Plants DAT Ch 9

Seed Coat

protects seeds from outside forces

Storage Materials

provides nutrients to embryo- stored in the form of endosperm

Embryo

turns into our plant, parts below the soil and above

Radical

develops into the young root, first embryo structure to come out of the seed

Young Shoot

part of the plant that is above the soil, hypocotyl, plumule, epicotyl

Hypocotyl

bottom part of the young shoot

Plumule

develops into young leaves on young shoots

Epicotyl

top region of young shoot

Germination

the sprouting of a seed from a previously dormant seed, will occur with the appropriate amounts of water temperature and light

water

the most important environmental cue to kick start germination by swelling and activating metabolic processes

Imbibition

the process of swelling caused by water that kick starts germination of dormant seed

Meristems

area of a plant where growth happens via repeated cell division , apical or lateral

Apical meristems

causes plants to grow vertically, tips of roots and tips of shoots

Lateral Meristems

causes plants to grow horizontally, sides of the plants

Primary growth

growth first happens at the apical meristem

Growth at the root tips

root caps, zone of division, zone of elongation, and zone of maturation

Root cap

protects the apical meristems, letting it grow deeper in the soil during primary growth

Zone of division

continual division of apical meristem cells during primary growth

Zone of elongation

the divided cells absorb water and elongate during primary growth

Zone of maturation

these cells differentiate into specific plant tissues

Secondary Growth

the horizontal growth of a plant at its lateral meristems, only woody plants undergo this

Vascular Cambium

Ring of meristematic tissue between the primary xylem (center) and the primary phloem (flowing away)

Secondary Xylem

and the pith form the wood, closer to the center of the tree, vascular cambium produces new additional secondary xylem year after year

Secondary Phloem

Contributes to the bark (outer part of the tree), secondary phloem replaces older phloem

Cork Cambium

a ring of meristematic tissue beyond phloem, closer to the edge , repeatedly divides to form cork (outermost layer of the bark)

Plant tissues

Ground tissue, vascular tissue, dermal tissue

Ground tissue

structural support for the plant, most of the plants mass, parenchyma, collenchyma, sclerenchyma

Parenchyma

tissue cells, fille tissue make up the bulk of the plant, thinnest walls of the three (packing peanuts)

Collenchyma

tissue cells, extra support to plant in areas of active growth, irregular cell walls (columns in different sizes)

Sclerenchyma

tissue cells, main structural support of the plant, thickets cell walls (skeleton)

Vascular tissue

Source and sink, Phloem and Xylem

Phloem

transports sugars, source is leaves (chloroplast) and sink is roots (high carbohydrate storage)

Xylem

transports water, source is roots (from soil) and sink is leaves (dont have direct access to water)

Sieve cells

phloem cells, long cells with pores that allow substances to flow through them, lack organelles in order to transport sugars

Companion Cells

type of phloem cells have all organelles needed for the metabolic functions in phloem sugar transport, plasmodesmata connection

Tracheid’s

xylem tissue, long and thin, water flows through the pits found at the ends of the tracheid cells

vessel elements

xylem cells, shorter and wider, in contact with other vessel elements, water flow through perorations, also provides structural support

Stele

central part of the root or stem, Phloem →Xylem→Pith→Xylem→Phloem

Pith

the tissue found at the center of the root or stem, stores and transports material, made of parenchyma

Dermal tissue

outer layer of the plant, provides protection and regulates how plant is affected by its external environment

Epidermis

type of dermal tissue that covers the outside of a plant, covered by waxy cuticle “waterproof”

Root hairs

tissue made out of epidermis, root cells, increases surface area to allow for greater water and nutrient uptake

Symplastic Pathway

water movement through the cells cytoplasm, simplistic

Apoplastic Pathway

water movement outside the cell, but withing the cell wall, about

Casparian Strip

regulates type and amount of substances that enter roots, fatty waxy substance that makes it impenetrable, helps filter substance coming through cell walls

leaf structures

covered by epidermal layer that is covered by the cuticle, opening called stomata’s that are controlled by guard cells

Low Co2

causes the stomata to open, during the daytime when photosynthesis is occurring and depleting the co2

K+ ions

diffuse into guard cells, water rushes into the guard cells making them turgid and causing them to open

high co2

causes the stomata to close, during nighttime where photosynthesis is not occurring

High temperature

stomata closes, needs to prevent transpiration K+ ions leave the guard cells water rushes out making them flaccid

Mesophyll

middle part of the leaf, palisade and spongy

Palisade Mesophyll

carry out photosynthesis, upper epidermis (light dependent reactions)

Spongy mesophyll

allows for gas exchange, very loosely packed closer to the lower epidermis with stomata

bundle sheath cells

surround and protect vascular bundles (xylem and phloem) spatial isolation of co2 in C4 plants

Transpiration

when water evaporates through stomata in leaves, causes transpirational pull, main driving force for the water moving up the plant

cohesion

when similar particles cling to one another, cohesion tension theory as water evaporates it pulls the water underneath it

Adhesion

when different particles are attracted to one another, capillary action is an adhesive force that causes waters movement upward adhesion happens between water and the xylem vessels

Root pressure

pressure that builds within the roots, an osmotic gradient drives water into the roots and pushes water up the xylem

Desiccation

downside of transpiration, controlled by stomata

Pressure flow hypothesis

explains the movement of sugar in phloem in relation to movement of water

1. sugar increases in phloem cells

2. water (from nearby xylem) is pulled bc of osmosis

3. Turgor pressure is created in phloem

4. sugar and water experience bulk flow movement from leaves to roots

Ethylene

gaseous hormone that increases the ripening of fruit

Auxins

promote the growth of cells by loosening cellulos fibers, increasing cell wall plasticity and causing cell growth

Plant tropisms

caused by auxins , phototropism, gravitropism, thigmotropism

phototropism

plant stem curves towards light, caused by auxins

gravitropism

plant stem curves to oppose gravity, caused by auxins

thigmotropism

plant grows in response to contact, caused by auxins

Cytokinins

hormone that regulates cell differentiation and division, prevents aging in plants

Root production

High auxin to cytokinin ratio

Shoot production

low auxin to cytokinin ration

Gibberellins

hormones that control the milestones of plant growth: stem and shoot elongation by giving energy to seed, flowering and fruiting, leaf and fruit death

Abscisic Acid

hormone in time of plant stress, promotes seed dormancy, closes stomata, inhibits growth, opposite of gibberellin

Alternation of Generation

ability of an organism to exist and alternate between both haploid and diploid forms, plants and fungi

Fusion

haploid + haploid = diploid

Mitosis

diploid organism undergoes ______to produce diploid daughter cells and to grow

Meiosis

diploid sporophyte undergoes ___ to produce haploid spores

Sporophyte

diploid life cycle, produces spores (sporangia)

Gametophyte

haploid life cycle, produces gamete (gametangia)

Homosporous Plants

can produce only one time of spore, bisexual gametophyte able to fertilize its own egg

Heterosporous Plants

male (microspore) and female (megaspore) spores, female variant> male variant

Bryophytes

nonvascular plants, must remain small and short, grow horizontally and need to be near water, moist habitats, flagellated sperm , rhizoids + gametophyte dominant (reduced sporophyte)

Rhizoids

found in bryophytes, pre- roots, hair like projections

Tracheophytes

vascular plants, have root system, sporophyte dominant , seeded or seedless

Seedless tracheophytes

mostly moist habitats but can be dry, homosporous, flagellated sperm, independent gametophyte and sporophyte life cycles (sporophyte dominant)

Seeded Tracheophytes

gymnosperms or angiosperms, most evolutionarily advanced because seeds are very advantageous

Gymnosperms

seeded tracheophytes, seeds are not protected, do not have flagellated sperm (wind dispersal), sporophyte dominant

Angiosperms

seeded tracheophytes, flower + fruit bearing, protected seeds, no flagellated sperm (wind or animal dispersal), sperm is in pollen, double fertilization ( female fertilized by 2 male gametes)

Petals

attract animals to achieve pollination

Stamen

male plant sex organ- anther(spores) and filament (support)

Generative cell

type of microspore that contains sperm (gene)

Tube cell

type of microspore that eventually develops into pollen tube

Pistil

female plant sex organ, stigma (top), style (tube down to ovary), ovary (contains eggs)

gene migration

spreading of genes to new locations using seeds in fruits by animals or wind

Monocots

type of angiosperm that has a single cotyledon (first leaves), parallel veins, flower organs in multiples of 3, scattered vascular bundles, fibrous roots

Dicots

type of angiosperm that has two cotyledon (first leaves), branching leaf veins, circular vascular bundles, taproots, multiples of 4 or 5

Ammonia and Nitrate

forms of nitrogen that can be absorbed by plants (nh3 and no3-)

Nitrogen fixing bacteria

fix atmospheric nitrogen into ammonia (nh3) and ammonium(nh4+)

Nitrifying bacteria

converts ammonia and ammonium into nitrites (no2-) and nitrites into nitrates (no3-)

detritus

once a plant or animal dies and decays, they decompose and become another soil of nitrogen into the soil

Denitrifying bacteria

convert leftover nitrates into atmospheric nitrogen (n2)