Which of the following must exist in a population before natural selection can act upon that population?
A) genetic variation among individuals
B) variation among individuals caused by environmental factors
C) sexual reproduction
D) the population has predators
A
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Development of drug resistance is encouraged by
A. use of two drugs simultaneously with the hope that each will prevent the emergence of resistance to the other. B. widespread use of broad-spectrum drugs. C. using drugs appropriate for the infectious agent being treated. D. avoidance of indiscriminate use of drugs. E. use of a high enough concentration of the drug to destroy any spontaneous resistant mutants that might arise.
The epigenetic state of a cell is called its ____________________
Fill in the blank(s) with correct word
Tropheryma whipplei is characterized by the presence of periodic acid–Schiff (PAS)–staining macrophages, which indicates mucopolysaccharide or glycoprotein, in almost every organ system. Without treatment, this disease is uniformly fatal. Identification is achieved using:
a. enzyme-linked immunosorbent assay (ELISA). b. IFA. c. immunoblotting. d. real-time polymerase chain reaction (PCR).
Please match the cell types with the statements that most accurately describe them to test your understanding of prokaryotic cells, eukaryotic cells, and viruses.
Contains nucleic acid A) Prokaryotic cells B) Eukaryotic cells C) Viruses D) Both eukaryotic and prokaryotic cells E) Prokaryotic cells, eukaryotic cells and viruses