BIO 148 Exam 3 (2025 / 2026) Actual Questions and Verified Answers, Guarantee Pass

BIO 148 Exam 3 (2025 / 2026) Actual Questions and Verified Answers, Guarantee Pass Ploidy after DNA replication before meiosis begins - Answer- 2n Ploidy after Meiosis 1 and cytokinesis - Answer- n Ploidy after meiosis 2 and cytokinesis - Answer- n Ploidy after fertilization - Answer- 2n nonsister chromatids - Answer- DNA molecules that can exchange small stretched of genetic material during prophase 1 of meiosis (T/F) nonsister chromatids have the same genes but may have different alleles of those genes - Answer- T (T/F) nonhomologous chromosomes have the same genes but may have different alleles of those genes - Answer- F in sexually reproducing species how does the number of chromosomes in offspring compare to the number of chromosomes in their parent - Answer- they have the same chromosome number Chimpanzees are diploid organism with 48 chromosomes, a chimpanzee cell at metaphase of meiosis 1 has which of the following - Answer- non homologous chromosomes, homologous chromosomes, sister chromosomes which of the following always have identical alleles in diploid cells directly after DNA replication but before they enter meiosis - Answer- sister chromatids for an organism with 2n=8 which of the following is true - Answer- there will be 8 chromosomes in cells that are just beginning meiosis, there will be 4 chromosomes in cells after meiosis 1 and cytokinesis a cell from an organism with 2n=4 has 2 chromosomes and 4 dna molecules what stage of meiosis is it in - Answer- metaphase 2 in cats, 2n=38 how many chromosomes are in a somatic cell in a cat - Answer- 38 a diploid organism has 18 chromosomes. a cell from this organism has 9 chromosomes and 9 dna molecules this cell is at what stage of meiosis - Answer- end of meiosis 2 AA and Aa determine black fur: aa determines white. BB and Bb determine brown eyes: bb determine blue.If a female dog with the genotype AaBb mates with a white-furred, blue eyed male dog, what is the predicted types and proportion of their puppies?A.All black fur with brown eyes. - Answer- 1/4 black fur with brown eyes, 1/4 black fur with blue eyes, 1/4 white fur with brown eyes, 1/4 white fur with blue eyes.The cross is AaBb x aabb. ¼ of the offspring are AaBb; ¼ are aaBb; ¼ are Aabb; ¼ are aabb humans are diploid with 2n=46. a human germline call at metaphase of meiosis 2 contains ____ chromosomes ____ homologous pairs and ____ dna molecules - Answer- 23, 0, 46 (in meiosis II, cells are haploid and since homologs separated in meiosis I, they are no longer in the same cell in meiosis II. In metaphase II, each chromosome still consist of 2 DNA molecules) in a dihybrid cross between two individuals with the genotype AaBb x AaBb what proportion of the offspring will have the genotype AABB - Answer- 1/16 a new mutation occurs in a germline cell and is passed on to offspring. The mutation creates a new phenotype not previously present in the population. which of the following has/have occured - Answer- evolution and an increase in genetic variation in the population In the graph, Why did average fitness stay the same from generations ? - Answer- beneficial mutation did not occur which of the following evolutionary forces can decrease the average relative fitness of a population over time - Answer- mutation, gene flow, genetic drift Which of the following statements is FALSE? a.Genetic drift can cause a population to evolve b.Without any heritable variation or any way to create it, evolution would not occur c.Gene flow between two populations can cause the two populations' allele frequencies to become more similar to each other d.A population can evolve without becoming better adapted to its environment e.New, beneficial mutations are more likely to occur when natural selection is acting on a population - Answer- new beneficial mutations are more likely to occur when natural selection is acting on a population what is absolutely required for evolution to occur - Answer- nothing is required 99% of birds in a population on an island have dark beaks and only 1% have light beaks. A category 5 hurricane hits the island and kills all but 8 of these birds: two survivors happen to have light beaks. Several generations later, 50% of the birds on the island have light beaks. What evolutionary mechanism best explains this? - Answer- genetic bottleneck and genetic drift when natural selection causes evolution in a population it _____ increases the average relative fitness of the population in the present environment - Answer- always n guppies (a small fish species), females prefer to mate with males with darker orange spots. You belong to a team of evolutionary biologists, and you are conducting an experiment in rivers in Trinidad. You select 10 pools where guppies can live. You make sure that there are no guppies or predators of guppies in those pools. In each pool, you introduce a number of male guppies; male coloration ranges from very dull orange to very dark orange. You then introduce the same number of females into each pool. You return after 2 years and you find that... - Answer- there has been directional selection in all the ten pools in the above scenario, there has been _______ in average relative fitness in _____ pools - Answer- increase, all you then introduce a few predators of guppies into all the ten pools. you return after another 2 years and you find that ________ has occured since you introduced predators to the pool - Answer- stabilizing selection in all ten pools During one year, a drought in the region leads to 4 of the pools having extremely low water levels leading to a high mortality in those populations of guppies. In these populations, __________ is going to be the mechanism of evolution. - Answer- genetic drift, selection, mutation The two graphs show the frequency distribution of male guppy coloration in two populations. 25% of the male guppies from Population A are transplanted to Population B; this causes evolution via _____ to occur, and the two populations to become more ______ than before the transplant. - Answer- gene flow, similar Homologous chromosomes _____. - Answer- contain information that affects the same traits Which of the following statements about nonhomologous chromosomes is TRUE? a.They may contain different alleles of the same genes b.They pair during prophase I of meiosis c.They have very different DNA sequences d.They are present in a single cell during meiosis I, but not present in a single cell during meiosis II e.They consist of two non-sister chromatids after DNA replication - Answer- c. they have very different DNA sequences