Exam 2 Study Guide
Exam 2 Study Guide Bio 112
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This 4 page Study Guide was uploaded by Sophie Kreutz on Sunday March 20, 2016. The Study Guide belongs to Bio 112 at College of Charleston taught by Bidwell in Fall 2016. Since its upload, it has received 44 views. For similar materials see Evol, Form, and Func of Organisms in Biology at College of Charleston.
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Date Created: 03/20/16
Bio Exam 2 Plant Nutrition- - need C, P, H, N, O, S from soil - 90% CHO - 4% NPK (limiting factors) - CO2 through the leaves, H2O and O2 released through leaves - O2, H2O and minerals absorbed through roots, and CO2 released - magnesium is used for chlorophyll - micronutrients are positively charged because the soil is usually more negative - to take nutrients from the soil, roots pump out H+ ions to displace the macronutrients from the soil so they can be absorbed. - as the roots add H+ it lowers the pH - plants that are phosphate deﬁcient have purple coloration in leaves - potassium deﬁcient have red on the edges and fade to yellow - Phosphate deﬁcient are red on tip and yellow down to the vein Nitrogen- greatest effect on a plant’s growth - helps feed and create proteins, nucleic acid, chlorophyll, and organic molecules - those who don’t have enough nitrogen become carnivorous - animals excrete nitrogen from urine and guano- why it is such good fertilizer N2 —> nitrogen ﬁxation —> ammonia —> ammonifying bacteria —> ammonium —> nitrifying bacteria —> NO3- (nitrate) —> denitrifying bacteria —> N2 - nitrate and ammonium can be utilized by plants Michrorizae - fungi that supply the plant with nutrients and water in exchange for sugar by increasing surface area - the relationship is symbiotic and mutualistic - farmers inoculate seeds with fungal spores - There is a symbiosis with nitrogen ﬁxing bacteria in the roots of legumes that increases nitrogen production - the plant gets nitrogen ﬁxers and the bacteria get ammonium - this is a crop rotation (beans-> roots-> fruit-> leafy greens) (reduces parasitic problems) - If there is too much fertilizer runoff, the water becomes eutrophic. Bacteria booms, then dies and they decay takes all the oxygen from the water and the ﬁsh die Topsoil: blown away by dust bowl because all the trees were clearcut and the drought killed all the plants Cover crops- suppress weeds, disease, control erosion, add nutrients, increase water inﬁltration, decrease loss of nutrients, feed livestock - alternative to letting ﬁelds go fallow Plant Responses- Physiology: - receptor cell transmits signal - hormones are released - change of activity occurs in responder cells (cells with receptors) Phototropism: - plants grow towards (+) or away (-) from the sun - plants actively grow towards blue wavelengths (sensed by phototropins) - Auxin is the signal molecule involved in light response - the side of the plant shaded from the sun has more auxin and grows faster because the cells elongate (promotes production of protons that ﬁll cell and trigger osmosis) Gravitropism: auxin and response to gravity - roots are (+) gravitropic and shoots are (-) gravitropic because they grow against gravity - FIRST: sensors in the root cap called statoliths (starch) fall in the direction of gravity - pressure receptors in root tip detect this and produce more auxin - the gravity sensed in the root causes auxin to respond and the side of the plant with more auxin tips the root. - this triggers expansion of cells on the opposite side of auxin - curves the root until it is vertical again - interaction of auxin and cytokyanin determine lateral branching and apical dominance - auxin is produced in the terminal buds of shoots and cytokyanin is produced in roots - auxin inhibits branching at axillary buds and cytokyanin triggers branching (that’s why there are more branches closer to the root) ** if you want a bushier plant, pinch off the terminal buds Phytochrome and seed germination: - helps plants determine reproductive periods - gives circadian rhythms (changes in burger pressure open plants in the day and close them at night) - seeds have light sensing proteins that can trigger a change in their shape to either start or stop germination - Gibberellins: trigger germination - Abscisic acid: causes seeds to stay dormant - if a plant sees red light, it will go into a far red light phase and germinate - if a plant sees far red light, it will go into a red light phase and stay dormant PHOTOPERIOD Thigmotropism - response to touch that helps plants climb - plants need wind to toughen their shoots before going outside (increases cellulose) Abscisic acid - controls seed dormancy - stress hormone that closes stomata when water is scarce Gibberellins - break seed dormancy - cell elongation (swelling of cells due to water) - stimulate a seedless fruit - involved in ﬂower formation Brassinesteroids - promote elongation of pollen for pollen tubes Ethylene - produced in aging parts of plants - is a stress response - promotes apoptosis (dropping of leaves and dying cells) - fruit ripening Predation Response: - produces spikes - lets off a hormone that attracts predators to kill the parasite that eats it (parasitoid) - this is a ﬁtness tradeoff because if you don't have herbivores, you don't have as many predators PLANT LIFE CYCLE: germination-> growth/maturity-> ﬂowering-> fruit-> abscission-> dormancy Fruit- forms from a ﬂower and has seeds Vegetable- ﬂowers, leaves, stem, root, and buds - all plants have spores - gymnosperms and angiosperms have seeds Mosses- transport seed and sperm via water Seedless vascular plants Gymnosperms - pollen in the male and seeds in the female plant Angiosperm - uses wind, explosive techniques and pollinators to spread seeds (since pollen has sperm in it, there is no need for water to spread sperm, it can be taken by wind or animals). - angiosperms that use wind means they do not ﬂower - ﬂowering plants usually only have one or two species that pollinate it - better xylem and vesicle elements - better support (ﬁbers) - faster seed production - better offspring survival (fruits) - hermaphrodites Plant parts: Female - sigma (sticky), style, ovary, and ovule Male - Stamen (anther), ﬁlament Other - receptacle, petals, sepals - Flowers can have one or many ovules - each ovule makes one egg (ovules= # of seeds in the corresponding fruit) - ovary enlarges and becomes the fruit Ovary —> fruit Ovule —> seed with fertilized egg inside —> embryo is formed within the seed Fruits disperse seeds through animals and inedible fruits use the wind, or drift at sea Anther —> sperm Sporophyte —(meiosis)—> haploid spores —Mitosis—> gametophytes —Mitosis—> gametes —fertilization—> zygote —mitosis—> sporophyte (2n) - spores can divide on their own and become multicellular without fertilization SPERM: - within anthers, we have sex cells called microsporocytes - they undergo meiosis and become 4 microspores - undergo mitosis and become a pollen grain (male gametophyte) which undergoes mitosis and creates two sperm - the two sperm are used in double fertilization EGGS: - Megasporocyte is the sporophyte that undergoes meiosis to make 4 spores - only one megaspore survives and undergoes mitosis to form the embryo sac (female gametophyte) - this makes the egg, and two polar nuclei Pollination- pollen lands on stigma Fertilization- pollen travels down the style to meet the egg - one sperm fertilizes the egg and makes the zygote - the other fuses with the two polar nuclei to make the endosperm (3n) which is tissue for the new embryo and food for us the embryo in the new seed is the new sporophyte * Zygote —> apical daughter cell (both shoots and roots) and basal daughter cell —> embryo and suspensor (connected to endosperm) —> root and shoot apical meristems form off the apical axis —> geo dicot protective leaves form (cotyledons). - pollen tubes grow towards the unfertilized eggs because they can sense the chemical gradient - plants can mate with themselves, but natural selection favors crossover - creates more genetic diversity - plants have developed ways to avoid self pollination physically (by making stigma higher than the anthers) or by timing the release of pollen (timing reproduction with the days and nights) Diecious ﬂowers separate sexes (papaya) Sporophytes are dominant in angiosperms Plant ﬁgures out all its needs and what cell will become what in the embryonic state - auxin is the hormone that gives the instructions - auxin tells the cell what it is - nitrate and organic nitrogenous material is transported through the shoots through xylem - plants prefer nitrate -
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