1777986
| Question | Answer |
| Flight evolved 4 times | -insects -teradaptors -birds -bats |
| How to get a hybrid | 1.start with a continuous population 2.barrir is formed 3.allopatric speciation 4.separated populations meet 5.Hybrid is formed |
| Barriers to hybridisation | 1.geographic isolation 2.habitat separation 3.temporal and pollinator isolation 4.pollen compatibility and competition 5.Hybrid viability, fitness, sterility, breakdown |
| Polysaccharide | polymer composed of many sugar residues linked to each other ex:starch, cellulose |
| Pectin | heteropolysaccharide. intercellular glue. Lubrification of wall to help cell expansion |
| hemicellulose | Matrix polysaccharide. tethering adjacent microfibrils |
| cellulose | Polysaccharide. structure of microfibrils themselves |
| xyloglucan | chain acting as tether to stop cells from separating |
| Agents capable of cutting xyloglucan | -XET -endo B-glucanase via hydrolysis |
| What regulates cell wall expansion? | Peroxidase action |
| Enzymes that digest polysaccharides | -Endo-glycosidases -Exo-glycosidases -Cellulose-cellobiodrolase |
| Rhizosphere | area around roots |
| Phyllosphere | leaf area |
| gene-for-gene hypothesis | plants search for pathogens effector proteins to activate defense mechanism |
| R-genes | Resistance genes that convey plant disease resistance against pathogens by producing R proteins |
| Avirulent pathogen | induces defense: plant = resistant |
| Virulent pathogen | No recognition: plant is susceptible to disease |
| SAR genes | encode/ synthesize pathogenesis related (PR) proteins |
| What signal activates SAR genes? | 1.Resistant response triggers release of signal 2.signal establishes LAR in local leaf 3.subsequently signal exists local leaf and establishes SAR in all leaves |
| Salicylc Acid (SA) is a signal for.. | -PR protein synthesis -SAR |
| Flavenoid function | 1.Chemotaxis 2.nod gene activation 3.Increase bacterial growth rate 4.Ensure lots of compatible Rhizobia species are around root |
| NOD genes | encode the signal that drives nodulation process (formation of nodules) |
| Root hair curling | A NOD factor where bacteria multiply and invade cell wall through invagination forming an infection thread aiming for the root cortex |
| Determinate nodules | Rhizobia infect outer root cortex ex: L. japonicus |
| Indeterminate nodules | Rhizobia infect inner root cortex ex: M. Truncatula |
| Annual crop | Grown from seeds, harvested within 1 year. Grain crops. ex: cereals |
| Perennial crop | Grown over several years and often harvested many times. Ex: Fruit trees |
| Tubers (crop) | Botanically perennials, not grown from seed but planted every year. Ex: potatoes |
| Grafting | Use of a twig of a parent plant and attach it to a root shoot. |
| Vegetative propagation | Asexual reproduction: new individual without production of seeds/spores. Only in perennials. |
| Advantages of clonal propagation | Offspring are genetically identical to each other and parents. Uniformity: no variation harvest at the same time. |
| Disadvantages of clonal propagation | Being genetically identical, offspring are susceptible to the same diseases. Ex: Most bananas are the Cavendish variety, which is susceptible to fungal panama disease which is globally decreasing yields. |
| What 3 things do plants need? | -Nitrogen (in form of nitrate) -Phosphorus (in form of phosphate) -Potassium |
| Past breeding targets | -uniformity -increasing yields |
| Current breeding targets | -High yields under stress -Increase in resistance to stress, pests, pathogens -Decrease in reliance on fertilizer -More water efficient |
| Elite breeding | Depends on finding better combinations of existing alleles but creates a genetic bottleneck. Some fear yield ceiling others contradict with illinois maize experiment. |
| Yield ceiling | Stabilization of yields, breeds have found best combination of alleles possible. |
| Hybrid vigour/ Heterosis | The improved function in a hybrid offspring. |
| Monocious | Have both male and female reproductive parts. Ex: maize |
| Polyploidy | Where there are more than 2 paired sets of chromosomes. |
| Autopolyploidy | Doubling already existing chromosomes |
| Advantages of GM crops | -quicker -cleaner (can add only transgene) -not limited to genes present in inter fertile species -Can use lab synthesized genes |
| Disadvantages of conventional breeding | -Costly -Takes time |
| Antisense gene | RNA strands are flipped around: decreases a genes expression promoter |
| Molecular markers | New technology. Reveal the polymorphism at the level of DNA. Identify and locate specific genes. Markers assisted selection. |
| Characteristics of fungi | -Eukaryotic -Heterotrophic -feeding via filamentous hyphae -Chitin cell walls -produce spores by means of sexual and asexual production |
| Hyphae | Apically extending, branching filaments |
| Features of filamentous fungi | -Extensive multicellular development -produce wide variety of spores -Hyphae exhibit tip growth and branching; have multinucleate compartments; undergo fusion to form interconnecting networks; produce septa (cross walls) with pores -Self fusion between genetically identical fungi |
| Hyphal networks function in... | -Allowing colony to operate as a single individual -Communication -Nutrient transport -Water translocation |
| Woronin body | organelle that acts as a septal pore plug |
| Non fungal fungi | -Protozoa (Plasmodial? cellular slime moulds) -Chromista (phylum Oomycetes) |
| Chytridiomycota | Most primitive. Degrade cellulose, chitin. Rhizoids instead of mycelium. Motile zoospores and gametes. Often aquatic. Caused worldwide amphibian decline (BD) |
| Zygomycota | Multinucleate mycelium with no septa. Produce spore in zygosporangium. Ex: R. Oligosporous |
| Glomeromycota | AKA AM fungi. form symbiosis with 80% plants. grow in roots and form arbuscules. |
| Dikarymycota | Ascomycetes and Basidiomycetes. Unicellular or filamentous. Flagella. |
| Fungal biotrophic pathogen | Ex: Tritici (Black stem rust wheat) form infection structures on leaves creating hypersensitive response in plant Infection via rust germ tubes Infection structures: appressoria, haustoria, penetration peg |
| Fungal hemibiotrophic pathogen | Infects like rust then kills host Ex: Magnaporthe grisea (Rice blast fungus) |
| Fungal necrotrophic pathogen | Cause host death by secreting enzymes or toxins. Don't produce specialized infection structures. Ex: Monilana Fructigena (Brown rot in fruit) |
| Causes of spread of fungal diseases | -Increase in trade -Poor application of photo sanitary measures -Lack of funding -Lack of expertise Ban of Methyl bromide |
| Homothalic | species can complete sexual cycle on its own Ex: ascomycetes |
| Heterothalic | Sexual reproduction requires 2 individuals |
| Heterokaryosis | Fusion of hyphae, nuclei migrate from 1 hyphae to another (hyphae contains 2 nuclei) creating a larger gene pool. |
| Functions of spores | 1.Reproduction: asexual (ex: conidia), sexual (ex: basidiospores) 2.Dispersal: structural adaptations, specialized mecanisms 3.Survival: low water content, thicker cell walls, pigmentation |
| Fungal associations | -Lichen -Mycorrhizas -Endophytes |
| Endophytes | Live part of their life in leaves without causing harm. Can enhance plant growth, improve pants resistance to tolerate abiotic stress, improve resistance to herbivores. |
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