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What are the closest relatives to plants
charophytes (green algae) Parts: blade, stipe, and holdfast (similar to leaves, stems, and roots, but are mostly homoplasies)
Similarities between plants and charophytes
rosette-shaped cellulose-synthesizing complexes - cells of both have circular proteins in plasma membrane peroxisome enzymes - contain enzymes that help minimize loss of organic products to photorespiration structure of flagellated sperm in plants that have it closely resembles sperm of…
Four plant groups
1. nonvascular plants (bryophytes) 2. seedless vascular 3. gymnosperms 4. angiosperms
When did land plants originate?
~475 million years ago
When did vascular plants originate?
~420 million years ago
When did seed plants originate?
~360 million years ago (or ~305 mya according to book)
Why are nonvascular plants found in damp, shady locations?
need water for fertilization can't carry water to plant structures without vascular tissue
Within the plant types, which two are the most closely related?
angiosperms and gymnosperms
What are the three basic plant organs?
roots stems leaves
anchors plant in soil absorbs minerals and water stores carbohydrates taproot and lateral (branch) roots root hairs increase SA, primary site of absorption (short lived and constantly replaced)
nodes: points where leaves are attached internodes: stem segments between nodes auxillary buds and apical buds; apical dominance do perform photosynthesis
in most plants, the main photosynthetic organ blade and petiole (joins leaf to stem at node) simple leaves, compound leaves, doubly compound leaves veins - vascular tissue
Dermal tissue
the plant's outer protective covering first line of defense against physical damage and pathogens called epidermis in non-woody plants called peridern in woody plants cuticle - waxy coating on surface prevents water loss
Vascular tissue
carries out long distance transport of materials between root and shoot systems xylem conducts water and dissolve minerals upward from roots phloem transports sugars from source to roots and sites of growth  stele: collective vascular tissue of a root or stem
Ground tissue
tissues that are neither vascular nor dermal when external to vascular tissue: cortex when internal to vascular tissue: pith various functions, such as storage, photosynthesis, and support
Primary cell wall
fully permeable membrane permits passage of small molecules and small proteins  key nutrients, especially water and CO2 are distributed throughout plant from cell wall to cell wall in apoplastic flow [apoplast is the continuum of cell walls plus extracellular space]
secondary cell wall
a thick layer formed inside primary cell wall after the cell is fully grown not in all cell types in xylem, secondary wall contains lignin which strengthens and waterproofs the wall
waxy coating on the epidermal surface which helps prevent water loss evolution of this has allowed for plants to live on land
small spine shaped leaves may have originated from sporangia supported by single, unbranched strand of vascular tissue
leaves with highly branched vascular systems may have evolved from the fusion of branched stems
Root hairs
increase surface area for nutrient absorption  absorption of water and inorganic nutrients anchoring the plant body to the ground function in storage of food and nutrients in response to the concentration of nutrients, roots also synthesize cytokinin, which acts as a signal as to how …
How do land plants prevent dehydration?
cuticle to reduce water loss uptake and distribution with vascular tissue stomata to regulate loss
What are the three basic cell types in plants?
parenchyma collenchyma sclerenchyma
-form: cell membrane primary cell wall: cellulose, thin and flexible, water and gas permeable -function metabolic activity and storage generally alive at maturity and many retail ability to divide and differentiate into other cell types -examples: photosynthetic, phloem, glandular c…
-form cell membrane primary cell wall: still cellulose, but unevenly thickened in some places -function provide flexible support but still allowing growth elongating with stems and leaves they support
-form cell membrane primary cell wall secondary cell wall btwn primary and membrane, thickened and generally lignified (lignin restricts water transport) -function usually strengthened by lignin and rigid (can not elongate) often dead at maturity mechanical sclerenchyma: sclerids a…
thin mm in length tapered ends water moves from cell to cell through pits found in all vascular plants
vessel elements
wider and shorter than tracheids make up longer (sometimes m in length) open "pipes" dead at maturity found in most flowering plants and few others
vascular tissue for sugar solution transport sieve cells and sieve tubes accompanied by companion cells - nonconducting cells that are connected to the sieve-tube cells by plasmodesmata; in some plants they help load sugar in the sieve tube elements live at maturity
At functional maturity, why is xylem dead but phloem alive?
xylem living tissue disintegrates leaving behind thickened cell walls as a nonliving transport system in which water moves laterally between pits in phloem, pores facilitate the flow of fluid from cell to cell along sieve tube
the diffusion of water across a membrane in plant cells the well wall affects osmosis, the physical pressure of the cell wall pushes back against the parts of the cell (creates turgor) water potential 
water potential
a gradient in water potential is the driving force for water movement across cell membranes increasing solutes in the water lowers solute potential pressure increases pressure potential and tension decreases water potential gradient = solute potential + pressure potential (units are MP…
3 Major pathways of water transport (soil to tissue)
apoplastic ("non-living" space) symplastic ("living" space) transmembrane
symplastic route of transport
the cytosol of the cell is referred to as the symplast water and solutes move continuum of cytosol withing plant tissue minerals and water only cross the membrane ones and use plasmodesmata (narrow channels connecting cells) to move through
apoplastic route of transport
ions can diffuse across a tissue through the apoplast - the continuum formed by cell walls, extracellular spaces, and dead interiors of tracheids and vessels one cross of the plasma membrane
internal layer of cells in the root cortex surrounds the stele and functions as a last check point for the apoplastic route minerals from symplast reach the the endodermis and continue through plasmodesmata of endodermal cells and pass in the stele
casparian strip
a belt made of suberin (impervious to water and minerals) forces water and minerals moving through the apoplast to cross the plasma membrane of an endodermal cells and enter the stele via symplastic route together the casparian strip and endodermis make sure not water and minerals reach…
Water, mineral, and sugar transport
can occur by short-distance diffusion or active transport and by long distance bulk flow diffusion is passive transport, uses aquaporins
bulk flow
driven by negative pressure - water enters through roots, and the xylem sap gets transported to leaves by bulk flow pusing xylem up: root pressure; root cells pump minerals to lower water potential in stele; water flows from root cortex generating root pressure and pushing xylem sap pul…
Why is the cohesion tension hypothesis the overall accepted hypothesis?
for the most part xylem sap is not pushed from below, but pulled up by leaves using transpiration-cohesion-tension mechanism water is constantly lost to transpiration, creating a negative pressure by surface tension, which creates a pull cohesion makes water molecules stick together as …
How do plants regulate how much water must be transported up?
plants determine how much water needs to be transported up based on how much water has evaporated plants regulate lose water through the stomata, which helps regulate the rate of transpiration thick cuticles regulate water loss
Phloem sap transported by positive pressure
loading of sugar in sieve tube at the source lowers water potential inside the sieve tube and takes up water by osmosis positive pressure forces sap to flow along the tube pressure is relieved by phloem sap being unloaded at the sink (active or storage cells)
How can water uptake be maximized by plants?
more root surface area - root hairs larger leaves maximizes surface area and evaporation, increasing the need and pressure for more uptake less SA in leaves -> less water needed some plants use fog as a leaf water source
Why do deciduous trees drop their leaves during severe droughts?
in order to reduce water loss from the leaves
What structural adaptations allow cacti to live in the desert?
smaller leaves to reduce transpiration extremely thick cuticles to reduce water loss some desert plants trap food in their leaves stem photosynthesis
How would phloem transport be different in summer vs early spring?
phloem transport is increased in summer due to plants photosynthesizing and making sugar in early spring it is not as hot so plants would need to produce less sugar
For plants, meristems allow plants to grow or extend in...
What is the adaptive advantage of producing pairs of leaves on different sides of a stem?
maximize light capture
If the cutting takes off the bark (not just the periderm), what happens to the tree? Why?
death phloem layer that takes food to roots from leaves is removed, then roots die and no water is sent to leaves
asexual reproduction
produces exact copies of offsprings single individual is the sole parent and passes copies of all its genes to the offspring gives rise to clones genetic differences come from mutations
sexual reproduction
2 parents give rise to the offspring offspring vary genetically and have unique genome 2 gametes join to form zygote that is diploid
animal reproduction
diploid multicellular organism  meiosis produces haploid gametes (single cell) fertilization produces a diploid zygote (single cell) mitosis develops into organism (multicellular diploid)
plants reproduction
diploid multicellular organism (sporophyte)  meiosis produces haploid spores (single cell) mitosis produces haploid multicellular organism (gametophyte) fertilization produces 2n zygote (diploid single cell) mitosis
fungi reproduction
2n zygote meiosis splits into haploid cells (spores) mitosis develops haploid unicellular or multicellular organism (hyphae) organism produces gametes through mitosis fertilization 
A life cycle with alternation of generations has:
multicellular gametophyte and sporophyte forms
For eukaryotes, alternation of generations is a shared derived trait for:
land plants
Sexual life cycles for animals, plants and fungi share which trait?
union of gametes producing a 2n zygote
Which type of plants display sporophyte dominance?
all vascular plants
plant organ where reproduction occurs Colorful petals used to attract insects for pollenation  stigma- sticky structure, receives pollen; part of carpal style: structure that leads from stigma to ovary carpal: female reproductive organs ovary: becomes fruit; at base of carpal, contai…
double fertilization
2 sperms are discharged in the ovary, one fertilizes to make zygote and other combines with cell to make 3n endosperm tissue, a food source for the zygote (packaged in seed)
mature ovary of a flower thickening of ovary around the seeds protects seeds and aids in dispersal disadvantage: takes a lot of energy to produce
pollen and pollination
pollen is male plant sperm formed by the anther in angiosperms, dispersed by wind, water, and animals pollination is the transfer of pollen to the ovule in the ovary
plant embryo packaged with a food source produced by fertilized ovary (ovule develops into seed) disperse diploid sporophytes
plant adaptations
flowers attract pollinators, contain reproductive organs, located at highest point so wind disperses pollen pollen dispersal and pollination: don't need water to disperse sperm (20% wind, 80% animals [~65% insects]) internal fertilization: embryo is safer, protected seeds: protection o…
plant hormone
organic compounds, either natural or synthetic, that modify or control one or more specific physiological processes within a plant control plant growth and development
seed dormancy
trait evolved for seeds to remain dormant until mobilized by external trigger to make sure they germinate only in favorable conditions: enough light, temperature, and moisture for the seedlings to survive ABA (absiciscic acid) keeps seeds dormant by lowering metabolic rate, suspending gr…
Seed germination
dormant seed triggered by water, water removes ABA and breaks dormancy triggers release of Gibberllin (GA) which targets seed's outside wall aleurone synthesizes and secretes alpha amylase - hydrolyzes nutrients in endosperm and breaks down starch to glucose scutellum absorbs nutrients…
signals ovary to start thickening -> forms fruit, makes it grow larger by elongating the cells gibberlin released during seed germination signals the aleuron to secrete the digestive enzyme and amylase that hydrolyzes the nutrients in the endosperm that will be used by the embryo while i…
phototrophism: as auxin moves down shoot it stimulates cell elongation a plant stem exposed to light will have shaded and lit sides shades side - more auxin the produce cell elongation cells with auxin elongate while those cells on the lit side do not causes stem to bend towards light…
fruit ripeningL a burst of ethylene triggers ripening process

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