Q1. A study of twin concordance in Canada looked at twins in which at least one twin of the twin pair had multiple sclerosis. The study found a 25% concordance in monozygotic twins, and a 5% concordance in dizygotic twins. What can you conclude about multiple sclerosis? A) Multiple sclerosis is caused by environmental factors. B) Multiple sclerosis is caused by genetic factors. C) Multiple sclerosis has a small genetic influence, but is largely caused by the environment. D) Multiple sclerosis has a small environmental influence, but is largely caused by genetic factors. Q2. Brittany and Jarod have been trying to have a second child for 10 years. They have one healthy child, but Brittany has had four early, spontaneous abortions. The most likely explanation for the many pregnancy losses is that Brittany and Jarod A) are not having sex frequently enough. B) are each heterozygous for lethal alleles of the same gene. C) are each homozygous for lethal alleles of the same gene. D) have different alleles for all of their vital genes. Q3. In DNA replication, A) parental DNA shatters into pieces and joins with newly synthesized pieces to fashion two double helices from one. B) parental DNA remains intact but guides formation of new double helices. C) the parental DNA splits and free nucleotides bond to their complements, building two DNA molecules from one. D) an entirely new double helix is built using information in the sequence of amino acids. 2 This study source was downloaded by 100000855842951 from CourseHero.com on 03-14-2023 23:41:49 GMT -05:00 https://www.coursehero.com/file/139915478/Version-B-MIDTERM-EXAM-Winter-2022-Elementary-Geneticsdocx/ Q4. A skin cell in a male dog has 76 chromosomes. How many chromosomes will there be in a sperm cell from the dog? A) 76 B) 38 C) 19 D) 152 Q5. Phenylketonuria is a disease in which toxic levels of phenylalanine can accumulate due to low levels of the enzyme phenylalanine hydroxylase. A person with phenylketonuria has a low level of a member of which category of major chemicals in the cell? A) Proteins B) Carbohydrates C) Lipids D) Nucleic acids Q6. A retrovirus produces an enzyme, called reverse transcriptase, which copies its RNA genome into DNA. This is opposite of the central dogma because A) a virus is not an organism. B) a virus lacks genetic material. C) the central dogma states that RNA is copied into DNA. D) the central dogma states that DNA is copied into RNA. Q7. Tanisha and Tawanda are twins but do not look alike. They are the result of fertilization of A) one oocyte by two sperm cells. B) two oocytes by one sperm cell. C) two oocytes by two sperm cells. D) one oogonium by one spermatogonium. Q8. At the end of meiosis, the number of chromosomes in each daughter cell is halved because meiosis has A) two cell divisions after no DNA replication. B) two cell divisions after one DNA replication. C) one cell division after two DNA replications. D) one cell division after one DNA replication