plant sci 2

arrangement

species (method of classification)

alternate arrangement

one leaf per node; alternates sides

node

where leaf is attached

opposite arrangement

2 leaves per node on both sides of stem

whorled arrangement

3+ leaves per node

spiral arrangement

spiraled along stem

simple leaf

1 undivided blade

compound leaf

divided into multiple leaflets

pinnate compound leaf

leaflets along central rachis

palmate compound leaf

leaflets radiate from 1 point

cuticle

outside waxy layer of leaf

leaf stipules

small, leaf-like appendage found at base of petiole; protects developing bud when leaf is young

petiole

stem of leaf

parallel leaf venation pattern

on monocots; same direction

reticulate leaf venation pattern

on dictots; repeatedly splits in 2

petiolate leaf attachment

has petiole

sessile leaf attachment

no petiole, blade attached directly to stem

trichome

hairlike appendage

modified leaves

changed structure + function from typical leaf role of photosynthesis, adapting to perform specialized tasks

tendril

modified curl

spines

modified on leaf for protection

trap

modified on leaf for catching food

bracts

modified on leaf to attract pollinators

woody stem

brittle, non-bendable, bark

herbaceous stem

soft tissue that bends

cortex

area btwn epidermis + vascular bundle

parenchyma cells

store starches, sometimes photosynthesis

collenchyma cells

thicken cell wall to support fxn of stem

pith

spongy tissue in center of stem, only herbaceous dicots, parenchyma cells

xylem

water + mineral transport moves up plant

phloem

sugar + nutrients transport from source to sink bidirectionally

vascular cambium

forms ring inside stem separating xylem from phloem, only dicots, responsible for secondary growth

tree rings

result of vascular cambium producing new xylem + phloem

modified stems

have adapted shape + fxn to perform specialized roles

tuber

swollen modified stem that stores starch

rhizome

horizontal, thick + fleshy underground modified stem that stores food, has nodes + internodes

stolon

modified stem that grows horizontally above (runner) or just below ground, producing new plants at nodes, thinner

corm

short, vertical, fleshy underground modified stem that stores food; center is solid tissue

bulb

short underground modified stem with layers of fleshy, immature leaves that store food

thorns + tendrils

can be modified stem if originating from stem tissue

tap root

one main root grows vertically, many smaller lateral roots, penetrate deeper into ground, dicots

fibrous root

dense network of fine roots, closer to surface of ground, monocots

root growth

occurs at tip of root thru cell division + elongation, root cap continuously replaced

cell maturation zone

root cells differentiate into special types with specific fxns

epidermis

outer cellular layer of leaf; protection, absorption

root hairs

extension of epidermal cells, increase surface area to increase absorption

root cortex

stores photosynthetic products, just inside epidermis, parenchyma cells

endodermis

separates cortex + vascular tissue, checkmate for materials entering

root vascular system

moves water + nutrients absorbed by root up to stem

contractile roots

develop in response to temp + light fluctuations at soil surface, pulls bulb deeper into ground by contracting to protect from environmental factors

epiphytes

plants that grow on surface of another plant and derives its moisture + nutrients from air + rain water, no attachment to ground

source to sink

materials moved from area where they originally exist to where they’re neeeded

source

water/minerals in soil/air

sink

stems, leaves, flowers, fruits

diffusion

mvmt of molecules from high to low concentration

osmosis

mvmt of water molecules across semipermeable membrane from low to high solute concentration

cohesion

polar water molecules tend to stick to each other

adhesion

attractive force btwn water molecules + surfaces of plant tissues; allows water to stick to plant’s neg cell walls in vascular system

capillarity

ascension of liquids thru slim tube, cylinder or permeable substance due to adhesive + cohesive forces btwn liquid + surface

transpiration

excess water in plant released as water vapor into air thru stomata on leaves

transpirational pull

force that moves water from roots to leaves; creates suction, pulling up more water

guttation

water released thru hydathodes; occurs at night/early morning bc water enters faster thru osmosis than can transpire thru stomata

hydathodes

specialized pores on leaf margin where water releases during guttation

oedema

cells rupture on bottom of leaf; occurs in cool, cloudy conditions when transpiration reduced

stomata

open + close in response to environmental cues/plant needs

translocaiton

mvmt of photosynthates in plants

nucleus

dna, directs protein synthesis

cytoplasm

supports + suspends cell parts

membrane

controls what enters/exits cell

mitochondria

generates energy thru respiration

cell wall

composed of cellulose, rigid but flexible, provide structural support, allows it to withstand internal/turgor pressure

large vacuole

store water (maintain turgor pressure/prevents wilting) + nutrients, pigments, waste, defense compounds

chloroplast

site of photosynthesis, engine of plant cell, contains chlorophyll

transduction

conversion of light to chem energy

light reactions

chlorophyll captures sunlight energy > chem energy > split water molecules

light independent (calvin cycle) reactions

co2 combined with organic molecules using chem energy converts it to glucose

holoparasitic plants

rely on other plants by stealing their food; have haustoria

hemiparasitic plants

retain ability to photosynthesize but supplement from host plant when available

saphrophytes

don’t have chlorophyll; feed on organic matter

phytochromes

receptor that monitors lvl, intensity, duration + color of light reaching plant

photomorphogenesis

adjusting growth + development in response to light

light intensity

affects rate of photosynthesis/chlorophyll production + stomata function and causes plant mvmt in some species

blue light

promotes vegetative growth

red light

promotes flowering + fruiting

circadian clock

ability of plant to use light to track time of day (heliotropism)

photoperiodism

ability of plant to use light (day length) to track time of year

phototropism

directional response; pos grows towards light, neg grows away

gravitropism

plant growth in response to gravity; pos roots go down, neg shoots go up

ethylene

affects speed of aging plant tissues (fruit ripening, flower wilting, leaf drop)

auxin

rooting hormone

thigmatropism

growth/mvmt in response to touch

twining

when stems curl