L14// Transpiration, Transport, and Nutrition in Plants

plants acquire nutrients from...

air, water, and soil

what plants obtain from soil

water, minerals, and some oxygen

photosynthesis

process that makes sugar

cellular respiration

process that breaks down sugars

the plasma membrane of root cells

control solute uptake

root hairs

greatly increase a root's absorptive surface

from soil, roots take up...

- water and dissolved ions

- metals

- inorganic nutrients

roots interact with...

microbes and fungi in the soil

water and solutes can move through the...

- epidermis and cortex

- through and between cells

water and nutrients

provided as xylem sap

xylem sap

flows from the roots through the shoot system to the tips of the leaves

xylem sap

flows through thin tubes within xylem tissue

water is pulled up from the roots through...

xylem vessels

xylem sap is pulled by...

transpiration

transpiration

- upward movement of water

- the loss of water from the leaves by evaporation

sap movement

- cohesion of water molecules

- adhesion to the xylem vessel surface

two types of water-conducting cells in xylem tissue:

- tracheids

- vessel elements

tracheids and vessel elements

- have rigid, lignin-containing secondary cell walls

- dead at maturity- forms overlapping ends that create tubes within vascular tissue

stomata

- leaf pores

- open and close and help plants adjust their transpiration rates to changing environmental conditions

leaf structures for photosynnthesis

- palisade mesophyll

- lower surface

- spongy mesophyll

- vascular bundle

palisade mesophyll

- where the bulk of photosynthesis occurs

- high concentration of chloroplasts

lower surface

many stomates to ensure sufficient gas exchange

spongy mesophyll

- intercellular air spaces for gas exchange

- stores/passes to vascular bundle photosynthates

vascular bundle

- transports water and minerals to mesophyll

- transports photosynthates to other parts of the plant

guard cells control...

transpiration

three factors influencing guard cell activity

1. sunlight signals guard cells to accumulate K+ and open stomates

2. low CO2 concentration in leaves also signals guard cells to open stomates

3. an internal timing mechanism (a biological clock) found in the guard cells will continue their daily rhythm of opening and closing

400 H20 are lost for...

every 1 CO2 that is gained

what phloem sap transports

- inorganic acids

- amino acids

- hormones

- sugars

phloem transports the products of __________ from where they are made or stored to where they are needed

photosynthesis

phloem

contains sieve-tube elements

sieve-tube elements

food-conducting cells

what each sieve-tube element has

companion cell

companion cell

- connected by the plasmodesmata

- may serve multiple sieve-tube elements by producing and transporting proteins to all of them

direction of which phloem sap moves through the plant

various directions

sieve tubes always carry sugars from a...

- sugar source

- sugar sink

sugar source

a plant organ that is a net producer of sugar

sugar sink

an organ that is a net consumer or storer of sugar

pressure flow mechanism

source to sink

at a sugar source, ______ is loaded into the _______ tube

sugar ; phloem

at a sugar source, _____ raises the _________ _____________ in the tube

sugar ; solute concentration

at a sugar source, the ______ solute concentration draws water into the tube by ________

high ; osmosis

as sugar departs the phloem, lowering the solute (sugar) concentration at the sink end....

water follows by osmosis back into the xylem

the exit of water ______ the water pressure in the tube

lowers

plant health depends on obtaining all of the...

inorganic nutrients

to survive and grow, a plant must obtain...

- carbon dioxide

- inorganic substances

essential elements

- completes its life cycle of growth

- have reproductive success

the 9 macronutrients are components of...

organic molecules

the 9 macronutrients

1. carbon (C)

2. hydrogen (H)

3. oxygen (O)

4. nitrogen (N)

5. sulfur (S)

6. phosphorus (P)

7. potassium (K+)

8. calcium (Ca+2)

9. magnesium (Mg+2)

almost 98% of a plant's dry weight consists of:

carbon (C)

hydrogen (H)

oxygen (O)

nitrogen (N)

sulfur (S)

phosphorus (P)

about 1.7% of a plant's dry weight consists of:

potassium (K+)

calcium (Ca+2)

magnesium (Mg+2)

the 8 micronutrients function in plants mainly as cofactors (0.3% of dry weight):

1. chlorine (Cl-)

2. iron (Fe+2)

3. manganese (Mn+2)

4. boron (B)

5. zinc (Z)

6. copper (Cu+2)

7. nickel (Ni+2)

8. molybdenum (mo)

fertilizers

- can help prevent nutrient deficiencies

- the availability of nutrients in soil affects plant growth and health

most plants depend on...

bacteria to supply nitrogen

the earth's atmosphere consists of about...

80% nitrogen

nitrogen deficiency

the most common nutritional problem in plants

soil bacteria converts ___ ____ from the air into forms usable by plants

N2 gas

nitrogen fixation

nirtogen-fixing bacteria converts atmospheric N2 to NH3

ammonifying bacteria adds to the supply of NH4+ by....

decomposing organic matter

nitrifying bacteria convert ______________ to ____________

ammonium (NH4+) to nitrates (NO3-)

- most often taken up by plants

plants have evolved...

mutually beneficial symbiotic relationships

some plants form symbioses with...

nitrogen-fixing bacteria

legumes

peas, beans, alfalfa

legumes

form root nodules to house nitrogen-fixing symbionts in the genus Rhizobium

bacteria converts atmospheric N2 to...

ammonium ions (NH4+)

about ____ of plants form mutually beneficial symbioses with fungi called _______

80% ; mycorrhizae

mycorrhizae

- act like extensions of plant roots, increasing area for absorption and water and minerals from soil

- have evolved with plants and were important to plants successfully colonizing land, as soil was not likely rich in nutrients