Test 2

Covers chapters 35, 36, 37, 38, and 40

three basic plant organs

roots, stems, leaves

root

an organ that anchors the plant, absorbs minerals and water, and stores carbohydrates

taproot system

eudicots and gymnosperms, consists of taproot and lateral roots

taproot

main vertical root

lateral root

branch roots, arise from taproot

fibrous root system

monocots, adventitious roots that arise from stems or leaves, lateral roots that arise from the adventitious roots

absorption of water and minerals from soil occurs via

root hairs

tiny root hairs increase

surface area

stem

organ consisting of an alternating system of nodes and internodes

node

the points at which leaves are attached

internode

stem segments between nodes

axillary bud

structure that has the potential to form a lateral shoot or branch, develop from meristematic cells left at the bases of lead primordia

apical bud

terminal bud, located near the shoot tip and causes elongation of a young shoot

apical dominance

helps to maintain dormancy in most axillary buds

adaptations of stems

rhizomes, bulbs, stolons, tubers

leaf

main photosynthetic organ of most vascular plants, consist of a flattened blade and a petiole

petiole

stem of the leaf

blade

fleshy part of the leaf

plant vein

transports glucose and water, support

midrib

central rib of the leaf

monocot vs. eudicot veins

monocots have parallel veins, eudicots have branching veins

each plant organ has

dermal, vascular, and ground tissues

trichomes

outgrowths of the shoot epidermis and can help with insect defense

vascular tissue system

carries out long distance transport of materials between roots and shoots

two vascular tissues

xylem and phloem

xylem

conveys water and dissolved minerals upward from roots into the shoots

phloem

transports organic nutrients from where they are made to where they are needed

major types of plant cells

parenchyma, collenchyma, sclerenchyma, water-conducting cells of xylem, and sugar-conducting cells of the phloem

parenchyma cells

thin, flexible primary walls, lack secondary walls, least specialized, perform the most metabolic functions, retain ability to divide and differentiate, alive at maturity, have chloroplasts, involved in storage of starch and oils, involved in secretion, healing and repair

collenchyma cells

grouped in strands and help support young parts of the plant shoot, thicker and uneven cell walls, lack secondary walls, provide flexible support without restraining growth

sclerenchyma cells

rigid because of thick secondary walls strengthened with lignin, dead at functional maturity, sclereids and fibers

sclereids

short and irregular in shape, have thick lignified cell walls

fibers

long and slender and arranged in thread

water-conducting cells of xylem

tracheids and vessel elements, dead at maturity

vessel elements

align end to end to form long micropipes called vessels

tracheids

found in the xylem of all vascular plants

sugar-conducting cells of phloem

sieve tube elements and sieve plates

sieve tube elements

alive at functional maturity, lack organelles, transport sugars over long distances, has a companion cell whose nucleus and ribosomes serve both cells

sieve plates

porous end walls that fluid to flow between cells along the sieve tube

indeterminate growth

plant can grow throughout its life, roots and stems

determinate

some plant organs cease to grow at a certain size, leaves, flowers, seeds, and fruits

meristems

perpetually embryonic tissue and allows for indeterminate growth

apical meristems

located at the tips of roots and shoots and at the axillary buds of shoots, elongate shoots and roots through primary growth

lateral meristems

add thickness to woody plants through secondary growth, vascular cambium and cork cambium

vascular cambium

adds layers of vascular tissue called secondary xylem or wood and secondary phloem, cylinder of meristematic cells one layer thick, develops from undifferentiated parenchyma cells

cork cambium

replaces the epidermis with periderm which is thicker and tougher

meristems give rise to

initials/stem cells which remain in meristem and derivatives which become specialized in mature tissues

in woody plants

primary and secondary growth occur simultaneously but in different locations

annuals

complete life cycle in a year or less, grasses, marigolds, petunias, zinnias, corn, wheat, peas, beans, lettuce, rice

biennials

require two growing seasons, two year lifespan, carrots, celery, parsley

perennials

live for many years, asparagus, artichokes, rhubarb, leeks, eggplants, most fruit trees, most herbs

root cap

covers root tip, protects apical meristem as the root pushes through soil

three zones of cells

zone of cell division, zone of elongation, and zone of differentiation or maturation

primary growth of roots

produces the epidermis, ground tissue, and vascular tissue

stele

in angiosperm roots, vascular cylinder

endodermis

innermost layer of the cortex, regulates passage of substances from the soil into the vascular cylinder

pericycle

lateral roots arise from within, outermost cell layer in the vascular cylinder

shoot apical meristem

dome shaped mass of dividing cells at the shoot tip

leaf primordia

leaves develop from, along sides of apical meristem

tissue organization of stems

lateral shoots develop from axillary buds on stem's surface, in eudicots, the vascular tissue consists of vascular bundles in a ring, in monocots, the vascular bundles are scattered throughout the ground tissue

stomata

interrupts epidermis in leaves, allow CO2 and O2 exchange between the air and the photosynthetic cells in a leaf

guard cells

flank each stomatal pore, regulate opening and closing

mesophyll

ground tissue in a leaf, sandwiched between the upper and lower epidermis

eudicot mesophyll has two layers

palisade mesophyll in upper part of leaf, spongy mesophyll in lower part of leaf where loose arrangement allows for gas exchange

secondary plant body

consists of the tissues produced by the vascular cambium and cork cambium

secondary growth is characteristic of

gymnosperms and eudicots, not monocots

dendrochronology

analysis of tree ring growth patterns, can be used to study past climate change

arabidopsis thaliana

model organism, first plant to have entire genome sequenced, fast generation time, produces many seeds, small size and genome, only 5 pairs of chromosomes, cells easy to transform

studies using arabidopsis have led to

important advances in gene mapping, impact of point mutations on gene function, gene expression during plant development, how genes potentially interact with other genes

positive correlation between

water availability and leaf size

phyllotaxy

arrangement of leaves on a stem, specific to each species

leaf area index

LAI, ratio of the total area of the top surfaces of the leaves to the area of ground covered by the plant, 0-\>6

importance of LAI

can be used to characterize primary productivity, canopy complexity and structure, gas-vegetation exchange processes, evaluation of vegetation stress, land cover change, effects of climate change and disturbance

apoplast

consists of everything external to the plasma membrane, includes cell walls, extracellular spaces, and the interior of vessel elements and tracheids

symplast

consists of the cytosol of the living cells in a plant, as well as the plasmodesmata

transmembrane route

across cell membranes

plasmodesmata

microscopic channels, enable communication and transport between cells

membrane potential

in plants, established through pumping H+ by proton pumps

water potential

physical property that predicts the direction of water flow

water moves from

high to low water potential

water potential is measured in

megapascals (MPa)

solute potential

osmotic potential of a solution, directly proportional to molarity

pressure potential

physical pressure on a solution

water potential equation

Ψ \= Ψs + Ψp

plasmolysis

occurs when the protoplast shrinks and pulls away from cell wall

diffusion and active transport are

involved in the movement from symplast to apoplast

guttation

exudation of water droplets on tips or edges of leaves, caused by root pressure

cohesion-tension hypothesis

transpiration and water cohesion pull water from roots to leaves, xylem sap is normally under negative pressure or tension

bulk flow

driven by differences in pressure potential, occurs in hollow dead cells, moves entre solution, faster than diffusion, does not require energy

translocation

the products of photosynthesis are transported through phloem

phloem sap

aqueous solution that is high in sucrose, travels from a sugar source to a sugar sink, moves through a sieve tube by bulk flow driven by positive pressure

soil

unconsolidated mineral or organic material on the immediate surface of the earth, serves as a natural medium for plant growth

basic physical properties of soil

texture and composition

soil particles are classified by size

largest to smallest is sand, silt, clay

soil horizons

soil stratified into layers

topsoil

consists of mineral particles, living organisms, and humus

humus

decaying organic material, fertile

loams

most fertile topsoil, contain equal amounts of sand, silt, and clay

ideal soil for plant growth should have

abundant humus, air spaces, good drainage, and high cation exchange capacity

inorganic components of soil

cations, help plant withstand harsh conditions and disease and to grow vigorously