What is clonal selection with regard to B cells? How does it occur?
What will be an ideal response?
ANSWER: Clonal selection is the process by which a particular B cell is specifically selected for
proliferation when it recognizes a particular foreign antigen. An individual has an
enormous number of unactivated B cells, each displaying a specific B-cell receptor on its
surface. After binding and processing the antigen that matches its B-cell receptor, and a clone of cells. Some of the B-cell clones differentiate into plasma cells, which are shortlived
cells and produce antibodies. A few B-cell clones differentiate into memory B cells,
which remain in circulation ready to mount a faster response against the same antigen at a
later time.
You might also like to view...
Lake Victoria is famous for its variety of cichlid fishes. In fact, they offer the most diverse assembly of vertebrates presently known to science. One trait that scientists have focused on as one possible reason for their adaptability is
A. a second set of scales that lie beneath the top outermost scales. B. a second set of jaws in their throats. C. gill arches that are not covered by an operculum, which prevents hiding places for gill parasites. D. digestive tracts that are able to process most substrates, which has eliminated the need for feeding specialization. E. ability to change color in relationship to their environment.
Genetic studies of an animal show that eye color is controlled by an autosomal gene with the dominant allele (R) for red
eye color and the recessive allele (r) for yellow eye color. A second autosomal gene has the dominant allele (T) for paws with thumbs and the recessive allele (t) for paws without thumbs. The genetic cross RRTT x rrtt creates offspring with genotype RrTt. One of those dihybrids is mated in a testcross (RrTt x rrtt). Based on the principle of independent assortment, the testcross should produce offspring with the phenotype ratio ____.
a. 3 red-eyed with thumbs : 1 yellow-eyed without thumbs b. 1 red-eyed with thumbs : 1 yellow-eyed with thumbs: 1 red-eyed without thumbs: 1 yellow-eyed without thumbs c. 1 red-eyed with thumbs : 1 yellow-eyed without thumbs d. 9 red-eyed with thumbs : 3 yellow-eyed with thumbs: 3 red-eyed without thumbs: 1 yellow-eyed without thumbs e. 3 yellow-eyed with thumbs : 1 red-eyed without thumbs
Cnidarians evolved from an ancestral group of
a. sponges. b. protists. c. fungi. d. plants.
Radioactive isotopes of various elements can be used to label molecules for use in studies of metabolic pathways. For example, 14C is a radioactive isotope of carbon and naturally occurs at much lower rates than non-radioactive 12C (i.e. most molecules
contain 12C carbon atoms). A cell can be fed a nutrient molecule labeled with the radioactive isotope and scientists can detect where the radioactive isotope ends up. For each of the following scenarios, trace the radioactive isotope to where it ultimately would end up after moving through the cellular respiration, fermentation, or biosynthetic pathways. Only consider these metabolic pathways; do not consider any other cellular processes. A. E. coli is fed 14C-labeled glucose and grown under aerobic conditions. B. E. coli is fed 14C-labeled glucose and grown under anaerobic conditions (fermentation). C. E. coli is fed 14C-labeled fatty acids and grown under aerobic conditions. D. E. coli is fed 14C-labeled acetyl CoA and grown under conditions that promote biosynthetic pathways. What will be an ideal response?