botany exam 1 slides

organ system

shoot system: vegetative organs (leaves & stems), reproductive organs (flowers and fruits)

root system

determinate growth

maximum size is genetically determined (usually cannot heal/regrow)

scientists

robert hooke: observes cells

schleidern & swann: cell theory

virchow: cells come from cells

all cells contain

plasma membrane, cytoplasm, dna, ribosomes

ribosomes

non-organelles that synthesize proteins

ER

modify proteins & synthesize lipids

features unique to plant cells

cell wall, central vacuole, plastids (chloroplasts)

tonoplast

membrane of central vacuole. plasmolyzed, flaccid, or turgid

label chloroplast

pigments stores in thylakoids

middle lamella

thin layer of pectin binding adjacent cells

primary cell wall

occurs on surface of all plant cells. composed of microfibrils that are thin and elastic, allowing for cell enlargement

secondary cell wall

made of layers deposited inner to primary wall, occurs when cells reach mature size. lignin + cellulose = rigidity

cell wall expansion

longitudinally but not laterally (up and down like a spring)

plasmodesmata

pores that allow for communication between cells

all tissues originate from

meristematic tissue. totipotent: can regenerate entire plant

meristems

regions of continuous cell division and growth

3 types: apical meristems, lateral meristems, intercalary meristems

apical meristem

located at very end of stems & roots

produce 3 types of primary meristematic tissues: protoderm, ground meristem, procambium

protoderm

gives rise to epidermis

ground meristem

gives rise to ground tissue (photosynthetic, storage, support)

procambium

gives rise to vascular tissue (transport)

lateral/secondary meristem

responsible for secondary growth (increases girth)

-vascular cambium (from procambium): gives rise to vascular tissue

-cork cambium (from pericycle & cortex): produces peristem

seeds allow populations to

-propagate next gen

-maintain genetic diversity

-survive harsh conditions (dormancy)

-disperse

typical seed contains

-embryo 2n

-nutrient source (endosperm 3n and/or cotelydon)

-seed coat

embryogenesis in eudicots

1. developing seed contains endosperm & zygote

2. zygote forms proembryo anchored by suspensor

3. embryo proper in globular stage

4. heart stage (cotyledons)

5. torpedo stage (shoot apical meristem)

6. mature embryo: radicle, hypocotyl, epicotyl, seed coat

seed coat components

testa: outer coat

tegmen: inner coat

hilum: scar where seed attached to endocarp (fruit)

micropyle: where pollen tube entered

plume

young shoot containing shoot apical meristtem & leaf primordia

radicle

embryonic root

hypocotyl

region between cotyledon attachment point and radicle

epicotyl

region between cotyledon attachment point and shoot tip

monocot seeds

pericarp is fused with seed coat, testa and tegmen fused

root tip protected by coleorhiza, plume by coleoptile

scutellum

single cotyledon in monocots

starchy endosperm

aleurone: outer layer, secretes enzymes during germination

dormancy barriers in seed coat

-physical dormancy: impermeability to water or oxygen

-chemical dormancy: compounds in seed coat inhibit germination

dormancy barriers in embryo

-physiological dormancy:embryo requires environmental conditions to complete maturation

-endodormancy: internal biochemical processes must be met before germination

-ecodormancy: external factors are not optimal

steps required to initiate germination

imbibition

enzyme activation

breakdown of starch into sugar

types of germination

epigeous: hypocotyl (plume hook) eloongates, cotyledons extend above ground

hypogeous: epicotyl elongates, cotyledons remain belowground

what emerges first

radicle

epigeous monocots

monocot bends into hook and emerges before coleoptile

area of cell elongation

right behind apical meristem, below area of maturation

plant anatomy vs morphology

morphology studies physocal form & external structure

anatomy studies the tissues and cell structures of organs

rhizosphere

thin area around roots where complex chemistry occurs for nutrient absorption

site of gravity perception

root cap

pericycle

outer boundaru of vascular cylinder, zone of root branching

epidermis

single layer of cells at outer boundary, arises from protodern. might elongate into sticky root hairs

cortex

several layers between epidermis and vascular cylinder, differentiates from ground meristem.

endodermis: innermost layer, helps control mineral accumulation

casparian strip: waxy material embedded in walls, forces movement through cells

vascukar cylinderr

vascular tissue that differentiates from procambium, occupies center of root.

consists of primary xylem, primary phloem, and peicycle.

in dicots, forms a central core in 2+ points, phloem in between radial branches of xylem. in monocots, central pith surrounded by rings of xylem & phloem

xylem tissue

tracheids and vessel elements

protoxylem: first xylem element to mature, capable of transporting water while elongating (form annural rings)

metaxylem: mature after cell elongation is completed. form thick secondary walls for water & mineral transport. crush protoxylem cells as they grow

phloem tissue

forms sieve tubes with companion cells

first part of vascular system to become functional

vascular cambium

in long-lived dicota, parts of pericycle cells combine wiith residual procambium

secondary phloem

forms inner bark, pushes pericycle outwards. remaining pericycle becomes cork cambium

bark & wood

bark: secondary phloem

wood: secondary xylem

true leaves arise from

leaf primordia

mesophyll

middle layer of cells in leaf

includes palisade and spongy tissue

cuticle

waxy layer that prevents water loss

guard cells

surround stomata, supported by subsidiary cells

when full of water, stretched open

trychomes

hairs that can secrete substances

makes leaf pubescent (hairy) instead of glabrous (shiny)

palisade cells

upper part of mesophyll, contains chloroplasts and are main tissues for photosynthesis

spongy cells

lower part of mesophyll, main function is to allow diffussion of gasses

veins

vascular bundles that form a network of xylem & phloem

stem tuber

modified stem used to store food underground

bulb

short, flattened stem-bearing fleshy, food-storing leaves

rhizome

underground, horizontal stem

shoot system has origin in

plume of the embryo

stem functions

support, conduction, photosynthesis, food storage

nodes

attachment points for leaves

axillary bud

area between a leaf and the stem, can give rise to new axillary shoot

types of meristematic tissue

-protoderm (epidermis)

-ground meristem (ground tissue)

-procambium (vascular tissue)

secondary growth

increase in thickness or girth of the stem caused by cell division of secondary meristem

consists of vascular cambium & cork cambium→ periderm

vascular cambium divides into

secondary xylem on inside and secondary phloem outside

periderm

replaces epidermis in shoots at end of first year growth. mostly impermeable due to waxy suberin

new layers produced inside the older layers (rhytidome), which die and are pushed out

bark

all tissue external to vascular cambium

inner bark: secoondary phloem, cortex, phelloderm

outer bark: cork cambium, periderm, cork, etc.

wood

consists of original pith, primary xylem, and secondary xylem

phloem on outside, xylem inside

heartwood

oldest (innermost) layers of secondary xylem which no longer conduct water

tylosesvessel prevent waterflow

sapwood

water-conducting xylem in periphery of heartwood

bundle scars

circular markings where leaves fall off

types of branching

monopodial: buds do not degrade, and all shoots continue to grow

sympodial: terminal buds degrade, and lateral buds closest to the apex become the new terminal shoot

true leaves

never in the apex, aways substend an axillary bud

petiole

stem-like part of leaf, connects blade to stem

sessile

leaves without visible petiole

peltate

petiole attaches underneath blade

perfoliate

stems pass through center of blade

phyllotaxy

arrangement of leaves on stem

reticulate venation

netlike pattern

palmately lobate

lobes outline palmate venation

toothed leaves

serrate: sharp teeth pointing forward

dentate: sharp, symmetrical teeth

crennate: teeth are rounded (mini bumps)

ovate

widest toward base

obovate

widest toward apex (top)

elliptic

single wide middle position

oblong

longer wide middele portion

attenuate

tapering to a point

acuminate

curving inward to a point

cuneate

wedge-shaped base

cordate

upside-down heart (base)

primary growth only

herbaceous stems

herbaceous stem anatomy

epidermis, cortex, pith, primary xylem tissue & primary phloem tissue, cambium layer

glabrous vs pubescent

glabrous: without hairs, pubescent: hairy

vascular bundles, derivatives from

xylem and phloem are arranged in bundles that arise from procambium bundles

xylem arises from cell facing inside (conducts from roots to rest of plant)

phloem arises from cell facing outside (distributes food from photosynthetic tissues to other tissues)

vascular bundle arrangement

solenostele: some eudictos, tissues in continuous ring

eustele: most eudicots. vascular bundles discrete but in a circle

atactostele: most monocots, vascular bundles scattered through stem

phloem tissue is composed of

sieve cells and companion cells

sieve cells

aranged in tube columns, end walls called sieve plates.

living cytoplasm but no nuclei. companion cells possess nuclei and perform all processes to keep them alive