Organismal Biology review session

significance of carpels (including ripening into fruit)

The ovary eventually becomes the fruit as it first develops into the seed. The ovary which contains the ovule is a structure that is part of the carpel

In ferns, are the gametophyte and sporophyte generations independent?

True as both generation are independent and photosynthetic. The young sporophyte is dependent, as an embryo, on the bisexual gametophyte, up until it gets its root system established and it's shoot, and once this happens the sporophyte generation is completely independent and becomes the dominant generation

Is a dikaryotic mycelium considered a separate individual?

you can consider that but it won't be haploid or diploid but rather a strange individual between plasmogamy and karyogamy

Alternation of Generations

-Alternation of generations refers to having a multicellular organism in the haploid phase of the life cycle and a multicellular organism in the diploid phase of the life cycle; that is, mitosis occurs in both ploidy states, after meiosis and after fertilization -Alternation of generations is seen in all land plants, which are descendants of green algae. Some green algae also have an alternation of generations but not the groups that are most closely related to land plants (Ulva, the sea lettuce, represents an independent evolution of alternation of generations). Land plants are most closely related to freshwater, multicellular green algae with only a haploid phase which is the charophytes (zygote is only diploid stage for them) -We have both a multicellular diploid organism(the sporophyte which literally means spore producing plant which produces spores and sporangia via my meiosis) which creates spores that then undergo mitosis to create multicellular haploid generation(the gametophyte which literally means gamete producing plant that produces gametes, eggs and sperm, via mitosis). -The gametes produced by plants are genetically identical to the gametophyte and then those gametes will get together from different individuals are genetically different and fuse to form a diploid zygote. -This zygote undergoes mitosis again top produce a new sporophyte

sexual life cycles

-Animals, the diplontic life cycle where there's only a diploid multicellular organisms, and the haploid stage is the gametes. -Fungi broadly fit into the haplontic life cycle where we only have a haploid multicellular organisms and the only diploid stage is the zygote. -haplodiplontic life cycle seen in plants and some alage in which both a diploid multicellular organism (sporophyte) and a haploid multicellular organisms(gametophyte). -All 3 life cycles involve the alternation of meiosis and fertilization which are the two essential components of sexual reproduction, which whose origin evolutionarily predates all three of these life cycles, at least in terms of the major group -all differs impart as well where mitosis occurs(if we get mitosis after fertilization then we end up with a diploid multicellular organisms and if we have mitosis after meiosis then we get a haploid multicellular organisms. -differing sexual life cycles in fungi, land plants, and animals have all been separated from common ancestors for a billion years or more so they all independently evolved multicellularity in each group so different life cycles make sense -multicellularity evolved independently in animals, land plants and fungi -Study life cycles of fungi (the Basidiomycota example), moss, fern, pine, and flowering plant, and how they are similar and different (trend in land plants toward increasing dominance of sporophyte and decreasing dominance of gametophyte) -How does alternation of generations compare to typical animal life cycle?

Bryophytes

-Bryophytes are a paraphyletic group at the base of the land plants -Include 3 major lineages: liverworts, hornworts, and mosses -Have a gametophyte dominant alternation of generation(not surprisingly since the sporophytes is an add on generation to land plants based on our understanding of the relationships of land plants to other photosynthetic organisms to the green algae) -Innovation of a sporophyte dominant generation is not that well developed yet in the bryophytes, but it comes to be dominant in all the vascular plants. -The transitional period happen at point 2 with the Rhinophytes that don't have any leaves or roots just these y shaped branching pattern or dichotomous branching that have equal dominance of the sporophyte and gametophyte generation

Fruit development and Precursory structure

-Fruit represents the ripened ovary wall and represents another innovation of the carpel that can be important in dispersal -there are a lot of pollination/dispersal syndromes that have evolved in flowering plants -Fruit is another major innovation of flowering plants, and one that promotes seed dispersal. -A fruit minimally is one ripened ovary, but may include additional ovaries or multiple flowers if those additional ovaries or flowers are part of a common protective or dispersal unit. Fruits can be fleshy or dry.

Heterospory (vs. Homospory)

-Heterospory: the production of two different types of spores (microspores and megaspores), which become unisexual gametophytes/seen in all seed plants, some ferns, some lycophytes -Homospory: Homospory is the ancestral condition in vascular plants, with only one type of spore that produces bisexual (hermaphroditic) gametophytes, with both types of gametangia (antheridea and archegonia) on the same plant/(seen in the fern life cycle) -Evolution of Heterospory: this division of having two different types of spores that are produced could be advantageous potentially under low light environments and under stories where you need a lot of resources to feed and protect the new sporophyte generation, the embryo, and an dark understory environment where photosynthesis isn't easily done, then you need a large spore to feed the female gametophyte and her progeny(the embryo) so it can get established. -one way of getting established is to just make really big spores and heterosporous vascular plants have the largest spores of any vascular plants, that is the mega spore, that germinates to become the female gametophyte. -wherever you have heterospory, you have unisexual gametophytes(male gametophytes and female gametophytes) -microspores germinate to become male gametophytes that only produce sperm -megaspores germinate to become female gametophytes that only produce eggs in the archegonia -solution: produce a large number of cheap microspores so you have a lot of male progeny who are relatively inexpensive to produce that just produce sperm along with producing a relatively small number of heavily invested female gametophytes with these large megaspores which represents the food for those gametophytes after these spore germinate to produce a female gametophyte and producing a relatively small number of these, then the provisioned megaspores that can nourish the female gametophyte and her progeny(the embryo) after fertilization occurs. -main point is that heterospory set the stage for the evolution of seeds and pollen in seed plants which allowed for the getting away from the need for free standing water for fertilization, among other benefits, including greater nurturing and protection of the male and the female gametophyte/protection of the vulnerable gametophyte generation (heterosporous plants with most gametophyte development occurring inside the spore wall) -in any heterosporous plant(all seed plants, some lycophytes including selaginella, some ferns called water ferns) all have endosporic development which is the gametophytes all develop within the confines of the spore wall so there's more reduction and sheltering of the gametophyte generation -mosses are not heterosporous because the male and female gametophytes germinate from spores that are similar along with having no endosporic development -heterospory vs homospory is only relevant vascular plants not bryophytes

Are ulva the only haplodiplontic algae?

-No, it is not the only example but just a simple example that we look at -All land plants have a haplodiplontic life cycle and none of the living land plants have morphologically similar sporophytes and gametophytes(only fossil land plants have this)

Would a disadvantage of heterospory be that it produces weak microspores?

-microspores don't really need to contain much in the way of nutrients/sperm is relatively cheap to produce by comparison with the female gametophyte which has not only to produce eggs but also has to nurture the young sporophyte generation -the embryo stage that we see in land plants requires a level of nurturing that requires more resources so that's why there is larger megaspore

Primary endosymbiosis and secondary endosymbiosis

-Primary endosymbiosis: A unicellular ancestor of the lineage(that gave rise to red algae and green algae as well as to land plants) takes in a cyanobacterium that wasn't digested and ultimately became the chloroplasts(became an organelle) -speciation then occurs in which we have the red algae group and the green algae group that descended from this ancestor after primary endosymbiosis -following the formation of red and green algae we had ancestors of a number of photosynthetic lineages in other major groups of eukaryotes that captured either a unicellular eukaryotic red alga or unicellular eukaryotic green alga which happened a couple of different times in different major lineages of eukaryotes(in the case of green algae) -this process established multiple secondary endosymbiosis in at least 3 different instances that are pretty clear -called secondary endosymbiosis because it's second order: the organism that was incorporated that became the chloroplasts in each of these three groups(following secondary endosymbiosis in the image)was a descendant of an ancestor here(before secondary endosymbiosis/these are the red and green algae) that it already captured a cyanobacterium that had become the chloroplasts of these lineages. -So the chloroplasts of the 5 lineages following secondary endosymbiosis (group of descendants of these ancestors were there was a secondary into symbiosis that gave rise to photosynthetic ability) have their chloroplasts represented by red algae or eukaryotic green algae that was incorporated and became the chloroplasts.

Type of hyphae

-Septate hyphae(found in the Ascomycota and Basidiomycota/the group of higher fungi): we have partitioning of the hyphae into cellular compartments that each have a set number of nuclei(in a haploid mycelium we would have one nuclei/in a dikaryotic mycelium we would have two nuclei that came from each parent -Coenocytic Hyphae(seen in all other fungi): hyphae that are open and have no compartmentalization at all

Symbiosis involving fungi and land plants

-Symbiosis between fungi and land plants are so critical to the success of land plants and probably to the original success of the land plants upon entry to land environments -Mycorrhizal associations: mutualism between filaments of fungi and roots of plants -picture shows arbuscular mycorrhizal associations(arbuscular penetrates cell wall of a root and spread out over the membrane) -mycorrhizal associations are important to plant performance in most land plants. -mycorrhizae and fungal endophytes are important mutualistic organisms that associate with land plants and are pervasive across land plants(especially vascular plants) -another type of symbiosis is lichens: symbiosis involving a fungus and unicellular photosynthetic organisms either blue green bacteria(cyanobacteria) or green algae(unicellular green algae). -these associations aid the performance of both the fungi in which it gains organic compounds from the plant that produces them like carbohydrates, sugars and amino acids as well and the plant gains better absorptive ability for inorganic nutrients in the soil, especially phosphorus, as well as water which causes the plants to perform better, or sometimes absolutely require the fungus in order to survive.

Reduction in size of the male gametophyte in angiosperm

-The male gametophyte at maturity consisting of only three cells, less than even the pollen tubes of gymnosperms -Male gametophyte of angiosperm is highly reduced by comparison with male gametophyte of a gymnosperm. -A mature male gametophyte (= pollen tube) of an angiosperm contains only 3 cells: 1 tube cell that mediates pollen tube growth and 2 sperm cells, both of which are necessary for the process of double-fertilization in flowering plants.

Are the dominant stages in land plant always the ones that are nutritionally independent?

-True. If this if it's a dominant phase, the dominant phases always nutritionally independent. -in ferns the nondominant gametophyte can also be independent even being reduced in size and complexity

Is ulva an example of a transitional species as it has both dominant gametophyte and sporophyte generations?

-Ulva is on a separate line of green algae than the one that gave rise to the land plants so, it represents an independent evolution of the alternation of generations and is not really it's not transitional to the sporophyte dominance in the land plants -its just another example or an alternation of generation where there is an isomorphic alternation of generation where both the gametophyte and the sporophyte generation look the same which is something we don't see in any of the land plants today

Vascular plant innovations

-Vascular plant innovations shown here also can be viewed as adaptations to land. •Dominant sporophyte generation/allows for: 1)complex genetic expression in which you can have heterozygosity with two sets of chromosomes which means different alleles and version of each gene and 2) buffering of genome against mutations by having two alleles from each gene) •Well-developed cuticle (waxy outer covering)/seen in the dominant generation or in this case the sporophyte compared to the gametophyte of bryophytes) •Vascular tissue (xylem & phloem)/Specialized conducting tissue that allowed for large plant bodies to capture more resources aboveground (light) and belowground (water, inorganic nutrients): -water & inorganic nutrients (xylem) -for organic nutrients (phloem) allowed for large plant bodies that can capture more resources aboveground (light) and belowground (water, inorganic nutrients)/ <Xylem>: water conducting tissues that conducts water from the roots up to the shoot to the leaves and stems <Phloem>:sugar conducting tissue that will conducts sugars from a point of production like leaves or points of storage to places where it's needed, like roots. <Both>:there's the potential to move substances over large distances. • Tracheid's (lignified xylary conducting cells)/evolution of tracheids resulted in rigid (lignified), decay-resistant conducting tissue that allowed for plants to grow tall and to branch extensively without collapsing under their own weight/trachieds have secondary walls that are strengthened by this tough polymer called lignin that imparts hardness to those cell walls and allows the plant to have a lot of structural strength to resist gravity and become large unlike the bodies of mosses and other bryophytes that can't get very big •Branched sporophyte/can have branched sporophytes can be quite large in vascular plants unlike the unbranded sporophytes of bryophytes like mosses •Roots/found in all modern vascular plants (unless secondarily lost), allowed for efficient uptake of water and nutrients from deep in the soil, as well as firmer anchorage than rhizoids of bryophytes (and storage of nutrients underground).

important to know distinguishing features of organisms

-ex)tree of life represents 3 domains(2 prokaryotic which are bacteria and archaea and 1 eukaryotic which is the eukarya)/ we talked about fungi and photosynthetic organisms(eukaryotic polyphyletic algae and cyanobacteria) along with land plants -be familiar with the algae, land plants(general features of land plants), vascular plants, bryophytes, seed plants(gymnosperms and angiosperm)

Land plant derived from where?

-land plants descend directly from green algae and are from that same eukaryotic lineage so they are example of primary endosymbiosis and their chloroplast descended directly from cyanobacteria just as green algae did the same - where as in the case of secondary endosymbiosis that involve green algae, the green algae are actually being captured by a different cell of a different eukaryotic lineage and the green algae are becoming the chloroplast(ex in the euglinids/eukaryotic lineage that is very distantly related to red and green algae)

Difference between gymnosperm seed and angiosperm seed

-female gametophyte(which is haploid(n)) is the nutritive tissue for the embryo of a gymnosperms -endosperm(which is triploid(3n)) is the nutritive tissue for the embryo of an angiosperm -Angiosperms delay the investment in the nutritive tissue until after fertilization is assured, so they're not wasting ovules, energy, and resources -The main difference between gymnosperm and angiosperm seeds is the embryo's nutritional source, which is the female gametophyte (haploid, 1n) in gymnosperms and endosperm (triploid) in angiosperms. -The embryo and the integument (which becomes the seed coat) have the same ploidy level (diploid, 2n). -In many eudicots, nutrients in the endosperm are absorbed by the cotyledons prior to dormancy of the seed.

Flowering plants

-flower is a simple cone(a simple cone is a stem with leaves) -4 different sets of leaves are called whorls(whorls is a set of three or more leaves that have position along the stem and vertical position or node) -includes sepals, petals, stamens, and carpels -this is a modified shoot and these 4 whorls are modified leaves but unlike a typical shoot, most of these parts are not photosynthetic -once the carpels are formed, the last innermost set of leaves have no more leaves produced which is referred to as a determinant shoot -an indeterminant shoot is a stem with leaves that will keep producing leaves indefinitely -flowers are still a stem with modified leaves with two different sets of sporangia bearing leaves(the stamens which have the microsporangia inside the anthers and the carpels which have the ovules(immature seeds) inside the ovary(the container the carpel forms around the ovule unlike in gymnosperms in which it is a sealed chamber that offers additional protection to the ovules) -carpel is considered to be one of the main innovations of the flower -Carpal offers a number of potential advantages to the flowering plants over other seed plants and might account in part for the great success over the gymnosperms through more containment protection of the ovules during their development(female gametophytes inside the ovules) -protection from both abiotic conditions like physical environment as well as the biotic environment such as potential herbivores, that could eat the ovules -eventually the ovule will mature into at least a part of what we call the fruit which is a novel structure produced by flowering plants unlike in gymnosperms which don't have a fruit -fruit aids in the dispersal of the seeds and prior to the dispersal, the protection of the seeds(function seen in angiosperm) -Flower is a simple cone (modified shoot = stem with specialized leaves, some bearing microsporangia (stamens) or megasporangia (carpels) -It has determinate growth, ceasing production of new appendages after carpels are formed) -A carpel is a modified leaf that contains immature seeds = ovules. -In all living angiosperms, the carpel is in the shape of a sealed container that completely surrounds the ovule(s). Remember eggs are not ovules in botany; the egg of a female gametophyte is just one cell inside the ovule — and the ovary is the part of the carpel that contains the ovules. -The carpel protects the ovules in flower and the carpel becomes at least part of the fruit, which helps to disperse the seeds

Development of the coal forest?

-forest in the Carboniferous back in the Paleozoic that were dominated by these giant ferns and lycophytes that are bigger than any of their modern versions -greater diversity of these free-sporing vascular plants back when this occurred -these ended by global cooling occurring when there CO2 has been removed from the atmosphere more rapidly than it has been returned to the atmosphere by decomposition -soils were holding a lot of carbon to support the roots of the organisms -plant material was building up in the understories and because these understories were very swampy and acidic anaerobic condition like in the modern peat bogs didn't allow for any fungal activity to occur so a lot of carbon doesn't decompose and these deposit made up the coal deposits which lead to the cooling and drying conditions which lead to the evolution of seed plants who were better accustomed to this style of weather and didn't need things like free-standing water for fertilization

Which life cycles are gametophyte vs sporophyte dominant

-gametophytes and sporophytes are only meaningful in land plants where you have the alternations of generation -Bryophytes(mosses, liverworts, and hornedworts) have a gametophyte dominant stage -In all vascular plants(ferns, gymnosperms, angiosperm) have a sporophyte dominant stage -the transitional stage between the dominant generation was seen in the organisms Rhyniophytes where the dominance was shared and had two similar generations, gametophyte and sporophyte. These were fossil plants that just had leafless and rootless branching axes

Fungi life cycle

-haplontic life cycle(there's only a haploid multicellular organisms and the only diploid stage is the zygote, -there is a delay between plasmogamy and karyogamy(these 2 are the two stages of fertilization) which causes dikaryotic stage(dikaryotic stage not seen in other life cycles) -the dikaryotic stage is not haploid or diploid and is nestled in between the fertilization. Dikaryotic stage is effectively like a distinct individual in the life cycle that is neither truly haploid nor diploid. -in fungi they have this separation in time and space between plasmogamy and karyogamy which has only evolved in the fungi. -there is asexual reproduction in fungi(not in Basidiomycota as much) -asexual reproduction in fungi results in genetically identical progeny(offspring) and involves the mitotic production of spores

Gymnosperm life cycle(pine)

-heterospory is seen which means we have this endosporic development in the confines of the spore wall for the male gametophyte and the female gametophyte -we have microspores born within the microsporangia and megaspores born within the megasporangia -The microsporangia are found under the cone scales of pollen cones -The megasporangia are found in the seed cones and they're located inside the integument of the ovule -ovule: immature seed and at its earliest stage it is megasporangium with integument around it and integument is a novel structure that becomes a seed coat at maturity -ovules are born on these cones scales of seed cones which are kind of the typical looking pine cones. -microspores are released from the microsporangium and have to travel by wind to reach the ovule have to land inside the pollen chamber(through opening at the end of the ovule) -microspores are protected on this wind bound journey by the pollen grain which has a thick desiccation resistant outer wall(immature male gametophyte inside the pollen grain) -the microspore only germinates and starts to turn into a mature male gametophyte(a pollen tube) after it's in the safety, nurtured, and sheltered environment of the ovule -the female gametophyte never leave the megasporangium/megasporangium never opens up to release the megaspore -the only functional megaspore(the only functional product of meiosis in the megasporangium) germinates to become the singular female gametophyte within the confines of the megasporangium and also the integument is around that as well so it's super protected, sheltered, nourished by the pine tree(female gametophyte) -female gametophyte produces multiple eggs that are fertilized by the pollen tube or the mature male gametophyte(one pollen tube per egg) -only one of the zygotes from fertilization will develop into an embryo that is heavily provisioned with resources and can in turn live off the tissues of the female gametophyte -then, maturation of the seed causes the seed coat to harden and seals around the embryo -female gametophyte is released in a dormant stage and will eventually germinate when conditions are right -all those resources of the female gametophyte that remain in the seed will be tapped by the germinating seedling, the embryo, as its becoming active again and it will establish a root system and a shoot system by taking advantage of the large number of resources in that seed which is way more than are in a spore, which is just a unicellular reproductive cell. -Note that pines and other conifers produce pollen and seeds in different cones. -Note that pollination is by wind and involves movement of pollen directly to ovule, unlike in flowering plants, which are usually pollinated by animals and pollination involves pollen being carried to stigma (not directly to ovule). -Note that unlike in the life cycle of the (homosporous) fern that we studied, the gametophyte generation in seed plants includes two different kinds of gametophytes (male & female); that is, the gametophyte generation is unisexual (and each type of gametophyte developed from a different type of spore --- a microspore or megaspore, born in microsporangia or megasporangia (in separate cones in a pine). -By having unisexual gametophytes, potential for self-fertilization is reduced. -Such separation of sexes in the gametophytes allowed for the evolution of the seed and pollen. -free-standing water is no longer necessary for sperm to reach the egg. Not only is the female gametophyte completely sheltered (never leaving the megasporangium or the confines of the ovule) and cared for by its parent sporophyte, but also the next sporophyte generation develops to the point of being an embryo within the now-mature seed and is potentially able to remain in an inactive state until environmental conditions are favorable for germination and establishment. -The young sporophyte can continue utilizing the tissues of its female gametophyte parent as nutrition while it establishes a root and shoot system, giving the young conifer a head-start before it has to produce all of its food from photosynthesis

Why are mosses not considered heterosporous if they have unisexual gametophytes?

-heterospory means having different spores where the spores of different sizes, large megaspores and little microspores, and they have different investment in them -we have development of the gametophytes inside the spore wall which might expand as the gametophytes develop -in mosses, the spores that give rise to males vs female gametophytes look the same so there is not large megaspores that require a lot of investment but rather the development is outside the spore primarily and doesn't have this size restriction by the spore wall so they are not considered heterosporous even though their gametophytes unisexual

In gymnosperms where is the female gametophyte located?

-it is located in the megasporangium and never leaves

How does the zygosporangium resist desiccation?

-its a very thick walled structure

Land plants

-land plants are descended from within the green algae -alternation of generations that we see in green algae are as a result of adding the sporophyte generation to the land plant life cycle -Freshwater multicellular green algae with a haplontic life cycle (only a haploid generation; only diploid stage is zygote) were ancestral to land plants. -The closest relatives of land plants among the green algae( freshwater charophytes) only had a haploid generation. The only diploid stage was the zygote in the the freshwater charophytes -land plants emerged from a freshwater rather than seawater ancestor and they also added the diploid sporophyte generation to their life cycle. -the alternation of generation we see in ulva(sea lettuce/2nd to the top) represents an independent origin of an alternation of generations life cycle by comparison with the presence of an alternation of generations in land plants. -the presence of photosynthetic ability in land plants is the result of the primary endosymbiosis that resulted in the capture of a cyanobacteria that became the chloroplasts. It's not as an example of secondary endosymbiosis.

Did desiccation tolerance evolve independently in the the bryophytes or was it ancestral in land plants?

-likely something that evolved in the bryophytes but the distribution is uncertain -only see it in certain bryophytes(common in mosses, occurs in some liverworts)

A spore always gives rise to one gameotphyte

-multiple embryos can form inside a pine ovule but that's because the female gametophyte can produce multiple archegonia so it might have more than one egg fertilized which would produce multiple embryos but those would be from a single gametophyte -In flowering plants there is one female gametophyte from the megaspore

More on pine life cycle and seed formation

-no longer any need for free standing water in this life cycle -extensive reduction of the gametophyte generation -sheltering of the female gametophyte -Ovule(the immature seed) is not the same as the egg(one of the cells of the female gametophyte/gamete of a female gametophyte) -At maturity, the seed is a structure that has three generations of tissue that including: a diploid seed coat(tissue that was furnished by the pine tree), a haploid female gametophyte(progeny of the pine tree/sporophyte), and a diploid embryo(the progeny of the female gametophyte and a pollen tube that joined with the female gametophyte to form a zygote that became the embryo) -There's a lot of protection and nourishment here, both for the gametophyte and for the young sporophyte(the embryo) -Mature seed contains 3 generations of tissue within it: (1) the new embryo, which represents a new sporophyte (diploid) generation, (2) the maternal gametophyte (haploid) parent --- and food supply --- of the embryo, and (3) the sporophyte generation that gave rise to the female gametophyte by meiosis (and contributed the seed coat and nourishment to the female gametophyte). -Male and female gymnosperm gametophytes each develop inside the spores that they germinated from. -The male gametophyte is eventually released from the microsporangium and then emerges from its spore wall (as a pollen tube) upon reaching the ovule (= immature seed). -The female gametophyte never leaves its spore wall or the megasporangium, which is contained inside the integument (= immature seed coat, a tissue of uncertain homology). -Only one of four megaspores produced by meiosis in the megasporangium is functional and germinates; that is, only one female gametophyte forms in the ovule. -Unlike ferns, no need for free-standing water to complete life-cycle. -More protection and nourishment of vulnerable gametophyte generation and the next generation of sporophyte by the resources in the immature and mature seed

Ferns have two independent generations. Would seeds be considered independent as well?

-no the female gametophyte inside the seed is completely dependent on resources provided by its parent sporophyte/ sporophyte is independent in seed plants but both male and female gametophyte are dependent/ the male gametophyte leaves the microsporangia as a pollen grain and ends up inside the ovule or on the stigma. As the pollen tube grows, it's using resources that are being provided by sporophyte that produced the ovule that its growing towards. -there is a gametophyte generation and sporophyte generation in all of the land plants(ferns, seed plants, and bryophytes) -in the case of seed plants, inside the seed there will be the development of the female gametophyte which will germinate from a megaspore -in seed plants the sporophyte is an independent generation that's photosynthetic and the gametophyte generations is not photosynthetic in seed a dependent on resources that have been provided to them.

Double fertilization in angiosperms

-not seen in gymnosperms -a process where one of the sperm fuses with the egg to become the zygote(seen in gymnosperms) and the other sperms fuses with the two polar nuclei of the central cell of the female gametophyte to form the endosperm mother cell that will go on to divide mitotically and produce the nutritive tissue for the developing embryo(not seen in gymnosperms) -the ovules of angiosperm are relatively cheap to produce compared to ovule of gymnosperms -gymnosperms have to make the investment in the nutritive tissue for the developing embryo before fertilization, because the female gametophyte is the nutritive tissue(haploid) for the embryo of the gymnosperm -In angiosperms, pollen is reduced to a tube cell and a generative cell; the generative cell divides mitotically to yield two sperms. One sperm fuses with the egg to form a zygote, as in other plants, but the other sperm of the same male gametophyte (= pollen tube) fuses with two nuclei (the so-called polar nuclei) of the female gametophyte's central cell to form a triploid (3n) cell, which undergoes extensive mitoses to produce the nutritive tissue that will feed the developing embryo. -The 3n nutritive tissue is called endosperm -Unlike in gymnosperms, angiosperm sporophytes put minimal investment in the female gametophyte, which is reduced by comparison with gymnosperm gametophytes. Only after fertilization occurs does the investment in a nutritive tissue (the endosperm) begin. That strategy prevents wastage of resources by the plant that produced the ovule in the event that fertilization never occurs.

How does cytoplasmic streaming different in septate hyphae and coenocytic hyphae?

-occurs in both -in septate hyphae, there's a sizable pore in the septum that can allow it to occur. -The contents that can be moved, even in separate hyphae from one point to another across the mycelium through the cellular compartments include things like organelles and large cellular components. So they really don't differ substantially in that way.

Role of peat and its relationship to peat moss?

-peat: poorly decomposed material in the soil peat occurs in areas like peat bogs where you don't have a high rate of decomposition so all of that poorly decomposed plant material which constitutes about 30% of all carbon in soils -peat deposits are hence very important in soil by holding that carbon

"algae"

-polyphyletic group -these various groups we called algae have distinctive morphological and ecological characteristics that you should review -photosynthetic ability came to be found scattered across the eukaryotic tree of life along with the cyanobacteria and we focused on this through the endosymbiotic theory -all eukaryotes in general are cynerric organisms(this tree of life that shows that archaea are more closely related to eukaryotes than bacteria are to eukaryotes is a bit misleading because it doesn't take into account that the mitochondria of all eukaryotes descend from Alphaprodium bacteria that were incorporated into the cell of an ancestral eukaryote and lived as an endosymbiont inside the cell of ancient eukaryote that wasn't digested, but instead eventually became inextricably united and became the mitochondrion) -Eukaryotes have an important bacterial component and the photosynthetic ones have a photosynthetic bacterial component that ultimately represents cyanobacteria -the reason that oxygen-generating photosynthesis is so scattered across the eukaryotes is because it has been co-opted across lineages (with capture of unicellular photosynthetic organisms that became primary or secondary endosymbionts and, eventually, chloroplasts)

Do algae have sporangia?

-there are structures in algae that are similar to gametangia and sporangia but they don't have a jacket of cells between the outside of the sporangium or gametangium and the cells inside that will either become gametes in the case of a gametangium or spores in the cases of a sporangium -in land plants, both gametangium and sporangium both have a jacket of cells that create a barrier between the outside of the gametangium or sporangium and the inside of the gametangium or sporangium where the spores and gametes are produced. This shows that there is additional protection to protect against desiccation from the atmosphere

Fern life cycle

-reduction of the gametophyte generation which is still free living but highly reduced -expansion and dominance in the sporophyte generation which now has roots and true leaves/this generation has a thick cuticle and other innovations that allow for survival on a dry land environment -still have this limitation where free swimming sperm has to be able to swim through the environment to get to the egg(need for free standing water in fertilization)/holdover from the aquatic ancestry of land plants in that ferns and lycophytes are limited by these free-sporing vascular plants -Most ferns have a life cycle like the one shown here, with a dominant sporophyte generation (as in all vascular plants) and one type of gametophyte bearing both types of gametangia (antheridia, producing sperm, and archegonia, producing eggs). -The sexual life cycle in ferns requires free-standing water for sperm to be able to swim to the archegonia; this need places some constraints on fern ecology, although asexual reproduction (and desiccation tolerance) allows some ferns to live in deserts. -The gametophyte generation, as in other modern vascular plants, is very small and simple (although free-living and photosynthetic in most ferns) -the sporophyte generation is the conspicuous generation, although it is dependent on the gametophyte initially (again, with an embryo, as in all land plants) but later becomes completely independent. -Sporangia are usually found on the underside of leaves in clusters called sori (the visible, brown circular units shown here on underside of leaf) and most have means of forcefully ejecting spores in relatively dry weather

Mechanisms that Prevent Self-Fertilization in flowering plants(helps reduced self pollination)

-self pollination in flowering plants can be an issue because we have microsporangia and megasporangia producing the same flowers a lot of the time which leads to close proximity of pollen and stigmatic areas -Self incompatibility(SI) is the ancestral way of preventing selfing but it is such a strict mechanism that under certain condition(look at these in last mentimeter q) such as population shrinks which will cause less S alleles leading to a decline in sexual reproduction which in turn will lead to more population decline -there may not be enough pollinators in the environment in which we would see a lack of outcrossing(crosses between genetically dissimilar individuals) and no reproduction -Self Incompatibility has been selected for a number of lineages of flowering plants but it is still good to outcross if you can and self if you must to stay alive -There is other various mechanisms like spatial separation of anthers and stigma or difference in timing of release of pollen vs receptivity of stigma that might give outcrossed pollen a headstart -most extreme example of a shift that results in outcrossing is Dioecious -in dioecious plants(like willows) you see unisexual plants where all the flowers are unisexual and are either all staminate flowers or all pistallete flowers which ensures selfing is impossible -in monoecious plants you see unisexual flowers but both types are found in different parts of the same plant so there can still be movement of pollen between flowers of the same plant which has the same effect of selfish genetically -Self-incompatibility prevents selfing in those angiosperms that possess such systems. -Flowering plants that have lost self-incompatibility run a risk of too much selfing (= forming seed from fertilization involving sperm and egg from gametophytes of the same individual sporophyte) without other mechanisms against selfing. -In those that have lost self-incompatibility, mechanisms that prevent selfing in flowers that produce both stamens and carpels include different timing of maturation of anthers and stigmas and/or different position of anthers and stigmas. -In addition to spatial separation of stamens & stigmas within a flower, or different timing of pollen release and stigma receptivity to pollen growth, species have evolved flowers that express only stamens or only carpels, making selfing within a flower impossible. -Angiosperm taxa that produce such flowers (with only stamens or with only carpels) may be monoecious or dioecious -In monoecious angiosperms, an individual plant has two types of flowers: (1) flowers with stamens but no functional carpels, and (2) flowers with one or more carpel(s) but no functional stamens. -In dioecious angiosperms, an individual plant has only one type of flower, either flowers with stamens but no functional carpels OR flowers with one of more carpel(s) but no functional stamens. -Dioecious plants are incapable of selfing.

coenocytic vs septate hyphae

-septate hyphae is the derived condition while the coenocytic is the ancestral condition -septate hyphae help set up that compartmentalization that allows for evolution of that dikaryotic stage where there is two nuclei per compartment which means expression from genes of two nuclei which allows for potential of more gene expression most likely leading to this high diversity -there is a huge diversity in Ascomycota and Basidiomycota and these account for the vast majority of described fungal species

Bisexual and unisexual in relation to monoecious and dioecious plants(look more into this/time-1:02:00)

-terms bisexual and unisexual can be used for the gametophyte generation where they are producing either sperm or egg or both(a particular gametophyte) -in monoecious and dioecious plants, we are talking about whether they produce both megasporangia and microsporangia or just one of the two which then give rise to gametophytes that are unisexual from the spores that germinate from those sporangia

Does peat lead to a high rate of decomposition?

-the peat itself is the poorly decomposed plant material in the soil -as log as peat bogs remain saturated with water and anaerobic with cool climate, they will retain carbon in the soil -excavating peat bogs will leads to the higher rates of decompositions

Where is a point of vulnerability in the gymnosperm life cycle and how does it compare to angiosperms?

-the pines cone scales have to separate and expose the ovules to the atmosphere so that the ovules can receive pollen wear the receptive surface on which the pollen has to land is inside the ovule. -period of time where the ovule is exposed -in the flowering plants the ovules are always sealed up in the carpel and not exposed to the atmosphere

What is an example of a homologous character?

-the posterior flagellum on motile cells of chritryds and animal sperm andthat is a similarity due to shared ancestry

How are angiosperm gametophytes more protected than gymnosperm gametophytes?

-the protection afforded by the ovary is another level of protection for the ovules which course include the female gametophytes and ultimately will include the developing embryo from the zygote that's formed by the fusion of the egg and the sperm inside the ovule so the ovary of the carpel of angiosperm provides some additional protection to the female gametophytes

Importance of carpel in regards to how the pollen germinates

-the receptive surface for flowering plants is the stigma of the carpel(not the ovule itself/this is seen in gymnosperms) -this allows for the carpels to have the possibility of selecting against particular male gametophytes(pollen tubes) that are growing down to try to fertilize the female gametophytes inside the ovules(ex. the self-incompatibility reaction where pollen from the same plant will be killed by the self-incompatibility reaction) -Some pollen tubes may grow more slowly than others or be unable to reach the ovules at all -Active inhibition by the sporophyte parent of the female gametophytes may come into play. The route an angiosperm pollen tube must follow from stigma, through the style, into the ovary, and finally into an ovule, to reach the egg of the female gametophyte. -In addition to its functions in protecting the ovules and dispersing the seeds (as a fruit), the carpel screens male gametophytes and can prevent some from reaching the ovules.

What do the yeast group consist of?

-the so called higher fungi(members of the Ascomycota and Basidiomycota

Reduction in size of the female gametophyte in angiosperm

-there is ovules with integument and megasporangium with only one female gametophytes inside(like we see in the ovules of gymnosperms/pines) -unlike the large female gametophytes inside the ovules of gymnosperms, the female gametophyte is microscopic with just 7 cell and 8 nuclui -Female gametophyte of angiosperms is highly reduced by comparison with the female gametophyte of gymnosperms. -In gymnosperms, the female gametophyte includes large numbers of cells and usually large archegonia. In angiosperms, the female gametophyte usually includes only 7 cells and 8 nuclei, without a distinct archegonium

Are the clades following secondary endosymbiosis heterotrophs or autotrophs(photosythensis)?

-they are both -can be seen in euglinids, chloroacniphytes

Difference between selfing and self fertilization?

-they are the same thing -self pollination means that pollen from the same plant ended up on the stigma of a flower of the same plant -selfing or self-fertilization is where the pollen tube successfully mated with a female gametophyte inside ovule which forms a zygote by pollen and ovules of the same plant

Moss life cycle

-this would a representative of the bryophytes -Have spores(desiccation resistant spores) being released under dry conditions -desiccation resistance was probably ancestral in land plants -mosses in particular have a structure called a peristome which regulates spore release and ensures that spores will be released under dry conditions/this is an adaptation we see in mosses that isn't seen in other land plants -mosses also have a desiccation resistant gametophyte generation that is something that we don't see in other land plants/this is abnormal because the dominant stage usually cannot dry out like that where as in seed plants we see the only see this case in the embryo being able to dry out and be dormant -include these jacketed gametangia being produced, the Archegonia and the Antheridia -The antheridia produce free swimming sperm that have flagella that need a film of water to swim through in order to get to the egg inside the archegonium. And that's a holdover from the algae. -This is a limitation in the life cycle as there is a need for free standing water in living on land for these bryophytes -We then have a retained zygote that becomes an embryo. This young sporophyte is protected and nurtured inside the archegonium. -we then have the emergence of the young sporophyte but it remains attached to the gametophyte throughout its life and is not the dominant generation. -Note some of the land plant innovations apparent in this moss life cycle: production of spores and gametes inside protective gametangia or multicellular structures (sporangia and gametangia), protection of the young sporophyte (embryo) in the archegonium, and desiccation-resistant spores dispersed under conditions favorable for wind dispersal (dry weather, with peristome releasing spores then). Remember, too, that the gametophyte of bryophytes is often desiccation tolerant. -All land plants have an alternation of generations; that is, a life cycle alternating between gametophyte (haploid) and sporophyte (diploid) generations. In addition, land plants have multicellular sporangia and gametangia, which are protective multicellular structures that produce reproductive cells (unless gametangia have been secondarily lost, as in angiosperms). -Sporangia are multicellular hollow structures in which (haploid) spores are produced, by meiosis; sporangia occur only on sporophytes, which have diploid bodies. Spores germinate and develop into (haploid) gametophytes. Gametes fuse to become a (diploid) zygote, which in land plants develop into a sporophyte. -Gametangia are hollow structures in which gametes are produced, by mitosis in land plants; gametangia occur only on gametophytes, which have haploid bodies. Two types of gametangia are produced by land plants in general (lost in some seed plants): (1) archegonia are gametangia that produce an egg (2) antheridia are gametangia that produce sperm. -The embryo stage of the sporophyte generation is an innovation of land plants, which protect the embryo inside the archegonium.

Does the female gametophyte and the egg get developed at the same time in angiosperm seed development?

-we have the megaspore germination followed by 3 rounds of mitotic division to give rise to the mature female gametophyte -we have 3 rounds of spore germination in angiosperms and one of the final product is the egg -egg differentiates after the female gametophyte starts to develop

How did heterospory lead to the evolution of pollen

-we see the endosporic development of the male gametophyte within the confines of the microspore which allowed for the development of the male gametophyte completely contained within the spore and the outer coving on the spore(the pollen grain) -this situation where we have unisexual gametophytes that can develop inside the spore walls is what we see in all the seed plants for both the pollen and for the female gametophyte defined inside the ovule so they're heavily contained and they're developing from resources that are contained in those spores and sometimes not even released from the sporangium in the case of a female gametophytes in seed plants -heterospory led to the evolution of pollen by setting the stage -in heterosporous lycophytes and ferns, the male gametophytes develop inside the spore wall just as they do in the case of pollen

-5 major clades of fungi

1. Chytridiomycota 2. Zygomycota 3. Glomeromycota 4. Ascomycota 5. Basidiomycota -Oomycota(water molds) and slime molds aren't true fungi -fungi most closely related to animals -major characteristics of fungi as whole(non-motile bodies, eukaryotes, can be unicellular or multicellular, filamentous multicellular structure, use an absorptive mode of nutrition through high SA/V ratio but can in turn dry out quickly, have cell walls made of chitin which helps with absorbing nutrients unlike plants which are made of cellulose , store energy as glycogen like animals(result of common ancestry probably) where plants store it as starch) -fungi are all heterotrophic(not photosynthetic/not chloroplast or plastids) -chytrids(chytridiomycota) have a flagellated spore with a single posterior flagellum(allows spores to move through water) so chrytrids are the only fungi that show motile stage/similar to animals in having that posterior flagellum probably due to common ancestry -zygomycota(zygomycetes) are important because of their desiccation resistance thick-walled zygosporangium which is a thick wall resting structure that forms after the gametangia come together(the sexual hyphae of different haploid mycelia that have compatible mating types) and when they fuse and they form this walled off spherical structure called a zygosporangium that houses a large number of nuclei from both parental mycelia that eventually fuse into a numbers of zygotes that immediately undergo meiosis as another fungi after we have the final karyogamy event -glomeromyota=important arbuscular mycorrhizal fungi that are responsible for the majority of mycorrhizal associations with the roots of land plants. Very critical even though they aren't that diverse -Ascomycota and Basidiomycota(include a wide number of the vast majority of described species of fungi) have septate hyphae(unlike the coenocytic hyphae of the other 3 types of fungi) and some associate with land plant roots as ectomycorrhizal relationship -be familiar with the Basidiomycota life cycle(on main quizlet)

23 multiple choice questions(about half will be single choice/half will be with 2 or more correct answers(at least 2 possibly more))

4 short answer

Which are more diverse, Angiosperms or gymnosperms?

Angiosperms

Do flowers have indefinite growth?

No they get to a certain point and can't grow anymore

Do fungi or animals have plastids or chloroplast?

No, that is ancestral that neither had plastids

Does secondary endosymbiosis relate only to red and green algae?

True. The organisms that were captured and became the chloroplasts in eukaryotic lineages that established a secondary endosymbiosis were either red algae or green algae and they descended from that one lineage of eukaryotes that originally became photosynthetic as as a result of incorporating a cyanobacteria in the cell as their chloroplast

Were plants the first ones to inhabit land?

We don't think so but rather believe it is that photosynthetic cyanobacteria along with other prokaryotes did first

Is heterospory present in all seed plants?

Yes all seed plants produce a large megaspore inside the megasporangium that germinate to become the female gametophyte and a tiny microspores in the microsporangium that germinate to become male gametophytes

Do only Ascomycota and Basidiomycota take part in ectomycorrhizal associations or do other fungal groups as well?

Yes as glomeromycota don't partake in this type of association but rather the arbuscular mycorrhizal assocation

Can unisexual fungi reproduce sexually?

Yes, they can reproduce sexually but usually reproduce asexually through budding or equal divisions into two daughter cells

What is the difference between a sporocyte and a sporangium?

sporocycte: an individual diploid cell inside of a sporangium that undergoes meiosis. Any diploid cell inside of the sporangium that undergoes meiosis is considered a sporocyte or a spore mother cell

Early adaptations to land of land plants

• Desiccation-resistant spores/The spores coated with a substance called sporropollenin(name of it's not important) but it renders those spores desiccation resistant and they're actually dispersed typically in free sporting vascular plants and bryophytes in dry conditions which allow for better wind dispersal • Cuticle/waxy outer covering found in most lineages of land plants and vascular plants but not well developed in bryophytes /relatively poorly developed in bryophyte sporophytes compared to those of vascular plants (but bryophytes often have desiccation-resistant gametophytes/they have the ability to dry out completely as gametophytes which is something that most vascular plants can't survive so they have another way of dealing with hydration •Stomata/Comes along with a cuticle. If you have this waxy outer covering then you know it's going to prevent water loss, but it also makes it difficult to absorb CO2 from the atmosphere which is needed for photosynthesis. Stomata are pores that are flanked by a couple of cells that regulate the size of that spore and can close it all together to prevent water loss if the plants losing water to too great of an extent. Well developed in vascular plants and present to some extent in the sporophytes of bryophytes •Gametangia/structures in which gametes are produced. It is a sterile jacket of cells that form a protective layer around cells that will become gametes. These gametangia not seen in green algae that are closely related to land plant. It is a nice adaptation to prevent the developing gametes from dessicating. Spores also are within structures called sporangia that are also jacketed by a sterile layer of cells that help provide some protection against desiccation of developing spores before they're mature. •Embryo/Protection of the young sporophyte generation. Not seen in any of the algae including the closest relatives of land plants among green algae. The protection of the embryo, the young sporophyte, in the archegonium by the gametophyte is something that's found in all land plants. The embryo stage is a multicellular stage of the young sporophyte that is protected by the female gametangium (= archegonium). •Fungal association/Associations that aid the uptake of inorganic nutrients (including mycorrhizae in the strict sense) are found throughout land plants, including (some) bryophytes. Done with glomeromycota. Well developed in the vascular plants where you have root systems that are associated with glomeromycota which is an arbuscular mycyhorrizal group of fungi. Critical to the originals successful colonization of land. •Rich secondary chemistry/These phenolics and compounds helped to render land plants as distasteful or toxic in many cases to herbivores or predators and also protect them from UV light. -lots of adaptations shared by bryophytes and vascular plants(land plants that aren't bryophytes) that were important to both