PBIO 1210 Exam 3 - Bensasson

Define: DiploidTwo copies of chromosome set (2N)What are homologous pairs of chromosomes?- They contain the same gene for the same traits. - One from mom, one from dad.What are the 3 phases of Interphase?- G1 (Gap1) - S (Synthesis) - G2 (Gap2)What does the cell cycle look like? (Picture).What occurs during G1 phase?- Cell increases in size - Enzymes, ribosomes, and membranes are synthesized - Mitochondria and chloroplasts replicate (In plants: nucleus migrates to center of cell)What does a checkpoint of a phase do?Stops the cycle if conditions aren't favorable.What phases of the cell cycle have a checkpoint?G1 and G2.What occurs during the S phase?- Chromosomes replicated - 2 exact copies stay attached at the centromere (held together by cohesion proteins)Define: CentromereRegion in the center of the sister chromatids where they are attachedWhat occurs during the G2 phase?- Rapid protein synthesisWhat are the 4 phases of mitosis (in order)?- Prophase - Metaphase - Anaphase - TelophaseWhat occurs during prophase?- DNA condenses (replication already occurred) - Microtubules appear - Nuclear membrane begins breaking down to allow separationWhat occurs during metaphase?- Each chromatid develops kinetochore - Chromatids are pulled in opposite directions (but not pulled apart)Define: kinetochoreA protein complex that attaches to microtubules and pulls them toward opposite poles.What occurs during anaphase?-Sister chromatids separate at the centromere and move apart - Chromatids are now daughter chromosomesWhat occurs during telophase?- New nuclear envelope forms around new chromosome sets - Spindle disappears - DNA decondensesWhat occurs during cytokinesis?- Phragmoplast forms b/w 2 daughter nuclei - Secretory vesicles from Golgi form cell plate at center of cell - Cell plate grows out toward edges - Cell membrane and new cell wall formWhat are some differences between mitosis and meiosis?- Mitosis: 1 division; 2 identical diploid cells are formed; ploidy stays the same; identical body cells formed; no pairing of chromosomes - Meiosis: 2 divisions; 4 nonidentical haploid cells are formed; ploidy halves; nonidentical gametes formed; pairing of chromsomesWhat are some similarities between mitosis and meiosis?- Both are forms of cell division - Both have prophase, metaphase, anaphase, and telophase -When a diploid nucleus (2N) undergoes MITOSIS, the result is: a) 2 haploid cells with identical genetic material b) 2 diploid cells with identical genetic material c) 2 diploid cells with distinct genetic material d) 4 haploid cells with distinct genetic material e) 4 haploid cells with identical genetic materialb) 2 diploid cells with identical genetic materialWhen a diploid nucleus (2N) undergoes MEIOSIS, the result is: a) 2 haploid cells with identical genetic material b) 2 diploid cells with identical genetic material c) 2 diploid cells with distinct genetic material d) 4 haploid cells with distinct genetic material e) 4 haploid cells with identical genetic materiald) 4 haploid cells with distinct genetic materialHow is meiosis similar to mitosis?- S phase: DNA replication produces 2 chromatids joined by centromere - Prophase: chromosomes condense, nuclear envelope disappears, spindle forms - Metaphase: chromosomes line up along the spindle's mid-pointHow is meiosis different from mitosis?- Two total divisions, producing 4 cells total with half of the parent's genetic content - Pairing step brings together homologous chromosomesWhat are the phases of Meiosis I (in order)?- Prophase I - Metaphase I - Anaphase I - Telophase IWhat are the phases of Meiosis II (in order)?- Prophase II - Metaphase II - Anaphase II - Telophase IIWhat occurs during Prophase I?- Chromosomes condense, nuclear envelop disappears, spindle forms - Homologous chromosomes pair - Homologous chromosomes exchange genetic material from the same part of the chromosomeWhat occurs during Metaphase I?- Homologous pairs of chromosomes line up randomly at center of cell - Attached to spindle microtubulesWhat occurs during Anaphase I?Homologous pairs separate to different cells --- duplicated chromatids go to the same cell at the end of meiosis; chromatids don't separateWhat occurs during Telophase I?Chromosomes start to uncoil, nuclear envelope starts to reformWhat is important to note about Telophase I?Most organisms only experience partial telophase, but some organisms skip it altogether.Define: NondisjunctionWhen meiosis/mitosis goes wrong. Homologs/sister chromatids fail to separate to opposite poles.What is a real-life example of nondisjunction and what is it's cause?Down's syndrome (Trisomy 21); failure in Anaphase I.Define: PolyploidyContaining more than 2 homologous sets of chromosomes.In what organisms would you find polyploidy?- Invertebrate animals - Some tissues (liver) in mammals - Plants (ex: wheat, potato, strawberry)Cell cycleCell goes from being a single cell, replicates itself, and divides into 2+ cells.Define: GametesSex cellsWhich of the following is polyploid? a) Mules b) Seedless watermelon c) Humans with Down's Syndromeb) Seedless watermelonWhat percentage of plants are polyploidy?30-70%What type of plants are most likely to be polyploidy?Agricultural crops.How might polyploidy arise?- Mispairing during meiosis - DNA replicates but chromosomes don't get segregatedWhy do farmers usually use polyploidy for crops?Because polyploidy plants have larger cells and tend to be larger plants. Larger plants = more nutritionHow does one create polyploidy?By using the chemical "colchicine" which disrupts mitosis by disrupting the formation of microtubules. (Plant has 2N leaves and tetraploid growth).What parts/types of plants are triploid?- Seeds of flowering plants (ex: wheat) - Seedless/sterile plants (newly-arisen triploid)Is it an issue for triploids to perform mitosis?No. There is less of an effect because there's no pairing stem in mitosis. The chromosomes just split down the middle and replicate.Is it an issue for triploids to perform meiosis?Yes. There is a pairing stem, which means that chromosomes can't pair properly.How do you make a triploid, seedless watermelon from diploid watermelons?- Create tetraploid watermelons - Cross a diploid watermelon with a tetraploid watermelon to create triploid seeds - Use triploid seeds and pollen (provided by diploid watermelons nearby) to create triploid watermelonWhat is a specialized way polyploidy can arise?Newly-arisen polyploid plants breed with each other but not with parental varietiesWhat is the significance of mules in relation to polyploidy?Mules have 63 chromosomes (1 more set than horse; 1 less than donkey) but pairing is usually fine, so mules are not polyploidy.What are the 2 major life cycles?- Asexual - SexualDescribe: asexual reproduction- Simple life cycle - Mitotic - Ploidy stays the same because no meiosis occurs - Simple life cycle produces the same asexual structures each generation - Prokaryotes, plants, fungi, and some animals performDescribe: sexual reproduction- Complex life cycle (haploid and diploid stages; specialized reproductive cells) - MeioticWhat are the 3 basic types of sexual life cycles?- gametic (2N - mitosis) - zygotic (N - mitosis) - sporic (N & 2N - mitosis)You observe a single-celled organism carefully for several generations and find that the cells that divide are always diploid. Sometimes the resulting daughter cells are diploid and sometimes they are haploid, but the haploid cells never seem to divide. This organism most likely has what kind of life cycle? a) Gametic (ex: animals) b) Zygotic (ex: algae) c) Sporic (ex: plants) d) Not enough information to tella) Gametic (ex: animals)Describe: gametic life cycle- Sexual because there is meiosis and fertilization - No mitosis in the haploid stage. - All cells except gametes are diploidDescribe: zygotic life cycle- Common in protists and other simple eukaryotes - Sexual because there is meiosis and fertilization - No mitosis in diploid stage - All cells except zygotes are haploid (mostly N)Describe: sporic life cycle- All land plants; some algae - Sexual because there is meiosis and fertilization - Mitosis in both the haploid and diploid stages - Plants differ in importance of each stageAlternation of generations in sporic life cycle- Diploid (2N) stage (sporophyte) that produces spores by meiosis - Spores grow into haploid (N) stage (gametophyte) that produces gametes by mitosis - Gametes fuse to produce zygote that grows into a sporophyteAsexual life cycle:Mitosis only (offspring are identical)Sexual life cycle:Mitosis and meiosis (offspring differ from parents) - Gametic: mitosis in diploid stage - Zygotic: mitosis in haploid stage - Sporic: mitosis in both stagesYou observe a single-celled organism carefully for several generations and find that the cells that divide are always diploid. Sometimes the resulting daughter cells are diploid and sometimes they are haploid, but the haploid cells never seem to divide. This organism most likely has what kind of life cycle? a) Gametic b) Zygotic c) Sporic d) Asexuala) GameticYou observe a single celled organism carefully for several generations and find that sometimes cells are diploid and sometimes they are haploid. Both haploid and diploid cells can divide by mitosis. This organism most likely has what kind of life cycle? a) Gametic b) Zygotic c) Sporic d) Asexualc) SporicDefine: GeneticsThe study of (genetic) inheritanceDefine: Blending inheritance- Assumes that genetic material mixes (like paints) - Offspring intermediate to parents - Problem: This means no new characteristics show up; population will become homogeneousWhat does "F1 Generation" mean?1st Filial Generation; 1st generation from parents (aka kids)What doe "F2 Generation" mean?2nd Filial Generation; 2nd generation from parents (aka grandkids)Who came up with the "gene" idea?Gregor MendelWhat is another name for the "gene" idea?Particulate inheritanceDescribe: Particulate inheritance- Parents pass on discrete heritable genes - Pass through generations unchanged - May be masked in certain individualsHow did Mendel's pea experiment work?- Controlled who the parents of the pea plants were - Controlled the traits that crossed - Counted resulting traitsWhen Mendel crossed true-breeding parents, all the offspring in the F1 were... a) All identical b) All the same as one parent c) All different d) A and Bd) A and B * Because offspring of white and purple flower were all purpleDefine: Dominant traitTrait that is expressed in F1; "stronger"Define: Recessive traitTrait that is "hidden" in F1What happened when Mendel- Ratio - 3:1 - purple:white - Recessive traits began to appearDescribe Mendel's model of inheritance.- Parents DON'T transmit traits to offspring; they transmit genes - Each individual gets 1 allele of each gene from each parent - 2 different alleles don't blend; only dominant is shown - Recessive trait is shown when there are 2 recessive allelesDefine: PhenotypeObservable trait (ex: yellow)Define: GenotypeGenetic makeup (ex: YY)Is the genotype always the same as the phenotype?No. (Ex: Genotype Yy doesn't mean that green phenotype is shown).In this cross between true-breeding green and yellow pea parents, the genotypes in the resulting F1 generation are... a) All yellow b) All Yy c) Yellow and green d) Y and yb) All YyIn this cross between true-breeding green and yellow pea parents, the phenotypes in the resulting F1 generation are... a) All yellow b) All Yy c) Yellow and green d) Y and ya) All yellowWhat is Mendel's first law (law of segregation)?- 2 alleles at a locus segregate into separate gametes; each half carrying 1 alleleAccording to Mendel's first law, 2 alleles at a locus (one on the chromosome from mom and the other on the chromosome from dad) segregate into separate gametes. When does this physically happen? a) Mitosis b) Meiosis I c) Meiosis II d) Fertilizationb) Meiosis I * Because the homologous chromosomes (mom and dad) separate; in Meiosis II, identical replicas are being separatedVisualize the separation of alleles in meiosis.True breeding lines of peas with purple flowers (PP) are crossed with those with white flowers (pp). The purple allele is dominant. Offspring in the F1 generation... a) All have white flowers (Pp) b) All have purple flowers (Pp) c) Have a mixture of white and purple (PP, Pp, pp) d) Have a mixture of white and purple (PP, pp)b) All have purple flowers (Pp)Define: HomozygousSame 2 alleles (ex: PP or pp)Define: Heterozygous2 different alleles (ex: Pp)Define: AlleleA version of a geneIf you cross an F1 mom (Pp) with an F1 dad (Pp), and purple is dominant, offspring in the F2 generation... a) All have white flowers (Pp) b) All have purple flowers (Pp) c) Have a mixture of white and purple (PP, Pp, pp) d) Have a mixture of white and purple (PP, pp)c) Have a mixture of white and purple (PP, Pp, pp)Define: TestcrossCrossing unknown purple plants (heterozygotes) with a true-breeding white plant (homozygotes)Red is dominant. Who are Joe's parents? a) Bill & Lill b) Vinny & Violet c) Neither d) Not enough infod) Not enough info * Because the red can either be homozygous or heterozygousNow crosstest... Red is dominant. Who are Joe's parents? a) Bill & Lill b) Vinny & violet c) Neither d) Not enough infoa) Bill & LillMendel's Law of Segregation (Mendel's First Law) is a consequence of... a) Sister chromatids separating during mitosis b) Crossing over during meiosis c) Homologous chromosomes separating during meiosis I d) Alleles from genes on different chromosomes segregate independently of one anotherc) Homologous chromosomes separating during meiosis IDescribe the segregation of alleles in meiosis.- Separation of homologous chromosomes (same traits but different variations) separate into Y and y during meiosis IA mystery pea plant has purple flowers, but an unknown genotype. A plant geneticist uses a test-cross with a pea plant with white flowers (pp) to determine the genotype of the pea plant with purple flowers. Half the resulting offspring have white flowers. The mystery pea plant is a... a) Heterozygous (Pp) b) Homozygous dominant (PP) c) Homozygous recessive (pp) d) Insufficient information to tella) Heterozygous (Pp)What is Mendel's second law (law of independent assortment)?- Involves different genes on different chromosomes - Inheritance of alleles at multiple loci - Inheritance at one locus independent of other loci - 2+ pairs of homologous chromosomes; different alleles on different chromosomes - AKA: 4 possible phenotypes instead of only 2; 16 possible genotypes instead of only 4What is the ratio of Mendel's 1st Law?3:1What is the ratio of Mendel's 2nd Law?9:3:3:1 (still 3:1 when looking at a single locus)What is a dihybrid cross?A cross between 2 different genes with different observable traitsA botanist crosses a true-breeding purple-flowered, yellow-seeded plant (PPYY) with a white-flowered, green-seeded plant. What genotypes do you expect in the offspring? a) PPYY, PPYy, PPyy, PpYY, PpYy, Ppyy, ppYY, ppYy, ppyy b) PpYy, Ppyy, ppyY, ppyy only c) PPYY, PpYy, ppyy only d) PpYy onlyd) PpYy onlyA botanist crosses two purple-flowered, yellow-seeded double heterozygous (PpYy). What genotypes do you expect in the offspring? a) PPYY, PPYy, PPyy, PpYY, PpYy, Ppyy, ppYY, ppYy, ppyy b) PpYy, Ppyy, ppyY, ppyy only c) PPYY, PpYy, ppyy only d) PpYy onlya) PPYY, PPYy, PPyy, PpYY, PpYy, Ppyy, ppYY, ppYy, ppyyA botanist crosses two purple-flowered, yellow-seeded double heterozygous (PpYy). What phenotypes do you expect in the offspring? a) 1 purple, yellow : 2 purple, green : 1 white, green b) 1 purple, yellow : 3 purple, green : 3 white, yellow : 1 white, green c) 9 purple, yellow : 3 purple, green : 3 white, yellow : 1 white, green d) Purple, yellow onlyc) 9 purple, yellow : 3 purple, green : 3 white, yellow : 1 white, greenMendel's Law of independent Assortment (Mendel's Second Law) is a consequence of... a) Sister chromatids separating during mitosis b) Crossing over during meiosis c) Homologous chromosomes separating during meiosis I d) Alleles from genes on different chromosomes segregating independently of one anotherd) Alleles from genes on different chromosomes segregating independently of one anotherDefine: linked traitsTraits that are located on the same chromosomeHow do linked traits affect Mendel's model?Linked traits alter the ratio in Mendel's 2nd LawWhat are the possible phenotype ratios of linked traits?- Close to 9:3:3:1 - far apart - Close to 3:0:0:1 - close togetherThe genes for plant height (tall-T; or short-t) and flower position (axial-A or top-a) are on the same chromosome. if you cross two double heterozygotes that are tall with axial flowers (TtAa), then what phenotypes do you expect in the offspring? a) 9 tall, axial : 3 short, axial : 3 tall, top : 1 short, top b) 3 tall, axial : 1 short, top c) somewhere between a and b d) 1 tall, top : 2 tall, axial : 1 short, topc) Somewhere between A and BThe genes for plant height (tall-T; or short-t) and flower position (axial-A or top-a) are on different chromosomes, then what phenotypes would you expect in the offspring of a double heterozygote cross (TtAa x TtAa)? a) 9 tall, axial : 3 short, axial : 3 tall, top : 1 short, top b) 3 tall, axial : 1 short, top c) somewhere between a and b d) 1 tall, top : 2 tall, axial : 1 short, topa) 9 tall, axial : 3 short, axial : 3 tall, top : 1 short, topHow does crossing over affect Mendel's model?When crossing over occurs, loci are more independent, so results are closer to Mendel's expected ratio.Define: Polygenic traitA trait controlled by multiple genesHow do polygenic traits affect Mendel's model?The traits will average together. Ex: different color gradients, heights, etc.What are the 5 exceptions to Mendel's Model?- Multiple genes on same chromosome - Multiple genes that affect the same trait - Codominance/Incomplete dominance - Epistasis (genes may interact to produce a phenotype) - Environmental impact on phenotypeDefine: Incomplete dominanceIntermediate phenotype; genotype is a direct reflection of phenotypeHow does incomplete dominance affect Mendel's model?Genotype is a direct reflection of phenotype; mixes are created rather than the dominant or recessive trait showingIn cattle, roan coat color (mixed red and white hairs) occurs in heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red : 2 roan : 1 white? a) red x white b) roan x roan c) white x roan d) It's impossible to tell based on the above informationb) roan x roanDefine: EpistasisSuppression of one gene by another/an allele from one gene is determined by the allele of another geneHow does Epistasis affect Mendel's model?The ratio of offspring phenotype is 9:7 instead of 9:3:3:1A couple who are both carriers of the recessive cystic fibrosis allele (Ff) have 2 children who have cystic fibrosis (ff). What is the probability that their next child will have cystic fibrosis? a) 0% b) 25% c) 50% d) 75% e) 100%b) 25%What are some examples of when genotype doesn't equal the phenotype because of environment?- Human height - Heart disease - Crop yieldDefine: Evolution- Change in an allele or genotype frequency over time - Cumulative change in a population's genetic characteristics over timeWhat are some ideas of evolution before Darwin?- Aristotle: life forms are permanent and unchanging - 1600s: date of creation estimated (4004 BC) - Fossil records show extinctions and change - 1800s: Geological phenomena due to gradual natural causesWhat is Earth's current estimated age?4+ billion years oldWhat are some examples for evolutionary change?- Trees of life - Fossil recordsWhat did Lamarck say about evolution?- Traits change through use or disuse - Ex: giraffes got longer necks through the usefulness of those who had long necksDarwin thought that cacti on the Galapagos Islands with tortoises came to be taller than those on other islands because... a) Tortoises ate the lower parts of cacti, so these adapted individuals had taller descendants b) Tall cacti were less likely to be completely eaten and therefore left more decedents c) Cacti are polyploid d) Cacti mated with native cacti from the islands to produce taller offspringb) Tall cacti were less likely to be completely eaten and therefore left more decedentsHow might Darwin have proposed that a gerbil evolved its long tail? a) Longer-tailed gerbils reproduced more often than short-tailed ones, and over time the population changed to have longer tails b) A gerbil's tail gets longer when it uses it for balance, so over generations the tail, originally short, became longer and longer c) Hamsters mated with rats, which have long tails, and produced long-tailed offspring d) Either A or Ba) Longer-tailed gerbils reproduced more often than short-tailed ones, and over time the population changed to have longer tailsHow might Lamarck have proposed that a gerbil evolved its long tail? a) Longer-tailed gerbils reproduced more often than short-tailed ones, and over time the population changed to have longer tails b) A gerbil's tail gets longer when it uses it for balance, so over generations the tail, originally short, became longer and longer c) Hamsters mated with rats, which have long tails, and produced long-tailed offspring d) Either A or Bb) A gerbil's tail gets longer when it uses it for balance, so over generations the tail, originally short, became longer and longerExplain Darwin's theory of natural selection.- Populations adapt to their environment - Every species is able to produce more offspring than can survive - Individuals in a population have heritable variation in traits, which affects survival/reproduction chances - individuals with the most advantageous traits will produce the most offspringDefine: Natural selectionProcess where best surviving genotypes in an environment gradually increase over time until the population overall survives.What are the 5 mechanisms of evolution?- Mutation - Genetic drift - Natural selection - Non-random mating - MigrationDefine: MicroevolutionChange in allele or genotype frequency over timeGenetic drift refers to: a) Allele frequency changes due to selection favoring a particular allele b) Allele frequency changes due to selection acting against a particular allele c) The transfer of alleles from one population to another via migration d) Random change in allele frequency from one generation to the nextd) Random change in allele frequency from one generation to the nextWhich of the following is true? Mutations... a) Will occur in a gene when they are needed in response to a selection pressure from the environment b) Lead to large random fluctuations in allele frequencies in small populations c) Occur randomly when DNA is replicated d) Usually have good phenotypic effectsc) Occur randomly when DNA is replicatedIn a classroom population of 200 dandelions, the "Ace of Spades" is a dominant allele (A) at a single locus that confers resistance to glyphosate (RoundUp) herbicide. We observed the following number of each genotype: AA: 0 Aa: 4 aa: 196 Allele frequency of A = A / (A + a) The allele frequency for A is therefore... a) 4 / 200 = 0.02 (2%) b) 196 / 4 = 49 c) (0 + 4) / 400 = 0.01 (1%)a) 4 / 200 = 0.02 (2%)How might Darwin have proposed that a gerbil evolved its long tail? a) Longer-tailed gerbils reproduced more often than shorter-tailed ones, and over time the population changed to have longer tails b) A gerbil's til lengthens when used for balance. Individuals that adapt in this way pass on their lengthened tails to their descendants c) Hamsters mated with rats, which have long tails, and produced long-tailed offspring d) Both A and Ba) Longer-tailed gerbils reproduced more often than shorter-tailed ones, and over time the population changed to have longer tailsHow did the presence of fossil organisms challenge the pre-Darwinian idea of special creation? a) Some of the fossil organisms were very similar to modern organisms b) Some fossils were intermediate in appearance to current species, suggesting that modern organisms descended from intermediate-looking ancestors c) Some of the fossil organisms were primitive looking and unattractive, which did not seem to fit with the idea of idealized organisms d) They were found under thick layers of rockc) Some of the fossil organisms were primitive looking and unattractive, which did not seem to fit with the idea of idealized organismsDefine: PopulationAll individuals of a certain species living in a particular areaDefine: Population GeneticsChange in allele or genotype frequency over time.Define: Genotype frequency- Proportion of a population with a certain genotype - Not necessarily equal to phenotypic frequency (# of individuals = # of genotypes)Define: Allele frequency- Proportion of gene copies of a certain type (alleles) in the population - Diploids have 2 copies of each gene (in diploid population... # alleles = 2x # individuals)Define: PolymorphicMultiple different alleles at a locusWhat are some forces that lead to evolutionary change?- Natural selection - Mutation - Genetic drift - Non-random mating - MigrationDefine: Mutation- Ultimate source of all heritable variation in evolution - Any change in organism's DNA - Occur randomly as a result of replication mistakes - Can be induced by chemicals or radiationWhat type of mutations are heritable?Those that occur in reproductive cellsWhat are the 3 types of mutation?- Substitution (CTA ---> CAA) - Insertion (CAT ---> CAGT) - Deletion (CAT ---> C-T)What are some effects of mutation?- No effect on phenotype (usually) - Phenotypic effects are usually bad (some are good)Define: Genetic driftRandom changes in allele frequencyWhat is the Founder Effect?Colonization of a new area by a small part of the original population that causes reduced genetic variability (fewer founders = larger effect)Define: FitnessThe ability of an organism to survive and transmit its alleles to the next generation... More alleles contributed to next generation = higher fitnessWhat are the 2 components of fitness?- Viability (survivorship from fertilization to reproduction) - Fecundity (# of offspring produced)Define: Selection pressureFactors that affect fitnessWhat are the 2 types of selection pressure?- Abiotic factors (interactions w/ environment) - Biotic factors (interactions w/ other organisms)What are some examples of abiotic factors?- Temperature - Elevation - Moisture - ChemicalsWhat are some intraspecific (within species) examples of biotic factors?- Mating - Competition - CooperationWhat are some interspecific (between species) examples of biotic factors?- Competition - Predation/herbivory - Parasitism - MutualismWhat are the 3 types of natural selection?- Directional Selection - Stabilizing Selection - Disruptive selectionWhat is directional selection?Extreme phenotype is favored over other extremeWhat is an example of directional selection?- the # of weeds that have evolved a resistance to RoundUpWhat is stabilizing selection?Intermediate phenotypes are favoredWhat is an example of stabilizing selection?- amount of flowers on a plant (too few = less reproduction; too many = costly, may die during drought)What is disruptive selection?Different extremes of phenotypes are favoredWhat is an example of disruptive selection?- divergence in floral forms (male primrose & female primrose; increases reproduction)A population of plants produces seeds which are eaten by ants, so the seeds that are not selected by ants are more likely to survive. The ants select for the seeds which are the largest they can carry (about medium-sized) to maximize the food content. For the plant population, this is an example of... a) directional selection b) disruptive selection c) stabilizing selection d) random genetic driftb) Disruptive selection (because smaller seeds and larger seeds aren't going to be eaten by ants)A population of plants produces seeds which are eaten by ants, so the seeds that are not selected by ants are more likely to survive. The ants select for the seeds which are the largest they can carry (about medium-sized) to maximize the food content. For the ant population, this is an example of... a) Directional selection b) Disruptive selection c) Stabilizing selection d) Random genetic drifta) Directional selection (stronger ants are favored so they can carry the biggest seed possible)If there are no ants around, then the plants that produce the most offspring are those that produce medium-sized seeds. This is because seeds that are too small are less likely to germinate, and a plant can only produce few very large seeds. This is an example of... a) Directional selection b) Disruptive selection c) Stabilizing selection d) Random genetic driftc) Stabilizing selectionWhat is non-random mating?What are the 3 types of non-random mating?- Inbreeding - Outbreeding - Population structureHow does inbreeding affect genotype frequencies?- Heterozygous genotype frequencies decrease - Homozygous genotype frequencies increaseWhy is inbreeding bad?- Exposes deleterious phenotypesDefine: OutbreedingMating between distantly related parents (heterozygotes)Why is outbreeding good?- Hides phenotypes of deleterious recessive allelesWhat is an issue with outbreeding?F2 generation will re-expose deleterious recessivesWhat is population structure?Population subdivision; different genotypes are present in different areas. Populations will diverge genetically.Define: MigrationMovement of individuals form one population to anotherDefine: Gene flowMovement of alleles from one population to another through matingDefine: HybridizationMovement of alleles from one species to another; not commonWhat happens when there is no gene flow?- Speciation. - Populations diverge until they are too different genetically, phenotypically, or ecologically to mate.What is the biological species concept?Species are groups that can breed with each other.What is the morphological species concept?Organisms that came from a common ancestor and look similar in appearance are in the same species.What are some problems with the morphological species concept?- Cryptic species are indistinguishable but cannot interbreed - Broccoli, cauliflower, kale, etc. all look different but can all interbreedWhat are some problems with the biological species concept?- Doesn't apply to asexual organisms (microbes and some plants) - Difficult to apply or test - Hybridization --- many species (esp. plants) can interbreed at least a little with other speciesWhen taxonomists use the Biological Species Concept to decide whether the individuals in 2 populations belong to separate species, they decide according to whether individuals... a) Are morphologically similar b) Are physiologically similar c) Have similar DNA sequences d) Can produce fertile offspringd) Can produce fertile offspringWhat are the 2 main patterns of speciation?- Allopatric speciation - Sympatric speciationDefine: Allopatric speciationGeographic isolation resulting in genetic divergenceDefine: Sympatric speciationGenetic divergence without geographic isolationWhere do geographic barriers come from?- Formation of new islands - Recession of glaciers - Fragmentation of habitat - Drying down of a water bodyDefine: Adaptive radiationRapid formation of many new species that are adapted to new nichesA river carves through a mountain range separating a moss population, which eventually becomes 2 species, as gene flow is absent. This ia representative of... a) Terrapatric speciation b) Sympatric speciation c) Aquapatric speciation d) Allopatric speciationd) Allopatric speciation

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