Biology Test 3
Biology 1220 with Johsnon/melbourne at University of Colorado Boulder
About this deck
By: Jamie Anderson
Textbook:
Biology with MasteringBiology? (8th Edition)
Created: 2011-04-02
Size: 123 flashcards
Views: 111
Textbook:
Biology with MasteringBiology? (8th Edition)Created: 2011-04-02
Size: 123 flashcards
Views: 111
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Fungi
o More like animals o 100,000 species of fungi have been described o Possibly 1.5 million? o Diverse: colonized all terrestrial habitats o Eukaryotes
Famous Fungi
o Athletes foot, humongous fungus, vegemite
Nutrition of Fungi
o Diverse: but nutrition is similar (decomposers, parasites, mutualists) o Fungi are heterotrophs (food from other organisms-don’t make food like plants/algae) o Fungi don’t “eat” food o Secrete exoenzymes into surroundings o Break down complex molecules (into smaller molecules) o Absorb smaller molecules o High surface area to volume ratio of mycelia enhances feeding efficiency
Structure of hyphae
o Have tubular cell walls o Cell walls contain chitin (chitin also found in insect exoskeletons) which make them different from plant cell walls that contain cellulose o Septa (sing. Septum) divide cells
Coenocytic hyphae
Fungi that lack septa
How hyphae can be specialized
To trap and kill prey
Haustoria
Haustoria
o To penetrate host tissues (“haustoria”)- outgrowth finger shape steals or exchanges nutrients from plant
Parasitic fungi Mutualistic fungi: mycorrhizae (“fungus roots”)
Types of mycorrhizae
Ectomycorrhizae: hyphae form on root surface
Endomycorrhizae: extend hypahe through root cell wall
Mycelium
o An interwoven mass that infiltrates the material on which the fungus feeds. o Its’ structure maximizies its surface area to volume ratio making feeding more efficient
Mycorrhizal associations: mutualism
o Mutualism (+/+): plant obtains nutrients (phosphorus, nitrogen, minerals) o Fungus obtains organic compounds (photosynthate)
Reproduction of fungi
o Reproductive cells are spores (sexual, asexual, dispersed by wind and water) o Nuclei and spores are haploid o Diploid stage is transient
Generalized sexual life cycle of fungi
o Sexual reproduction:
- Hyphae from 2 distinct mycelia fuse (plasmogamy: fusion of cytoplasm from two parent mycelia)
- Mycelia are now heterokaryotic (“different nuclei”), heterogeneity in their karyotypes
- Karyogamy then occurs: fusion of nuclei, creates diploid zygote
Generalized asexual life cycle of fungi
o Spores germinate, form mycelia o Mycelia produce spore-producing structures (puff balls) o Spores germinate, cycle repeats o All structures are haploid
Asexual reproduction is common in:
o 20% of fungi o Molds o Yeasts: cell division or budding (small portion of parent cell pinches off)
What is the primary role of a mushroom’s underground mycelium?
Absorbing nutrients
Evolutionary relationships of fungi
o Phylogenetic evidence suggests that fungi evolved from a flagellated unicellular ancestor o Molecular clock suggests that animals and fungi diverged 1.5 billion years ago o But, oldest fossils of fungal hyphae and spores are from 460 million years ago o Fungi and animalia are sister kingdoms
Which of the following is a characteristic of hyphate fungi (fungi featuring hyphae)?
o They are adapted for rapid directional growth to new food sources
Characteristic of hyphate fungi
o They do not acquire their nutrients by phagocytosis o Their cell walls do not consist mainly of cellulose microfibris o Their body plan is not a unicellular sphere o They do not reproduce asexually by a process known as budding (done by other fungi such as yeasts)
Phylogeny of Fungi
o Three good phyla: club fungi (basidiomycota), sac fungi (ascomycota), arbuscular mycorrhizal fungi (glomeromycota) o Two groups complicated relationship: zygomycota (zygote fungi) and chytridiomycota (chytrids) o Fungi and animalia are sister kingdoms o Fungi have radiated into a diverse set of lineages
Fungal evolution is a key frontier of science
o Molecular phylogenetics o Used DNA to construct evolutionary tree o Homology: similar due to shared ancestry o Method: mathematical biology (6 genes, 200 species) Results: the tree with the greatest support
Results of fungal evolution research
o Many more phyla o Unicellular, flagellated o Phylogenetic tree is paraphyletic
Chytridiomycota (chytrids)
o Most ancient but not monophyletic o About 1000 species known o Simple fungi o Produce flagellated spores (zoospores) o Mostly decomposers and parasites in aquatic habitats
The amphibian chytrid
o Has been found on over 90 species of frogs o Invades skin, affects ability of frog to regulate exchange of water and oxygen with environment o Main cause of amphibian declines and extinctions in Latin America, Australia, and North America
If there were no mycorrhizae then which of the following would be true?
o Most vascular plants would be stunted in their growth
Characteristics of mycorrihzae
o They don’t cause disease (mutualism) o They do not give use antibiotics, we get them from other places o Not all produce mushrooms o They do not produce cheese, yeasts do
Ecology and human uses of fungi
o Fungi can be: § Decomposers § Mutualists § “Predators” carnivores § Parasites (of plants, animals, even fungi) § Useful
Use of fungi as decomposers
o Fungi are essential for the cycling of dead materials o Convert organic compounds to inorganic nutrients o Without decomposers, life as we know it would cease, nutrients would stay locked up
Fungi: symbionts
o Symbiosis: interspecific relationship where partners are in direct contact (mutualism = +/+ interaction)
Lichens
symbiotic association between a photosynthetic mircroorganism and a fungus in which millions of photosynthetic cells are held in a mass of fungal hyphae:
Mutualism between: · Fungus: provides structure · Usually ascomycota · Alga or cyanobacterium provides food · Orange stuff on rocks
Symbionts: plant pathogens (parasitic fungi)
About 30% of 100,000 known species of fungi are parasites, mostly on or in plants Dutch elm disease, chestnut blight (chestnut trees wiped out on East coast) Other fungi, such as rusts and ergots, infect grain crops
Practical uses of fungi
o Antibiotics (penicillin from penicilium o Production of bread, cheese, wine and beer (yeast) o Things we eat: mushrooms, truffles
· When a mycelium infiltrates an unexploited source of dead organic matter, what are most likely to appear within the food source soon thereafter?
Fungal enzymes
· Which of the following characteristics is shared by both chytrids and other kinds of fungi?
nucleotide sequence of several genes
Evolution of plants from water to land
o Land plants evolved from green algae: § Most plants are terrestrial § Land plants = all plants, in contrast to algae, which are photosynthetic protists § 290,000 described species of land plants § Plants supply O2 § Plants supply food (most are autotrophs)
Charophyceans
· (a group of green algae) are closest relatives of land plants
Embryophytes
land plants
Closest living relative of land plants:
charophyceans (chara and coleochaete, based on morphological, biochemical, and genetic evidence)
Three groups of plant phyla
o Nonvascular plants (bryophytes) o Seedless vascular plants o Seed plants (gymnosperms, angiosperms)
If all fungi in an environment that perform decomposition were to suddenly die, then which group of organisms should benefit most, due to the fact that their fungal competitors have been removed?
Prokaryotes (bacteria)
· Terrestrial adaptations: alternation of generations:
o The gametophyte produces haploid gametes by mitosis o Two gametes unite (fertilization) and form a diploid zygote o The zygote develops into a multicellular diploid sporophyte o The sporophyte produces haploid spores by meiosis o The spores develop into multicellular haploid gametophytes
· Terrestrial adaptations: multicellular, dependent embryos: “embryophytes”
o Embryo develops from zygote retained within female parent o Parental tissues provide sugar, amino acids o Placental transfer cells in embryo enhance transfer of nutrient
· Terrestrial adaptations: walled spores (with sporopollenin) produced in sporangia:
o Sporopollenin makes walls of plant spores resistant to desiccation
· Terrestrial adaptations: multicellular gametangia
o Multicellular gametangia: organis in which gametes are produced o Archegonium: female simple egg o Antheridium: male, many flagellated sperm
· Terrestrial adaptations: apical meristem:
o Apical meristem: localized region of cell division at tips of roots and shoots
· Summary of 5 traits to set first land plants apart from closest algal relatives:
o Alternation of generations o Multicellular, dependent embryos o Walled spores produced in sporangia o Multicellular gametangia o Apial meristems
· Which of the following is a symbiotic relationship?
o Mycorrhizae, chytrid fungus and frogs, glomeromycota and plants, lichens
· Origin and diversification of land plants: 3 distinct groups:
o Nonvascular plants (bryophytes) o Seedless vascular plants (lycophytes, pterophytes) o Seed plants (gymnosperms, angiosperms)
· The most recent common ancestor of all land plants was most similar to modern-day members of which group?
Charophycea
Nonvascular plants (bryophytes) characteristics of life cycle
o Gametophyteis dominant stage o Sporophyteis dependent on gametophyte for nutrients o Archegonium= female gamete-producing organ o Antheridium= male gamete-producing organs o Water required for fertilization (sperm need water to move) o Embryo develops within archegonium
Haploid stage of the life cycle of a moss
§ Spores develop into threadlike protonemata § The haploid protonemata produce buds that grow into gametophores § Sperm must swim through the film of moisture to reach the egg
Diploid stage of the life cycle of a moss
§ Fertilization occurs within the archegonium § The zygote develops into a sporophyte embryo § The sporophyte grows a long stalk that emerges from the archegonium § Attached by its foot, the sporophyte remains nutritionally dependent on the gametophyte § Meiosis occurs and haploid spores develop in the capsule. When the capsule is mature, its lid pops off and the spores are released
Primary research article: mosses reduce the rate at which nitrogen is lost from the soil:
o Field experiment o Microcosms: moss intact, moss removed o Measured N inputs and outputs o Key principles of experimental design were replication and randomization
Conclusion of experiment
o Polytrichummosses are very efficient at capturing N o Captured 95% of the input N o Without moss, 85% of N from rainfall was lost by leaching
Importance of replication and randomization in field experiments
o Better experiments are randomized to avoid unintentional bias o Better experiments have many replicated experimental units to ensure that the experimental manipulation is causing the observed outcome rather than chance
One major distinction between plants and green algae
o Embryos are not retained within parental tissues in green algae
· Sphagnum moss; peet deposits
o Important to global carbon cycle: peatlands store an estimated 400 billion tons of organic carbon
What is a lichen?
Fungus-algae mutualism or fungus-cyanobacteria mutualism
Traits that characterize vascular plants
o Sporophyte generation dominant and independent o Vascular tissue o Evolution of roots and leaves o Sporophylls and spore variation o Branched sporophytes
Life cycle of a fern (dominant sporophyte) seedless vascular plant
o Sporangia release spores once meiosis occurs Most fern species produce a single type of spore that develops into a bisexual photosynthetic gametophyte (haploid) o Goes from mature gametophyte (n) and then sperm use flagella to swim from antheridia to eggs in the archegonia o Fertilization occurs and a 2n zygote is created o Zygote develops into a new sporophyte and the plant grows out from an archegonium of its parent (diploid)
Difference between fern life cycle and moss life cycle:
moss: dominant gametophyte
fern: dominant sporophyte
Vascular tissue of vascular plants
o Vascular tissue= transport o Xylem: conducts water and minerals o Phloem: conducts sugar, amino acids o Presence of lignin (xylem) means stronger stems: reach higher heights!
Evolution of roots and leaves in vascular plants
o Vascular plants have roots: absorb water and nutrients from soil o Note: bryophytes have rhizoids (anchor plant, but do not have specialized conducting cells), these are NOT true roots
· Origin and traits of vascular plants: leaves
o Leaves: increase surface area and therefore enhance photosynthesis
· Origins and traits of vascular plants: sporophylls and spore variations
o Sporophylls: modified leaves that bear sporangia o Ferns: undersides of the sporophylls produce sori (clusters of sporangia) o Lycophytes and gymnosperms: groups of sporophylls form cones (strobili) o Spore production: homosporous and heterosporous
Homosporous
(most seedless vascular plants) · Sporophyte: single type of spore: typically a bisexual gametophyte: eggs and sperm
Heterosporous
(most seed plants) · Sporophyte: either megaspore which produces a female gametophyte and eggs or a microspore which produces a male gametophyte and sperm
flagellated sperm, xylem, separate gametophyte and sporophyte generations, and no seeds. This plant is probably most closely related to?
Ferns
· Working from deep geologic strata (old) toward shallow geologic strata (young), what is the sequence in which fossils of these groups should make their first appearance?
o Single-celled green algae o Charophyceans o Hornworts o Plants with a dominant sporophyte
Ferns and other seedless vascular plants
o Lycophytes (lycophyta) o Pterophytes (pterophyta) o Both formed forests during the carboniferous period about 300-360 million years ago o First forests (carbonifersou)
Role of lycophytes and pterophytes in global climate, past and present
o Vascular tissue, roots, leaves
- Accelerated rate of photosynthesis
- Co2 decreased 5x
- Global cooling & glaciation
- we now burn (electricity)
- global warming
· Which taxon is another name for embryophytes?
Plantae (embryos are a key innovation of plants)
Traits that characterize seed plants
§ Further reduction of gametophyte § Heterospory: the rule among seed plants § Ovules and eggs § Pollen and sperm § Seeds and pollen gains are key adaptations for life on land
Heterospory rules of seed plants
§ Sporophyte: either megaspore which turns into female gametophyte and produces eggs or microspore which produces male gametophytes and sperm
Ovules and eggs in seed plants
§ Unfertilized ovule: megasporangium (diploid) with haploid megaspore inside becomes a fertilized ovule (haploid megaspore) and then becomes a gymnosperm seed with embryo inside (new sporophyte that is diploid) integuments
Pollen and sperm in seed plants
§ Pollen grain: male gametophyte within pollen wall of sporopollenin § Gametophyte is 2 cells (pollen tube & generative cell) § Generative cell produces sperm § No water needed
Gametophyte and sporophyte evolution in seed plants
o Gametophyte: reduced (usually microscopic) dependent on surrounding sporophyte tissue for nutrition o Sporophyte: dominant
As a group seedless vascular plants are:
paraphyletic
Seed
o Has 3 things: sporophyte embryo, food supply, seed coat o Multicellular structure resistant to environmental stress
· Which of the following is an ongoing trend in the evolution of land plants?
Reduction of gametophyte phase of the life cycle
Seed plants: gymnosperms
o Naked seeds”: seeds that are exposed on modified leaves that usually form cones (strobili) o Include: § Conifers (pines, firs, redwoods, juniper, cypress, cedar) § Cycads § Gingkos (1 extant species) § Gnetophytes (Welwitschia Ephedra)
Key features of the gymnosperm life cycle
o Dominance of the sporophyte generation o Development of seeds from fertilized ovules o The transfer of sperm to ovules by pollen
The life cycle of a pine
o The pine tree is the sporophyte and produces sporangia in male and female cones o Small cones produce microspores called pollen grains, each of which contains a male gametophyte o The familiar larger cones contain ovules which produced megaspores that develop into female gametophytes o It takes nearly three years from cone production to mature seed
What is the gametophyte in the life cycle of a pine?
Archegonium
What is the sporophyte in the life cycle of a pine?
o The pine tree, produces sporangia in male and female cones
Which stage is haploid in the pine life cycle?
o The megasporocyte undergoes meiosis producing four haploid cells. One survives as a megaspore o Female gametophyte develops within the megaspore and contains two or 3 archegonia, each of which will form an egg o When the eggs are mature, 2 sperm cells extend to the female gametophyte and fertilization occurs when sperm and egg nuclei unite
Which stage is diploid in the pine life cycle?
o Microsporocytes divide by meiosis producing haploid microspores. o A microspore develops into a pollen grain (a male gametophyte enclosed within the pollen wall) o After fertilization which usually occurs more than a year after pollination. All eggs may be fertilized but usually one zygote develops into an embryo. The ovule becomes a seed consisting of an embryo, food supply, and seed coat
Role of megasporangium in pine life cycle
o Diploid, pollen grain germinates forming a pollen tube that slowly digests its way through the megasporangium
Megaspore in pine life cycle
o The female gametophyte develops within the megaspore, haploid
Microsporangium in pine life cycle
o (diploid) Microspores divide by meiosis in microsporangium. And the microspore develops into a pollen grain
Pollen cone in pine life cycle
o Microsporocytes undergo meiosis producing haploid microspores
Ovulate cone in pine life cycle
o Megasporocytes undergo meiosis and produce haploid megaspores inside the ovule
· How many generations make up the seed are they diploid or haploid and where do the seed parts come from?
o The seed is diploid and the ovule becomes a seed, consisting of an embryo, food supply, and seed coat
Flower
o Shoot with modified leaves that is specialized for sexual reproduction: both wind and animal pollination o Up to four rings of floral organs (sepals, petals, stamens, carpels)
Flower: stamen
microsporophyll, produces microspores: pollen
Flower: carpel
o megasporophyll, produces megaspores: female gametophyte
Flower: petals and sepals
sterile floral organs
Flower: filament
the stalk in the stamen
Flower: anther
terminal sac in the stamen where pollen is produced
Flower: stigma
at the tip of the carpel, sticky and receives pollen
Flower: style
leads from the stigma to the ovary at the base of the carpel
Flower: ovary
at the base of the carpel, contains one of more ovules
Flower: ovule
if fertilized, develops into a seed, inside the ovary
Fruits for dispersal
§ Example of dispersal by wind: tumbleweed, dandelion parachute, winged fruit of maple, winged seed of asian climbing gourd § Example of dispersal by water: coconut § Example of dispersal by animals: fruits in fur, seeds in feces from nutritious fruits, seeds buried in caches, seeds carried to ants nest, barbed fruit
Pollination in flowers
o Many plants have highly specific animal pollinators § Flower structure evolved to promote a single species of pollinator
Fruit
o Usually includes mature ovary, and may contain other floral parts as well o Wall of ovary becomes pericarp, the thickened wall of the fruit
Angiosperm lifecycle
o The flower of the sporophyte produces microspores that form male gametophytes and megaspores that form female gametophytes o Male gametophytes are contained within pollen grains produced by the microsporangia of anthers o The female gametophyte, or embryo sac, develops within an ovule contained within an ovary at the base of a stigma o Most flowers have mechanisms to ensure cross- pollination between flowers from different plants of the same species
Process of angiosperm lifecycle
o A pollen grain that has landed on a stigma germinates and the pollen tube of the male gametophyte grows down to the ovary o Double fertilization occurs when the pollen tube discharges two sperm into the female gametophyte within an ovule o One sperm fertilizes the egg, while the other combines with two nuclei in the central cell of the female gametophyte and initiates development of food-storing endosperm (triploid) o The endosperm nourishes the developing embryo
Steps of angiosperm life cycle
1. On the anther, each microsporangium contains microsporocytes that divide by meiosis, producing microspores (haploid)
2. A microspore develops into a pollen grain (haploid). Pollen tube is produced
3. In megasporangium (diploid), the megasporocyte divides by meiosis producing 4 megaspores. One forms female gametophyte
4. After pollination, 2 sperm cells are discharged in each ovule (haploid)
5. Double fertilization occurs
6. Zygote develops into embryo that is packaged along with food into a seed
Basic organs of plants
o Leaves o Stems o Roots
Three tissue systems of plants
o Dermal tissue: protection o Vascular tissue § Xylem: water and minerals § Phloem: food o Ground tissue § Bulk of plant (photosynthesis, storage, support) o Each organ has these 3 tissues
Plant growth
o Indeterminate growth: continued growth throughout plant’s life (meristems) o Determinate growth: cease growing at certain size (animals)
Meristems
o Perpetual embryonic tissue that results in indeterminate growth o Apical meristem: how a plant grows taller or longer o Lateral meristem: how a plant grows wider
Primary growth
o Primary growth produces the primary plant body = the parts of the roots and shoots produced by the apical meristem o Herbaceous plants (all parts are from primary growth) o Woody plants (only youngest parts are from primary growth
Primary growth: roots
o Root cap: protects apical meristem o Zone of cell division: includes apical meristem o Zone of elongation: root cells lengthen o Zone of maturation: cells complete differentiation
Primary growth: shoots
o Much the same as roots o Elongation: behind the tip o Cell division in apical meristem
Secondary growth
o Increase in thickness of stems and roots, produced by lateral meristems o Cambium cells divide to give new cambium cells to increase circumference of cambium o Cambium cells divide to give xylem cells on the inside and phloem cells on the outside
Secondary growth: aging in trees
o Early wood: spring- thin cell walls to maximize water delivery o Late wood: late summer- thick walled cells for stem support o Tree rings: visible where late and early wood meet o As a tree of woody shrub ages, the older layers of secondary xylem, the heartwood, no longer transport water and minerals o The outer layers, known as sapwood still transport materials through the xylem o Older secondary phloem sloughs off and does not accumulate
Transport in plants
o Bulk flow of xylem sap: transpiration-cohesion-tension mechanism o Plants need to transport water and nutrients from roots to leaves o Transpiration and tension in leaf o Cohesion and adhesion in xylem (vascular tissue) o Water uptake by roots o Upper epidermis (dermal tissue) o Mesophyll (ground tissue)
Transpirational pull
o Transpiration produces surface tension in the leaf, which exerts a pulling force on water in the xylem, pulling water into the leaf o Transpiration is: evaporation of water molecules from leaves through the stomata
Cohesion and adhesion in xylem sap
o The transpirational pull on xylem sap is transmitted all the way from the leaves to the root tips and even into the soil solution o Transpirational pull is facilitated by cohesion of water molecules to each other and adhesion of water molecules to cell walls
Xylem sap ascent by bulk flow
o The movement of xylem sap against gravity is maintained by the transpiration-cohesion-tension mechanism o Transpiration lowers humidity in leaves, and this generates tension that pulls water up through the xylem by cohesion and adhesion o There is no energy cost to bulk flow of xylem sap
· Comparing gymnosperm and angiosperm seeds, which of the following is true?
o Angiosperm seeds have parts that represent three generations that are respectively diploid, triploid and diploid
About this deck
By: Jamie Anderson
Textbook: Biology with MasteringBiology? (8th Edition)
Created: 2011-04-02
Size: 123 flashcards
Views: 111
Textbook:
Biology with MasteringBiology? (8th Edition)Created: 2011-04-02
Size: 123 flashcards
Views: 111
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
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Dennis
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