Ch 33-34: Plant Transport

What happens in the absence of essential elements

their abesence severely disrupts plant growth & reproduction

Essential elements: micronutrients (7)

Fe, Cl, Mn, Zn, Cu, Ni, Mo

• needed in small quantities

Essential elements: macronutrients (6)

N, P, K, Ca, S, Mg

Why do plants need water? (4)

Photosynthesis, cooling, transporting solutes, internal pressure for support

Water & ions move into the root thru ___ & ___

Apoplast (intercellular) & symplast (extracellular)

Plants regulate…

nutrient uptake

What do soils provide?

• anchorage for mechanical supprt

• mineral nutrients & water from soil solution

  • minerals dissolved as ions in water

• O₂ for root respiration from air spaces between soil particles

• services of soil organisms: bacteria, fungi, protists, earthworms, arthropods

Soils develop a soil profile of horizontal layers called ______

horizons

A Horizon

Topsoil

• most living/dead organic matter

B Horizon

Subsoil

• accumulates materials from topsoil & parent rock

C Horizon

parent rock from which soil arises

Soil fertility

ability to support plant growth

What is soil fertility determined by?

• particle size

• soil composition

• soil organic matter (humus)

• cation exchange capacity

What soil composition is most ideal?

loam

Xylem vessel

• 1-way

• carries water & mineral

• thick walls stiffened w lignin

• no end walls between cells

Phloem vessels

• 2-way flow

• carries water & food

• cells have end walls w perforations

How do root cells take up water?

osmosis

What is the water potential of pure water?

0

What is water potential?

tendency of water molecules to move in response to pressure & solute concentration gradients

What does a more negative water potential mean?

greater driving force for water movement across membrane

Water enters cells until what happens?

pressure potential balances solute potential

Turgor pressure

Positive pressure potential

• maintains structure of many plants

What happens to a plant when pressure potential drops?

the plant wilts

Water moves from cell to cell along a gradient of _____ _____

Water potential thru xylem vessels

Passive transport

no energy required

• bulk flow

• aquaporins

Bulk flow

movement of water from higher pressure potential to lower pressure potential

What in cell membranes allows water to diffuse rapidly?

aquaporins & tonoplasts (vacuole membrane)

Active transport

energy required

• ion channels & pumps

Label

Label the adaptations

How does xylem move water up?

Transpiration

• cohesion

• tension

• adhesion

What does the stomata do? (4)

• manage water loss

• allow CO₂ to enter by diffusion

• waxy cuticle - minimize water loss

• guard cells control the opening & closing

How are solutes transported in the phloem?

solutes transported upward/downward

• translocation

What does the phloem carry?

sugars & waters

What is translocation?

movement of carbohydrates & other solutes thru the phloem

Products of photosynthesis are called ______

photosynthates

What is the content of the phloem?

phloem sap

How does the phloem carry photosynthates & solutes

from source to sink thru bulk flow

What are sources?

organs that produce more sugars than they require (leaf)

What are sinks?

sinks consume sugars for growth or storage

True or false? Organs & tissues can switch between sources & sinks sometimes.

True

What do the phloem conducting tubes have?

sieve tube elements that meet end-to-end

• have walls between different segments

• pores allow for movement

What is the driving force for bulk flow, site of bulk flow, & pressure potential in sap flow for the phloem & xylem

Phloem

• driving force: transpiration from leaves

• site: nonliving vessel elements & tracheids

• potential: negative (pull from top, tension)

Xylem

• driving force: active transport of sucrose at source & sink

• site: living sieve tube elements

• potential: positive (push from source, pressure)

What are nutrients?

elements required to build macromolecules

Where do the nutrients carbon, nitrogen, & hydrogen come from?

Carbon - CO₂

Hydrogen - water

Nitrogen - soil

Plants ______ nutrient uptake

regulate

How do polar molecules & nutrient ions enter epidermal cells?

transport protein

What are the 3 ways to replenish nutrients? Define.

1. Shifting agriculture - when soil is depleted, move to another location & let natural processes replenish soil

2. organic fertilizer - humus used as food source by soil organisms, which releases simpler molecules to the soil solution

3. inorganic fertilizers - supply mineral nutrients in forms that are easily used

• NPK percentages - produced in manufacturing that uses lots of energy

1g of soil contains _____ many bacterial species & up to ___ meters of fungal hyphae

6,000-50,000 & 200 meters

What are exudates? What do they influence?

Exidates are compounds that plants actively secrete, they influence organisms living in nearby in the region called rhizosphere

__ percent of plants have symbiotic relationships with bacteria & fungi

90%

What does mycorrhizal fungi do?

• expand the surface area, increasing amount of soil plants can explore for nutrients

• mainly obtains phosphorus

Can plants use N₂?

no

What do bacteria with nitrogenase do?

convert N₂ to NH₃ thru nitrogen fixation

What reaction is nitrogen fixation?

reduction reaction that requires lots of energy

Formation of nitrogen-fixing nodules

• legume plants form symbiois w rhizobia bacteria

• these roots release flavenoids & other signals to attract rhizobia

Purpose of legumes in crop rotations

• clover or alfalfa to increase available nitrogen in soil

Why are industrial nitrogen fertilizers produced?

because bacterial N fixation may not be sufficient to support agriculture

How do carnivorous plants get nutrients? Where are they found?

• get nutrients by capturing & digesting insects

  • they get nitrogen by capturing animals & digesting proteins

• Live in boggy habitats that are nutrient deficient & acidic

How do parasitic plants get nutrients?

they get minerals, nutrients, or photosynthate from bodies of other plants

Hemiparasites

can photosynthesize but get water & mineral nutrients from living plants

• mistletoe

Holoparasites

completely parasitic, n