Which of the following statements are fundamental to the clonal-selection theory of how the adaptive immune system functions? I) Each lymphocyte has a unique membrane receptor that recognizes one antigen
II) When the lymphocyte binds an antigen, it is activated and begins dividing to form many identical copies of itself. III) Cloned lymphocytes have slight differences and are selected by the spleen for removal if they do not bind an antigen. IV) Cloned cells descend from an activated lymphocyte and persist even after the pathogen is eliminated. A) only I and III
B) only II and IV
C) only I, II, and IV
D) only II, III, and IV
C
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Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fructose 1,6-bisphosphate, by adding a phosphate group. This is the first committed step of the metabolic pathway of glycolysis, and thus it is very tightly regulated. AMP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and stimulates the formation of fructose 1,6-bisphosphate. ATP binds
to PFK at a site distinct from the binding site for fructose 6-phosphate, and inhibits the formation of fructose 1,6-bisphosphate. There are other regulators of this enzyme as well. What is the role of AMP in this example? A. Competitive inhibitor B. Noncompetitive inhibitor C. Allosteric inhibitor D. Allosteric activator E. Catalyst
Describe the general relationship between total genome size and the proportion of the genome that encodes mobile genetic elements for plants and animals
What will be an ideal response?
Hans Selye defined stress as
A. environmental factors that result in anxiety B. the physiological reaction of the body to environmental factors C. a negative emotion resulting from environmental unpleasantness D. the nonspecific response of the body to any demand made on it
All of the following are correct about primary atypical pneumonia except
A. it can also be caused by adenoviruses. B. it is mainly caused by Mycoplasma pneumoniae. C. it has symptoms similar to pneumococcal pneumonia. D. it is transmitted by aerosol droplets. E. community resistance is high.