by too much __________ in the soil.
Some plants are adapted to growing in saline conditions (__________________________)
Have ___________ leaves with water stored that _____________________ salt in the roots
Actively _____________________ the salt out of the roots or block the salt so that it
cannot enter the ________________
Produce high concentrations of ___________________________________ in the roots to
alter the ___________________________ gradient of the roots