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