The first photosynthetic organisms probably
A. lived in the ocean.
B. were prokaryotic.
C. were cyanobacteria.
D. All of these answers are correct.
D. All of these answers are correct.
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A scientist reports the isolation of a new blood-borne virus that completely shuts down presentation of viral epitopes on MHC molecules in the cells it infects
He produces an internet video describing it and how it will be indestructible by CD8+ cytotoxic T cells and will kill millions (if not billions) of people.The medical community quickly denounces the dire warning as irrevlevant, and the whole thing is quickly forgotten-why? A. CD8+ T cells are not the cells that are responsible for killing virally infected cells. The terrorist mad scientist is a misinformed idiot. B. While CD8+ T cells ARE important for eliminating a viral infection, they are not the ONLY things that are capable of doing so. Natural killer cells can kill virally infected cells that have shut down MHC antigen presentation, and interferons can assist in cleaning virally infected cells. C. A blood-borne virus would not be capable of rapidly infecting millions of people, due to its difficult mode of transmission. D. B cells would be primed right away to produce complement proteins to destroy the virus. This would prevent cells from being infected with it in the first place. His plot would be foiled. E. While CD8+ T cells ARE important for eliminating a viral infection, they are not the ONLY things that are capable of doing so. Natural killer cells can kill virally infected cells that have shut down MHC antigen presentation, and interferons can assist in cleaning virally infected cells AND a blood-borne virus would not be capable of rapidly infecting millions of people, due to its difficult mode of transmission.
Classification of viruses into families involves determining all the following characteristics except
A. biochemical reactions. B. type of nucleic acid. C. presence of an envelope. D. type of capsid. E. number of strands in the nucleic acid.
Which cells make you immune to a disease that you were previously exposed to?
a. effector cells. b. memory cells. c. dendritic cells. d. phagocytes. e. fibroblasts.
Explain why high blood pressure can be both a cause and consequence of renal damage.
What will be an ideal response?