Biology 203: Final Exam Review 100% Correct Solutions

What cellular events occur in the G1 phase of the cell division cycle? - ANSWER normal growth and cell function What is the best way to describe homologous chromosomes? - ANSWER they carry information for the same traits In some parts of Africa, the frequency of individuals who are heterozygous for the sickle-cell anemia allele is higher than the frequency in North America, presumably because this reduces the frequency of malaria. Such a relationship is related to what? - ANSWER Darwin's theory of natural selection Red-green color blindness is an X-linked recessive trait in humans. Two people with normal color vision have a son with colorblindness. Given this information, the genotypes of the parents are ________________. - ANSWER X^N X^n and X^N Y What investigator was responsible for determining that DNA contains equal amounts of adenine and thymine, and equal amounts of guanine and cytosine? - ANSWER Erwin Chargaff What is a nondisjunction? - ANSWER An error in cell division that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell When can nondisjunction occur? - ANSWER In mitosis and meiosis, when sister chromatids fail to separate & in meiosis, when homologous chromosomes fail to separate. What syndrome is characterized by the XO chromosome abnormality? - ANSWER Turner syndrome What kind of cell results when a diploid and a haploid gamete fuse during fertilization? - ANSWER A triploid cell What type of chromosomal abnormalities is most likely to be viable in humans? - ANSWER trisomy If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n - 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred? - ANSWER A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell. If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n - 1 chromosomes, what type of error occurred? - ANSWER A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell. What is the difference between a DNA and an RNA molecule? - ANSWER DNA is usually double-stranded, whereas RNA is usually single-stranded. What nitrogenous base is found in DNA but not in RNA? - ANSWER thymine In a nucleotide, the nitrogenous base is attached to the sugar's _________ carbon and the phosphate group is attached to the sugar's _________ carbon. - ANSWER 1' ... 5' Nucleic acids are assembled in the ____________ direction. - ANSWER 5' to 3' In a DNA double helix an adenine of one strand always pairs with a(n) ___________ of the complementary strand, and a guanine of one strand and always pairs with a(n) ____________ of the complementary strand. - ANSWER thymine ... cytosine Who demonstrated that DNA is the genetic material of the T2 phage? - ANSWER Hershey and Chase The radioactive isotope 32P labels the T2 phage's ___________. - ANSWER DNA Hershey and Chase used ___________ to radioactively label the T2 phage's proteins. - ANSWER 35S