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Bio Exam Four
Ch. 36, 37, 38, 39
| Question | Answer |
|---|---|
| What is nutrition? | Chemicals needed to survive |
| What are the major ingredients for macromolecules? | Carbon, hydrogen (from water), oxygen (from water), and nitrogen (from bacterial activity) |
| What are mineral nutrients and where do they come from? | Necesary for geological activities; S, P, Mg, Fe, Ca; from rock |
| What must sessile organisms do? | Grow toward nutrients |
| What is an essential element? | One that is required for plant that cannot be replaced |
| When is a plant showing deficiency symptoms? How can this be fixed? | When it is not getting an essential element; Can be helped with fertilizer containing N, P, O |
| What are the components of soil? | Living components including roots, bacteria, fungi, protists, and animals; non-living components including rock fragments; water; dissolved minerals; air spaces for cellular respiration; dead organic matter |
| Describe topsoil. | Contains living organisms and dead organic material; nutrients can be leached; needed for agriculture |
| What is leaching? | When nutrients is washed or blown away |
| What are the differences in sand, clay, and loam? | Sand contains air spaces, won't hold water, leached away easily; Clay contains no air spaces, holds water, negatively charged which binds minerals and makes them available to plants; loam is a combination, best |
| Describe subsoil. | Contains materials that accumulate from topsoil like little rocks with little nutrients |
| Describe parent rock. | Breaks down to form soil. Roots rarely enter. Totally intact rock with nothing organic. |
| What is weathering? What are the two different types of weathering? | When rocks are broken down into soil particles. Mechanical - when rock is physically broken down by water, drying, freezing; Chemical - oxidation by atmospheric oxygen, hydrolysis by reacting with water, and acids like carbonic acid |
| Describe Red Georgia Clay. | Red color from iron oxides. The warm, humid climate causes weathering. Rainfall easily leached much out of the soil. Iron, Al, Silica are left. Bad for plants because there isn't enough air spaces and not enough nutrients. There is too much rainfall. |
| Describe ion exchange in plants. | Clay is negatively charged so positive ions to bind to it. Plants much extend energy to get positive ions. Plants kick out protons (H+) which attach to the clay causing the clay to release other positive ions that the root sucks up |
| Why would the clay release positive ions during ion exchange? | H+ over powers other positive ions so clay kicks off others to gain it. |
| What are fertilizers used for? | Cations (positive) and remain in topsoil; however, anions (negative) can be leached rapidly. This is used to replace the anions that are loss. Also, it is used for the replacement of the minerals lost during irrigation and rain water. |
| What is the difference between commerical and organic fertilizers? | Commercial are characterized by N, P, K content and are readily available but leaching occurs more. Organic is composed of manure or crop residues. It releases nutrients slowly causing less leaching but it is not readily available. |
| What is the importance of soil pH? | Affects nutrient availability and binding of cations to clay. Rainfall and organic materials can lower it. Low can be reversed by liming (basic). High can be reversed by adding sulfur. Slightly acidic is good. |
| What is humus? | Dead organic material. Soil bacteria and fungi break down dead plant litter, animal feces, and dead animals into this. Super nutrient rich with perfect oxygen spaces. |
| What is mycorrhizae? | Associations between fungi and plant roots. |
| What is mycelium? | Multicellular fungus composed of rapidly growing individual tubular filaments called hyphae. |
| What is ectomycorrhizae? | Hyphae that do not penetrate the root cell. The are outside the cell. |
| What is arbusular mycorrhizae? | Hyphae that enter the cell and form treelike structures inside the root cells. They are inside the cell. |
| Describe the relationship between plants and fungi. | Fungi gets sugar. Plants get nutrients (P). |
| What are the benefits of mycorrhizae? | Expand root surgace area 10-1000 fold. Mutualism type of relationships. |
| How does mycorrhizae actually happen? | 1. Plant secretes strigolactones, stimulate frowth of hyphae. 2. Fungi produces signals that stimulate plant symbiosis related genes. 3. Prepenetration apparatus (PPA) guides hyphae growth. |
| Mycorrhizae continued....... | 4. Arbuscules form within root cortex cell, sites of nutrient exchange. 5. Cytoplasms do not mix. They are separated by periarbuscular membrane (PAM). |
| Describe nitrogen fixation. | Plants cannot break down triple bond so bacteria is used. N is in short supply. N2 is common in atmosphere as a triple bond. Some bacteria have enzymes that convert N2 to ammonia. Rhizobia break down triple bond. |
| What are the requirements for nitrogen fixation? | Strong reducing agent, energy supplied by ATP, Nitrogenase (to catalyze the reaction) |
| Describe Industrial Nitrogen fixation. | Requires energy from fossil fuels. Take more energy than any other aspect of crop production. |
| What is the nitrogen cycle? | 1. Fixation of atmospheric N2 to NH3 and NH4+ by bacteria and abiotic processes (non-living). 2. Nitrification of these molecules to nitrate by bacteria. 3. Nitrate reduction by plants back to ammonia. 4. Denitrification of nitrate by bacteria back to N2 |
| Why do carnivorous plants ROCK?! | Found in acidic, nutrient-poor areas. Digest animal protein. |
| Describe parasitic plants. | reak phloem of other plants and thake their sugar. |
| What are haustoria? | Absorptive organs that invade hosts and tap into vascular tissue. |
| What are hemiparasites? | Can photosynthesize but get water and minerals from other plants (mistletoes). They still have chlorophyll. |
| What are holoparasites? | No photosynthesis. Complete parasites. They have no chloroplasts nor chlorophyll. |
| What mades a vascular plant a parasite? | The presence of a haustorium. |
| Is plant development regulated? If so....HOW?! | YES! Environmental cues, receptors, hormonse, genes. |
| Describe germination. | Dormant before - seed takes up water (imbibition), embryo digests stored food. Complete when radicle emerges = seedling. If occurs underground, it must move in right direction. |
| What are the advantages of see dormancy? | Can last years! |
| What things maintain dormancy? | Impermeable seed coat that has no water nor oxygen which protects the embryo. Chemical inhibition of embryo development. |
| What things stop dormancy? | Seed coats worn down in the digestive tract. Soil bacteria, freezing, and thawing soften coats. Fire melts waterproof wax which cracks it open. Leaching of chemical inhibitors. Light. |
| What are the three plant growth hormones we need to know? | Auxin (promose stem elongation, adventitious root initiation, fruit growth). Ethylene (promotes fruit ripening, leaf abscission). Gibberellins (promote seed germination, stem growth, fruit development). |
| What is genetic screen used for? | Make mutants, look for weird phenotypes, figure out what genes did the mutations. |
| What is the "foolish seeding disease"? | Caused by fungus (Gibberella fujikuroi), which produced a molecule that stimulates plant growth. The plant hormone Gibberellin caused stem elongation, helps with germination, and increases fruit growth. |
| What happens when no Gibberellin is present? | A repressor is formed. When it comes in, it is claimed by a receptor and turns the repressor off allowing transcription to continue. Repressor is turned off by Ubiquitin. |
| What is phototropism? | Growth of a plant towards or away from light. Auxin is involved. Receptor absorbs light and redistributes auxin transport carriers. |
| What is coleoptile? | Sheath to protect monocot shoots. |
| The movement of Auxin is..... | POLAR! |
| Describe the movement of Auxin. | Unidirectional from apex to base. 1. Polar molecules diffuse less readily. 2. Active transport molecules are on basal end of cell. 3. Protons pumped out cell (electrochemical gradient). pH higher in cell. 4. pH higher, more ionized auxins (weak acid). |
| Describe gravitropism. | Amyloplasts store starch, like little pebbles, which triggers auxin transport. |
| What kind of awesome things does auxin do!!!!!????? | Can organize new meristems for new roots which can develop into new plants. Inhibits abscission (lead detachment). Apical dominance (high auxin, no lateral branches). Treat unfertilized ovary with auxin - parthenocarpy. Expansion of cell walls. |
| Describe ethylene. | Produced by all parts of the plant. Promotes senescence (nighttime, dying out, end of life....promotes maturing!). Speeds ripening of fruit. Begets more ethylene. Maintains apical hook which protects apical meristem (inhibits cell elongation). |
| What affect does photoreceptors have on plant growth? | Plants respond to quality (wavelength) and quantity (intensity, duration) of light. Phytochrome is a photoreceptor pignment in the cytosol that exists in two interconvertible forms (Pr and Pfr). Plants in shade have Pr dominant and respond by growing tall |
| Describe Pr and Pfr. | Pr converts to Pfr with red light. Pfr converts to Pr with far-red light. Perceives whats going on with light physically. |
| Describe reproduction in plants. | Flowers contain sex organs. Most plants reproduce sexually and make new gene combinations. Some reproduce asexually and produce clones with no genetic variation. |
| What is the difference between complete (perfect) and incomplete (imperfect) flowers? | Complete have a common pattern of sepals, petals, stamens, and carpels. Incomplete does not exhibit this pattern. Imperfect monoexious is corn. Imperfect dioecious is bladder campion. |
| What is another name for male gametophyte? | Pollen grain. |
| What is another name for female gametophyte? | Embryo sac which contains 7 cells with 8 nuclei. |
| Describe the embryo sac? | The megasporocyte undergoes meiosis which produces four haploid cells. Only one survives which is the megaspore. The megaspore goes through 3 mitotic divisions producing 8 nuclei in 7 cells (6 surrounding cells which surround the 7th cell - has 2 nuclei) |
| Is cytokinesis performed by the embryo sac?! | No! The cell wall forms at the end producing a gametophyte with 7 cells with 8 nuclei. The are all haploid cells. |
| Describe the components of the embryo sac? | Two synergids, three antipodal cells, one fertilized egg, and two polar nuclei are present. |
| What do synergids do? | They attract the pollen tube an receive sperm nuclei. |
| What do antipodal cells usually do? | Degenerate. |
| What do the polar nuclei do? | Together they combine with one sperm nucleus. |
| Describe the formation of the male gametophyte. | Microsporocyte undergoes meiosis and produces 4 haploid microspores. Each develops a spore wall and divides mitotically to form 2 haploid cells (pollen grain). One cell turns into the tube cell and the other is the generative cell that makes sperm. |
| What is monosulcate? | Occurs in monocots. Pollen grain has one groove. |
| What is tricolpate? | Occurs in eudicots. Pollen grain has three grooves. |
| Describe wind pollination. | Need a huge amount of pollen. Sticky stigma is required. |
| Describe animal pollination. | Flowers are pigmented and scented to attract animals that recieve the nectar (nutrients) and pollen. |
| What is homozygosity? | Same genetic structure (identical). |
| How do plants try to prevent self-fertilization? | Male and female gametophyte are physically separated. Dioecious species separate. Monoecious separate flowers. Different bloom times. Genetic self-incompatibility is also used. |
| What is genetic self-incompatibility? | Reject polled fromt heir own pollen. S gene locus has many alleles (S1, S1, ...). If alleles are the same then they are rejected. |
| Describe double fertilization. | One synergid degenerates when pollen tube arribes. Two sperm cells are then released. |
| Describe the endosperm. | Accumulate starch, lipids, and proteins. In some species like beans cotyledons absorb nutrients from the endosperm. In other species like corn cotyledons thin and use nutrients from endosperm. |
| Describe seed development. | Abscisic acid (ABA) controls it. Levels rise as seed matures. This prevents cells death as seeds dry out. |
| What is vivapary? | Premature germination. The seed germinated before detaching from the parent plant. |
| What do plants do for plants? | Protect seeds from animals and microbes. They aid in seed dispersal which spreads genetic diversity and causes less competition with parent. They disperse by wind, animals, and water. |
| What are the three flowering types? | Annuals (complete life cycle in one year, have little to no secondary growth, energy on flowers and fruits), Biennials (complete life cycle in 2 years, vegetative 1st year, store carbs in underground roots or stems), |
| Flowering types continued...... | Perennials (live 3+ years, flower every year, or grow for many years and then flower once and die). |
| What are meristems? | General name of anything that will produce stem (undifferentiated cells). |
| What do floral organ identity genes determine? | Determine the fate of cells in floral meristem. |
| How is the flowering state cued? | Photoperiodism which controls the flowering by length of day or night. Critical day length which flowers depending on day length shorter than 14 hours. |
| When do short day plants flower? | Day must be shorted than critical maximum, flower in late summer or fall. |
| When do long day plants flower? | Day must be longer than critical maximum, flower in midsummer. |
| What is florigen? | Protein that causes flowering. It is a diffusible (travels around) signal to flower. |
| What are the three gene that produce proteins? | FT (flowering locus T; florigen, small, through plasmodesmata; diffused quickly), CO (constans; transcription factor that activates synthesis of FT), FD (flowering locus D; protein that bind to FT in apical meristem) |
| What is vernalization? | Flowering signaled by cold temperatures. Uses temperature rather than light to determine when to flower. |
| Describe asexual reproduction. | No genetic variation. If plant well-adapted to environment, then it preserves that good genotype. Vegetative reproduct including runners (stolons), top layers, tubers (enlarged stems), rhizomes (horizontal underground stems, new shoots). |
| What do bulbs and corms have? | Short, vertical, underground stems. |
| Describe bulbs. | They have fleshy, modified leaves for food storage which is a large, underground bud. These can give rise to new plants. |
| Describe corms. | They have stem tissue and lack modified leaves. Also, they have a disc on the bottom. |
| What can leaves be a source of?! | NEW PLANTLETS! |
| What does it mean that most plant cells are totipotent? | They can give rise to entirely new plants. |
| What are apomixis? | Such as dandelions and blackberries. They perfrom asexual production of seeds. Their female gametophyte prduces diploid gametes and the ovary wall becomes fruit. They don't perform meiosis and instead keep the diploid cells and make cloned seeds. |
| Why is apomixis is used in agriculture? | Desirable hybrid could carry gene. |
| What are the advatages of grafting? | Must connect to xylem! Faster flowering and fruiting, dwarf (easy to reach fruit), hardiness, sturdiness, repair, and changing cultivars. |
| What are pathogens? | Bacteria, fungi, "protists", and viruses. They are in an evolutionary "arms race" with plants. Plants will make defenses against viruses and continually changes. |
| What are the plant defenses? | Mechanical and chemical. They are either constitutive (always turned on) or induced (only when pathogen enters). There are also physical barriers like epidermis and cork. Fungi can secrete substances to break down cork. Plants try to seal off damage areas |
| What is the first response? | Deposit more polysaccharides and more lignin on the inside of the cell wall. They block plasmodesmata, more lignin, and the precursors are toxic. |
| What are elicitors? | Chemicals that trigger defenses. Peptides made by bacteria, fungi cell wall fragments, and plant cell wall fragments. Pathogen genes that code for elicitors are avirulence genes (Avr). Plants have resistance genes that code for response (R). |
| Elicitors continued...... | The plant needs to have the receptor for elicitor to repond. Gene-for-gene resistance meaning if R and Avr match then there is resistance. |
| What are the three prongs for hypersensitive response? | Phytoalexins - ANTIBIOTICS, kills plant cells too, seals off injection, induced response. Pathogenesis-related proteins - ENZYMES to BREAK DOWN pathogen walls or ALARM. Area of damage sealed off - cells undergo apoptosis, necrotic lesion, containment. |
| Describe systematic acquired resistance. | "Body-wide", whole plant recongnizes. Long lasting. General increase in resistance of the whole plant to pathogens. Initiated by salicylic acid which is produced in local hupersensitive reaction. Synthesis of PR proteins. Also produce methyl salicylate. |
| What does methyl salicylate do? | Can travel to nearby plants and they will produce PR protins. |
| How do plants respond to RNA viruses? | Plant uses own enzymes to convert the virus' RNA to dsRNA, then chop it into siRNA (small interfering). Some viral RNA is transcribed causing the siRNA to degrade mRNA. |
| Plants' response to RNA viruses continued.. | There is no viral replication (RNA interference - RNAi). RNAi immunity spreads to whole plant, viruses try to confound it. |
| What do herbivores do to plants? | They cause physical damage and spread pathogens. Insects (hexapods) and vertebrate ore involved. |
| Why is limited herbivory good? | Removing some of the leaves is alright because it increases production and decreases shading. Grasses grow from base of shoot. They have evolved to be grazed on by having the apical meristem on the bottom. |
| What are some defenses that plants do to protect against herbivors? | Mechanical defenses include latex (white, sticky, toxic), thorns, hairs, cuticle (thick on leaves). Chemical defenses include secondary metabolites like coffee, drugs; protect plant which is constantly evolving. |
| Defenses continued... | Primary metabolites include things for photosynthesis that are needs to survive. These include proteins, nucleic acids, lipids, and carbs. There are 10,000 known. Some act on nervous system, mimic hormones, and damage the digestive track (cyanide). |
| Why do humans use secondary metabolites? | Pesticides used to protect plants. Pharmaceuticals. Nicotine was used as pesticide because it had a nervouse function that messed with insects. Canavanine is a N-storing compound in seeds, insecticide, and goes where arginine should be, defective proteins |
| How do plants sense herbivore damage? | Membrane signaling (electrical) which occurs when herbivore chomps and an electrical potential in the membrane changes. With symplast (slow lane), signal travels across plant. |
| Sensing damage continued... | Chemical signaling involves insect saliva compounds and fatty acids in plant (ELICITORS). A corn elecitor is volicitin which travels to other plants (volatile...goes in air). |
| What is Jasmonic acid? | Herbivore damage intiates signal transduction pathway with this acid. Makes protease inhibitor, stunts growth, and does "call for help" signal tha attracts insects to prey on herbivores. |
| How do plants protect themselves from toxins? | 1. Isolate toxin in special compartment (vacuoles or laticifers = tubes or in waxes). 2. Producing toxins after cells have been damaged. 3. Using modified enzymes/receptors that don't react with toxin. |
| Protection from toxins continued... | 4. Put precursor to toxin in one place and enzymes in another - only made if cell is damaged (ex. cyanide). |
| How do plants deal with climatic extremes? | Adaptation genetically encodes resistance to stress. This occurs overtime and is not controlled. Acclimation increases tolerance for extremes based on prior exposure. This happens during lifetimes. (change with environment) |
| What are desert plant adaptations? | Xerophytes are plants that adapt to dry environments. Drough avoiders have their lifecyles occur during rainfall. Plants shed their leaves during drought for water conservation. Leaf adaptations are thick cuticles, trichomes, and stomotal crypts. |
| What do trichomes do? | Reflect sunlight and prevent water loss. |
| What do stomatal crypts do? | Protect stomata so wind won't take water. |
| More desert plant adaptations?! | Succulant cacti have photosynthetic stems, spines reflect sunlight, dissipate heat. Succelence have fewer stomata, CAM, water storing. Roots are shallow to intercept rain water or super long to get buried water. They use water from condesation on leaves. |
| If there is too much water....what happens? | There is little oxygen that get to the roots which is necessary for cellular respiration. Shallow roots can carry out fermentation (fast but not enough energy), slow growth. Pneumatophores! |
| What are pneumatophores? | Root extensions out of water, many lenticels for gas exchange. |
| Talk about them aquatic plants. | They have air spaces in the parenchyma of petioles called aerenchyma. Oxygen produced by photosynthesis is stored there and little is released. Buoyancy. |
| What happens if there is drought stress? | ABA travels to shoots from root, stomatal closure, other responses. LEA means late embryogenesis abundant, increases. Hydrophobic proteins accumulate in maturing seeds at they dry out, stabilize. Recognized first in ROOTS. TRANSPIRATION first to stop. |
| What happens to plants in extreme high temperatures? | Denature proteins, destabilize membranse. Xeric adaptations. Heat shock proteins protect proteins and decrease denaturation. |
| What happens to plants in extreme low temperatures? | Less fluiditym alter permeability, ice crystals damaging. Unsaturated fats will make it so the cells don't freeze. They are increased and solidify at lower tempertures. Antifreeze proteins also slow formation of ice crystals. |
| What affect does salt have on plants? | Salinization of agriculture land is a big problem from irrigation and salt water intrusion. Plants must have even more negative water potential to obtain water because there are too many ions inside. |
| Salt affect on plants continued..... | Accumulate ions in vacuoles of leaf cells cause the water potential of cells to be more negative. Salt glands can also excrete salt. Halophytes. |
| What are halophytes? | Plants adapted to saline environments. |
| What affect does heavy metal have on plants? | Heavy metal produced by natural/human activity. Common mechanisms include increased ion transport to roots, increased translocation of ions to leaves, accumulation of ions into vacuoles (gets metals in other areas), resist toxicity. Hyperaccumulators. |
| What is hyperaccumulators? | Store large quantities such as arsenic, cadmium, nickel, aluminum, and zinc. |
| What is phytoremediation? | Involves algae. Using plants to clean up pollution. Natural and transgenic hyperaccumulators are used. After use of plants, they must be disposed because they are considered biohazard. They are used after chernobyl, sunflowers removed uranium. |
| What are the pros and cons of natural phytoremediation? | Pros: out of soil Cons: takes long time; still in there because they can't go deep. |
| What is phytomining? | Get iron out and use it by harvesting plants. |
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