BIOS 1208 Exam 4

photo-

obtain energy from sunlight, light energy to make ATP

chemo-

breaking/forming of chemical bonds to release energy for respiration or fermentation to generate ATP

auto-

make organic matter from inorganic carbon (CO2)

hetero-

obtain carbon from organic compounds

nutrients

substances required for cells to build molecules required to sustain life

essential nutrients

the organism cannot synthesize it and must acquire it from another source

beneficial nutrients

stimulate growth and development but are not required or could be substituted

macronutrients

essential nutrients that are required in large amounts

micronutrients

essential nutrients required in smaller amounts

what are the essential macronutrients

carbon, hydrogen, oxygen, phosphorus, sulfur

mineral nutrients

inorganic compounds from soil or water, elements

vitamin nutrients

organic compounds from other living things, water or fat soluble

how does a stationary organism acquire nutrients

grow in search of new resources, root mines minerals and water as it grows

plant nutrient needs

require light, water, and 20 essential nutrients; carbon: used for glucose to construct cellulose; nitrogen: proteins and nucleic acids, limiting growth factor; phosphorus: synthesize nucleic acids and phospholipids, food energy → chemical energy, liming growth factor; potassium: regulates stomata, water balance, limits growth

nutrient deficiencies

concentration of nutrient decreases between typical range, leads to visual characteristics, nitrogen deficiency is most common

excessive nutrients

can be toxic to certain tissues or cell types

herbivores

plant based, digestive systems that can handle large amounts of plant material

carnivores

eat other animals

omnivores

eat both plants and animals

3 organic precursors that animals can synthesis molecules from for energy

carbohydrates, proteins, fats

carbohydrates

organic carbon for herbivores/omnivores, carnivores rely on protein and lipids

proteins

dietary sources of nitrogen and sulfur

fats

chemical energy, absorption of fat-soluble vitamins and production of fat-soluble hormones

essential nutrients for animals (must be eaten)

amino acids, fatty acids, vitamins, minerals

essential amino acids

protein building blocks, meat sources, grain/legume

essential fatty acids

fat building blocks, humans only have 2

why is it easier to overdose on fat-soluble vitamins

water-soluble dissolve in water and are excreted in urine, fat-soluble is stored in adipose tissue and can cross cell membranes easily, allowing them to build up

why is sodium essential for animals but not plants

animals use sodium for electrical signaling and it drives nutrient absorption, plants use

diffusion

molecules move from area of high to low concentration, no energy required, down concentration gradient

facilitated diffusion

through protein channels embedded in cell membrane, specific, for molecules too large or polar to cross nonpolar cell membrane,

active transport

movement of molecules using energy against concentration gradient, requires energy

proton pumps

protein complexes that use energy from ATP to “pump” protons across membrane, electrochemical gradient, source of energy to move molecules against gradient

co-transport

movement of two molecules at the same time, one “down” which releases energy to move the other against, protein channels called co-transporters

does co transport require an energy source

active transport powered by proton gradients, not ATP directly

importance of concentration gradient in nutrient acquisition

naturally diffuse from high to low, energy not required, higher the concentration = faster rate of diffusion, ex. plant roots, animal digestive tracts

importance of distance in nutrient acquisition

longer distance = slower rate of diffusion, evolution selects shorter travel, ex. circulatory systems: nutrient absorbing capillaries are next to absorption surface

importance of surface area for nutrient absorption

larger = more nutrients can be absorbed, ex. plant roots have root hairs, mammalian digestive tracts’ small intestine is highly folded with microvilli

formation of soil

weathering of rock by mechanical, chemical, and biological processes, made of living and nonliving components: humus, rock fragments, water, gasses

humus in soil

organic matter, plant roots, microorganisms, decomposing plants/animals, 5% of soil volume

rock fragments in soil

inorganic, slowly broken down into smaller particles that vary in size, 40-45% of soil

water and gasses in soil

dissolved in soil particles, 50% of volume

soil texture

determined by proportions of differently sized particles in the soil, affects ability of plant roots to penetrate soil and ability of soil to hold water

categories of soil texture

gravel, sand, silt, clay, loam

factors that affect soil formation

parent material, climate, topography, biological factors, time

soil composition

require certain ions and minerals from soil, mediated by root hairs, properties directly affect ion availability

sand

low water availability, low nutrient availability, high oxygen availability, high root penetration ability

clay

high water availability, high nutrient availability, low oxygen availability, low root penetration ability

organic matter

high water availability, high nutrient availability, high oxygen availability, high root penetration ability

clay and anions

anions are easily dissolved in soil water, do not stick to clay, absorbed by root hairs, also easily leached from soil

presence/absence of clay

prevent leaching of cations from soil, also prevents absorption of cations by clay

root hairs

increase surface area for absorption

proton pumps in plants

used by root hairs to move nutrients into cell, line epidermal tissue, pump H+ into soil, positive charge outside with high concentration, low concentration inside and negative charge; drives ion channels and co-transporters, requires ATP

ion channels in plants

cation exchange: H+ displaces cations from clay and enters root via cation channels (passive)

co-transporters in plants

anion uptake: protons move back in through anion co-transporters, against gradient (active)

mycorrhizal fungi

80-90% of plants form mutualistic relationships with, ecto-wrap around epidermis, endo- hyphae penetrate cell walls, decomposing dead matter and enhanced absorption and plant for nitrogen and phosphorus, fungi gets sugars from root, increases the surface area, not oxygen sensitive

Rhizobia in legumes

mutualistic relationship, fix atmospheric N2 into ammonia inside root nodules, bacteria obtain carbon compounds and plants obtain ammonia, nitrogenase inactived by O2

carnivorous plants

digest insects to obtain N, P, and K in nutrient poor soils

leghemoglobin in legume root nodule

regulates the amount of oxygen available

mobile nutrients

nitrogen, magnesium, potassium, move from old to new tissue when deficient, symptoms appear in older leaves first

immobile nutrients

calcium, iron, cannot be relocated, symptoms in new leaves first

water potential

potential energy of water, determined by solute potential and pressure potential

increase water potential

removing solutes, adding pressure

decrease water potential

adding solutes, removing pressure

directional flow

(highest) soil to root to stem to leaf to atmosphere (lowest), water upward

osmosis

diffusion of water down its concentration gradient

when does water stop moving

when the water potential is equal on both sides of the membrane

cell in an environment with higher solute concentration than the cell

lose water, plasmolyzed

cell in environment with lower solute concentration

cell gain water, turgid

hypotonic

solution on one side of membrane where solute concentration is less than other side of membrane

hypertonic

solution on one side of membrane where solute concentration is greater than on other side

how does soil becoming too dry affect gradient

can result in decreased solute potential and or decreased pressure potential, too low = water into soil

symplast

water moves cell-to-cell through cytoplasm via plasmodesmata, “shared cytoplasm”

transmembrane

water repeatedly crosses plasma membranes through aquaporins, membrane-regulated

apoplast

water travels through porous cell walls without entering cytoplasm, fastest route, Casparian ship forces apoplastic water to cross a membrane

why does air becoming drier increase the rate of transpiration

drier air has a lower water potential than the air inside a leaf, this increases water potential gradient between leaf and atmosphere, leading to a higher rate of transpiration

what are the three hypotheses for water movement in xylem

root pressure pushes water up, capillary action draws water up with xylem, cohesion-tension properties pulls water up (tall trees)

root pressure

water enters roots by osmosis and builds positive pressure, push water a few meters, guttation at night, not strong enough for tall trees

capillary action

driven by cohesion, adhesion, and surface tension, narrow tubes, insufficient for tall trees, pulls water up within a xylem tube

cohesion-tension

transpiration creates negative pressure in leaves, pulls water upward like a straw through entire plant, cohesion keeps this continuous, xylem walls reinforced with lignin to withstand tension, open stomata and water between mesophyll cells utilized

transpiration

evaporation of water from stomata, passive, energy source is extreme difference in water potential between water in soil (high) and water in atmosphere (low)

solute potential

dissolving solutes makes solute potential more negative, through active transport of ions and accumulating sugars

pressure potential

tension from transpiration makes more negative, positive when there is turgor pressure, manipulated through opening and closing of stomata

sugar source

any tissue that produces or releases sugars; mature leaves, stems during growing season, storage organs at start of new growing season, where sugar is coming from

sugar sink

any tissue that uses or stores sugars, growing tissues, storage tissues during growing season, where sugar is going to

translocation

movement of sugars through plant phloem to where they are needed

what is the pressure flow model

for sugar translocation, depends on how solute potential and pressure potential change as sugars move

at the source of pressure flow model

sugars move in phloem, high concentration of sugar creates low solute potential, which draws in water from xylem raising the pressure potential, pushing phloem sap toward sink via bulk flow

sugar source at start of growing season

roots

sugar source in the middle of growing season

mature leaves

at the sink of pressure flow model

sugars are removed, raising the solute potential, water exits the phloem and returns to the xylem, lowering the pressure potential

proton pumps in pressure flow model

use ATP to pump protons out of companion cells, form electrochemical gradient allows for proton-sucrose cotransporter to use the gradient to pull H+ back in along with sucrose against gradient

when sugar is moving down concentration gradient

sugar diffuses down its concentration gradient from the companion cell and into the phloem sieve-tube elements through the plasmodesmata

co transporters in pressure flow model

use energy of protons moving down their gradient to move sucrose against its gradient, symporters bring H+ and sucrose into companion cells

facilitated diffusion in pressure flow model

sucrose in companion cells, down gradient into sieve tube elements

if sink has lower sucrose concentration than the phloem

diffusion is sufficient for unloading

if sink has higher sucrose concentration than the phloem

active transport is required

driving force for fluid movement in xylem

transpiration from leaves, cohesion and tension of water (passive)

driving force for fluid movement in phloem

active transport of sucrose from source cells into phloem sieve tube (energy)

cells facilitating fluid movement in xylem

non-living vessel elements and tracheids

cells facilitating fluid movement in phloem

living sieve tube elements