When a cell is preparing to divide, it makes an exact copy of all its nuclear DNA. Each chromosome then consists of two parallel filaments called ________.
Fill in the blank(s) with the appropriate word(s).
chromatids
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If one of Mendel's genes had three alleles that differentially affected the phenotype rather than two, what would he have observed among the progeny of many crosses between all pairs of the three pure-breeding lines in the F1 and F2 generations?
Comments: This case brings up the chance of codominance or incomplete dominance and provides for multiple phenotypes among a large set of crosses. In any one cross, there would be specific pure-breeding strains used, but there could be white, pink, and red flowers that are all pure breeding that may have complete or incomplete dominance. The population effects of this kind of genetics could move toward a broader range of phenotypes leading to the idea of blending inheritance. Mendel's innovative idea was to narrow the traits to simple binary phenotypes. This complication could show what could happen if he had not been so thoughtful. A. In each of the crosses, two phenotypes in the F1 generation. B. Only a single phenotype would be observed in the F1 generation because only one allele can be dominant. C. No evidence would exist for the law of segregation. D. No pure breeding plants produced in the F2. E. None of the responses are correct.
Examine Figure 41.1c. Which of the following best describes conditions at equilibrium?
A. No water molecules are moving across the barrier between the two compartments. B. A net movement of water molecules continues to add water to the right-hand compartment. C. A net movement of water molecules begins to add water to the left-hand compartment. D. Water molecules move randomly across the barrier with no net addition of water to either side. E. None of these choices accurately describe conditions at equilibrium.
Basic dyes
A. have negative charges. B. have positive charges. C. are electrically neutral. D. contain both positively and negatively charged particles.
Darwin faced which of the major challenges to his theory?
a. accounting for complex structure with multiple intricate parts b. explaining traits and organs of seemingly little importance c. geographic features playing an important role in the clustering of similar, closely related spe-cies d. All of the above