Caenorhabditis elegans is a nematode. During its development, it produces more than 1000 cells. However, the adult worm has only 959 somatic cells. The process by which 131 cells are specifically targeted for destruction is called______________
(a) directed cell pruning.
(b) programmed cell death.
(c) autophagy.
(d) necrosis.
(b)
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According to the Shannon Diversity Index, which of the five blocks above, with each containing thirty-six squares, would show the greatest diversity?
A) 1 B) 2 C) 3 D) 4 E) 5
You would like to cut down a tree in your backyard, but you have no axe or chainsaw. Instead, you cut around the trunk of the tree with a pocketknife and peel off the "bark" in a three-inch thick strip
You are confident that this action will kill the tree. Are you correct? A. No, because only the cork and cork cambium were removed. B. No, because the vascular cambium will continue to produce xylem and phloem. C. Yes, because the phloem has been disrupted and sugar transport will no longer occur. D. Yes, because the xylem has been destroyed and sugar transport will no longer occur. E. Yes, because the vascular cambium has been destroyed and xylem and phloem will no longer be formed.
Intragenic recombination can be detected __________
A) based on recombination between homologs carrying different mutant alleles B) by the recovery of 100% double-mutant chromosomes C) by the recovery of both wild-type and double-mutant chromosomes D) based on recombination between homologs with different mutant alleles and recovery of 100% double-mutant chromosomes E) based on recombination between homologs with different mutant alleles and recovery of both wild-type and double-mutant chromosomes
Cell-mediated immunity is directed by:
a. B cells, which secrete antibodies. b. T cells, which secrete antibodies. c. macrophages, which produce histamines. d. B cells, which react with APCs. e. T cells, which react with APCs