Test 3 horticulture

What is water potential?

A measure of the potential energy of water

Water moves from ___ to ___ potential

High; low

Water movement via mass flow is

Movement in response to a pressure or tension gradient

Give an example of positive pressure in the cell

Turgor pressure

The movement of fluid in phloem is driven by _____ (±) pressure. This is an example of _______

Positive; mass flow

The movement of fluid in xylem is driven by ____ pressure (____)

Negative; tension

Which roots are most permeable to water?

What increases absorptive surface area?

Forming symbiotic relationships with ____ fungi increases it even more

Fine roots; root hairs; mycorrhizal

The apoplastic pathway is the area ____ the plasma membrane, including the ____ and _____ (_____ parts).

Outside; cell walls; intercellular spaces; nonliving

The symplastic pathway is the area ____ the plasma membrane (_____ parts). Connected by _____

Inside; living; plasmodesmata

The apoplastic pathway is blocked at the _____ because of a band of _____. This band is _____ and is called the _________

Endodermis; Suberin; hydrophobic; Casparian strip

The endodermis is important because it is ____. This means it does not _____

selective; allow harmful materials to be taken up by the roots

Forces that are moving water in plants

Root pressure, capillary action (cohesion and adhesion), transpiration pull

What is root pressure?

Ions move into the xylem and because of the higher concentration of ions, water flows in

Capillary action is made up of

Cohesion and adhesion

What is transpiration?

The loss of water from the aerial parts of the plant, especially the stomates

What is the main factor that causes water to move up the xylem?

Transpiration pull

Why is transpiration important? (Name 2)

Main factor moving water and minerals throughout the plant, cools down the plant

What factors affect transpiration?

Be able to list one factor and DESCRIBE how it affects transpiration

Light intensity, air humidity, air temperature, and wind

Air temperatures: As temperature increases, rate of transpiration will increase, until it becomes “too hot” and stomates close in response.

What allows xylem vessels and tracheids to withstand negative pressure force?

Strong secondary cell wall

Mass flow EXAMPLE

Xylem flow (negative pressure) and phloem flow (positive pressure)

What is diffusion?

Water movement due to differences in concentration of water molecules

What is the difference between mass flow, diffusion, and osmosis?

Mass flow: Water movement due to differences in pressure or tension

Diffusion: Solute and solvent movement due to differences in concentration of water molecules

Osmosis: Movement of solvent across a semi-permeable membrane

Example of diffusion

Transpiration

What moves in diffusion vs osmosis?

In diffusion, solute and solvent move from high to low concentration. In osmosis, ONLY THE SOLVENT moves across a semipermeable membrane from high to low concentration

Osmotic potential is also known as

Solute potential

Two forces are most important to water potential inside the plant. They are:

Solute (osmotic) potential and pressure potential

Difference in ____ potential determines the ______ water moves across the membrane
Δ ψ_w ≠ ψ_w

water; direction

Δ ψ_w ≠ ψ_w
Remember

ok

You have two adjacent living cells with the following water potential values:
Cell A: = -0.5 Mpa
Cell B: = -0.7 Mpa
Which way will the water move?

A to B

More solutes inside cell vs. outside:

Which way will water move?

Into the cell

Number solutes inside cell = number outside:

Which way will water move?

No net movement of water

Less solutes inside cell vs. outside:

Which way will water move?

Out of the cell

How are guard cells unique? What does this allow for?

They are not connected by plasmodesmata; water potential gradient

What is the atom?

Smallest unit of an element that retains its chemical properties

What is a molecule? What is a compound?

At least two atoms bonded together; At least two atoms of DIFFERENT elements bonded together

What is an ion?

charged atom or molecule

Plant roots _____ nutrients in their ___ form

absorb; ionic

What three criteria make an element “essential”?

1. A shortage stops a plant from completing growth or reproduction

2. Element is directly involved in nutrition

3. Shortage can be corrected only by supplying the element

Where does a plant get carbon, hydrogen, and oxygen?

Air and water

Where/how does a plant primarily get mineral nutrients? How else?

soil; foliar spray

What are the primary macronutrients?

Nitrogen, phosphorus, and potassium

To reach the xylem, how many membranes must nutrients pass?

Where are they?

Does the nutrient need to pass an additional membrane if it is going to be used?

Two

one at or before the endodermis, one when they get into the xylem

Yes

How do nutrients cross the plasma membrane?

Transport proteins

What are the two main types of transport proteins?

What kind of transport do they use?

Channel; passive; Carrier; USUALLY active

In passive transport, ____ is required. Movement happens in response to a ______________.

There are two types: ______ and _____

No energy; concentration gradient; simple diffusion; facilitated diffusion

Simple diffusion is a type of ____ transport where ___________________________.

Passive;
small, non-charged solutes pass through a membrane in response to a gradient;
is not

Facilitated diffusion is a type of ____ transport where ____________________________.

Passive;
Things move in response to a gradient, but a transport protein is involved.

All of our channel proteins move things via ______ transport, specifically ______. Carrier proteins may do both _____ transport and _______

passive; facilitated diffusion; active; facilitated diffusion.

When you have a charged solute, you need to consider the ______ and _______.

chemical gradient; electrical gradient

The movement of ____ions are usually favored because of the ____ charge on ____________. As long as the ______ and ______ gradients are favorable, they will proceed.

cat; negative; on the inside of the membrane; electrical; chemical

In active transport, we are moving ______, so it requires ______. It is always mediated by ______ proteins. There are three different kinds: _____, _____, and _____

something across a membrane against the electrochemical gradient; energy; carrier; Primary active transport, secondary active symport, and secondary active antiport

Primary active transport is a type of _____ transport that ______

active; uses energy directly to move something across a membrane against its electrochemical gradient

Give an example of primary active transport

H+-ATPase, cleaving a phosphate from ATP and using the energy to drive H+ ions against their electrochemical gradient

Secondary active transport is a type of _____ transport that ______

active; pairs the movement of a solute against its gradient with the movement of a solute (usually H+) with its gradient

Secondary active symport is a type of _____ transport that ______

secondary active transport; couples the movement of a solute across a membrane against its electrochemical gradient with the movement of something else (usually a hydrogen ion) in the same direction

Secondary active antiport is a type of _____ transport that ______

secondary active;
pairs the movement of solutes against their electrochemical gradient with the movement of something like hydrogen ions in the opposite direction

This is showing

Secondary active symport

This is showing

Secondary active antiport

This is showing

Primary active transport

This is showing

Facilitated diffusion of cations (passive transport)

This is showing

Simple diffusion (passive transport)

Plants use the ____ forms of elements.

Name the two main forms of nitrogen: _____ and _____

charged/ionic; nitrate; ammonium

What are soil colloids?

Small clay and humus particles with a slight electrical charge

What is cation exchange capacity (CEC)?

The degree to which a soil can adsorb and exchange ions

What is pH?

Hydrogen ion concentration

What type of charge is on the surface of inorganic and organic soil particles?

What are these spots called?

What gets exchanged at these spots?

Negative; Cation exchange sites; Cations

Cation adsorption: why is it important?

Ability prevents leaching and holds nutrients for plants to access

A higher CEC means the soil can hold more _____. Sandy soils have a ____ CEC

cations; low

Nitrate has a _____ charge, meaning ________________________. This means that it _______ easily

Negative; it does not attach to the cation exchange sites; leaches

How does CEC influence fertilizer practices?

Small amounts of fertilizer are applied frequently to low-CEC soils and high amounts are applied less often to high-CEC soils. Adjust fertilizer practices to reduce runoff and maximize nutrient absorption

What is the main thing that gets exchanged with nutrients at CE sites?

Hydrogen ions

When acids dissolve in water, they release ________

Hydrogen ions

When ____ dissolve in water, they release hydrogen ions

acids

A strongly acidic solution contains a lot of

Hydrogen ions

Base – what do they combine with?

What does a base do to an acid?

Hydrogen ions; neutralize it

Salt

What is it?

When does it have a charge?

When you react an acid with a base; individual components have a charge if dissolved in water

Balance between _____ ions and ____ ions dictates pH

H+; OH-

Describe TWO ways that nitrogen is good for a plant

Better, faster growth and improved water utilization by providing a limiting nutrient

Describe TWO ways that too much nitrogen is bad for a plant

Plants that are more lush are more prone to pests and disease; Encourages new growth that cannot harden off in time for the winter

Which forms of nitrogen can the plant absorb?

Ammonium and nitrate

Which element is the most commonly deficient in plant growing systems?

Nitrogen

What is immobilization?

What is mineralization?

Removal of nutrients from the soil by organisms;
When you put nitrogen back into its usable inorganic form

What is nitrogen fixation, as root bacteria do it?

What also converts nitrogen to a usable form (2)?

Conversion of atmospheric nitrogen to ammonia, then ammonium

Lightning and Haber-Bosch

What is required in the Haber-Bosch process?

What is done in the Haber-Bosch process?

High temperatures, high pressure, lots of energy; atmospheric nitrogen is converted to ammonia

What converts atmospheric nitrogen to ammonia using high temperatures and pressures?

Haber-Bosch process

Nitrate is a(n) ______, so it requires ______ transport, specifically __________.

Unlike _____, nitrate can be ______ and _______ without major ______ to the plant.

However, it is more _________ for the plant.

Anion; active; secondary active symport;
ammonium; translocated; stored; harm;
energetically costly

Ammonium is a ____, so it is _____ taken up via ______ protein. At first glance, it is the better option because it is less ___________.

But this means there is ________ ammonium is taken up, which can be _____ for the plant because it has the potential to __________.

Cation; passively; channel; energetically costly
Less control over how much; dangerous; mess up hydrogen ion gradients

Briefly explain the uptake and assimilation of nitrate.


THEN Briefly explain the uptake and assimilation of ammonium

Nitrate:

1. Taken up via secondary active symport, moved in with hydrogen ions

2. Reduction to nitrite by NR

3. Moved to the plastid (if in roots) or chloroplast (if in leaves)

4. Reduction to ammonium by NiR

5. Conversion to amino acids

Ammonium:

1. Taken up into the cytoplasm via passive transport and channel proteins

2. Moved to plastid (if in roots) or chloroplast (if in leaves)

3. Conversion to amino acids

What are crop residues? Give an example

Waste materials generated by agriculture; plant parts left after harvest

What is green manure?

Crop cultivated specifically to be incorporated into the soil while still green

What is complete fertilizer?

Fertilizer with NPK

What are quick-release fertilizers?

Fertilizers that release all available nutrients in a short time after application

What are controlled-release fertilizer

Fertilizers that provide nutrients in a form that cannot all immediately be absorbed.

What is one impact the development of synthetic fertilizers has had?

Improved yields, reduced world hunger

Immediate release aka quick release fertilizers: provide one downside

Adding too much can cause leaching and/or runoff

Split applications: how are they helpful with quick release ferts?

Avoids the fertilizer burning the plant and runoff, improves nutrient uptake

Controlled-release fertilizer

One advantage:

One disadvantage:

Able to do more infrequent fertilization; Microplastics

Principles of proper fertilization: be able to list ONE of the 5 “R’s”, and describe what effect it has and why it is important

Right placement: spread fertilizer in the drip line, around the edges of the tree leaves; Fertilizer will reach the smaller roots and be absorbed more effectively