The embryonic yolk sac, the liver, and the bone marrow are sites where
A. immune responses to antigen occur.
B. antigen is filtered from the blood.
C. stem cells give rise to immature lymphocytes.
D. T lymphocytes complete maturation.
E. antigen is filtered from tissue fluid.
Answer: C
You might also like to view...
Some bacteria are metabolically active in hot springs because _____
A) they are able to maintain a lower internal temperature B) high temperatures make catalysis unnecessary C) their enzymes have high optimal temperatures D) their enzymes are completely insensitive to temperature E) they use molecules other than proteins or RNAs as their main catalysts
Feedback inhibition
A. is a means of regulating the amount of product produced. B. often involves the use of allosteric enzymes. C. involves inhibiting the last of a series of reactions. D. results in raising the activation energy for the reaction. E. is a means of regulating the amount of product produced AND often involves the use of allosteric enzymes.
A parasitic disease known as Schistosomiasis is caused by several species of flatworms in the
phylum Platyhelminthes. The life cycle includes an aquatic snail where the larvae develop; these larvae then hatch into the water and swim around until they find the appropriate vertebrate host. Adult males and females reproduce sexually in the vertebrate host, and eggs are usually shed into water via feces or urine. The snail would be considered a(n) __________.
a. intermediate host b. vector c. primary host d. cyst
A pine tree is
a. an angiosperm. b. a haploid plant body. c. a sporophyte. d. a living fossil. e. a gametophyte