Which microscope shows cells against a bright background and the intracellular structures of unstained cells based on their varying densities?

A. phase-contrast
B. fluorescence
C. dark-field
D. bright-field
E. electron


Answer: A

Biology & Microbiology

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A viticulturist wants to grow larger grapes by elongating the stems of the vines. Which specific hormone would a viticulturist apply to the plants?

A. Ethylene B. Gibberellin C. Auxin D. Abscisic acid E. Cytokinin

Biology & Microbiology

Which embryonic tissue is defective if an embryo

develops into a creature that cannot move and has no supportive or circulatory system? a. ectoderm b. endoderm c. mesoderm d. somatoderm e. all of these

Biology & Microbiology

The following statements regarding penicillin production and applications are true EXCEPT

A) Penicillin is a secondary metabolite produced by a filamentous fungus. B) Penicillin derivatives can be produced by biosynthetic or semisynthetic methods. C) Natural penicillin (penicillin G) inhibits a wide spectrum of bacteria. D) Penicillin selection method is used to enrich the auxotrophic mutations. E) -lactamases, which cause penicillin resistance, are easily transferable when they are located on plasmids.

Biology & Microbiology

All of the following are true about prosimians except

A. they are nocturnal. B. they are big-eyed mammals with increased visual acuity. C. they are widespread. D. only two lineages survive today.

Biology & Microbiology