How does complement help in defense against bacterial invasion?
A) It promotes phagocytosis.
B) It neutralizes bacterial toxins.
C) It prevents bacteria from penetrating the skin.
D) It fuses lysosomal granules to bacterial cell walls.
Ans: A) It promotes phagocytosis.
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In the first step of their experiments, Jacob and Monod treated E. coli cells with ultraviolet light or X-rays to _____
A) decrease the rate of gene expression B) induce DNA repair enzymes C) increase the frequency of mutations in all genes D) selectively mutate the lac operon, leaving all other genes unmutated
From an evolutionary perspective, germ-line mutations are more significant than somatic mutations. This is because:
A. somatic mutations affect only one or a few cells. B. somatic mutations are generally harmful. C. only germ-line mutations will appear in an individual's descendants. D. only germ-line mutations are potentially beneficial. E. somatic mutations affect only one or a few cells and only germ-line mutations will appear in an individual's descendants. Answer Point Value: 1.0 points Answer Key: C 5 Remember that, in Mendel's garden peas, the yellow gene determines flower color, with the A (yellow) allele dominant to the a (green) allele. In a population of 200 plants, the genotype frequencies are 50% AA, 25% Aa, and 25% aa. What are the allele frequencies? A. 50% A, 50% a B. 50% A, 25% a C. 87.5% A, 12.5% a D. 62.5% A, 37.5% a E. 75% A, 25% a
Because of its negative charge, there is more _______ in a cell than in the extracellular fluid.
a. potassium (K – ) b. chlorine (Cl – ) c. sodium (Na + ) d. potassium (K +
In gel electrophoresis, DNA fragments move at different rates because they have different
A) electrical charge densities. B) sizes. C) base sequences. D) amino acid compositions. E) overall electrical charges.