Which kind of T-cell synthesizes perforins and granzymes to destroy viral infected cells, and cancer cells?
A. CD4
B. MHC
C. TH
D. TC
Answer: D
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Ganglia, which still occur in some extant taxa, were the evolutionary precursor to the centralized concentration of neurons that we now call a brain
A. true B. false
Of all the different codons that exist, three of them do not encode a particular amino acid. Their role is to:
a. allow for any amino acid to be added in their place. b. encode tRNA molecules. c. provide instructions on the tertiary structure of the protein. d. signal the start of translation. e. provide instructions to stop translation.
All of the following are characteristic of life in a marine environment except?
a. Many nutrients and gases are dissolved in the water and are readily available. b. Buoyancy helps to support the organisms. c. Currents may wash organisms away from suitable habitats. d. Osmotic balance is very difficult for invertebrates to maintain. e. Temperatures are relatively stable.
Before Darwin published his work, Lamarck and others had suggested mechanisms for evolution. By what means did Darwin propose species evolved over time?
A) Overproduction of young B) Passing on acquired traits C) Survival of the strongest D) Natural selection