PCB 3063 Final Exam 100% Pass 2025

Which of the following events of meiosis creates genetic variation among the gametes? A. Crossing over B. Independent assortment of maternal and paternal chromosomes C. Separation of homologues so each gamete only gets one copy of each chromosome D. A and B E. All of the above - Correct Answer-E. All of the above Tall (T) is a dominant trait in corn plants over dwarf (t). A tall plant is test-crossed, and half of the offspring produced are tall and half are dwarf. What are the genotypes of the individuals that were crossed if the mating followed exactly what was predicted? A. TT x tt B. Tt x tt C. Tt x Tt D. TT x Tt - Correct Answer-B. Tt x tt For the recessive X-linked eye color gene in fruit flies, Morgan crossed a homozygous red eyed female with a white eyed male. Which result made Morgan think that the locus affecting eye color was on the X chromosome? A. All F1 male and female flies had red eyes. B. All F1 male and female flies had white eyes. C. In the F2, all females had red eyes, and half of the males had red eyes and the other half had white eyes. D. In the F2, half of males and females had red eyes and the other half had white eyes. - Correct Answer-C. In the F2, all females had red eyes, and half of the males had red eyes and the other half had white eyes. A child who is blood type A has a mother who is blood type B. In a paternity suit, a man is accused of being the father. He has blood type AB. Is he the father? A. Yes for sure B. No for sure PCB 3063 PCB 3063 C. He can not be excluded at this point. D. There is a 50% chance he is the father. - Correct Answer-C. He can not be excluded at this point. If the mom is IBi, he could be the father. What characteristic would you NOT expect to see in a pedigree of an X-linked recessive trait? A. The trait is more commonly seen in males. B. The trait can skip a generation. C. The trait is commonly passed from fathers to sons. D. Whenever a daughter receives the trait, the father is affected. E. An affected son's mother either has the trait or is heterozygous (carrier). - Correct Answer-C. The trait is commonly passed from fathers to sons. Which of the following is NOT an assumption of the Hardy-Weinberg law? A. Large populations B. No natural selection C. Non-random mating D. No gene flow E. No mutations - Correct Answer-C. Non-random mating Consider the following three-point cross: A B C x a b c a b c a b c Which of the following is NOT a possible progeny genotype? (Consider both recombinant and non-recombinant progeny.) PCB 3063 PCB 3063 A. A B C a b c B. a B C a b c C. A B C A B C D. A b c a b c E. a b c a b c - Correct Answer-C. A B C A B C A species' diploid number is 52. How many chromosomes would be found in individuals with a monosomy, trisomy or is a triploid? A. 51; 78; 53 B. 26; 53; 104 C. 78; 51; 53 D. 51; 53; 78 E. 51; 53; 104 - Correct Answer-D. 51; 53; 78 With 2n = 52, n = 26. PCB 3063 A monosomy would be 2n-1 so 52-1 = 51. A trisomy would be 2n+1 so 52+1 = 53. A triploid would be 3n so 3 x 26 = 78. A new virus has been discovered in a species of bacteria that inhabit hot springs. The viral genome is found to consist of four nucleotides in the following ratios: 8% A, 42% C, 42% G, and 8% U. The genome must be made of: A. double-stranded DNA. B. double-stranded RNA. C. single-stranded DNA. D. single-stranded RNA. - Correct Answer-B. double-stranded RNA. It is not DNA because there is U (uracil) in the genome. Since the % of A = % of U and the % of C = % of G, this suggests it is a double stranded RNA genome. Heterochromatin is characterized by all of the following EXCEPT: A. it is present all over the inactive X chromosomes in female mammals. B. it contains genes that are transcribed at high levels. C. it remains highly condensed. D. it is present at centromeres and telomeres. - Correct Answer-B. it contains genes that are transcribed at high levels. Okazaki fragments are associated with synthesis of: A. the leading strand. B. the lagging strand. C. both the leading and the lagging strands. D. single-stranded circular DNA. - Correct Answer-B. the lagging strand. PCB 3063 PCB 3063 PCB 3063 Which of the following statements is NOT correct about the process of transcription? A. Transcription of a given gene takes place on only one of the two DNA strands. B. During transcription, the RNA molecule is synthes