What condition triggers apoptosis in immature T-cells?
a. premature exposure to viral pathogens
b. sufficiently high T-cell concentrations
c. T-cell receptors binding to “self” proteins
d. insufficient levels of ATP phosphorylation
c. T-cell receptors binding to “self” proteins
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Which of the following is NOT a characteristic of
viruses? a. Contains DNA or RNA genetic material. b. Contains cytoplasm and ribosomes. c. Has a protein coat. d. Can only replicate inside a living host cell. e. Is very small.
Nitrogen-fixing bacteria convert gaseous nitrogen into:a
amino acids. b. phosphate. c. ammonia. d. nitrite. e. nitrate.
What is the role of the epithelium?
A) Helps protect the body from the external environment B) Transmits electrical signals throughout the body C) Contracts to create body movement D) Provides the padding between the joints
In science, reliable results are obtained when
A. experiments give the same results repeatedly. B. a careful scientist sees a clear pattern. C. additional testing is required. D. most experiments give the same results.