bis2c Midterm 2

Challenges of life on land

1. dry out ( desiccation )
2. water trasnport
3. gravity
4. intense UV radiiaotn
5. dispersal of gametes

Advantages of life on land

1. easier to capture sunlight
2. easier to exhance gasses ( o and Co2 )
3. innitally lower compettion for resources

Algal grade plants what innovations?

1. storing the products
2. photo pigment chlorophyll b
3. retention of the egg on the parent plant
4. encasement of the egg on the parent plant

multicellularity in algal grade evolved..

independetly

plants are a monophyletic group t or f

t

chloroplasts are a unqiue primary endosymbiosis w what?

cyanobacteria

charales is what to land plants?

sister group

A huge evolutionary event that:

1. happened once
2. took long
3. manyyy innovations

diagnostic features of land plants

vegetative innovations

* cuticle,
* pigments


* mutualistic fungal associations )

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reproductive innovations ( mitosis → same ploidy, and meiosis reduction in ploidy, sporophyte and all its jazz, archegonia, antheridia, protected embryo )

Diplonitc life cycle

expansion of the diploid phase, only diploid stage of the life cycle is multicellular

Haplontic life cycle

only haploid stage is multicellular, makes gametes by mitosis not meiosis. zygote is unicellular

sporic life cycle

alternates between multicellular haploid and diploid stages

diagnostic feature of land plants

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multicellular haploid org makes haploid gametes → gameotophyte

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multicellular diploid organism makes haploid spores → sporophyte

sporic life cycle is thought to be innovation of…

land plants

archegonia

gametangia that produces female gametes

antheridia

gametangia that form male gametes

sporangia

multicellular organs of the sporophyte that produces spores

sporocyte

diploid cells within sporangia that undergo meiotic cell division

spores

single haploid cells that undergo mitotic cell division after germination that gives rise to the multicellular haploid gametophyte

byrophytes features

“amphibians” of the plants bc in cool damp places

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1. lack true vascular system ( relies on capillary action for water, diffusion for nutrient )
2. lack true leaves, stems, roots
3. cuticle poorly developed
4. need water for sperm to travel

major lineages of byrophytes

liveworts, mosses ( some have a vascular system) hornworts

sister group of vascular

hornworts

completley extinct fossil group that is the sister to vascular plants, what are features

rhinophytes

* lacked leaves and roots but


* branched sporophyte
* vsacular tissue

diagnostic feature of vascular plants

* the sporophyte is nutritionally independent of gametophyte at maturiy
* tracheid cells with lignified cell walls

vascular tissue evoved separtely in mosses and vascular plants, t or f?

T

What. evovled before hornworts

green sporophyte

the sporophyte of bryophytes is…

inconspicuous and nutritonally depedent

gameotophyte of bryophytes is…

dominant and nutrtionally INdependent

the sporophyte AND gameophyte of vascular plants is…

dominant (spor) and inconspicious ( gametophyte ) and nutritionally independent ( not embedded )

Xylem does what

transport water and minerals ptissue

Xylem info

occurs through tracheid cells that are dead at maturity, passive, unidirectional ( upward from roots to aerial )happens through transpiration cohesion tension/ walls fortified with lignin

phloem does what

transport sap, horomones, photosynthetic

phloem info

occurs through sieve tube elements and companion cells that are alive at maturity

active ( actively loaded into phloem at source, sucrose actively unloaded from phloem at sink )

bidirectional ( upward or downward within plant,always moves from source to sink )

follows a gradient of positive pressure potential

vascular plant adaptive value

efficient transport of water and nutrients allows plants to colonize more fully terrestiral enviornemnets

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rigid structural support allows plants to grow taller, thus compete more effectively for sunlight and also to enhance spore dispersal

many innovations of vascular plants exhibit…

homoplasy

how many times have leaves and roots evovled in vascular plants?

twice.

microphyllous leaves

nOT SMALL!!

lycophytes

relatively simple leaf with a single vascular strand

derived from sterile lateral sporangia

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megaphyllous leaves

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uphyllophytes

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more complex leaf with ramified vascular tissue

derived from laminated side branches

Stigmarian roots

lycophytes

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simple dichotomously branching root system derived from rhyzomes

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spirally arranged rootlets derived from microphyllous leaves

complex roots

complex branching and root hairs derived from dermis, evolved in euphyllophytes

Heterospory vs homospory!

First one we know is the homosprous

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hetero has two types of sporangia ( mega and microsporangium )

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also two types of gametoptye, but unisexual only makes one or the other unlike homo which is hermaphrotdite

How many times did heterospory evolve independently and with what?

3 times…

* Lycophytes (spike mosses)
* Monilophytes (leptosporangiate ferns)
* MRCA of seed plants (gymnosperms and angiosperms)

hetereospory adaptive value

1. geentic diversity
2. parental investment

Overtopping growth

the apical meristem, a region of continuously dividing cells that give rise to the plant body

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unbranched - one, bryophytes !!

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dichotomous - sporophyte branches dichotomously, lycophytes !!

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Overtopping- asymmetrically, sporophyte has a main axis and side branches, euphyllophytes !!

overtopping growth adaptive

taller, better competition, better reproduction, side branch = allows elaboration of novel organs,

Euphyllophytes include monilophytes and seed plants . T or F

T

what are the main groups of seedless vascular plants?

1. lycophytes (club mosses, spike mosses, quillworts)
2. monilophytes (whisk ferns, horse tail ferns, leptosporangiate ferns)

diagnostic features of lycophytes

1. lateral sporangia
2. microphyll leaves
3. simple roots

diagnostic features of euphyllophytes

1. overtopping rowth
2. megaphyll leaves
3. complex roots

seed plant innovations

1. secondary growth
2. reduced and dependent megagametophyte
3. seed
4. pollen

What is inferred to have evovled in seed plants?

Secondary growth

whats secondary growth

produced by lateral meristems!

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vascular cambium: ring of cells between 1 xylem and 1 phloem.

Allows shoot and root to increase in girth ( diamtere )

produces 2 xylem and 2 phloem

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secondary xylem and secondary phloem gives rise to what in seed plants?

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secondary xylem gives rise to wood, secondary phloem gives rise to bark ( everything outside vascular cambium

secondary growth adaptive value

allows vascular tissues to constantly be rejuvenated, very efficient transport

increase diameter - taller

bark prevents water loss and infection!

in seed plants, the megagametophyte is…

greatly reduced, embedded within, and nutrition dependent on the sporophyte. this enabled the evolution of the seed!!

Moss - bryophyte

conspicious gametophyte

sporophyte embedded in gametophyte

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sporophyte nutritonally depednedt on gameotophyte

fern ( seedless-vascular plant )

conspicuous sporophyte

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sporophyte and gametophyte independent, not independent

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sporophyte and gametophyte nutritionally independent ( photosynthetic )

Angiosperm ( seed plant )

conspicuous sporophyte

gametophytes embedded in sporophyte

gametocytes nutritionally dependent on sporophyte

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**opp of bryophyte!!** opens door

A typical gymnosperm seed plant life cycle

uh yeah

Seed Cone

megasporangium, makes female

Pollen grain

male microgametophyte of seed plants

has 4-8 haploid cells

2 of the cells are male gametes

antheridia ( male gamtangia ) are lost

enclosed in coat of sporopollenin ( protects pollen )

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pollen adaptive value

fertilization can occur without water! ( allows colonization of more fully terrestrial habitat )

sperm can travel further by wind or animal pollinator ( genetic diversity! very good outcrossing )

adaptive significante of seeds

good dispersal, efficient dispersal of the next sporophyte,

protection and DORMANCY and seedling survival ( aka seed can stay viable and just pause.

When conditions are favorable it will germinate and resume! )

seed contains nutrients that help young plant

2 major lineages of seed

gymnosperms and angiosperms

Major angiosperm innovations

flower: reproductive strucutre of flowering plants. a complete flower has four concentric groups of organs

adaptive significance of the flower

in bryophytes/seedless vascular plants - sperm swims through water

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gymnosperms - pollen and seed cones, sperm reaches egg by wind

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angiosperms - rely on animals!! they use this flower hehe to attract animals, rewards

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carpel - home of megasporangia

how many times does the megaspore divide

by mitosis 3 times to give the embryo sac (52min in vid)

carpel

stamen

microsporangia, has an anther, microsporocytes divded by mieosis to give micrpsore, then give by mitosis to get pollen grain

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microgameotpye is just 2 cells

Double fertilization

There are two fertilization events. Each pollen grain (microgametophyte) releases to two sperm cells.

one sperm is involved in the formation of the diploid zygote by merging with the egg. (2n)

sperm number 2 unites with the two polar nuclei in the formation of the triploid endosperm (3n)

What is endosperm

triploid tissue that nourishes developing embryo

anatomy of gymnosperm seed!

inside - mature diploid embryo

middle - nutritive HAPloid tissue ( endosperm, from megagametophyte )

outer - diplioid protective seed coat ( from previous sporophyte or integumnet )

gymnosperm is known as

naked seed ( ovule not enclosed in the ovary of the carpel )

gymnosperm’s fleshy tissue surrpondng seed ( fertilized ovule) are homologus with the fruit of angiosperms

false

what are the 4 main lineages of gymnosperms?

1. cycads
2. gingkgo
3. gnetophytes
4. conifers

cycads

dioecious, cone shaped, swimming sperm that swim within the megagametophyte to fertilize egg after pollination

gingko

single sepciies!! (ginko biloba ) dioecious, smelly, swimming sperm, ovules borne in pairs surrounded by fleshy integument. fertilized ovule has fleshy fruit like swelling of integument tissue

gnetophytes

monoecious and diocious, motile sperm, double fertilization and vessel elements in their xylem, once thought to be sister to angiosperms but turns out it is sister to conifers

conifers

monoecious and dioecious, cone bearing, needle leaves, non motile sperm. Pollen cones have scales that are modified leaves, scales of seed cone are modified branches. half of conifers have fleshyfruit like swelling of feritilized ovule

consequences of long stem leading to modern flowering plants

1. cannot find the root… found in ANITA grade of plants
2. provided opp for many innovations to accumlate, mostly related to reproduction

anatomy of angiosperm components!

inside - mature diploid embryo

middle - nutritive TRIploid tissue ( endosperm )

outer - protective seed coat ( from previous sporophyte )

ovary wall - from proevious sporophyte ovary, becomes fruit!

major angiosperm innovations!

1/ flower

carpel

fruit

double fertilization

endosperm

highly reduced gemale megametophyte; embryo sac ( usually w 7 cells and 8 nuclei )

new vascular cell types

angiosperm life cycle

flower anatomy?

comprised of four whorls

* two outermost whorls: outer whorl is sterile ( perianth, sepals; inner whorl are the petals ( collectively corolla )
* two inner whorls are spore bearing, outer of stamens ( have filament ) and apical microsporangia ( anthers )
* thus stamen = **anther** + filament
* anthers have microsporcytes… pollen
* innermost layer has carpels, which has an apical stigma, a neck-like style, and a basal ovary. 4 megasores but only 1 survives and that makes the megagametophyte ( aka the embroyo sac! )
* thus carpel = **stigma**, style, ovary, ovule

flower adaptive value

animals = good reproduction

what are progymnosperms?

Progymnosperms were trees that exhibited secondary growth (wood) but lacked seeds ( extinct)

what are seed ferns

were tres with fern-like leaves that bore seeds ( also extinct )

What is a flower?

An expanded ovary

whats a carpel?

enclosed megasporangia

the seed is developemed from

the integument of the ovule

what is the ovule?

integument + enclosed megasproangium

Adaptive significane of fruit

protection for embryo, efficient dispersal of emrbyo.

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Whats a drupe?

simple fruit developed from a single flower with a single ovary that contains a single ovule LOL

perfect flowers

has both carpels and stamens!

Imperfect flowers

has either just stamens (staminate) or just carpels (carpellate)

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only imperfect can be monoecious or dioecious

monoecious meaning

the plant has both imperfect staminate and imperfect carpellate flower (the guy and the girl live in one house/plant but in two rooms/flower)

dioecous

plant has ONLY imperfect staminate flowers or ONLY imperfect carpellate flowers

( the girl and guy live in 2 separate houses)

What does inflorescence mean?

Flowers may be grouped in various ways! diff arrangements

long stem made it difficult to read… what did we use to root flower plants?

Duplicate gene rooting with two phytochrome copies

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* focused on weird angiosperm species
* sequenced both gene copies
* estimated unrooted tree
* identified duplication event, and rooted in duplication

Dicots are paraphyletic. t or f

This is discovery one btw! T! also eudicots = true plants?

eudicot features

* two seed leaves
* star shaped roots
* net like leaves
* 3 pollen grooves