Theme 4 - Dr. Samuel Flashcards by Elizabeth Bales

What is the Green Revolution?

Plant breeding. Yield was increased to sustain the demand from the growing population.

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What are the 5 elements of the homeostasis environmental metabolism umbrella?

Temperature
pH
Solutes
Water
Pressure

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How do plants maintain their balance physically?

Structure. Lignified cells that support the weight and defy gravity

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What are the essential elements for plants?

17 elements
nucleic acids (N,P), aminos (N,S)
enzyme cofactors (Ca2+)
Photosynthesis (Mg2+, Fe2+, Fe3+)or regulation of osmotic potential (k+)

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What are the mineral macronutrients and how are they available to plants?

N, P, K, S, Ca, Mg (Neil PatricK Says “Cats”..My God) and they are available to plants through the soil as dissolved ions in water

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What are the essential trace micronutrients?

Cu2+, Cl-, Ni2+

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What are characteristics of Nitrogen?

-Abundant in air, most limiting to plant
- Triple bond requires a specific enzyme
- Nitrogen cycle provides soil nitrogen

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What is Nitrogen Fixation?

Incorporates the atmospheric N2 into plant available compounds NH4+ (Nitrogen fixing bacteria)

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What is ammonification?

Bacterial ammonification breaks decaying organic N compounds into NH4+ (plants take up NH4+ to NO3-

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What does bacterial nitrification do?

Oxidizes NH4+ to NO3-

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What types of things depleted nitrogen levels in soil and how did they combat this?

Too much harvesting and continuous use of the land. They allowed land to replenish lost N through free living bacteria or symbiotic association with roots.

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How did they improve Nitrate content in soil?

-Crop rotation
-Use of nitrate fertilizer increased yield

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How to deal with too tall plants?

Bred cereals
Dwarf breeds of rice and wheat
This allowed crop to produce more yield with fertilizers

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What percentage of nitrogen added to crops ends up in the biomass and where does the rest go?

10% in biomass, the rest are lost as surface runoff

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What major ecological problem is caused by nitrogen runoff?

algal blooms, which sink to the bottom where bacteria feed and therefore deplete oxygen

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What is Eutrophication?

Enrichment of an ecosystem with chemical nutrients such as compounds containing N and P

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What is contained in soil?

mineral particles, compounds, ions, decomposing organics, water, air, organisms

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What determines soil properties?

relative amount of soil particles

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Does Humus increase or decrease water availability?

increases availability

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What soil properties are influenced by relative amount of soil particles?

Water availability
Mineral availability

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What is soil solution?

A combo of water and dissolved substances that coats soil particles and partially fills pore spaces and is available for plant uptake after gravity drainage

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Water molecules are attracted by what in soil solution?

negatively charged clay and humus particles

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How do minerals enter plant roots?

Passively along with water
Selectively absorbed by roots via non-specific transport proteins

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Both cations and anions are present in soil and they are equally available to plants (T/F)?

False. They are both present but not equally available

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What three mineral cations are absorbed to negative soil particles?

Mg2+, Ca2+, K+

What does cation exchange do?

Replace mineral with H+ produced by the roots as excreted H+ or carbonic acid produced by respiring root cells

What are the 3 anions and their characteristics?

NO3-, SO42-, PO4- Weakly bound to the soil move freely into the root hairs Leach easily by excess water

Soil is usually (acidic/alkaline) with negatively charged clay particles bound to cations (Ca2+, Mg2+)

alkaline

Under alkaline conditions, what happens with the anions?

They are readily available but can leach out easily

What happens when the soil turns acidic due to pollution?

negative charges on the clay are occupied by H+ and the cations are leached out easily and become unavailable to the plant

In acidic soil, cations leach out easily (T/F)

True

Describe passive transport

Substances move down a concentration gradient, requires no energy input. Use transport proteins such as ion channels

Describe active transport

Substances move against concentration gradient and require ATP. Use transport proteins using energy like the sodium potassium pump

What are the functions of root hairs?

Greatly increase root surface area and absorbs water and minerals

What do Mycorrhizae do?

Allow the plant to take up PHOSPHOROUS

What type of association is there between fungus and plant roots?

symbiotic

What does the plant provide a fungus?

A Carbon source

What does the Fungus do for the plant?

Increases plant's supply of soil nutrients

What are located on the root cell plasma membrane?

Membrane transporters (K+ channel)

What 3 micronutrients are needed for plants?

Cu+ Cl+ Ni+

What layer of soil is most important?

Top soil with Humus (Dead layer)

Clay is (positively/negatively) charged and holds onto (cations/anions)

Clay is negatively charged and holds onto cations

What allows for the uptake of cations?

Cation Exchange mechanism

What do Root Nodules do?

Fix Nitrogen

What does Nitrogen Fixation do?

Incorporates atmospheric N2 into plant available compounds such as NH4 and NO3-

Do plants prefer ammonium or nitrate?

Nitrate

What are the 3 ways water moves throughout cells?

Into and out of cells Laterally from cell to cell Over long distances from root to shoot

What percentage of water leaves plants and by which process

90% leaves through transpiration

What is osmosis?

Passive movement of water across a selectively permeable membrane

What is Aquaporin?

Proteins that allow rapid movement of water through hydrophobic membrane core

What is Water Potential?

The potential energy of water The driving force

How many MPa is pure water?

0MPa

Which direction does water move in water potential?

High to low water potential

Presence of solutes (raises/lowers) water potential?

lowers

What is a pressure potential?

The force required to stop water movement

Positive pressure (increases/decreases) water potential

increases

True or False. solute potential is always positive

False. It is always negative

How long does water move within a system?

Until equilibrium is reached on both sides

How are plant cells different than animal cells?

Cell wall massive vacuole

Plant cells want to keep (high/low) solute concentration inside?

high concentration of solutes inside the cells

What is a tonoplast?

it is a membrane inside the central vacuole and maintains turgor pressure

When does wilting occur?

When plants lose more water than they gain (plasmolysis) low water potential of dry soil

What will happen when there is an increase of solutes inside a cell?

This will result in a more negative solute potential and more positive turgor pressure inside the system

What does a plant cell adjust in order to achieve equilibrium?

Plant cells will adjust solutes to keep itself turgid and allow water to come in

Water always follows what?

Solutes!

What are the three types of pathways of water into roots?

Apoplastic Symplastic Cell to Cell

What is the apoplastic pathway?

Water moves across cortex to endodermis via cell walls and intercellular spaces (never crosses the cell membrane)

What is the symplastic pathway?

Water flows form cytoplasm of one cell to the next via plasmodesmata (Crossed membrane)

What is the fastest pathway of water into cells?

Apoplastic Pathway

What is the Casparian Strip?

A waxy substance that acts as a guard for the endodermal layer in a plant cell. It forces apoplastic water and nutrients into the symplast.

What does the Casparian strip prevent?

Back flow of solutes

In shorter plants, what contributes to upward water movement?

root pressure

What regulates the loss of water by transpiration?

Stomatal movements

What is transpiration?

Evaporation of water out of plants Greater than water used in growth and metabolism

What are the 3 elements of cohesion-tension mechanism of water transport?

1. Evaporation from mesophyll walls 2. Replacement by cohesion. water in xylem 3. Tension, negative pressure gradient, adhesion water to xylem walls adds to tension

What is cohesion in plant cells?

Interaction between water and water

What is adhesion in plant cells?

Interaction between water and cell wall

Is lignin hydrophilic or hydrophobic?

hydrophobic

What 3 things help the effect of negative pressure on the column?

1. lignified secondary cell wall 2. Adhesion force in the xylem 3. Weight of the column

What provides the surface area for evaporation?

large volume of air space

What is Root pressure in small plants?

Positive pressure in roots that forces xylem sap upward.W

When does Root pressure take effect?

High humidity or low light moves water up short distances

What is guttation?

When root pressure is strong enough to force water out of leaf openings. Water is pushed up and out of veins.

What affects transpiration?

relative humidity air temperature air movement

What is translocation?

Long distance transport of substances via the phloem. It is multidirectional

What is phloem sap?

Water and organic compounds that flow through the sieve tubes. Not just sugar

What drives the flow of phloem sap?

Differences in pressure between source and sink.

What is the Source?

Any region of a plant where organic substances are loaded into the phloem. (Green is source)

What is the Sink?

Any region of a plant where organic substances are unloaded from the phloem (Growing tissues and storage region)

What is the phloem comprised of?

Sieve tubes and companion cells

Are sieve tubes alive at maturity?

Yes

What do sieve tubes undergo in order to make room?

Programmed cell death.

What do sieve tubes lose in order to make room for flow of sap?

Nucleus, vacuoles, and organelles, except for mitos, plastids, and the ER.

What cannot be transported by sieve tubes?

Large molecules such as protein, lipids, and complex organic compounds cannot cross the membrane

What keeps the sieve tube alive when it undergoes PCD?

The companion cell (twin)

What are sieve plates?

Modified cell walls with plasma membrane lined pores.

What connects sieve tubes and the life supporting companion cells?

Sieve tubes

What is absent in mature sieve elements?

Nucleus Tonoplast Ribosomes Cytoskeleton Golgi bodies