PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Plant DiversityPlant DiversityC&R distinguish Green AlgaeGreen Algae from PlantsPlants by adaptations to terrestrial livingterrestrial livingFossilized plant spores place plants on land over 500 mybp. Sporopollenin in cell wall is the most durable organic material knownPhotosynthesisPhotosynthesis uses light energy to split H2O, release O2,make ATP & NADPH, andput the ‘hydrate’ in carbohydrate.Fig 10.4Plants w/ chlorophyll look green because chlorophyll does NOT absorb green - it absorbs red and violet.Plants Plants and nearest relative green algaegreen algae use chlorophyll achlorophyll a as photosynthetic pigment & chlorophyll b as an accessory (catch photons at other colors - see ch 10)12H2O 6CO26O21C6H12O66H2OFig 10.8Fig 10.13Note reduced ratio of red/(far-red) in shade:Manipulative approaches to testing adaptive plasticityadaptive plasticity: Phytochrome-mediated shade-avoidance responses in plants. {see C&R ch 39}Schmitt et al. 1999. AM NAT 154:S43-S54.Because chlorophyll selectively absorbs red wavelengths, the ratio of red (R) to far-red (FR) wavelengths is an accurate signal {to phytochrome, Fig 39.20} of vegetation shade and neighbor proximity. Many plants respond to low R : FR with a suite of photomorphogenic changes such as stem elongation, suppression of branching, altered biomass allocation, and accelerated flowering, commonly referred to as the "shade avoidance syndrome". the "shade avoidance syndrome". Such responses are often elicited by FR reflected from neighboring plants before canopy closure, indicating that plants can detect and respond to potential future competitors … {bolt - race up high to compete for scarce light vs branch – spread out low to collect abundant light}The cellulose-manufacturing rosettes found only in the plasma membranes of charophyceans and land plants are evidence of cell wall homology.Charophyceans are the only algae with their anti-photorespiration enzymes packaged in peroxisomes, as they are in plants.Phragmoplasts occur during cell division only in plants and charophyceansMany plants have flagellated sperm, which match charophycean sperm closely in ultrastructure.Comparisons of chloroplast DNA place the charophyceans as the green algae most closely related to land plants.Molecular systematics of key nuclear genes for cytoskeletal proteins support all the other evidence connecting charophyceans and plants to a common ancestor. C&R Fig 29.2:Several lines of evidence suggest that modern Chara (common pond algae) is in sister group to modern plants.{It is not the ancestor, any more than chimps are ancestors to humans}Five derived characters unique to land plants.1. apical meristemsapical meristemsIn terrestrial habitats, the resources that a photosynthetic organism needs are found in two very different places.Light and carbon dioxide are mainly available aboveground; water and mineral nutrients are found mainly in the soil. Thus, the complex bodies of plants show varying degrees of structural specialization for subterranean and aerial organs - roots and leaf-bearing shoots …Though plants cannot move from place to place, the elongation and branching of their shoots and roots maximize their exposure to environmental resources. This growth in length is sustained by the activity of apical meristemsapical meristems localized regions of cell division at the tips of shoots and roots Fig 35-12. Apical meristems near the tips of roots and shoots are responsible for primary growth in length. Woody plants also have lateral meristems that function in secondary growth.Five derived characters unique to land plants.2. “the embryophyte condition”“the embryophyte condition”Multicellular plant embryos develop from zygotes that are retained within tissues of the female parent. The parental tissues provide the developing embryo with nutrients, such as sugars and amino acids. The embryo has specialized placental transfer cells …This interface is analogous to the nutrient-transferring embryo-mother interface of eutherian (placental) mammals. Land plants are also known as embryophytesembryophytes, a distinction that recognizes multicellular, dependent embryos as a derived characteristic common to the land plants. {note: only seed plants package these embryos into a seed}embryophytesFive derived characters unique to land plants.3. Alternation of generationsAlternation of generationstwo multicellular body forms alternate, diploid sporophytes & haploid gametophytes, each form producing the other. Alternation of generations is a special type of haploid - diploid sexual cycle w/ both stages represented by multicellular bodies.In bryophytes, the gametophyte is larger and more conspicuous. In pteridophytes, gymnosperms, and angiosperms the sporophyte form is the dominant. The fern plant most of us are familiar with is the diploid sporophyte. The gametophyte is a tiny plant.In gymnosperms & angiosperms the gametophyte is retained within the sporophyte.C&R Fig 30.1Five derived characters unique to land plants.4. Walled sporesWalled spores {in flowering plants - pollen}Plant spores are haploid reproductive cells, produced by the diploid sporophyte sporangia, that grow into multicellular, haploid gametophytes by mitosis. This chemical adaptation makes it possible for wind-carried spores {pollen} to disperse through dry air without harm. All four major plant groups produce spores.Fossilized plant spores place plants on land over 500 mybp. Sporopollenin in cell wall is the most durable organic material known5. Multicellular gametangia …Multicellular gametangia …C&R Fig 29.16mossLife cycle w/ alt of gen in BryophytesBryophytesliverworthornwortGametophyte (n) Gametophyte (n) dominatesdominatessporophyte (2n)sporophyte (2n)note sperm need water film to swim to eggsphagnum - future peatC&R Fig 30.1division Pterophyta - fernsfernsLife cycle w/ alt of gen in Ferns Ferns C&R Fig 29.23 w/ a little independent gametophyte ‘homosporous condition’- note sperm need water film to swim to eggPteridophytes:Pteridophytes: Seedless Seedless