Chapter 13 – Genetics
26. The British biologists who first reported linkage in sweet peas were
27. Chromosomal mapping primarily involves
Chapter 13 – Genetics
28. Which of the following increases the probability of genes being inherited together?
29. In a variety of cornflowers in which blue flowers and dwarf plants are controlled by
dominant genes carried on separate pairs of chromosomes, and white flowers and tall plants
are their recessive counterparts, assume a cross has been made between a homozygous blue,
dwarf plant and a homozygous white, tall plant. Which of the following would be represented
in the F1 generation?
Chapter 13 – Genetics
30. Assume the same cross as in question 29. How many different kinds of genotypes would
occur in the F2 generation?
31. Assume the same cross as in question 29. Which of the following phenotypic ratios would
be represented in the F2 generation?
Chapter 13 – Genetics
32. Since Mendel’s time, types of inheritance that don’t follow Mendel’s rules have been
discovered. Which of the following situations is NOT an exception to Mendel’s rules?
33. If the cross BbDD x bbDd is made, which of the following would NOT be represented in
the offspring?
Chapter 13 – Genetics
34. In a cross between a long and a globe-shaped radish, the F1 generation consisted of 247
oval-shaped radishes. The F2 generation consisted of 62 long radishes, 127 oval radishes, and
59 globe-shaped radishes. Which of the following pertaining to this cross is true?
35. The most significant cause for exceptions to the Hardy-Weinberg law is
Chapter 13 – Genetics
36. In sweet peas, purple flower color and oblong pollen grains are dominant, with the
recessives being red flower color and spherical pollen grains. When a homozygous purple,
oblong plant is crossed with a homozygous red, spherical plant, the F1 generation consists
entirely of purple, oblong plants. When an F1 plant is crossed with a homozygous red,
spherical plant, the offspring are produced in a ratio of 7 purple, oblong to 1 purple, spherical
to 1 red, oblong to 7 red, spherical. Which of the following is the only plausible explanation
for such results?
37. What is the correct genotype of a homozygous dihybrid individual having dominant
phenotypes for both traits?
Chapter 13 – Genetics
38. Which of the following is NOT known for the pioneer experiments and theories that led to
the development of the science of genetics?
True / False Questions
39. Mendel discovered the rules of inheritance only after the discoveries of chromosomes
and meiosis.
40. When Mendel crossed tall pea plants with short ones, all of the offspring were
intermediate in height.
Chapter 13 – Genetics
41. Mendel’s law of unit characters says that the inheritance of characteristics is controlled by
factors that always occur in pairs.
42. A recessive factor is one that cannot manifest itself in the phenotype.
43. Lack of dominance means that only recessive genes are present.
44. A tRNA molecule can fit into a slot in a ribosomal subunit.
Chapter 13 – Genetics
45. A tRNA molecule relays amino acids in response to a specific “blueprint” coded by the
DNA.
46. Messenger RNA is a small molecule composed of a few nucleotides.
47. The law of independent assortment is illustrated only in monohybrid crosses.
48. A backcross is one in which both parents are homozygous.
Chapter 13 – Genetics
49. The Hardy-Weinberg law addresses itself to proportions of genes in a normally
interbreeding population.
50. Bateson and Punnett could not adequately explain unusual genetic ratios that occurred as a
result of linkage.
51. The pinpointing of relative locations of genes on chromosomes CANNOT be brought
about by calculating percentages of crossing-over in large populations.
Chapter 13 – Genetics
52. The genetic information encoded in DNA is difficult to alter, making mutations rare.