Describe, in detail, the components and characteristics of an experiment.
You wish to determine whether a fertilizer actually improves the yield of corn in your vegetable garden, so you decide to do an experiment. 50 plants get fertilizer, 50 plants do not get fertilizer, and you weigh the ears of corn as you harvest.
What is the independent variable?
What is the dependent variable? can be defined as the effect of “cause and effect”, or as any change in initial conditions induced by the independent variable.
Which is the experimental group and control group?
What variables must be controlled in the two groups?
Why must you have a control group?
What does it mean when scientists have a “95% confidence” in experimental results?
What do scientists mean when they say there is a “significant difference” between two groups?
Describe the relationship between radioactive isotope half-lives and geologic time.
What is the relationship between epochs, eras, periods, and eons?
Define systematics. The study of the diversity of the organisms of life
What factors are studied in systematics and used to establish evolutionary relationships between types of organisms?
Morphology, biochemistry, life cycles, analysis of DNA and RNA base sequences, ecological roles.
Describe the relationship between the following terms: symbiosis, commensalism, mutualism, parasitism, definitive host, intermediate host, ectoparasite, endoparasite, and accidental host.
List the basic Linnaean taxons in the proper order.
How are scientific names derived?
Was taxonomy, as devised by Linnaeus, phylogenetic? no
Describe the relationship between the following: monophyletic, paraphyletic and polyphyletic clades; phylogenetics, clade, cladogram.
Monophyletic – a clade such that all the organisms within it share a common lineage
Polyphyletic – undesirable, occurs when a clade combines organisms from different lineages
Paraphyletic – undesirable, occurs when a clade is incomplete
Clades – a monophyletic group of organisms with a common ancestor
Describe traditional versus cladistic approaches to classification—which is the favored approach? The traditional approach lumps organisms together according to morphology. Similar organisms go together and dissimilar organisms are put with a different group. This approach doesn’t involve evolutionary relationships and organisms that are lumped together may not be all that related. The cladistics approach looks at morphology or genes that are derived from some ancestral type taking into account the fossil record when morphologies are involved. This approach lumps organisms together that are closely related regardless of how similar they look.
What is Occam’s razor/parsimony and what is its role in classification? This is a “less is better” concept. This is often paraphrased as "All other things being equal, the simplest solution is the best.
Describe the Domains of life and the characteristics of each.
Eubacteria – Prokaryotic, have Peptidoglycans in their cell wall, and polycistronic mRNA which means it codes for several proteins. Have characteristic phospholipids which make up their plasma membranes. Important as detritivores in ecosystems. Form spores under some conditions
Have prokaryotic ribosomes
Control genes via operons
Some fix nitrogen
Have circular chromosomes and plasmids.
Archaea – Prokaryotic, have Ether linked phospholipids in its membrane, and trans membrane phospholipids, and branched membrane lipids. They have monocistronic mRNA
Have prokaryotic ribosomes
Control genes via operons
Some fix nitrogen
Have circular chromosomes and plasmids
Eukarya – Eukaryotic, have membrane bound organelles, monocistronic mRNA
Have a true nucleus
Have characteristic plasma membrane phospholipids
Have characteristic ribosomes and monocistronic genes
Typically much larger than prokaryotes
Linear chromosomes composed of chromatin
What is the evolutionary relationship between the three Domains? Archaea is thought to have branched off of Eubacteria 3 bya, and Eukarya are thought to have branched off of Archaea 2.5 bya.
What is the justification for three Domains, why not lump the Archaea and Eubacteria together? The Archaea share traits with both the Eukarya and Eubacteria which suggests a common ancestry with both groups. Unique traits of Archaea are considered derived traits
Describe factors considered in prokaryotic classification (shapes, etc). morphology is considered such as rod shaped (Bacilli), sphere shaped (Cocci), spiral shaped (Spirilla), and comma shaped (Vibrio). Biochemistry is much more important in prokaryotic classification, especially with the composition of the cell wall.
What is the purpose of a gram stain? The stain differentiates two different groups of Eubacteria.
Gram+ stains purple, it possesses a thick layer of peptidoglycans in the cell wall
Gram- stains pink, their cell was is composed of a thin layer of peptidoglycans and lipids, sandwiched between two plasma membranes
Describe the following: obligate aerobes, obligate anaerobes, faculative anaerobes, faculative heterotrophs, photoautotrophs, and chemoautotrophs, obligate heterotrophs.
Obligate aerobes – require oxygen, their energy pathways are oxygen dependent
Obligate anaerobes – are oxygen sensitive and have only fermentation energy pathways
Facultative anaerobes – can tolerate oxygen, but can live without it.
Facultative heterotrophs – must consume organic molecules and can live in an oxygen environment or not.
Photoautotrophs – use solar energy to construct organic molecules
Chemoautotrophs – use energy from exergonic inorganic chemical reactions to supply the energy to construct organic molecules.
Obligate heterotrophs – organisms that must consume organic molecules
Describe the relationships and general characteristics of the following clades: Gram positive bacteria, gram negative bacteria, high G+C bacteria, low G+C bacteria, Actinomycetes, Lactic Acid Bacteria, Mycobacteria, Acid-Fast Bacteria, Endospore forming bacteria, Mycoplasmas, Proteobacteria, Purple-sulfur bacteria, N-fixing bacteria, Rickettsias, Myxobacteria, Green Sulfur bacteria, Green Nonsulfur bacteria, Enteric bacteria, Chlamydias, Cyanobacteria, Cyanota, Spirochaeta, Thermophilic bacteria, Eubacteria, Archaea, Methanogens, Thermoplasma, Hyperthermophiles, Extreme Halophiles, Crenarcheota, Euryarchaeota, Viroids, Prions, BSE, variant Crutzfeld-Jacob Disease, Scrapie.
Domain Eubacteria – contains 2 kingdoms
Kingdom Gram positive bacteria – Domain Eubacteria. Contains the divisions; High G+C and Low G+C. They possess a thick layer of peptidoglycans in their cell wall that retains the dye crystal violet; as a result they stain a dark purple or blue-black
Division High G+C bacteria / Firmicutes – contains three classes
Class Actinomycetes – most non-motile; decomposers; some parasites examples include; Streptomyces, and Actinomyces. A very common bacteria; mold like.
Class Lactic Acid Bacteria – they practice lactate fermentation. Examples include; Lactobacillus
Class Mycobacteria / Acid Fast Bacteria – these have mycolic acid in cell wall making them sensitive to acid fast stain; examples include; Mycobacterium (tuberculosis, leprosy)
Division Low G+C bacteria. Includes 2 classes
Class Endospore forming bacteria – bacteria forms an internal spore at one end of the cell. Examples include; Clostridium (botulism, tetanus) Bacillus.
Class Mycoplasmas – smallest bacteria (0.2 um). No cell wall, obligate intracellular parasites, amoeboid and colonial at times. Examples include Mycoplasmas (pneumonia)
Kingdom Gram negative bacteria – of Domain Eubacteria. Lacks the classic Gram+ cell wall. They have a cell wall composed of a thin layer of peptidoglycans and lipids, sandwiched between two plasma membranes; the crystal violet washes out and stain pink with safranin stain. Contains 8 divisions
Division Proteobacteria – a diverse clade that includes 4 Classes
Class Purple Sulfur bacteria – sulfur using photoautotrophs, anoxygenic (oxygen is not a byproduct). Important for sulfur cycling in nature
Class Nitrogen fixing bacteria – includes Rhizobium; a soil bacterium that fixes atmospheric nitrogen into ammonia; it an others are responsible for cycling of nitrogen in nature
Class Rickettsias – very small; possess cell wall; obligate intracellular parasites examples include; Rickettsia.
Class Myxobacteria – rod shaped shaped “gliding” bacteria; mostly decomposers. Examples include; Myxococcus, Chondromyces.
Division Green Sulfur Bacteria – photoautotrophic; anoxygenic; obligate anaerobes; elemental sulfur is one of the products. Can tolerate high temps.
Division Green Non Sulfur Bacteria - photoautotrophic; anoxygenic; obligate anaerobes; often found in thermal pools. Can tolerate high temps. Have different pigments than the Green sulfur bacteria.
Division Enteric Bacteria – group of gram negative rods that are found in the intestinal tract of mammals and other animals; many pathogenic; examples E. coli, Shigella, Salmonella, Klebsiella, etc.
Division Chlamydia – STD, small intracellular obligate parasites with the cell walls. Example; Chlamydia.
Division Cyanobacteria – (Cyanota) the so-called blue green Algae. They are photosynthetic, producing oxygen, they contain sheets of plasma membranes that contain photosystems. They utilize chlorophyll-a like plants, but contain a phycolibin pigments that aren’t found in plant chloroplasts; form heterocysts that are Nitrogen fixing; form akinetes (spores). Some have separation discs that cause filaments to fragment. Prochloronta a subclades that is ancestral to plant chloroplasts
Division Spirochaeta – long spiral; flagella within cell wall(internal); decomposers and pathogens. Examples include; Treponema, Borrelia.
Division Thermophilic bacteria – tolerate extreme heat; often found with Archaea; examples include; Thermusaquaticus, source of Taq polymerase used in PCR.
Domain Archaea – members are known as extremeophiles. Two kingdoms are recognized
Kingdom Crenarcheota – contains 3 divisions
Division Hyperthermophiles – are thermophilic and most also acidophilic; typically live in hot sulfur springs or deep ocean vents; can tolerate pH to 0.9 yet maintain neutral cytoplasmic pH. Example; Sulfobus.
Division Extreme Halophiles – salty environments; many contain carotenoids and have reddish-orange color, common in many inland seas. Example; Halobacterium.
Division Thermoplasma – thermophilic and acidophilic; lack cell walls; have been found in coal deposits, genome only 1100 kilobase pairs (less than 200 genes)
Kingdom Euryarchaeota – contains the following division
Division Methanogens – obligate anaerobes that produce methane (flatulence) by reducing carbon dioxide; some live in animal guts. Example; Methanopyrus.
Viroids – a strans of free RNA, without envelope or capsid, transmittable, possibly derived from viruses. Active in some plant diseases.
Prions – infectious proteins. Heat tolerant, and hard to destroy. They all cause holes to form in the brain because it attacks nerve tissue. This abnormal version of protein induces normal proteins to refold into abnormal form, then the immune cells clean up the mess which leaves holes in the brainCauses the following diseases;
Scrapie - in sheep,
BSE(Bovine Spongiform Encephalopathy) in cows,
CWD (chronic wasting disease) in eld and deer.
Crutzfeld-Jacob Disease in humans..
Arrange the evolution of the following from earliest to most recent: Eubacteria, Archaea, Eukaryotes (Protists), Fungi, Rhyniophyta, Bryophytes, Conifers, Anthophytes.
Eubacteria Archaea Eukaryotes
Rhyniophyta – from the early Devonian period
Bryophyts appear in the fossil record 385 ma in the Devonian period of the Paleozoic era
Coniferophyta - conifers appear in the fossil record 320 ma in the Mississippian period, a subdivision of the Carboniferous period of the Paleozoic era
Anthophyta – Anthopytes (flowering plants, formerly called the angiosperms) probably evolved from Gnetophyta approximately 150 ma in the Jurassic period of the Mesozoic era
Describe the relationships and general characteristics of the following terms/clades: Excavata, SAR, Unikonta, Plantae, Diplomonada, Trichomonada, Kinetoplastida, Trichonympha (Hypermastigophora), Amoeba, Flagellate, Protozoa, Algae, Rhizopoda, Foraminifera, Actinopoda, Radiolaria, Heliozoa, Ciliophora, Opalinida, Apicomplexa, Choanoflagellida, Myxomycota, Dictyostelida, Acrasida, Oomycota, Euglenophyta, Chrysophyta, Bacillarophyta, Desmids, Dinoflagellates, Diatoms, Pyrrophyta, Phaeophyta, kelp, Rhodophyta, Chlorophyceae, Charophyta, Coleochaetales, Desmidiales, Zygnematales, Ulvophyceae.
Domain Eukarya – is composed of four Superkingdoms
Superkingdom Excavata – lack classical mitochondria. Contains the following 5 kingdoms
Kingdom Diplomonada – spore forming flagellates that lack mitochondria. Includes the genus Giardia which contaminates water and causes severe diarrhea.
Kingdom Trichomonada / Parabasalia – small oval or round Protozoa; lacks mitochondria. Have several flagella at one end; a small undulating membrane and an axoneme (not sure of function). All are obligate parasites. Includes; Trichomonas which causes urinary tract infections and vaginitis.
Kingdom Kinetoplastida – has a single large mitochondria that includes a structure called a kinetoplast. Kinetoplast contains DNA and proteins. Trypanosomes are Kinetoplastids that have a single flagellum that runs the length of the cell within the cell membrane. When it beats it creates an undulating membrane (characteristic of the clade) Trypanosoma causes sleeping sickness in Africa and Chagas Disease in South America.
Kingdom Hypermastigophora – have numerous flagella unlike most flagellates. Members of the genus Trichonympha live in the gut of cows, sheep and termites digesting cellulose for their hosts in a mutualistic relationship. It’s actually the bacteria living within the Trichonympha that digests the cellulose.
Kingdom Euglenophyta – are faculative heterotrophic algae. Unicellular, flagellated green algae. Possess flagella; cell walls don’t contain cellulose; can live for extended periods w/o light; have light sensitive organelle called a stigma; are common fresh-water phytoplankton. Includes genus Euglena.
Superkingdom SAR – (Stramenopila – Alveolata Rhizaria) Algae with tetramembraneous chloroplasts, exhibit flagellae in life cycle, some amoeboid, some exhibit indentation in the cell membrane known as alveolae. Contains the following 11 kingdoms
KingdomRhizopoda – the typical amoebas
genera Amoeba and Chaos are free living aquatic examples
genera Naeglaria is a brain parasite that can enter via the nasal mucous membranes and Entamoeba causes amoebic dysentery and is ingested
Kingdom Foraminifera – are marine plankton that have a calcium carbonate test shell external to the cell membrane. Readily form fossils; form skeleton date time periods; form limestone deposits.
Kingdom Actinopoda – have thin stiff pseudopods with microtubular endoskeletons. Functions in feeding and locomotion; found in marine and fresh water plankton; contain two divisions
Division Radiolaria – are exclusively marine; have internal shell of silicon to support pseudopods and body
Kingdom Ciliophora – ciliated protozoa; all members have cilia; Ciliates have two morphologically different nuclei. Most have a micronuclei and a single macronucleus that is polyploid. Can reproduce asexually and sexually. Most free living in marine or aquatic habitats. Examples Paramecium, Stentor, Vorticella.
Kingdom Opalinida – are ciliated protozoa; members are similar to ciliates, but only have micronuclei and several of them that are iridescent under microscope looking like jewels. Most are parasites of amphibian intestines.
Kingdom Apicomplexa – protozoa that lack flagella. All members are obligate parasites and lack motility (no pseudopods, cilia or flagella) in part of life cycle. Most for spores which helps survive unfavorable periods; members often demonstrate complex life cycles, and modes of transmission. Example Plasmodium (causative agent of malaria)
Kingdom Oomycota – fungi-like protists; known as water molds and downy mildews; form filaments called hyphae; the mass of hyphae is mycelium; cell walls composed of cellulose w/o chitin; aquatic and terrestrial forms; feed by absorption of detritus, or act as parasites; will form diploid flagellated zoospores under proper conditions. Examples Saprolegnia forms mold on dead fish or insects; Phytophthora infestans is a parasite
Kingdom Chrysophyta – common name = the golden (yellow) algae; unicellular, some colonial or filamentous; two flagella of unequal lengths. Includes the groups golden-brown algae and yellow-brown algae; cell wall composed of pectin (not cellulose); store oils rather than starch; contain chlorophyll-a & carotenoid accessory pigments; most unicellular forming a large part o marine and freshwater plankton
Kingdom Bacillariophyta – common name = Diatoms; have a shell composed of two halves that fit together like a petri plate.
Kingdom Pyrrophyta/Dinoflagellida – common name = fire algae; unicellular flagellates; possess two flagella in grooves(longitudinal)makes the cell spin as it swims; cell wall composed of cellulose; contain chlorophyll-a and red pigments (responsible for red tides); secretes toxins; many forms also bioluminescent
Kingdom Phaeophyta – common name = brown algae; multicellular algae, includes the larges algae in the world, coastal brown kelps; plastids contain fucoxanthin and phycobilin and carotenoid pigments; stores excess energy as oils; cell walls contain alginic acid; most brown kelp are anisogamous, heteromorphic, and sporophyte dominant; examples Sargassus (free floating), Macrocystis (coastal brown kelp); one of three clades of algae
Superkindom Unikonta – heterotrophs whose motile cells possess a single flagellum. There are 3 kingdoms of slime molds. Slime mold characteristics; motile, detritivores, form spores on elaborate fruiting bodies, change forms
Kingdom Myxomycota – acellular slime molds. life cycle; form a diploid plasmodium (non reproductive phase). Plasmodium is syncytium or coenocytic meaning has a shared cytoplasm which streams about like an amoeba. When conditions change they’ll convert to one of two structures; a sclerotium ( a dehydrated plasmodium that will reform as a plasmodium when rehydrated), or a fruiting structure. Cells form and rise above the plasmodium, sporangia forms and undergoes meiosis to form haploid spores, spores disseminated and develop into amoeboid cells called swarm cells that divide mitotically, swarm cells may fuse and form a zygote, zygote divides forming a plasmodium
Kingdom Dictyostelida – cellular slime mold. Life cycle; numbers of individual haploid cells called myxamoebas are the vegetative form, they migrate and ingest detritus, bacteria and fungi. In response to the production of cAMP the myxamoebas aggregate to form called a pseudoplasmodium. The cells form a fruiting structure, haploid spores form and are released, they germinate to produce myxamoebas in favorable conditions. Sexual cycle; haploid myxamoebas may fuse to form a zygote, spores or capsule forms, and meiosis occurs, it germinates to yield haploid myxamoebas.
Kingdom Acrasida – cellular slime mold. Does not respond to cAMP
Kingdom Choanoflagellida / Choanomastigophora – flagellated protozoa. Have collar-like structure supported by microtubules around flagella. Filter feed catching matter in collar. Considered ancestral to Metazoa
Superkingdom Plantae – some algae, some true plants
Kingdom Rhodophyta – common name Red Algae. Multicellular, some filamentous algae. Store energy as Floridian starch. No motile gametes or spores. Cell wall contains a mucilaginous polysaccharide that forms agar. Harvested for agar.
Kingdom Chlorophyceae – Chlorophytan green algae. Genus Volvox can exist as single celled flagellated individuals, or multicellular colonies
Kingdom Ulvophyceae – Chlorophytan green algae. true multicellular green kelp. Example Ulva (sea lettuce)
Kingdom Charophyta - Chlorophytan green algae. Ancestors to plants. Includes unicellular Desmids, filamentous green algae such as Spirogyra. Includes 3 divisions
Division Desmidiales – unicellular green algae. Resembles diatoms but has different pigment.
Division Zygnematales – filamentous green algae. Examples Spirogyra. Sexual cycle; + and – haploid filaments contact each other and a conjugation tube forms. Cytoplasm from + streams into the – cell and encapsulates. Nuclei fuse and form a zygote which drops to the bottom, undergoes meiosis yielding haploid cells. They grow into new filaments.
Division Coleochaetales – ancestral and monophyletic to the plant kingdom. Chloroplast pigments are the same. Tissues present.
Kingdom Euplantae – true plants and direct relatives. True plants; sporophyte begins life within gametophyte tissue.
Be familiar with life cycles of the clades in bold in the previous question.
What stage of the malarial organism, Plasmodium, is infective to humans? Which stage is infective to the Anophales mosquito? The infective state to humans is the sporozoites. The infective stage for the Anophales mosquito is the gametocytes that are free floating in our blood
How is Plasmodium different from a plasmodium? Plasmodium is the protozoan that causes malaria. From the Kingdom Myxomycota of the S.Kingdom Unikonta, A Plasmodium is described as a coenocytic mass in which the internal walls and membranes break down forming a huge cytoplasmic mass with multiple diploid nuclei.
How are Fungi different from fungal-like protists?
Fungi-like protists include the slime molds of Kingdom Unikonta, and Oomycota of the S.Kingdom SAR. They’re motile, ingest food by Endocytosis
Fungi are absorptive heterotrophs (digest food externally) they don’t endocytose
Describe the relationship between the following: thallus, blade, holdfast, and stipe.
Thallus – this is the body of a nonvascular plant. The algal plant
Describe the relationship between the following: hypha, hyphae, and mycelium.
Hypha – is a singular term. A hypha is a filament grown by a fungus or fungi-like protist.
Hyphae – this is the plural term for hypha. Typically coenocytic.
Mycelium – the mass of hyphae is called the mycelium
Describe the relationship between the following: haploid, diploid, and dikaryotic.
Haploid – a nucleus with one set of chromosomes
Diploid – a nucleus with two sets of chromosomes
Dikaryotic – N + N. having two haploid nuclei
What are lichens, and are the organisms? A lichen is a mutualistic symbiotic relationship with a fungus and an algae (sometimes bacteria). The fungus is typically Ascomycota (sometimes Basidiomycota or Deuteromycota, and only one known of Zygomycota). The algae component is typically a unicellular chlorophytan and sometimes a Cyanobacteria.
What are soredia? Lichens typically reproduce by the formation of soredia. Soredia are algal or cyanobacterial cells surrounded by hyphae. Soredia are carried away by wind or water.
Describe the relationships, characteristics, and life cycles of the following fungal clades: Chytridiomycota, Zygomycota, Basidiomycota, Ascomycota, Euascomycota, Hemiascomycota, Deuteromycota.
Division Chytridiomycota – (flower pot mold) the most ancient group of fungi. Extremely diverse; saprobes, parasites, marine, freshwater, and soil varieties
Division Zygomycota – the zygospore forming fungi. Characterized by the formation of heavy walled, black zygospores. Life cycle of Rhizopus stolonifer (black bread mold);
haploid hyphae are coenocytic. Hypha may asexually reproduce by forming terminal sporangia at the end of the hyphae. These produce spores which germinate into new hyphae and mycelium. Sexual reproduction is triggered when + and – grow near one another. Gametangia form at the tips of the hyphae; the gametes fuse forming a diploid zygote. The zygote forms heavy walls, resistant to enviro stress and is now called a zygosporangium. The zygosprangium under goes meiosis forming numerous haploid zygospores. These spores germinate into new + and - hyphae
Division Basidomycota – the club fungi. Includes mushrooms, shelf gungi, rusts, smuts, and puffballs. Life cycle;
+ and – haploid hyphae in the soil grow together and produce dikaryotic cells and a dikaryotic mycelium which is highly compact (basidiocarp). It will develop into the stipe (stalk) and pileus (cap) of the mushroom. Gills / lamellae develop in the pileus and dikaryotic cells called basidea (club-shaped) for at the end of hyphae. Within the basidia haploid nuclei fuse forming a zygote which undergoes meiosis. The resulting haploid nuclei are born within spores on the tip of the basidum called basidiospores. They germinate into new + and - hyphae
Division Ascomycota – the sac fungi. Includes the unicellular yeast, morels, truffels and cup fungi. They produce spores within a sac-like structure called an ascus.
Class Hemiascomycota – primarily unicellular – yeasts. Yeasts asexually reproduce by budding. Haploid yeasts can fuse with other yeasts of a different mating type (+ or -). The nuclei fuse forming a zygote which undergoes meiosis producing 4 or 8 spores within the cell which serves as the ascus (sac)
Class Euascomycota – includes all other ascomycota. Has haploid hyphae. They may form conidia at the ends of the hyphae which produce conidiospores (chains of spores unprotected by sporangium). These germinate to form new hyphae. + hypahal cells fuse with – cells to form dikaryotic cells which grow into dikaryotic hyphae. The dikaryotic hyphae form a fruiting structure of some type called an ascocarp. This is often cup-like in appearance and called an apothecium. On the surface the apothecium will develop the sac-like sporangia called asci. When asci develop, the nuclei fuse forming a zygote which undergoes meiosis. The ascus typically contain 8 spores which germinate into new + and – hyphae
Deuteromycota –(now considered apart of Ascomycota) The imperfect fungi. The dumping ground for fungi in which a sexual cycle was not known. Includes many beneficial and dangerous members: Penicillium, Aspergillus.
Which fungal clade is not monophyletic and rarely seen in fungal cladistics? Deuteromycota
Plants are monophyletic with which Protist clade? ‘Choleochaetales. They both store starch. The plastids of both contain the same photosynthetic pigments: chlorophyll-a and chlorophyll-b, xanthophylls, beta-carotene, and other characteristic carotenoids. Both have cellulose cell walls. Both demonstrate anisogamy.
How are plants different from algae? – plants are multicellular with well developed tissues. Have cell walls made primarily with cellulose.
Describe alternation of generations.
Diploid sporophyte produces sporangia within which specific cells undergo meiosis yielding haploid spores which get disseminated by wind or water
Spores germinate into multicellular haploid plants called gametophytes.
Gametophytes produce haploid gametes with in structures called antheridia for male, and archegonia for female.
Sperm released from the antheridia must swim in primitive plants or are carried by wind or pollinators in advanced plants to the ova
Sperm fertilizes an ovum yielding a diploid zygote which mitotically divides into a new diploid sporophyte.
How are homosporous plants different from heterosporous plants?
Homosporous plants produce spores of only one type. Spores germinate into a gametophyte, the gametophyte bears both antheridia and archegonia
Heterosporous plants produces spores of two types: microspores (male) and megaspores (female). Microspores germinate into male gametophytes bearing only antheridia. Megospores germinate into female gametophytes bearing only archegonia.
Describe the relationship between the following terms: gametangium, gametangiophore, gamete, archegonium, antheridium, sperm, and ovum.
Gemetangium is a structure that produces gametes.
Archegonium is a female type gemetangium that produces ova (gamete)
Antheridium is a male type gametangium that produces sperm (gamete)
Describe the relationship between the following terms: sporangium, spore.
Sporangium is a diploid structure within which special cells undergo meiosis to yield haploid spores.
How is the root system different from the shoot system?
Shoot system is above ground. Adaptations for this environment include: leaves to absorb light, support tissue for leaves, stems and branches to offset gravity, waterproofing, stomata to take in CO2 with minimal transpiration, vascular system (xylem, phloem), defense mechanisms.
Root system is below ground. Adaptations include: root hairs and numerous root branches to form a high surface to volume ratio for efficient uptake of H2O and minerals, and to anchor the plant in the soil, vascular system.
Describe the relationship between the following terms: xylem, phloem, transpiration, translocation of sugars, living, dead, lignin.
Xylem – dead tubes under negative pressure that carries water from the ground up. Tissue was alive but as secondary wall gets lignified, the cell dies and holes through the cell wall are created. Cells stacked on top of each other creates the tube that works with capillary action. Functions via transpiration (water loss through leaves)
Phloem – living tubes under positive pressure that carries sap from areas of high pressure to areas of low pressure called sinks (translocation). Sieve tubes: actual vascular cells. Large holes in ends of sieve tubes = sieve plates, allow for bulk flow of sap. Companion cells regulate translocation.
Endosperm – remnants of the megagametophyte used as nutrients for the embryo
Radicle – the tip of the embryonic root
Epicotyl – the part of the seedling above the site where the cotyledons attach to the seedling. Some of the epicotyl may be below ground
Hypocotyl – the part of the seedling below the site where the cotyledons attach to the seedling. Some of the hypocotyl my be above ground
What are characteristics of monocots and dicots?
Monocot – flower part comes in 3’s, leaf venation is parallel, root system is fibrous, stem venation is scattered
Dicot – flower part comes in 4’s or 5’s, leaf venation is netted, root system has a tap root, stem venation is peripheral
Plant tissues will be tested in the laboratory.
Describe the primary functions of the following plant hormones: Indole acetic acid (auxin), Giberellic acid (giberellin), Cytokinins, Abscissic acid, Ethylene, Florigen.
Indole acetic acid (auxin) – IAA, growth stimulatory – elongation of cells, abscission repression. Stimulates cambium (secondary growth), fruit maturation
Giberellic acid (giberellin) – GA, originally discovered as a fungus product, found in young leaves of plants. Growth stimulatory, stimulates maturation or stimulates reversion to juvenile status, releases some buds and seeds from dormancy, results in growth. Related to flowering in some plants as concentrations change in relation to day length. Causes stem elongation, stimulates pollen tube growth in angiosperms
Cytokinins – related to adenine. Mitotic stimulator – growth. Stimulates bud growth, stimulates fruit and embryo development, prevents leaf senescence (inability for a cell to divide), mimics effects of phytochrome
Abscissic acid – ABA, general growth inhibitor, induces dormancy in buds and leaves (winter). Closure of stomata, resistance to stress
Ethylene – a gaseous hormone, playas role in fruit ripening, fruit abscission, stimulates own production in many fruits, initiation of fruit hairs
Florigen – flowering hormone. Florigen is a long hypothesized hormone for flowering that has yet to be identified.
What are factors that affect flowering in plants.
Plants flower in response to day length or night length, and temperature and nutritional influences can affect the timing and amount of flowering on a given plant. Plants fall into one of the following categories
Long day plants
Short night plants
Long night plants
Short day plants
What are nitrogen fixing bacteria, and how are they related to nitrogen fixing plants?
Rhizobium is a Nitrogen fixing bacteria within the Division Proteobacteria within the Kingdom Gram Negative bacteria. Together with plant roots, they allow plants to fix nitrogen. Mycorrhizae are fungi tat associate with plant roots. They absorb phosphates, nitrates or other nutrients from the soil and transfer to the root hair in exchange for sugars from the plant root.