Are superantigen reactions beneficial or harmful to the host? What is different about a superantigen reaction compared to normal antigen-host cell interactions?
What will be an ideal response?
Answer: Superantigen reactions are harmful to the host because too many T cells are activated, causing an excess of cytokines and inflammatory mediators to be released. Excessive inflammation, fever, and nausea occur due to superantigens. A superantigen binds to non-specific parts of the T-cell receptor and MHC proteins, activating 5-25% of all T cells. Normal antigens only bind to the specific binding site of a T cell receptor that is very unique, and less than 0.01% of T cells are activated in a normal immune response to a foreign antigen.
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Routine microbiology cultures should include all of the following media except:
a. nonselective nutritive media. b. highly selective specialized media such as Löwenstein-Jensen agar. c. selective and differential media based on site of infection. d. an enrichment or supplemental broth.
In the selfish herd, there is an advantage to
a. being on the outside. b. being near the front. c. being in the middle. d. being isolated. e. none of these; position is of no advantage.
Our sense of balance depends most directly on
A. the vestibular system. B. the visual system. C. chemoreceptors in the environment. D. mechanoreceptors in our hands and feet. E. the auditory system.
If both parents express a particular trait, but their child does not, what does this indicate about the trait?
a. The trait is an autosomal recessive trait. b. The trait is an autosomal dominant trait. c. The trait is sex-linked recessive d. The trait is sex-linked dominant.