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BSC2011 Plants
Objectives
| Question | Answer |
|---|---|
| Explain why a phylogenetic tree reflects the nested hierarchy (sharing or common ancestors=related) resulting from the diversification of life through evolution, in particular speciation. | Phylogenetic trees show the patterns of the relatedness among selected species. As species evolve the tree is able to depict the evolutionary advantages within that species thus reflecting a "nesting hierarchy" |
| Properly interpret phylogenetic relationships in terms of recency of common ancestry. | All phylogenies thought of as subsets of the “one true tree” and used to show the patterns of relatedness among selected species. It is now possible to use the pattern of homologous characters (esp. from DNA sequences) among species to accurately reconst |
| Identify the three principal domains of life. | Bacteria (prokaryotes), archaea (prokaryotes), eukarya (eukaryotes) |
| Recall the basic inputs and outputs of the photosynthesis reaction. | Carbon dioxide (reactant), water (reactant), Sunlight (reactant), Glucose (sugar), oxygen |
| Identify the two main metabolic reactions of cyanobacteria that make them valuable symbionts. | 1. Ubiquitous photosynthetic prokaryotes (no nucleus, circular chromosomes, etc.) 1st organisms to do oxygenic photosynthesis (typical carbon-fixing type seen today). 2. Can also “fix” nitrogen gas from atmosphere. N2 (gas) → NH4, NO-2 & NO-3 Ammoni |
| Explain the origin of the earth’s oxygen rich atmosphere, and oxygen dependent life in terms of photosynthesis. | Oxygen rich atmosphere favored organisms that could withstand and utilize oxygen. O2 from photosynthesis set the stage for the rise and diversification of the eukaryotes. |
| root | original common ancestor for that group. |
| Branches | lineages leading from an ancestor |
| clade | is an ancestor and all of its descendants. It can be big or small; all of the circled groups are cla |
| Sister groups (clades, species) are each other’s closest | relatives, biologically. |
| Outline the key evidence for the endosymbiotic origin of mitochondria and chloroplasts. (1+2) | 1. Two Membranes: Chloroplasts have 2 membranes, resulting from the engulfment of a cyanobacterium by a eukaryotic cell during primary endosymbiosis. 2. Own DNA: Chloroplasts + mitochondria both contain separate genomes, =origin independent of bacteria |
| Define ”Plants” phylogenetically | Plantae: that clade (of eukaryotic life) with chloroplasts derived from primary endosymbiosis. Most of the earliest splits in this tree have led to aquatic lineages (either marine or fresh water): ALGAE |
| name the lineages of photosynthetic eukaryotes that are, and are not, considered “plants.” | PLANTS: 1. red algae 2. green algae 3. Streptophytes |
| Explain the general outline of the phylogeny of the primary plastid clade with respect to the positions of the Chlorophytes, the Land Plants. Recall that there are differences between the book’s depiction of the phylogeny of the 4 main lineages of the the | Primary Plastid group: Red algae, Land plants, Charophycean green algae, glaucophytes |
| Identify main traits of the following groups: Red algae, Chlorophytes (typical green algae) | Red Algae: single celled, elaborately branched multicellular organisms, have cellulose cell walls, have chlorophyll a (like Cyanobacteria). “Coralline” red algae are among the oldest eukaryotic fossils. Cell walls have calcium carbonate. important a |
| Recall characters that are present in land plants that evolved in different algal ancestors, including chlorophyll a & b, starch, oogamy, plasmodesmata, and apical growth. | chlorophyll a & b for photosynthesis, starch storage for energy reserves, oogamy for sexual reproduction, plasmodesmata for intercellular communication, and apical growth for vertical elongation. |
| Discuss how different phylogenetic hypotheses for the streptophyte clade imply different evolutionary histories for these characters. | suggest varying timelines and patterns for the evolution of key traits like sexual reproduction, and adaptation to terrestrial environments. Some hypotheses propose traits evolved independently multiple times, others suggest a single origin. |
| Identify main traits of the following groups: Chlorophytes (typical green algae) | Green algae are the earliest branching green plants. They mainly occur in marine or fresh water environments. -> Chlorophyta: Ulva, Oocystis, Volvox ->Streptophytes: Other green algae, Coleochaetophytes, Stonewarts -> Land plants: embryophytes |
| Identify the first trait of the following groups: Streptophytes (including Chara, Coleocheate, “other green algae” and the Land Plants). | 1. Phragmoplasts are thought to help algae grow 3-dimensionally- create cell plates with plasmodesmata -> Chloroplasts: phycoplast= daughter nucleus close together, transverse fibers -> most Stretophytes: phragomoplast= daughter nuclei far apart, persi |
| What is a green plant? | 1. Eukaryote with chloroplasts derived from primary endosymbiosis (same as all plants) 2. Chloroplasts with chlorophyll a and b 3. Store carbohydrates as starch* which has 2 main types of polysaccharide |
| Identify the traits of the following groups: Streptophytes (including Chara, Coleocheate, “other green algae” and the Land Plants). | 2. plasmodesmata, or channels that penetrate the cell walls of adjacent cells. 3. Parenchyma: the basic tissue type in the streptophytes with cells linked by plasmodesmata 4. Oogamy 5. Apical growth |
| Describe key adaptations ( function) that allowed the ancestors of plants to begin to grow on land, including mycorrhizae, sporopollenin, accessory pigments, stomata, and waxy cuticle. | They had to: Adapt to dry, high light (xeric) conditions, Develop transport systems for water and nutrients, Develop structural support, Find new ways to disperse reproductive cells and progeny |
| Diagram the life cycle of land plants. Select stages that include the same ploidy, and explain how the different forms of adult plants, gametes, and spores are formed. | -Diploid Stage: Sporophyte undergo meiosis = make haploid spores. Fertilization = diploid zygote. Zygote = sporophyte. Cycle repeats. |
| Distinguish genetically distinct individuals in the alternation of generations life cycle. | 1. Sporophyte: produces spore producing sporangia 2. Gametophyte: produce haploid gametes (sperm and eggs) by mitosis in structures gametangia. Fertilization= sperm and egg combine to form a diploid zygote, which develops into a new sporophyte |
| Identify characteristics and adaptations of Bryophytes and of the three lineages that comprise them. | 1. Liverworts 2. Mosses 3. Hornworts all nonvascular |
| Describe the new understanding of the phylogenetic position of Bryophytes within the land plants. | Phylogenetic tree based on nuclear genes puts mosses and liverworts as most closely related, then vascular plants, THEN hornworts. Chloroplast genomes however place hornworts closer in relation than vascular plants, |
| Describe the function of antheridia and archegonia. | Antheridia: male reproductive structures produce and release sperm cells. Archegonia: female reproductive structures in plants that produce and house the egg cells until fertilization occurs. |
| Describe general characteristics & unique attributes of mosses | Green, leafy gametophytes Cells = hydroids (die and leave channels for water) Sporophyte attached to gametophyte, dependent for water, most sugars. Sporophyte unbranched, producing a single capsule. Many have stomata on capsules. Peristome teeth aid dispe |
| Describe key adaptations (structure) that allowed the ancestors of plants to begin to grow on land | Cuticle: a waxy coating slows water loss, Stomata: regulate gas exchange (most lineages), Pigments: protect UV radiation, Spores: thick walls w/ sporopollenin, Mutually beneficial with fungi (mycorrhizae) that promotes nutrient uptake from soil |
| Outline the key evidence for the endosymbiotic origin of mitochondria and chloroplasts. (3+4) | 3. Phylogenetic Evidence: DNA sequences of chloroplasts related to cyanobacteria, vs mitochondrial DNA is similar to proteobacteria, = bacterial ancestry. 4. Universal: eukaryotic cells have mitochondria, and photosynthetic eukaryotes have chloroplasts |
| Describe general characteristics & unique attributes of liverworts | Green, flat leaf gametophytes, apical growth Sporophyte attached to gametophyte, Asexual and sexual, • Capsule and stalk o Elaters help w/ dispersal and responds to humidity o Release spores like peeling fruit No internal water conduction + stomata |
| Describe general characteristics & unique attributes of hornworts. (100 species) | Sporophytes = small horns • Grows in basal region > indefinite growth Cells = 1 chloroplast Symbiosis w/ cyanobacteria = fix nitrogen |
| Diagram the life cycle of land plants. Select stages that include the same ploidy, and explain how the different forms of adult plants, gametes, and spores are formed. | -Haploid Stag e: Spores develop = gametophytes. Gametophytes = gametes by mitosis. Gametes fuse in fertilization. Zygote forms and develops into sporophyte. Alternation of generations continues. |
| Key Adaptations Permitted Plants to Colonize Land | Gametangia, (singular: gametangium) are organs that enclose gametes and prevent them from drying out: Embryos, young plants contained within a protective structure |
| name types of mosses and their characteristics 1 | 1. Sporophyte = unbranched (single capsule) • Stomata on capsules for drying out • Peristome teeth help dispersal o Hygroscopic = change shape w/ humidity • Release spores like salt shaker • Opercula = opening • Stipes = stalks |
| name types of mosses and their characteristics 2 | 2. Splachnum = unusual • Uses nitrogen from dung to grow fast • Specialized capsules for flies to disperse spores |
| name types of mosses and their characteristics 3 | Sphagnum (peatmoss) • Grows in wet areas • Exploding capsules • Covers boreal countries • Acidic and cold = resist decay (stores carbon) o Climate change thawing them > methane release |
| Detail how morphological and physiological features of the different bryophyte lineages represent solutions to the challenges of terrestrial life | features of bryophyte lineages, water-conducting cells in mosses, desiccation tolerance in liverworts, and the development of stomata in hornworts, represent adaptations to terrestrial like water retention, nutrient acquisition, and gas exchange. |
| Identify the clade with the sporophyte phase dominant in the lifecycle. | Tracheophytes: Vascular plants The gametophyte is reduced. often supported by sporophyte |
| Identify the key vascular tissues and their primary functions. | Xylem = move water and minerals from roots throughout plant Phloem = move sugars from leaves to roots Allows for larger size |
| Identify the main organs of a typical plant. | Roots Stems Leaves Flowers (in angiosperms) Fruits (in angiosperms) Seeds |
| Explain how a heterosporous lifecycle differs from a homosporous life cycle in the context of the typical alternation of generation found in plants. | Homosporous plants produce 1 type of spore that develops into a gametophyte producing both eggs and sperm. Heterosporous plants produce 2 types of spores, leading to separate male and female gametophytes, each specialized for producing sperm and eggs |
| Explain what is meant by “microphylls” | Microphylls = little leaves (1 vein w/ no branch) |
| Associate “microphylls” with the lineage in which they are found | • Lycophytes = club mosses (1200 species) o evolved Microphylls = little leaves (1 vein w/ no branch) o Dichotomous branching o Sporangia = clusters (strobili) o Independent gametophyte and sporophyte o Can help latex from sticking to itself |
| Homosporous Lifecycle | Spore Production: Plants produce 1 type of spore. Gametophyte Development: spores grow into bisexual gametophytes, each gametophyte can produce both male (antheridia) and female (archegonia) sex organs. Ex: common in ferns, horsetails, lycophytes. |
| Heterosporous Lifecycle | Spore Production: make 2 spores - microspores and megaspores. Microspores= male gametophytes, make sperm. Megaspores = female gametophytes, make eggs. Gametophyte Development: separation of spores = male and female unisexual gametophytes. |
| Define “sporangium” | releases spores that can develop into new gametophytes. |
| Define “strobilus” | cone-like structure composed of tightly packed, overlapping scales or modified leaves (sporophylls) that bear sporangia. found in Lycophytes, Gymnosperms, Equisetum (Horsetails): |
| Predict genetic consequences of matings within and between gametophytes. | Mating within gametophytes can lead to reduced genetic diversity and increased expression of deleterious alleles, while mating between gametophytes promotes genetic diversity and can enhance adaptability within populations. |
| List synapomorphies of Euphyllophytes | o Megaphyll = multiple veins Due to overtopping growth o Multiflagellate sperm o Roots w/ endogenous branching |
| List synapomorphies of Leptosporangiate ferns | -has leptosporangia: sporangia that release spores via single slit. -Complex vascular tissue= xylem and phloem. -True roots, stems, and leaves -Sori: clusters of sporangia where spores produced -typically small and short-lived |
| Distinguish megaphylls from microphylls | megaphylls have multiple strands of vascular tissue/ multiple veins, while microphylls have one. large leaves. |
| what lead to the evolution of megaphylls | overtopping growth |
| Explain the life cycle of a typical fern in terms of the appearance and ecology of the gametophyte, and the longevity of the sporophyte | haploid spores released from mature sporangia germinate = small, heart-shaped gametophyte= prothallus. gametophyte found in moist, shaded environments. produces both male and female gametes. then, zygote develops into a diploid sporophyte =long life |
| Explain the function of the leptosporangium | site of spore production and dispersal, essential for fern reproduction and life cycle. |
| Explain the function of the annulus | facilitating the controlled release of spores from the sporangium, aiding in their dispersal and reproductive success. |
| Explain leptosporangium and the annulus distribution of these sporangia on a fern. | Leptosporangia, specialized structures found in leptosporangiate ferns, are typically clustered in sori on the undersides of fronds, with the annulus facilitating controlled spore release for efficient reproduction |
| Recognize the strobilus and true leaves (& they are microphylls resulting from an evolutionary reversal) on a horsetail plant. | • Reduced true leaves • True roots • Independent sporophyte and gametophyte • Silica in cell walls • Sporangia inside strobilus. strobilus short lived microphylls • Much larger in carboniferous period |
| Monilophytes (horsetails and ferns) | Most ferns = sporangia walls 1 cell thick (leptosporangiate) Clusters = sori Most terrestrial, Homosporous, fiddleheads = leaves unroll Need liquid for sperm movement (live in moist areas) Heart shaped gametophyte = both antheridia and archegonia |
| Xylem cells | o Tracheids evolved first = in all vascular plants Tapered = overlapping allowed o Vessels in flowering plants (easier to move water) o Functional xylem tissue = dead Cell walls only |
| • Leaf anatomy | o Waxy cuticle = waterproof o Upper and lower epidermis o Palisade mesophyll = photosynthesis o Spongy mesophyll = allow for air spaces o Stomata = gas exchange |
| • Phloem | o Sap = sucrose, amino acids o High flow rate (.5 m/h) o Sieve tubes conduct in diff. directions No organelles (rely on companion cells for metabolism) o Living cells |
| • Stem | o Xylem most center o Phloem surrounds xylem |
| Explain the pressure flow model | Relies on active transport, passive transport (facilitated diffusion) of sugars, and osmosis. Bc of active transport, moving sugar requires energy. Osmosis occur: water try to dilute sugar. Causing pressure. Facilitated transport bring sugar to cherries. |
| Explain the pressure flow model of phloem movement. | Transpiration pulls H2O up xylem. Source cells load sucrose into phloem, reducing water potential. draws H2O into phloem, increasing pressure, push sugar along sieve tube. Sucrose unloads at sinks, raising water potential in sieve tubes. H2O returns xylem |
| Describe the two ways that stomata operate in different lineages of plants, | Ferns and lycophytes, stomata operate PASSIVELY, relying on turgor changes in guard cells without requiring energy. In seed plants, stomata operate ACTIVELY, using energy to pump ions into and out of guard cells to regulate opening and closing. |
| identify which stomata in the lineages require energy and explain why it's beneficial | Stomata in seed plants require energy to actively pump ions, which is beneficial because it allows for precise regulation of water loss and gas exchange, enhancing the plant's adaptability to diverse and fluctuating environments. |
| Define and characterize the apoplastic routes water can take through a plant. | cell walls and intercellular spaces a continuous meshwork of cellulose in cell walls water and solutes never cross a membrane |
| Define and characterize the symplastic routes water can take through a plant. | continuous cytoplasm of living cells connected by plasmodesmata plasma membranes control movement |
| Explain the transpiration-cohesion-tension model for water flow in a plant. | o Cohesion and adhesion Adhesion stronger in smaller containers o Capillary action Causes meniscus o Transpiration cohesion tension mechanism Energy from evaporation pulls water up |
| Correctly explain whether or not the process of transpiration itself requires energy from the plant to do the work. | The whole process is controlled by evaporation- the (plant does not need to “pump” or even expend ATP). Because increased evaporation increases force and rate of water movement, plants passively move more water on hot, dry, windy days than cool, days. |
| Identify synapomorphies for the seed plants (note that there are some reversals) | seeds, pollen, and heterospory (production of distinct megaspores and microspores). Additionally, they have a dominant sporophyte generation and complex vascular tissues, including secondary growth (wood). |
| Characterize the apical meristem in terms of its location and function | elongation of the growing tip of a plant by apical meristem |
| Distinguish the three tissue systems of a vascular plant | Dermal (outer protective layer of the plant, including structures like the epidermis and cuticle), Ground (photosynthesis, storage, and support), Vascular ( transporting water, nutrients, and sugars throughout the plant, consisting of xylem and phloem) |
| Primary growth | increase length plants roots + shoots. occur apical meristem- produce new cells to elongate plant. forms primary xylem and phloem. |
| Secondary growth | increase thickness. occur lateral meristem- primarily the vascular cambium + cork cambium. Vascular cambium produces secondary xylem (wood) towards the inside and secondary phloem towards the outside, while cork cambium produces cork cells (bark) outside |
| Outline how secondary growth provides diameter to large vascular plants | vascular cambium adds secondary xylem internally and secondary phloem externally, increasing the plant's diameter. The cork cambium produces cork cells outward and phelloderm inward, |
| Explain why a tree can have rings | undergoes annual growth, ring representing a year of growth, formed by the seasonal production of secondary xylem by the vascular cambium. |
| Describe the function of the cork cambium | produces waxy-walled protective cells; some become the outer bark. |
| Describe the features and diversity of the cycads. | Short woody trunks (soft) Males and females (dioecious) Nostoc (cyanobacteria) Motile sperm |
| name the four main groups of gymnosperms | Cycads, tropical, sister to remaining gymnosperms Gingko, today only one species: Gingko biloba Gnetophytes, some characteristics similar to angiosperms; 3 genera, Welwitschia, Ephedra, and Gnetum Conifers, cone-bearing plants. most diverse clade |
| Ginkygos | (1 species) Big fossil record Fan shaped leaves Motile sperm (like cycads) Dioecious Live long Used medicinally |
| Gnetophytes | Gnetum = Lianas (perennial vines) Welwitschia = large and grow old Ephedra = no real leaves |
| Describe the key features of conifers including those that distinguish them from other gymnosperms. | (700 species) Dominate forests at high latitudes and altitudes Megastrobilus (woody cone) and microstrobilus (soft) = monecious • Microgametophyte = pollen mother cells > 4 pollen grains (meiosis) • Megagametophyte = megaspore mother cell > megasp |
| Distinguish mega and micro-strobili in terms of sporangia and reproductive function | Megastrobilus (woody cone) and microstrobilus (soft) = monecious (seperate male and female parts on the same plant) |
| Distinguish dioecious plants from monoecious, and provide examples among the gymnosperms. | Dioecious: plants have seperate male and female plants (cycads, ginkygo) Monecious: seperate male and female parts on the same plant (ex. conifers) |
| Explain the function of the mega- and microstrobili | megastrobili producing megaspores that develop into female gametophytes, and microstrobili producing microspores that develop into male gametophytes, facilitating sexual reproduction. |
| Define the terms monoecious and dioecious | Monoecious both male and female reproductive structures on the same individual, while dioecious where male and female reproductive structures are found on separate individuals. |
| Summarize the synapomorphies of the angiosperms. | o Xylem tracheids + vessels o Flowers, fruits Flowers = modified leaves o Ovules and seeds inside carpel o Pollen formed on stigma o Double fertilization o Endosperm = nutritive tissue o Many veins in leaf |
| Define inflorescence | Group/clusters of individual flowers Ex. umbel / carrot family / sunflower family / grass family |
| main structures of flowers, and describe the function of each. | o Stamen (male parts) = anther (pollen production) + filament (stalk) o Carpel (female parts) = ovary (ovule inside) + style + stigma Ovule = megasporangium o Petals = corolla o Sepal = calyx |
| Explain the main hypothesis for how stamens and carpels evolved. | Carpel + stamen = evolved from leaves |
| Distinguish flowers from inflorescences. | A flower is a single reproductive structure, whereas an inflorescence is a cluster of multiple flowers arranged on a stem. |
| Explain the steps required for pollination to occur | Pollen other anther land on stigma. It germinates, forming a pollen tube that grows down the style. The generative cell divides into two sperm cells. The pollen tube reaches the ovule, releasing the sperm cells for fertilization. |
| summarize how flowers accomplish reproduction from the point of view of female functioning. | ovule forms from a megasporangium. 1 of 4 haploid megaspores survives and undergoes 3 mitotic divisions, creating a single cell with 8 nuclei. Cell walls form, = 7-celled megagametophyte with 8 nuclei. one egg cell + a central cell 2 polar nuclei |
| Describe the stages in gymnosperm seed development. | Ovule formation: in gymnosperm cones. Pollination: Pollen transferred, often by wind. Fertilization: Sperm fertilizes egg in ovule. Seed maturation: Zygote becomes embryo, surrounded by seed coat. Seed dispersal: Mature seeds released for dispersal. |
| Describe the stages in angiosperm seed development. | Ovule development: in ovary. Pollination: Pollen transferred to stigma. Fertilization: Sperm + egg fusion in ovule. Seed maturation: Embryo + endosperm development. Seed coat formation: Maternal tissue hardens. Seed dispersal: Mature seeds released |
| Explain how different “layers” in a gymnosperm and angiosperm seeds represent different “generations” in the alternation of generations life cycle. | seeds represent different generations in the alternation of generations life cycle, with the seed coat derived from the maternal tissue representing the sporophyte generation, and the embryo inside representing the gametophyte generation. |
| summarize how flowers accomplish reproduction from the point of view of male functioning. | Each anther sac is a microsporangium. Meiosis of each diploid microspore mother cell produces four haploid microspores. Each microspore undergoes mitosis to form a 2-cell pollen grain: one generative cell (divides to form 2 sperm cells) and one tube cell |
| Differentiate the genetic relationships between the two sporophyte (parental; offspring) and the, nutritive tissues (megagametophyte and endosperm) for gymnosperms and angiosperms, respectively. | sporophyte (parental generation) + the nutritive tissue (endosperm) differs btwn gymnosperms and angiosperms, with gymnosperms relying on megagametophyte and angiosperms utilizing the endosperm, formed through distinct fertilization processes. |
| Characterize pollination as a type of symbiotic interaction | usually mutualistic |
| evaluate whether pollination has resulted in coevolution between plants and their pollinators. | led to coevolution between plants and their pollinators. Through mutual adaptations, plants develop features like colorful flowers and nectar to attract specific pollinators, while pollinators evolve traits to efficiently access floral resources. |
| Outline the ways in which flowering plants can distribute their sexual parts within and among individuals | Colors + special structures = more attraction • Pollination syndromes = features that hint what type of pollinator goes w/ the flower o Ex. grass flowers, oaks, birches, sedges, sunflower family (ragweeds) o Furry stigma flopping in air |
| Describe the consequences of inbreeding and how avoidance of inbreeding can conflict with the assurance of reproduction in sessile organisms. | o Self-pollination = decrease heterozygosity (can backfire) • Stigma open = blocked anthers • Stigma closed = accessible anthers • Some self-incompatible (half flowering plants) o Pollen from same plant rejected o Pollen tube no reach ovule |
| compare the ways in which gymnosperms and angiosperms can arrange male and female function within and among indivduals. | Gymnosperms typically have separate male and female cones on the same individual plant, while angiosperms often have separate male and female reproductive structures within the same flower or on separate plants. |
| Correctly define “fruit” in the botanical sense and recognize that this differs from the common usage. | o Matured ovaries w/ seeds o Develop after fertilization o Dispersed by animals and protect seed |
| Explain why dandelion fruits do not cause seasonal allergies | Dandelion fruits do not typically cause seasonal allergies because their pollen is heavy and sticky, designed for insect pollination rather than wind dispersal, and the proteins in dandelion pollen are not highly allergenic. |
| Outline common strategies for surviving in hot, water-limited environments. | • Avoid drought = life cycle in rainy times + dormant w/ no rain • Succulent leave/stems (water storage tissue) • Stomata in crypts • High solute tissues (plant takes in water) • Small/no leaves, shallow roots, no more water storage / spines dissipate |
| Explain what photorespiration is and why it is bad for plants | • Issue: photorespiration (RuBisCO fixes O2 instead of CO2) o Reduces photosynthesis o Plant has to undo this w/ ATP and NADH |
| Compare and contrast C3, C4 and CAM photosynthesis and explain how they solve the problems of water loss and photorespiration. | C4 = photosynthetic near vascular tissue • CO2 + PEP > malate (more CO2 near RuBisCO) • Ex. grasses • Evolved 67 times CAM = stomata open night / closed day • Night = CO2 > malate • Day = malate > CO2 > glucose w/ RuBisCO • Ex. cacti / pineapples / |
| Explain why carnivorous plants are not “eating” in the same sense that animals eat- what “nutritional” needs are being met? | o Conditions = High light / high rain / low soil nutrients o Don’t get energy from insects (get nutrients not available in environment) Some plants have symbiosis w/ Rhizobium bacteria (fixes nitrogen) to counteract low nutrient soil • Ex. legumes |
| Describe ways in which plants use microbial symbioses to ”fix” nitrogen. | Legumes have a symbiotic association with nitrogen-fixing Rhizobium bacteria to supply their nitrogen |
| Distinguish constitutive from induced defenses and identify examples of each. | Elicitors: Distinctive molecules in pathogens that trigger plant defenses Avr (avirulence) genes: genes that code for elicitors (Avr proteins) R (resistance) genes: plant genes that confer resistance to specific pathogens |
| Explain the primary reason why plants produce diverse chemical compounds not strictly needed for their own biological functioning. | not strictly needed for their own biological functioning primarily to interact with their environment, including deterring herbivores, attracting pollinators, and defending against pathogens. |
| Explain why plant secondary compounds are important sources of toxins and medicines. | serve as important sources of toxins and medicines due to their diverse chemical structures, which allow them to deter herbivores and defend against pathogens, while also possessing properties that can be harnessed for therapeutic purposes in humans. |
| Outline in a basic sense the way that plant resistance to pathogens can be induced and what form these responses take (local vs. systemic). | Plant resistance to pathogens can be induced by activating defense genes and producing antimicrobial compounds, leading to local or systemic defenses. |
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