BIOL 420 Exam 2
Mitosis maintains the ____
"ploidy" if mitosis starts with a diploid cell, it will result in two diploid daughter cells....Meiosis cuts the ploidy in half (one 2n cell --> FOURga haploid cells)
Mosses and leafy liverworts have _____ and _____ to "breathe"
'leaves' and 'stems' (different than leaves and stems from higher plants)
Bryidae life cycle
(MOSS LIFE CYCLE) In the true mosses, the SP is an erect structure growing out of the tip of the GP (the archegonial head).
Sporophyte?
(in the life cycle of plants with alternating generations) the asexual and usually diploid phase, producing spores from which the gametophyte arises. It is the dominant form in vascular plants, e.g. the frond of a fern.
fun fact brown algae
the giant kelp Macrocystis shows the highest level of differentiation having sieve tubes which are structurally and functionally very similar to plant sieve tubes in the phloem see fig15-21 & 23-20 - they are very efficient in transporting nutrients (up to 60 cm/hour)
In phaeophyta (brown algae), there is a progressive _________ of ______
reduction; gametophyte 1) Cutleria - small sporophyte, gametophyte is dominant life stage 2) Dictyota - sporo- and gametophyte isomorphic 3) Laminaria - sporophyte dominant, gametophyte reduced to microscopic stage 4) Fucus - gametic life cycle, no gametophyte
If meiosis leads to spore formation, it is
sporic meiosis (alternation of generations)
The moss life cycle may be an adaptation for
terrestrial life as the archegonium helps to protect zygote/embryo against desiccation
What most strongly differentiates bryophytes from vascular plants?
the absence of xylem and phloem
What is triggered when a diatom reaches threshold level of size reduction?
*sexual reproduction* which results in zygote formation --> this is then follows by asexual reproduction until the size threshold is reached again and triggers sexual reproduction - sexual reproduction leads to loss of frustules, which form sediments on ocean floor - this can cause the formation of huge diatom sediments, called diatomaceous earth, over millions of years
What characterizes the cellular slime molds phylum?
- 50 species - closest relatives probably amoebas - *have cell wall and cellular organization (unlike plasmodial)* - feed by *phagocytosis* - most famous species = Dictyostelium discoideum..popular model for studying developmental processes
What characterizes the Oomycota phylum?
- 700 known species - cell walls contain cellulose (like plants, unlike fungi) - unicellular, filamentous, highly branched or coenocytic - heterotrophic
What characterizes the plasmodial slime molds phylum?
- 700 species of myxomycetes - NOT related to fungi - A *plasmodium* is a thin streaming multinucleate mass of protoplasm moving like an amoeba --> lacks a cellular organization and cell walls, but moves in an organized manner and produces reproductive structures that are differentiated into an anchor, a stalk, and a sporangium. - nuclei in the plasmodium are diploid - Nutrient uptake is by *phagocytosis* and by *absorption* - A plasmodium can spread over several square meters.
Describe the Laminaria life cycle?
- a species of brown algae - after fertilization, zygote remains attached to gametophyte and develops into sporophyte, which differentiates into highly complex thallus - unicellular sporangia develop on surface of blades and produces zoospores via meiosis - after shedding flagella, they develop into microscopic male and female GPs - gametangia and unicellular, called *oogonium and antheridium* - *both produce only one motile sperm or immotile egg cell* - sperm cell actively swims to egg, attracted by female pheromones - after fertilization and zygote formation, a new diploid SP dedvelops
Describe the Fucus life cycle.
- after fertilization, zygotes develop into highly complex 2n sporophytes - at tips of blade, hollow chambers called receptacles form; inside receptacles, gametangia are formed inside spherical structures called conceptacles - there are both oogonia and antheridia in one conceptacle - sperm cell actively swims to egg, attracted by female pheromones, and fertilizes egg - zygote grows into SP - NOOO GP generation - meiosis results in gamete formation (this is gametic meiosis -- NO sporic meiosis)
What are cryptophyta? (name phylum and importance as well)
- also called cryptomonads; small single-celled aquatic or auto-heterotrophic flagellates (flagellate are single-celled protists with one or more flagella, a whip-like organelle often used for propulsion) - Protista kingdom, dictyosteliomycota (cellular slime molds) phylum - of special interest to evolution because they have a *chloroplast with 4 membranes*
Describe the life cycle of brown algae:
- alternation of generations* to various degrees - series of progressive reduction of gametophyte within brown algae (i.e. in Laminaria and rockweed Fucus) --> in Laminaria, GP is reduced to a microscopic structure; GP and sporophyte are very heteromorphic, but it is still life cycle with alternation of generations - in Fucus, only haploid phase are gametes produces by meiosis, so there is NO GP! the life cycle is similar to standard animal life cycle
Possible causes of strong increase in harmful algal blooms in last three decades:
- anthropogenic eutrophication - invasive algal species - global warming - natural causes
What is the size cycle?
- associated with diatoms - half the cells of each generation become progressively smaller when they reconstruct the missing half of the frustule; the size of the other half of the cells remains constant - once the diatom is as small as it will be, it goes through meiosis and sexual reproduction to form a zygote and reestablish maximal size
What characterizes dinophyta? (dinoflagellates)
- cellular slime molds phylum - mostly unicellular - important components of phytoplankton, but also found in fresh water - unique flagella arrangement: two flagella beating within grooves--> special way of spinning around for propulsion - many produce one or more highly toxic compounds to protect themselves from predators (and to attack and feed on others --> i.e. killing fish) - can cause algal blooms (massive increase in P. piscidia which uses toxin to attack fish respiratory system) --> leads to death of many fish
Why are Rhodophyta (red algae) red?
- chloroplasts contain red *phycobilin* (phycoerythrin) which masks the green chlorophyll a - complimentary colors of red, blue, and blue-green are absorbed, while red is not absorbed - blue/blue-green is predominant wavelength range in deeper ocean waters down to 200m --> phycoerythrins are an adaptation to the ocean habitat
What is peat moss not decomposed?
- contains antimicrobial compounds that prevent decomposing - functions in plant defense against possible microbial pest - creates a very acidic environment hostile to many microbes..bog pHs are after less than 4 which is too low for most plants to grow (mosses also secrete protons) - very low oxygen content in bogs; no oxygen deeper under surface - moss decomposition is partial because of these conditions and results in the formation of peat, which is partially decomposed plant material *sometimes other organisms are well preserved in bog (such as bog mummies)
How to combat phytophthora and protect plants:
- fungicides - systematic pesticides move within plant - resistance breeding* using wild naturally resistant potato species such as *Solanum demissum* (serve as source for resistance genes, *R genes*) -- R genes trigger plant defense responses. E.g. plants produce defensive chemicals which deter and/or kill the pathogen. -- resistance breeding can be accelerated by genetic engineering; resistant varieties of potato would reduce pesticide applications and thus the negative environmental impact of potato growing
Sequencing the genome of physocomitrella revealed...
- it is separated from flowering plants by more than 400 million years - genomic changes are concomitant with the evolutionary movement to land (increased gene family complexity), loss of genes associated with aquatic environments (like flagellar arms), acquisition of genes for tolerating terrestrial stresses (like variation in temperature or water availability), and development of the *auxin* and *abcisic acid signaling pathways* for coordinating multicellular growth and dehydration response
What characterizes the Bryidae (True Mosses) group (in the bryophyta phylum) ?
- like in hornworts, the true mosses have stomata on sporophytes, some consisting of only one doughnut-shaped cell - like vascular plants, true mosses have conducting tissue differentiated in: a) water conducting tissue: hadrom b) food-transporting tissue: leptom (food-transporting cells called leptoids) --> - some similarities to sieve element cells in phloem of seedless vascular plants ---> may be intermediate stage in the evolution of vascular plants with xylem and phloem
What characterizes phaeophyta? (brown algae) phylum
- mainly marine - 'seaweeds' on rocky shores - *kelps* of offshore waters, reach down to 30m, up to 10 km away from coast - size range from microscopic to 60m and greater than 300kg - has many features that are highly adaptive to their environment
What characterizes Rhodophyta? (Red algae)
- many are macroscopic algae (up to one meter in length) - 4-6,000 known species (must abundant number among marine algal phyla) - most are marine, multicellular, and attached to a substratum - often referred to as seaweeds - red color
What characterizes hornworts?
- only ca. 100 species - gametophytes resemble liverwort thallus - antheridia and archegonia are located on surface of gametophyte - sporophyte is upright elongated structure that holds capsule (which contains sporangium) *the sporophyte has STOMATA in the epidermal cell layer (liverworts have pores in the gametophyte, but not the sporophyte...the liverwort pores are morphologically unlike stomata...the horwort stomata are structurally similar to stomata in vascular plants) --> evolutionary link to vascular plants which have dominant sporophyte and stomata in leaves
List ecological roles of protists:
- plankton - phytoplankton --> primary marine producers (base of the marine food chain); produce about 50% of atmospheric oxygen - zooplankton (heterotrophic) --> includes some protist taxa - carbon cycle --> protists assimilate CO2 into carbohydrates and *calcium carbonate CaCO3* for their shells; many protists in the plankton possess shells..when they die and drop to the bottom of the ocean, they form sediments which represent important carbon sinks (aka the carbon sediments are no longer part of the global carbon cycle...over millions of years the sediments will turn into limestone.) --> heterotrophic Foraminifera are most important protist contributors to limestone (autotrophic planktonic organisms contribute too)
Describe the reproductive characteristics of bryophytes most distinguishing from Charophyceae
- presence off *antheridia* (male gametangia) and *archegonia* (female gametangia); antheridia are also present in some protists and in the Charales, but multicellular archegonia that harbor only one egg cell are a synapomorphy for bryophytes (only descendants to get it). - *multicellular embryo that develops inside the archegonium* - *sporopollenin* - the most decay-resistant and chemical-resistant bipolymer known; increases survival of air dispresed spores (this is a synapomorphy shared by all embryophytes, and zygotes of some charophyceae)
How do free living slime mold cells know when and how to aggregate?
- they migrate towards a source of cyclic adenosine monophosphate (cAMP) (concentrations increase in response to extracellular signals and initiate intracellular signaling cascade which amplifies extracellular signal) - cAMP is secreted by starving slime mold cells (myxamoeba) and functions as an extracellular signal, which is perceived by membrane-bound receptors in the plasma membrane of the other slime mold cells, which then move towards cAMP source and start secreting cAMP themselves - cAMP triggers cytoskeleton rearrangement leading to slug formation (which is aggregate of single dictyostelium cells)
What characterizes the Bacillariophyta phylum? (Diatoms)
- unicellular or colonial - most diatom species live IN phytoplankton - photoautotrophic - *may account for 25% of total primary production on Earth* --> primary production made possibly by photosynthesis --> oxygen is a biproduct --> our life depends on diatoms! - 100,000 species estimates - account for *greatest biomass and species diversity in phytoplankton* - essential food for many freshwater and marine animals - two-part cell walls containing SiO2 and nH20 (opaline silica) and overlap --> called frustules - often highly symmetric; cell walls account for body shapes - mainly asexual at diploid cell
What characterizes phylum Chlorophyta? (green algae)
- very diverse group, 17k+ species - most species in freshwater, some marine algae - some terrestrial ones (on snow, tree trunks, soil, lichens, and other symbioses) - unicellular forms with complex thallus resembling plants; can become up to 8 meters long (codium manum) *Chlorophyta and land plants (plantae) share a common ancestor*
How many species comprise the bryophyta phylum?
-9,500 known species
CM nucleus contains genes derived from:
1) a heterotrophic proto-CM cell (that existed before endosymbiosis), 2) the cyanobacterium that gave rise to the chloroplast (via red algal nucleus), 3) the bacterium that gave rise to mitochondria (primary endosymbiosis) 4) the nucleus of the endosymbiotic red alga (secondary endosymbiosis) --> nuclear CM genes are derived from 4 different genomes (horizontal gene transfer) --> genes in a CM cell are transcribed from 4 different groups of chromosomes (or sets of chromosomes) located in 4 different compartments: - circular chloroplast chromosome - circular mitochondrial chromosome - linear chromosomes in nucleomorph - linear chromosomes in nucleus
Describe the life cycle of a typical moss:
1. Fertilization (male has antherdial head with sperm which fertilizes female with archegonial head with egg cell and venter) 2. Zygote forms in Venter --> *mitosis* --> early embryo grows --> venter wall enlarges and *calyprta* develops 3. Young sporophyte forms 4. Young sporophyte matures into female gametophytes with a foot, seta, and capsule 5. The mature sporophytes release spores from the sporangium (a receptacle in which asexual spores are formed) 6. Meiosis 7. Spores goes through mitosis 8. Bud forms --> Maturation --> Male gametophyte (antheridia)
List the three phyla of Bryophytes?
1. Marchantiophyta (liverworts) 2. Anthocerotophyta (hornworts) 3. Bryophyta (mosses)
Moss Life Cycle
Egg and sperm formation takes place in the leafy green moss plants (gametophytes). Spore formation and release takes place in the tiny, attached spore plants (sporophytes). Spore germination results in a branching algal-like filament that is called a protonema (pl. protonemata; proto, first + nema, thread).
What is the advantage of two generations in a sporic meiosis life cycle?
1. Meiosis increases genetic diversity through independent assortment of chromosomes and recombination events Fertilization increases genetic diversity by combining two different parental genomes. 2. The number of offspring as a result of a meiotic event is smaller in a life cycle of gametic meiosis (without an independent haploid generation) than in a life cycle of sporic meiosis in which the number of offspring is multiplied by a second haploid generation 3. Total number of offspring can be very high with two generations both producing germ cells 4. Having two independent generations may be particularly advantageous if fertilization is a rare event, as it may be in marine environments and may have been at the transition from aquatic to terrestrial life, when fertilization was still completely dependent on water
List the phyla that makeup Protist Kingdom
1. Myxomycota (Plasmodial Slime Molds) 2. Dictyosteliomycota (Cellular Slime Molds) - Dictyostelium discoideum - Cryptophyta (cryptomonads) - Dinophyta (dinoflagellates) 3. Oomycota - Phytophthora infestans 4. Bacillariophyta (Diatoms) 5. Rhodophyta (Red algae) 6. Phaeophyta (Brown algae) 7. Chlorophyta (Green algae) - Chlorophyceae - Ulvophyceae - Charophyceae
What are the adaptations of brown algae that reflect their environment?
1. Need to be able to float or grow from bottom of sea up to surface --> air-filled *bladders* provide buoyancy 2. need to withstand exposure at low tides --> *alignin* prevents drying out (acts similarly to gelative and evaporates water very slowly; also contributes to buoyancy and prevents other organisms from colonizing the algae) 3. Need to withstand mechanical stress or surf --> interwoven filaments produce tough tissue, cellulose and alignin in cell walls help to endure surf stress
Describe the endosymbiotic events leading to the formation of the Cryptomonad (CM)
1. Primary = eukaryote engulfs cyanobacterial ancestor --> genes from cyanobacterial chloroplast precursors transferred to host nucleus (horizontal gene transfer), giving rise to photosynthetic red algal cells 2. Secondary = red algal cell is engulfed by a heterotrophic eukaryotic host cell --> the third membrane of the CM chloroplast is equivalent to the red algal cell plasma membrane, and the fourth membrane is derived from the food vacuole membrane of the heterotrophic host cell. A special feature is that this fourth membrane is fused with the ER, which in turn forms a continuum with the nuclear membrane. And, of course, there is the plasma membrane of the host cell representing the fifth membrane in the CM cell. Again, the inner four membranes look like the boundaries of a chloroplast on an electron micrograph, but they represent the 2 chloroplast membranes, the plasma membrane of the endosymbiotic red algal cell, and the membrane derived from the host food vacuole. two successive horizontal gene transfers: a) from cyanobacterial nucleus to eukaryotic host cell nucleus (primary endosymbiosis); b) from red algal cell nucleus to nucleus of CM host, leading to reduction of red algal nucleus to nucleomorph (secondary endosymbiosis)
What are the three types of protists?
1. photoautotrophic (generally these are algae) 2. heterotrophic (oomycetes and slime molds) 3. mixotrophic (mixed autotrophic and heterotrophic life style...i.e. euglenophyta --> depends on light conditions in environment)
The first moss genome was sequenced in ____ and was the ____
2008; PHYSOCOMITRELLA PATENS
Peat moss holds ____x its weight in water, which is the reason it is harvested for gardening and used as a soil ______
20; conditioner (was also used as an antiseptic at one points and did a decent job of keeping wounds from being infected...tribal people in Canada and Alaska still use it)
What is the difference between a gametophyte and a sporophyte?
A gametophyte is the haploid generation that gives rise to GAMETES; a sporophyte is the diploid generation that gives rise to SPORES.
What is the main difference between Bryophytes and Charales?
Bryophytes have true plasmodesmata (PD) with ER connections through the PD between two adjacent cells...Charales have PDs without ER connections
Difference between gametophytes and sporophytes?
Gametophytes are haploid (n) and have a single set of chromosomes, whereas Sporophytes are diploid (2n), i.e., they have two sets of chromosomes. ... A sporophyte reproduces asexually and a gametophyte sexually. Significance: For a diploid (2n) sporophyte to produce haploid (n) spores, the cells have to undergo meiosis
What is zygotic meiosis?
In the life cycle of fungi, zygote formation is immediately followed by meiosis. So, the zygote is the only diploid stage in the life cycle. The haploid generation exists in a fungal-specific dikaryon stage called zygotic meiosis
Why does peat moss have such an enormous water holding capacity?
It's anatomical features --> large dead cells surrounded by smaller living cells containing chloroplasts; walls of the dead cells are perforated allowing for fast filling with water
Why is brown algae brown?
Most abundant accessory pigment is *carotenoid fucoxanthin* which is dark brown/olive-green...accessory pigments TRANSFER energy obtained from light absoprtion to chlorophyll in the photosystems
What characterizes liverworts?
Most liverworts have a distinctive shape, characterized by sometimes liver-shaped ground-covering flat thalli Best know liverwort is Marchantia*
What is a nucleomorph?
Nucleomorphs are small, vestigial eukaryotic nuclei found between the inner and outer pairs of membranes in certain plastids. They are thought to be vestiges of primitive red and green algal nuclei that were engulfed by a larger eukaryote. - located in residual cytoplasm of the former red algal cell inside the third membrane of CM cell and outside of chloroplast membranes...whole structure is inside lumen of host's rough ER
Dead moss can form ____ _____.
Peat bogs; a bog or bogland is a wetland that accumulates peat, a deposit of dead plant material—often mosses, and in a majority of cases, sphagnum moss, which is an important contributor to formation in bogs. Bogs obtain all water from rain --> no access to running water by streams of ground water note: bogs are endangered habitats in many countries; they provide for an amazing plant and animal life (many endangered species); consider ecological importance versus commercial interest; the Southern Appalachian bogs (or fens) are especially endangered habitats due to encroachment by people; many bogs have been drained and new bogs have been prevented from forming; ® wildlife biologists work on conservation of bogs and their flora and fauna.
What order within Oomycota contains a number of infamous plant pathogens?
Perenosporales - Plasmopara viticola causes downy mildew on grapes - Phytium causes damping-off diseases of seedlings of many plants --> results in rotting of seedlings while still in soil - Phytophthora ('plant destroyer') causes blight disease in about 35 species
What species of oomycota is associated with the Great Potato famine of Ireland 1846-1847?
Phytophthora infestans; causes late blight in potatoes and tomatoes...caused decline in Irish population from 8.5 mil to 6.5 mil over 6 years...800k people starved *still a serious pathogen of potatoes
What is a bryophyte? Where can they be found?
Plantae kingdom; small non-vascular plants such as mosses, liverworts, and hornworts. - regulate ecosystems by providing buffer system for other plants that benefit from water and nutrients the bryophytes collect *only male gametes (sperm cells) are motile and depend on water to reach egg; spores are nonmotile - can be found in extreme environments (such as deserts, cold climates, or on tops of high mountains...can also survive on antlers or bones of dead reindeer, dung of herbivores or carnivorous animals); most prefer moist habitats - forests, streams, bogs.
Impact of red algae:
Produces well-known compounds important for daily-life: - *agar* (mix of agarose and agaropectin) --> agar is used to make capsules containing vitamins and drugs, for dental impression material, as the base for cosmetics, as the culture media for microorganisms and cell cultures, and as agarose for gel electrophoresis. Also as temporary preservative for meat and fish - *carrageenan* (similar structure to agar) --> stabilizer for emulsions in dairy products, paints, and cosmetics
Moss Life Cycle VIDEO
Rhizoids - small filaments that anchor moss to whatever it is growing on; high moisture content Small leaves attached at intervals to moss stem; overlapping leaves around the tip hold a film of water with reproductive structures containing gametes, making the plant a gametophyte Antheridia are found in the water film -- male reproductive structures that are each reported by a stock and surrounded by jacket cells (for protection)...when fertile tissue is ready to be released, the jacket cells separate and the cells float upwards to the surface of the water. During a rain shower, rain drops splash some of the fertile cell water out of the plant and it can hit the tip of an adjacent female gametophyte...each fertile cell will release a sperm into the surrounding water Paraphyses - in female plant; aid in the retention of water...*archegonia* , the female reproductive structures are found in between these structures. The *neck* is the narrow upper portion, the lower enlarged piece below is the venter, and then a single *stalk* attaches the archegonium to the stem. *Neck canal cells* - extend from the egg to the tip of the archegonium As archegonium matures, neck canal cells disintegrate (filling canal with mix of organic compounds). When the egg is ready to be fertilized, jacket cells at tip of neck separate, releasing contents of neck canal into surrounding water. Many of the compounds released are sperm attractives...sperm will swim towards the source and are then guided down the neck canal. The first sperm to enter the venter will fertilize the egg cell...two sets of chromosomes (one from egg one from sperm) for a *DIPLOID* cell. Fertilized egg = diploid zygote --> begins to divide and enlarge...resulting diploid tissues = embryo sporophyte and will form spores when it matures... lower end of embryo sporophyte grows through the end of the archegonium and results in an absorbing structure inserted into the tip of the female plants called the *foot* which absorbs nutrients and water to nourish the embryo. At other end of sporophyte, embryo grows and enlarges venter until it is split in half --> when it splits, the top half is lifted upwards and results in a *sporified plant* The plant now has a seta (stalk) with a capsule at its tip that is exposed when the venter shell falls away. The capsule contains a sporangium Sporangium contains numerous sporocyte cells...inside each one there is a *DIPLOID nucleus, which will divide via meiosis, yielding four haploid daughter nuclei* Sporocyte cell undergoes cleavage, creating a thin walled cell around each haploid nucleus...this results in a cluster of four adhering cells that eventually separate. Deposit of protective, tough, sporopollenin eventually covers each, making them *spores* As the spores mature, walls of capsule dry out and harden...the tip of the capsule falls away, leaving peristome teeth (entrance to sporangium)...outer teeth bend backwards as they dry out, allowing spores to escape...spores can be dispersed far from the plant (as they are lightweight) If a spore lands on a moist surface, it will absorb water and divide repeatedly to form a filament of photosynthetic cells...branch filaments then form (called *Protonema*) Sometimes, a bud will form from the protonema (instead of a branch) and contain rhizoids and filamentous leaves...further growth results in the formation of an erect stem with leaves and the formation of rhizoids at the base for support -> ADULT MOSS PLANT IS FORMED * Sexual and spore producing phases both *
What is the IPCC?
The IPCC is a science-based intergovernmental organization that measures globally changing climate dynamics and comes up with computer models aimed at predicting climate change under varying conditions such as different extents of greenhouse gas emissions.
Sporic meiosis
The life cycle of organisms with "alternation of generations" is characterized by each phase consisting of one of two separate, free-living organisms: a gametophyte ( thallus (tissue) or plant), which is genetically haploid, and a sporophyte (thallus or plant), which is genetically diploid. A haploid plant of the gametophyte generation produces gametes by mitosis. Two gametes (originating from different organisms of the same species or from the same organism) combine to produce a zygote, which develops into a diploid plant of the sporophyte generation. This sporophyte produces spores by meiosis, which germinate and develop into a gametophyte of the next generation. This cycle, from gametophyte to gametophyte, is the way in which plants and many algae undergo sexual reproduction.
What is primary endosymbiosis?
The process in which a *eukaryote* engulfs another living *prokaryote.* An organism may then use that organism to its advantage. If a eukaryotic cell engulfs a photosynthetic alga cell, the larger organism can then use the products of the alga and become an autotrophic organism.
Who was the bog man?
Tollund Man - found in a bog in Northern Denmark and estimated to be over 2000 years old... Only Tollund Man's head was conserved, and remains to this day on display at the Silkeborg Museum, six miles from his place of death.
What is probably the longest organism that ever lived on earth?
a brown algae kelp that was measured as 274 meters (900 feet long)
What is a rhizoid?
a filamentous growth or root hair on the underside of the thallus in some lower plants, especially mosses and liverworts, serving to anchor the plant (DO NOT function in water/nutrient uptake like it roots of higher plants)
What characterizes a protist?
a group of eukaryotic organisms defined by exclusion of its members from the animal, plant, and fungi kingdoms; a *paraphyletic* group; most protists are aquatic
What is hadrom?
a tissue composed of water-conducting cells called hydroids --> when mature, they resemble xylem cells of vascular plants and have NO protoplast...do NOT contain lignin
the placenta of mosses is _______ to the mammalian placenta
analogous
The life cycle of dictyostelium is _______
asexual; 1. free-living amoeba reproduce 2. they aggregate 3. then they mount together and form a slug shape 4. develops into stalk cells and spores --> then releases mature spores
What is the source of color in algal blooms?
bioluminescene; similar biochemistry as in fire flies... luciferin comes into contact with luciferase enzymes and oxygen and ATP and creates oxyluciferin and light...represents an example for convergent evolution (luciferases found in bacteria, fireflies, and marine organisms...can be structurally very different)
Anatomy of brown algae?
body = thallus; some brown algae have highly differentiated complex thalli resembling plant bodies, some are much simpler organized pseudoparenchyma = aggregation of branched filaments; in complex brown algae like kelps, it looks like tissues of higher plants with differentiation into leaves ('blades') and stems ('stipe') and roots ('holdfasts') adjacent cells can be linked by plasmodesmata, just like in land plants (also in some green algae) - however, phaeophycean plasmodesmata are different because they do not have ER connections between adjacent cells like vascular plants (
What is assumed to be one of the greatest threats to biodiversity and human welfare?
climate change https://www.ipcc.ch/report/ar5/syr/ ,
What's the connection between a type of cellular slime mold and coral?
dinoflagellates and corals are mutualistic symbionts...dinos called zooxanthellae are essential for corals, providing up to 90% of their nutrition...they also transfer photoassimilates (mainly carbs) to the coral host while the coral provides nitrogen and other micronutrients to the dino ** Zooxanthellae are extremely temperature sensitive and increasing water temperature in the oceans due to global climate change has resulted in loss of the zooxanthellae which is fatal for the corals. The consequence is 'coral bleaching' and dead coral reefs. Coral reefs are enormously productive ecosystems exhibiting an amazing biodiversity.
the fusion of gametes results in the formation of a _____ zygote
diploid
All bryophytes have ______ gametophyte
dominant; sporophyte is small and attached to gametophyte
Bryophytes and vascular plants can be classified as ______. WHY?
embryophytes; a multicellular matrotrophic *embryo* is found in all phyla of Plantae (embryophyte is synonymous with planate). Even the green algal groups most closely related to embryophytes do not have a true embryo.
How do bryophytes take up water?
entirely through diffusion from surrounding water (rain); some have precursors of xylem/phloem for water/nutrient conduction
Describe adaptations of bryophytes -
epidermal cells produce hydrophobic cell well material (cuticle) to prevent desiccation; to enable gas exchange across this barrier, liverworts possess surface pores and hornworts and mosses evolved true stomata like the vascular plants (eg ferns and flowering plants)
Liverworts and hornworts have _____ _____
flat thalli (gas exchange without vasculature)
What is leptom?
food-transporting tissue; composed of food-transporting cells called leptoids that have some similarities to sieve element cells in phloem of seedless vascular plants
During diatom reproduction, each daughter cell receives half of _____
frustule; and reconstructs the similar missing half (size of frustule is decreasing over generations because when the missing half is reconstructed it is always with one of a smaller size)
Phytophthora are NOT
fungi *common misconception because they are defended against with fungicides
If meiosis leads to gamete formation, it is
gametic meiosis (i.e. animals)
What are the two independent haploid generations in the moss life cycle?
gametophytes and spores; *The haploid stage, in which a multicellular haploid gametophyte develops *from a spore* and produces haploid gametes, is the *dominant stage in the bryophyte life cycle*
Bryophytes are related to:
green algae and vascular plants (see cladogram in lecture notes and know synapomorphies)
a gametophyte (thallus or plant) is genetically ______ and a sporophyte (thallus of plant) is genetically ______
haploid, diploid
Spores are ALWAYS
haploid; (reproductive cells used in asexual reproduction) --> gametes are also haploid (the reproductive cells in sexual reprod)
gametes are _____ reproductive cells that fuse to form a _____
haploid; zygote
Dinoflagellates are known for causing...
harmful algal blooms and fish poisoning ---> if toxins released accumulate in higher trophic levels such as shellfish, they can be harmful to humans May-august is most intense algal blooms
What is the technical term for the embryo in bryophytes?
immature sporophyte
What is matrotrophy?
life cycle element in which the zygote is not released but remains in the archegonium of the gametophyte and is nutritionally dependent on the gametophyte; when the zygote starts cell divisions, it develops into an embryo, which further develops into a mature sporophyte...at all times the SP is attached to the GP and nutritionally dependent on it *very important synapomorphy of bryophytes shared with all other plantae*
Of all land plants on a cladogram, which is the outgroup?
mosses
In Northern European countries, what did they burn and use as fuel?
peat moss
At the intersection between gametophyte and developing sporophyte (initially the embryo) in a bryophyte, a tissues called the _____ facilitates ____
placenta; nutrient transport from the GP to the SP... the placenta consists of transfer cells with extensive wall ingrowths, which increase the surface area through which nutrient transport occurs
Describe the life cycle of liverworts:
two conspicuous structures emerge from thalli, the antheridiophores and the archegoniophores which harbor the antheridia and archegonia, resp. (=male and female gametangia) - in general, the life cycle is a typical bryophyte life cycle with the following hallmarks: - sporophyte is attached to gametophyte and develops inside the archegonium - flagellated sperms depend on water to fertilize egg in archegonium - egg develops inside archegonium into an embryo (=immature sporophyte) - embryo and sporophyte nutritionally dependent on gametophyte: placenta tissue for nutrient supply from gametophyte tissue to embryo - sporophyte matures, and in sporangium meiosis takes place - sporophyte never detaches from gametophyte - spreads immotile spores which grow into new gametophyte
What is a thallus?
type of body made up of filaments of cells; the body is not differentiated into root, steam and leaf as in vascular plants and bryophytes; generally, specialized cell types are lacking
What are oogonia?
unicellular female sex organs in which one or several eggs are produced; some algae have these instead of archegonia
What is secondary endosymbiosis?
when a living cell engulfs another eukaryote cell that has already undergone primary endosymbiosis. It has happened often enough that it has lead to genetic diversity among the organisms on Earth. *responsible for the cryptophyta having a chloroplast with four membranes --> plasma membrane from the endosymbiotic red algal cell and the membrane derived from the host food vacuole.*
If there is no independent diploid generation and the only diploid stage in the life cycle is the zygote, it is
zygotic meiosis
NOTE:
® It was assumed that CO2 -fixation by marine phytoplankton (into CaCO3) compensates for anthropogenic CO2, a potent greenhouse gas released by burning fossil fuels. However, the currently observed continuing increase in atmospheric CO2 is not consistent with plankton playing a major role as a carbon sink for the excess of anthropogenic CO2. The sedimentation process is very slow whereas anthropogenic CO2 output is rapid. Furthermore, plankton growth is limited by other factors, e.g. nutrients such as iron.
