Biology 1M03 Midterm1 Exam Questions With Correct Answers

change from gen to gen via selection of heritable traits evidence for evolution - Answer - fossils - extinction - transitional forms - vestigial traits why is the myth about evolution being goal oriented false? - Answer species do not adapt because they "want" or "need" traits; they adapt them because an ancestor with that triat just so happened to reproduce sooner or more successfully than others why is the myth that evolution is a hierachy false? - Answer evolution is more a network of evolutionary paths; the size of a genome does not necessarily equate to complexity why is the myth that behavious is selfless in animals false? - Answer all "selfless" traits are not favoured because they would kill the organism; those who are selfless are killed off why is the myth that natural selection leads to the best phenotype false? - Answer there are constraints and trade offs to consider genetic correlation - Answer when the selection of one allele unintentionally leads to a change in another trait historical constraint - Answer there is already bias for future possibility in selection formal constraint - Answer adaptations must be within the laws of physics temporal constraints - Answer traits will be favoured while they exist and while the organism is still alive natural selection - Answer explains how the process of evolution works; can be thought of as a change in allele frequency over time what does natural selection rely on? - Answer - variation - heritability - fitness - competition explain what happened in the mycobacterium TB bacteria - Answer antibiotics gave rise to a resistant population because of a small mutation in RNA gene rpoB; in normal conditions this mutation wouldn't survive but the antibiotics switched the case gene that influences beak size expression - Answer Bmp4 candidate study - Answer using an accessible species to study the molecular basis for a selection in a target species that is not as easy to access/test artifical selection - Answer humans alter course of evolution but purposely selecting traits what influences speed/degree of artificial selection? - Answer how many times its repeated, how many traits the animal has, and # of constraints unintended artificial selection - Answer does not benefit humans or nature and is a direct consequence of human activity examples of unintended artifical selection - Answer large horned sheep; smaller cod typical result of artificial selection - Answer smaller size, time of maturation, behaviour why does unintended artificial selection result in this? - Answer humans go after the strongest and best in a population whereas natural selection is the opposite what is the purpose of hardy weinberg? - Answer to analyze allele frequencies and apply it to make predictions about a population what are the 4 factors that influence allele frequency? - Answer - natural selection - genetic drift - gene flow - mutation what does hardy weinberg assume? - Answer assumes that allele frequencies are not changing over time what are the steps to test for HWE? - Answer analyze genotype frequencies; analyze allele frequences; estimate expected frequnecies; compare expected with observed if a population is in HWE what does that mean - Answer there's no proof its in HWE you just fail to reject it; it means that none of the 4 factors are acting on the population directional pattern of natural selectin - Answer one extreme genotype is favoured stabilizing pattern of natural selection - Answer intermediate (heterozygous) phenotype is favoured; reduces variation in the extremes disuptive pattern of natural selection - Answer favours both extreme genotypes and reduces variation of the intermediate negative frequency dependant pattern of natural selection - Answer rare phenotypes in a population are favoured positive frequency dependant pattern of natural selection - Answer common phenotypes in a population are favoured genetic drift - Answer random change in allele frequency; is unbiased and non adaptive fixation outcome of genetic drift - Answer trait that was polymorphic is now present in every individual extinction outcome of genetic drift - Answer new allele appears and then goes extinct over an infinite amount of time what is the concern regarding genetic drift? - Answer small populations are at risk because reduction in genetic variation happens quicker which may make the population less able to respond to their environment founder effect - Answer continental population moves to an island; some alleles are randomly sampled; some alleles are overrepresented and some are not; may increase occurence of disease bottleneck concept - Answer reduction in population size for at least one generation leads to reduced genetic variation; degree of reduction depends on extene of population decrease, # of generations it lasts for, and if natural selection is affecting anything gene flow - Answer movement of alleles from one population to another when does gene flow happen - Answer when individuals leave a population, join another, and breed what is the outcome of gene flow - Answer equalizing of allele frequencies; reduces the genetic variation between the two populations what is the mode of inheritance from females when they reproduce with males - Answer - 100% mtDNA - 67% X chromosomal DNA - 50% autosomal DNA - 0% Y chromosome DNA non random mating - Answer biased mating; not random with respect to gene in question inbreeding - Answer mating between close relatives what is the disadvantage/danger in inbreeding? - Answer decreases heterozygosity and increases homozygousity. this couldmdecrease fitness because deleterious mutations are recessive and heterozygosity is therefore more advantageous mutation - Answer way of generating new alleles and restoring genetic variation in a population; is slow and random why are bacteria used to investigate mutation? - Answer they go through several generations in one day; past studies have shown that descendants increase in fitness over time what is the difference between mutation and other evolutionary processes - Answer on its own, it wouldn't really make a difference in allele frequency and genetic diversity but combined with the other processes it's really important