Bio 203 Exam 4 practice test questions & answers(Scored A)

What is the reason that closely linked genes are typically inherited together? - ANSWER The likelihood of a crossover event between these two genes is low All female mammals have one active X chromosome per cell instead of two. What causes this? - ANSWER Activation of the XIST gene on the X chromosome that will become the Barr body In his transformation experiments, what did Griffith observe? - ANSWER Mixing a heat-killing pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form In trying to determine whether DNA or protein is the genetic material of phage using radioisotopes, Hershey and Chase made use if which of the following facts? - ANSWER DNA contains phosphorus, whereas protein does not Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments? - ANSWER DNA polymerase can assemble DNA only in the 5' to 3' direction Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? - ANSWER 8% DNA replication is said to be semiconservative. What does that mean? - ANSWER Each new double helix consists of one old and one new strand What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called? - ANSWER Telomeres DNA replication image: Enzyme that untwists the double helix at the replication forks - ANSWER C DNA replication image: Enzyme that corrects "overwinding" ahead of replication forks - ANSWER A DNA replication image: Enzyme that adds RNA nucleotides using the parental DNA as a template - ANSWER B DNA replication image: proteins that bind to and stabilize single-stranded DNA - ANSWER D