Biology 1202 EXAM 3 Other mechanisms used by bisexual flowers to avoid self fertilization o Genetic self incompatibility gauged by S genes o 50 60 alleles diploid plant gets 2 alleles Female part of the flower carpel made up by millions of cells o Stigma top of the carpel Pollen then takes up water increases in size pollen grain talks with stigma to determine if they are the same different at these genes Still diploid 2 copies allele of the S gene Why contain single nucleus that has 2 copies of the chromosomes Genotype of stigma S1S2 What makes S1 and S2 different different nucleotides ATGC but they have AUGC RNA is much less stable than DNA DIFFERENT DNA SEQUENCES Pollen grain sperm is haploid 1 copy all the same S3 Since S3 is different from S1 and S2 it can use double fertilization If one of the pollen sperms is the same as S1 or S2 it will not fertilize If both pollen sperms are the same as S1 and S2 neither will pollinate This causes more variation o Single diploid cell zygote After fertilization what happens HUMANS Several rounds of mitosis occurs cell divides forming a clump of cells Different tissues in plants YES 3 different kinds Development of the seed and fruit The first mitotic division of the zygote is asymmetric o This asymmetry provides the first environmental difference experienced by the differentiating cells and establishes the root shoot axis Difference between animals and plants after first round of division cells in plants start to differentiate How do they become different if they contain the EXACT same DNA turn on different genes for different amounts of time First round if division is SUPER IMPORTANT o Protoderm becomes skin of the plant o Procambium becomes into the pipes of the plant o Ground meristem will be material that is neither skin nor pipes o Embryo multicellular diploid plant encased in a seed The sporophyte embryo develops from the zygote o The endosperm develops from the triploid endosperm nucleus o Endosperm is the white substance that forms around the inside of the plant The ovule integuments become the seed coat Tissues of the ovary diploid and sometimes the receptacle bottom part become the fruit purpose of sweet tasting fruit around the seed to attract animals dispersers to get the fruit which contains the seeds to move the seeds away from the parent plant o Has anything to do with pollination NO o Example pit of a peach Development of seeds and fruits Function of fruit is to aid in seed dispersal so the seeds don t germinate over the already existing root system of the parent plant Mechanical dispersal must be touched to expel the seeds into the Wind dispersal wind blows seeds fly land and develop root system begin environment to grow Dandelions Water dispersal coconuts Seeds dispersed through water movement hit land develop root system and grow Animal dispersal Velcro stickers stick to animals people and move Bird dispersal 3 parts of plant embryo Hypocotyl root hypo below Parts of the plant found below the cotyl Epicotyl shoot epi above Parts of the plant found above the cotyl Cotyledon seed leaves leaves that form within the seeds First photosynthetic organisms Dicots have 2 leaves Monocots have 1 leaf o Example of monocot corn and sugar cane o Example of monocot apple tomato beans 2 main things need to know in seed embryonic plant and endosperm Angiosperms Monocots 1 cotyledon or seedling Ex corn and sugarcane grasses Leaves are different in monocots and dicots When germinating roots come out first and roots go down How does plant know which way is down sunlight gravity Positive phototropism growing towards the light Positive gravitrophism roots growing down bc of gravity When kernels become imbided absorb water seeds break their dormancy enzymes turn on in seed and root always grows down towards center of the earth Structure that pops out of ground coleoptile Sugar is used by developing embryonic plant Corn kernels are good example of sugars First foliage leaf Eudicots dicots makes 2 cotyledons seedlings Example beans Endosperm that formed during double fertilization is all gone converted into the 2 cotyledons that are produced Cotyledon makes up most of the bean we eat very little starch sugars Beans supply you with energy and fiber breaks down cellulose Organ systems of flowering plants Flowering plants produce flowers angiosperm Root system below and shoot system above Diploid same DNA but produces different plants Roots o Primary root first to appear Dicot taproot system Main root and lateral root branches that continue to grow out The root system is normally mirrored to the shoot system above ground How does top of plant talk to bottom hormones Monocot fibrous root system Bulb at the end o Root hairs are extensions of epidermal cells Single cells that turn on a gene telling it to grow out as single cell for surface area Definitely occurs in dicots not sure about monocots Root hairs dramatically increase a root s surface area for absorbing water and nutrients Skin cells of a root are only one cell thick epidermis Root hairs were plain skin cells of the root that came from o Food storage Function in all roots but some carrot taproots are highly modified for storage Carrots are starchy veggies Aboveground aerial or prop roots give extra support breathing roots conduct oxygen to waterlogged roots o Epiphyte a plant living on another plant Roots of orchids are photosynthetic Another example is Spanish moss which actually isn t a moss it s a flowering plant Stolons runner are horizontal wandering aboveground stems Plants communicate using hormones As these runners run away Rhizomes edible base of a ginger plant Horizontal belowground stem Tubers potatoes yams Are the swollen ends of rhizomes specialized for food storage Used for food storage potatoes store starch used for growing in the next cycle Onions are bulbs that are vertical underground stems consisting mostly of the swollen bases of leaves specialized to store food Tendrils specialized branches that twist around structures to lend support Ex grape plants Don t worry about nodes internodes Terminal buds generally exercise apical dominance over axillary buds SAM shoot apical meristem cells o Some differentiate to become leaves Thorns rigid sharp branches that deter potential herbivores especially mammalian browsers Leaves o Simple leaves blade petiole attaches leaf to branch axillary bud meristem cells o Compound leaves leaflet axillary bud o Doubly compound leaves axillary
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