LECTURE 7 STUDY GUIDE (MOSSES, FERNS, ALLIES)

which group of protists are plants most closely related?

they are most closely related to charophytes

which characteristics do plants (embryophytes) share in common with green algae in general and charophytes specifically?

• both eukaryotic, multi-cellular, photoautotrophic, possess cellulose cell walls and chloroplasts with chlorophyll a and b pigments

• charophytes and plants share nuclear and chloroplast DNA congruence, cellular structures, and similar flagellated sperm

what are the five shared derived characters used to define plants (embryophytes)?

1. alternation of generation

2. walled spores produced by sporangia

3. multicellular gametangia

4. dependent embryos

5. apical meristems

what happens in the first stage: alternation of generation and what is it?

• plants (like some algae but no charophytes) alternate between multicellular diploid and haploid morphs

• gametophytes (haploid) produce gametes via mitosis within gametangia (sex organs)

• gametes (haploid) fuse during fertilization forming a zygote (diploid)

• zygote grows mitotically into a mature sporophyte (diploid)

• sporophytes produce spores (haploid) via meiosis within sporangia (sex organs)

what happens in the second stage: walled spores produced by sporangia?

plant sporophytes produce walled spores with sporopollenin (tough outer wall of pollen grains and plant spores) within multicellular sporangia

what happens in the third stage: multicellular gametangia?

• archegonia produce eggs

• antheridia produce sperm

what happens in the fourth stage: dependent embryos?

zygote (diploid) grows into an embryo dependent on the archegonium for nutrients and protection

what happens in the fifth stage: apical meristems?

• zones of intense mitotic division that enable extended growth

  • root meristem permits roots to grow deeper to access water and nutrients

  • shoot meristem grows the shoot increasing photosynthesis and reproductive tissues

what is a spore and what role does it serve in spore-bearing plants? what structure makes spores? why, what process is used to make spores? what is a sporophyte? what material makes spores resistant to damage?

• a spore (haploid) is a reproductive cell that can asexually reproduce

• spores serve as a means of dispersal and reproduction in spore-bearing plants

• sporangia makes spores

• sporophyte is a multicellular structure that is diploid

• spore wall makes spores resistant to damage

what is a gamete and what roles does it serve in plants? what structure(s) make gametes? why, what process is used to make gametes? what are male and female gametangia called?

• gametes (haploid) are reproductive cells that fuse with each other during fertilization forming a zygote (diploid)

• gametophytes (haploid) make gametes with mitosis

• archegonia = produces eggs

• antheridia = produces sperms

in what structure do early plant embryos initially grow and sustain nutrients?

zygote grows into an embryo which is dependent on the archegonium for nutrients and protection

what are the four shared derived characters that characterize the majority of embryophyte evolution?

1. dependent embryos

2. vascular system

3. seeds

4. flowers

what advantages did these characters confer the plant taxa that evolved them?

• tracheophyta evolved vascular systems that allows plants to grow larger than moss because they conduct water/minerals through the biomass via xylem and organics via phloem

• spermatophyta evolved seeds as seeds expanded offspring dispersal, permitted dormancy during unfavorable seasons and coordinated germination with season environmental cues, and offered embryos some protection and nutrition

• anthrophyta evolved flowers as flowers increased pollination success by enticing animal pollinators. they also evolved fruits that increased dispersal of seeds by seed dispersers

when did each plant group evolve and according to the available evidence: embryophytes, tracheophytes, spermatophytes, and anthophytes? what are their character traits? what are their informal groupings?

embryophytes (dependent embryos): 500-450 MYA, land plants

tracheophytes (vascular system): 450-400 MYA, vascular and land plants

spermatophytes (seeds): 350-300 MYA, extant seed and land plants

anthophytes (flowers): 130 MYA, flowering and land plants

which plant group has the most species?

angiosperms

what is the life cycle of a typical moss including the nuclear ploidy of each stage and cell division processes used? what life stage dominates?

1. spore (haploid) grows into a protonema —> buds into either a male (antheridia) or female (archegonia with rhizoids) gametophyte (haploid)

2. antheridia mitotically produces flagellated sperm that swims through water to fertilize eggs in archegonia —> zygotes (diploid) develop into ephemeral sporophytes (diploid) nourished by female gametophytes —> sporophytes sporangia produces spores (haploid) via meiosis

3. gametophytes dominate as sporophyte depends on the gametophyte for nutrition

mosses are heterosporous. what does this mean?

produces male and female spores

do sporophyte and gametophyte stages live apart from one another? are they both phototrophic?

they live at the same time with the sporophyte depending on the gametophyte for nutrition

gametophytes are phototrophic and sporophytes are not

what is a peristome and what role does it serve?

it has capsules that open when dry releasing spores in the wind

why do plants disperse spores and why do they do so during dry conditions?

plants disperse spores to colonize new areas/fertilize and they disperse during dry conditions because spores have a protective covering and can wait until there is ideal conditions to reproduce when there are wet times

where do mosses live in southern Nevada? why?

moss inhabits primarily in the spring and sheep mountain ranges because there is more moisture

what division are mosses classified?

bryophyta

how do liverworts differ from mosses in the location of their sporophyte and spore-dispersing structures?

their sporophyte is located underneath while mosses’ sporophyte is located at the top

what are gemma cups and gemmae? what role do they both serve?

gemma cups (haploid) are also called splash cups that produce asexual gemmae when it rains hard

gemmae (haploid) are like spores and reproduce asexually, can develop into new gametophytes

do liverworts form these structures during wet or dry times? why?

wet time because it is the most favorable for reproduction

why use asexual reproduction when times are favorable but sexual reproduction when times are less favorable for growth?

in asexual reproduction, they can disperse into a new area while sexual reproduction only limits them to one area

do liverworts live in nevada?

yes

which division are liverworts classified?

hepatophyta

what is the life cycle of a typical fern including the nuclear ploidy of each stage and cell division processes used?

1. spore (haploid) grows into a small, bisexual gametophyte with archegonia and antheridia gametangia

2. antheridia mitotically produce flagellated sperm that swim through water to cross-fertilize eggs in archegonia of other gametophytes

3. zygotes (diploid) develop into sporophytes (diploid)

4. sporophytes sporangia found in collections called sori which produce spores (haploid) via meiosis

what life stage dominates in the typical fern?

sporophyte dominates

ferns are homosporous. what does this mean?

they produce bisexual gametophytes

do sporophyte and gametophyte stages life apart from one another? are they both photosynthetic?

yes, gametophytes are independent

gametophytes are phototrophic and sporophytes are not

what is a sorus(-i) and role does it/they serve?

collection of sporophyte sporangia that produce spores

what is an induism?

protective membrane that covers the sori on a fern

where do ferns live in southern nevada? why?

yes, they inhabit the spring mountains and red rock canyon in moist microclimates

which division are whisk ferns, ferns, and horsetails categorized?

monilophyta

what kind of branching do whisk ferns exhibit?

dichotomous branching

where do horsetails (equisetum spp.) produce spores?

in terminal strobili

what kind of taxa exists in the embryophyte?

liverworts, mosses, hornworts, lycophytes, monilophytes. gymnosperms, angiosperms

what kind of taxa exists in the tracheophyte?

lycophyte, monilophytes, gymnosperms, angiosperms

what kind of taxa exists in the spermatophyte?

gymnosperms and angiosperms

what kind of taxa exists in the anthophyte?

angiosperms