BCOR 12 1nd Edition Lecture 12 Outline of Last Lecture I. Gram Dyed BacteriaII. Metabolic Adaptations of ProkaryotesIII. Types of Prokaryotes based Metabolic and Nutritional ModesIV. The Human MicrobiomeOutline of Current Lecture I. Land Plant OriginII. BryophytesIII. Obstacles and Rewards for moving to landIV. Shared Derived Traits of the Land plantsV. Key features of Non-vascular plants/bryophytesVI. Alternation of GenerationsCurrent Lecture- Land plants evolved from a green algae- Embryophytes = land plants o Some embryophytes live in water but they went back to water after originally being on land- Charophytes – sister taxa of the embryophytes- Embryophytes – they protect the embryoo Beneficial evolution- Land plants originated 475 MYA- Vascular plants originated 420 MYA- Extant seed plants originated 305 MYAo The oldest fossil of angiosperms (type of seed plant) is 125 MYA, but using DNA evidence evaluation we can actually determine that they originated 305 MYA- Types of bryophytes/non-vascular plants:o Mosseso Liverwortso Hornworts- Most dominant plants on Earth = seed-bearing plantsObstacles and Rewards for making the transition from water to landThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Obstacles:- Gravity! Plants were used to being weightless in water – gravity made them feel how heavy they are!- Water was necessary for reproduction- Desiccation (i.e. drying out)Rewards:- More efficient photosynthesis and CO2 availableo Water didn’t disperse the light rays and there was plentiful amounts of CO2o Few competitors since land was inhibited o Abundant nutrients due to few competitorso No predators or pathogensThe Green Algae were the species that survived and diversified into many species of land plantsShared Derived Traits of the Land PlantsI. Alternation of generations – a life cycle in which there is a multicellular diploid form (sporophyte) and a multicellular haploid form (gametophyte) ~ unique to plants (thisidea is further discussed later in the notes)II. Multicellular, depend diploid embryosIII. Walled spores produced by sporangia (a part of the sporophyte)a. Spore – haploid reproductive cell produced by the sporophyte by meiosis (2n -> n)IV. Multicellular gametophytesV. Apical meristems – localized regions of cell division at the tips of roots and vegetablesNonvascular plants were the first to conquer land and have a life cycle dominated by gametophytesKey Features of Nonvascular plants/bryophytes- First plants to move from water to land- Dominant gametophyte generation- Form ground-hugging carpets, only a few cell layers thick- No true roots, leaves or vascular tissues- Vascular tissue – gives plant support, structure, and transport water, nutrients, and sugars around the plant- Mosses have sporophytes that take MONTHS to grow- Gametophytes support the sporophyte in the nonvascular plantsAlternation of Generations- Haploid part of plant = GAMETOPHYTE- Gametophyte – produces the gametes through mitosiso Starts out as a spore but germinates and grows via mitosis into a gametophyte- Gametes combine in water and fertilize- Diploid part of plant = SPOROPHYTE- Sporophyte – produces the spore via meiosisWhy is alternation of generations a beneficial adaptation?It divides up the labor of reproduction:- A multicellular gametophyte is specialized for fertilization - A multicellular sporophyte is specialized for dispersal of spores on land- This idea is unique to land plantsREMEMBER:Sporophytes -> spores Gametophytes ->