exam 3 biodiversity

key synapomorphies of green plants clade

was ancestor uni or multicellular

cholorphyll b, starch

unicell

key synapomorphies cholorphytes clade

was ancestor uni or multicellular

freshwater or saltwater

phycoplast

unicell

saltwater

phycoplast

system of microtubles parallel to plant of division

• new cells get slip off by pinching

key synapomorphies of streptophytes clade

was ancestor uni or multicellular

freshwater or saltwater?

a) phragmoplast / desdomesmata

b) egg in retained in parent cell

unicell

freshwater

phragmoplast

a system of microtubules outside the spindle and perpendicular to the plane of division

• for cell wall plate perforated by PLASMODESMATA

what kind of evolution do pycoplasts and phragmoplasts exhibit

convergent evo

key synapomorphies of embrophytes clade

was ancestor uni or multicellular

2n embryo is retained in parent gametophyte plant

multicellelar

why are cholorphytes and streptophytes different?

what happened in evo to make them different clades

cholorphytes and streptophytes are different clades b/c there are geographically separated and how they become multicellular is different

chlamydomonas life cycle

not alt of gen b/c not multicellular

1. pop of haploid cell grow my MITOSIS

2. low Nitogen causes cell to devleop into gametes

3. Gametes of diferent mating types and released and fuse

4. diploid zygote forms and develops a tough wall

chlorophyte examples

chlamydomonas

volvox

ulva

ulva lifecycle

alt of gen

1. diploid sporophyte by means of sporangia does meiosis to make spores

2. haploid spores geminate to make haploid gametophyte

3. gametophyte by means of gametangia make halpoid gametes

4. gametes fuse to make diploid zygote

gametophyte= parent plant

chara life cycle

not alt of gen

1. haploid parent does mitosis to make haploid nucule

2. nucule does mitosis do that the egg is retained in tissue

3. IF fertilized… haploid cell becomes diploid zygote

4. zygote does meiosis to make further cells

surrounded by sporopollenin

liverwort / marchantia lifecycle

alt of gen

1. diploid sporophyte by means of sporangia does meiosis to make spores

   • elaters present (burst to disperse spores)

2. haploid spores geminate to make haploid gametophyte

3. gametophyte by means of gametangia make halpoid gametes

   • anthridia = m

   • archegonia = F

4. gametes fuse to make diploid zygote

   • raindrop ricochet

sporopollenin

resistant structure

• resistant to chemical denaturation, desiccation

makes walls of spore tough/resistant

its general durability is significant in plant life cycles

What distinguishes the embryophytes from the other streptophytes?

2n embryo is retained in parent gametophyte plant

Compare the life cycles of stoneworts (Chara) and liverworts

chara

not alt of gen bc not multicellular and only diploid phase is zygote

1. haploid parent does mitosis to make haploid nucule

2. nucule does mitosis do that the egg is retained in tissue

3. IF fertilized… haploid cell becomes diploid zygote

4. zygote does meiosis to make further cells

liverwort

1. diploid sporophyte by means of sporangia does meiosis to make spores

   • elaters present (burst to disperse spores)

2. haploid spores geminate to make haploid gametophyte

3. gametophyte by means of gametangia make halpoid gametes

   • anthridia = m

   • archegonia = F

4. gametes fuse to make diploid zygote

   • raindrop ricochet

Where do we see sporopollenin?

part of spores

What are gametangia vs sporangia?

structures for making —-

gametangia in gametophyte is specilized tissue for making gametes

sporangia in sporophyte is the specilized tissue for making spores

archegonia

F gametangia

produces/retains egg

antheridia

M gametangia

produces and releases sperm

embryophyte

both the egg and zygote develop within the parent tissues

Compare and contrast spores vs gametes

spore= haploid cell that can grow

gamete= haploid cell that has to fuse to grow

isogamous gametes

gametes that are morphologically similar, meaning they are indistinguishable in size and shape

anisogamous gametes

gametes differ in size or form

gametophyte

haploid multicellar stage that produces gametes

gametes

haploid cells that must fuse to grow

sporangia

the structure inside the sporophyte that makes spores

spores

halpoid cells that can grow

meiosis

change in ploidy

sporophyte → spore

mitosis

same ploidy

all but sporophyte→ spore

feterlization

when gametes fuse

zygote

name of fused gametes

germination

when spore is in the right conditions it can grow

• aka growing of spore

What is meant by “dominant life stage”?

one of these stages (haploid or diploid) is the more prominent and longer-lasting part of the organism's life cycle

Why is the gametophyte stage of nonvascular plants considered “dominant”?

longer/larger life stage

gametophyte has the photosynthetic ability

Nonvascular plants don’t grow very tall and live in moist environments. Why?

no lignified zylem/phloem → can’t grow tall or retain water

Name the three groups of nonvascular plants. Do these organisms comprise a clade?

liverworts

mosses

hornworts

paraphyletic clade

How is water required for reproduction (sexual, asexual) in liverworts?

asexual: mitotis

• no way to keep water in cells

sexual: raindrop richochet to combine gametes

• need water to richochet

What other characteristics of liverworts restrict this group to moist environments?

lack of xylem of phloem

pores (not true stomata) on the tops of leaves

thallus from= roots and pores

What are elaters, what produces them, and what is their role?

what is / role: green/blue strands that help release the spores

produced by: sporophyte

Why don’t liverworts(gametophyte or sporophyte) grow very tall?

lack xylem and phloem

how is water used in reproduction for the nonvascular plants

liverworts / mosses / hornworts

asexual: cannot keep water in cells

sexual: raindrop richochet

how is water used in reproduction for the streptophytes plants

embrophytes/ stoneworts

rely on water for the motile sperm to reach and fertilize the eggs

how is water used in reproduction for the chlorophytes plants

rely on water for the motile sperm to reach and fertilize the eggs

Which is the most species-rich: liverworts or mosses?

mosses= 15 thousand

liverwort= 9 thousand

What is the role of hydroids and leptoids in moss gametophytes?

Why are these not considered ‘true’ vascular tissues?

hydriods= non lignified water conducting tissues

• analogous to xylem

leptioids: food conducting cells

• analogous to phloem

true vascular tissues?: no because there xylem/phloem

Why are the ‘leaves’ of a moss plant not considered ‘true’ leaves?

microphylls

no xylem and phloem

Are moss successful in dry or moist environments? Why?

moist

can’t hold water (nonvascular)

What clades of plants have stomata?

tracheophytes

lycophytes

euphyllophytes

mosses

what generation is the stomata found in

sporophyte

What clade of embryophytes lack stomata in any life stage?

liverwort

What is the significance of stomata for success in dry/drier environments?

help keep water in cells

when gen is dominant in nonvascular plants

what are the clades inside nonvascular plants

features of nonvascular plants

gametophyte

liverworts, mosses, hornworts

cannot grow tall, must live in moist enviro. Small sporophyte that is nutritionally dependent on gametophyte parent. symbiosis with cyanobac

liverworts

9k species

possess elators for releasing spores= synapomorphy

thallus from:

• root like rhizoids

• pore (not true) stomata on top

antheridia= disks on stalks

archegonia= under the surface of stalked finger like structures

sexual= alt of gen

asexual= gemmae (clumps of haploid cells dispersed by rain)

mosses

• key features of clade

• dominate stage

• synapomorphy

• reproduction

15 k species

stomata and cuticle in sporophyte

gametophyte= photosynthesis = dominant

sporophytes= dont do photosyn

hydroid and leptoid tissues

sexual: alt gen

asexual: fragmentation

What is a peat bog?

wetland vegitation overlaying acidic/anaerobic envrio

• swamp

efficent c sink

Why are carnivorous plants often found in peat bogs?

acidic, nutrient-poor environments force plants to adapt and find alternative sources of nutrients

Why are peat bogs a carbon sink?

acidicity and low N mean that plants don’t fully decompose

• carbon sink= trapped c

hornwort

100 species

single large chloroplast

sporophyte has basal meristem and is persistently green!

possess symbiotic n-fix cyanobac

What keeps the hornwort sporophyte from growing more than ~30 cm tall?

lack of true vascular system (lignified xylem and phloem)

• it grows super tall but snaps under its own weight

What is the basal meristem of the hornwort sporophyte?

region of cell growth

• cell that are always actively doing mitosis (“stem-cells”

Name the synapomorphies of the tracheophytes

lignified xylem and phloem

• found only in 2n sporophyte

Name the ‘trifecta’ of features that result in a dominant sporophyte in all tracheophytes

xylem/phloem

persistently green

stomata

what is xylem

what is it made of

water movement

tracheids/vessel elements

• some with lignin

what is phloem

what is it made of

photosynthate movement

sieve tube / companion cells

Which tissue type transports only in one direction, and which can transport in both directions?

• xylem and phloem

1 direction= xylem

2 direction= phloem

When did the first vascular plants appear (as suggested by fossil record)?

late silurian

• ~420 mill years ago

what is the extinct clade precursor clade in the vascular plants

rhyniophytes

Which features of a rhyniophyte fossil would suggest that it is a sporophyte?

spores inside sporangium

phases of meiosis present

how can we tell if a fossil is a vascular plant

size

xylem/phloem present

Look out the window.

Are the plants you are looking at gametophytes or sporophytes?

How do you know?

If you don’t know, what information would you need in order to make this determination?

most tall plants= sporophytes

• confirm with presence of spores in sporangium and phases of mitosis present

• possess vascular tissues

most short/ground hugging plants= gametophytes

• nonvascular plants lack xylem/phloem → cant get big

• if nonvascular→ gametophyte phase if dominant as it is the photosyntheic phase

How many times did leaves evolve in tracheophytes?

2

• microphylls

• megaphylls

Name the two leaf types and identify which clades of tracheophytes have each

microphylls = lycophytes clade

• single vein

• no branching

• no leaf gap

megaphylls = euphyllophytes

• branched veination in leaf

• leaf gap

lycophytes

synapomorphy= microphylls

12k species

ex: club moss, spike moss, quillworts

lycopodium life cycle

1. green sporophyte that produces strobilus (comb)

2. strobilus produces spores via sporangium with sporophyll

3. spore mother cells do meiosis → spores

4. spore makes gametophyte

5. gametophyte makes gametes

6. gametes fuse to make zygote

gametophyte and sporophyte are INDEPENDENT at maturity

What is the spore mother cell, and where is this found?

Is this cell diploid or haploid?

diploid cell that does meiosis to make 4 daughter cells

found in sporangium

Compare the gametophyte and sporophyte in liverworts, mosses, hornworts, and tracheophytes.

Which is the dominant generation in each clade?

liverwort

• sporophyte: dependent of gametophyte

• gametophyte: main phase

mosses

• sporophyte: dependent of gametophyte BUT now has stomata

• gametophyte: main phase

hornwort:

• sporophyte: dependent of gametophyte BUT now has stomata, is persistently green, and exhibits basal growth

• gametophyte: main phase

traechophytes

• sporophyte= main phase

• gametophyte= dependent of sporophyte

Where does the zygote form and the sporophyte initially develop in all embryophytes?

inside the archegonia (F gametophyte)

—- sister clade to the rest of the tracheophytes

what is the outgroup in the tracheoophyte clade

lycophytes

What is a strobilus?

cone-like structure at the end of upright stems, containing specialized leaves called sporophylls that bear sporangia (structures producing spores)

what is the outgroup of the streptophytes

stoneworts

what is the outgroup of the embryophytes

liverwort

homospory

spores are the same size

heterospory

spores are different sizes

microsporangia

makes microspores

“M spores”

megasporangia

makes megaspores

“F spores”

megaspore mother cell

diploid cell that undergoes meiosis to produce four haploid megaspores, which develop into the female gametophyte

microspore mother cell

diploid cell in plants that undergoes meiosis to produce four haploid microspores, which develop into the male gametophyte (sperm/pollen)

Compare/contrast the lifecycles of Lycopodium and Selaginella.

lycopodium: alt of gen that is exosporic

1. 2n sporophyte that makes strobilus

   • spore mother cell inside sporangia/strobilus → spores

2. spore develops into independent gametophyte

3. gametophyte makes gametes

4. gametes fuse → zygote

5. zygote grows into new sporophyte

Selaginella: alt of gen that is endosporic

1. 2n sporophyte that makes heterosporous strobilus

   • spore mother cell inside sporangia/strobilus → spores

2. gametophyte develops inside spore coat

3. gametophyte makes gametes

4. gametes fuse → zygote

5. zygote grows into new sporophyte

what is the life cycle of lycopodium

alt of gen that is exosporic

1. 2n sporophyte that makes strobilus

   • spore mother cell inside sporangia/strobilus → spores

2. spore develops into independent gametophyte

3. gametophyte makes gametes

4. gametes fuse → zygote

5. zygote grows into new sporophyte

seleginella life cycle

alt of gen that is endosporic

1. 2n sporophyte that makes heterosporous strobilus

   • spore mother cell inside sporangia/strobilus → spores

2. gametophyte develops inside spore coat

3. gametophyte makes gametes

4. gametes fuse → zygote

5. zygote grows into new sporophyte

what kind of gametophyte development is associated with homospory

exosporic

what kind of gametophyte development is associated with heterospory

endosporic

What is endosporic development?

gametophyte is made inside the spore/spore coat

this results in a small gametophyte

Would you expect the gametophyte of heterosporous species to be larger or smaller than the gametophyte of a homosporous species? Why?

a heterosporous gametophyte is smaller than a homosporous gametophyte

heterosporous= gametophyte develops in spore coat

• growth is restricted by spore coat

homosporous= gametophyte develops OUTSIDE of spore coat

Which trait is ancestral: homospory or heterospory?

homospory

Euphyllophytes are the major group of vascular plants.

Name the clades of the euphyllophytes (plants with megaphylls).

monophillophytes

seed plants

• gynmosperms

• angiosperms: monocots, dicots

Only ~15 species remain in Equisetum.

What property of horsetails made them useful for scrubbing pots & pans?

silica in cell walls → rough/sturdy leaves

What kinds of environments will horsetails thrive in?

temperate with moist soil

lifecycle of horsetails

alt of gen via exosporic develop

1. 2n sporophyte that makes homosporous strobilus on the fertile shoot

   • spore mother cell inside sporangia/strobilus → 4 spores

2. gametophyte develops outside of spore coat

   • rhizoid gametophyte= M/F gametophyte on same plant

   • gametophyte is GREEN with no stomata

3. gametophyte makes gametes

4. gametes fuse → zygote

5. zygote grows into new sporophyte