Normally, the mold Neurospora can synthesize all 20 amino acids. A certain strain of this mold cannot grow in minimal nutritional medium, but grows only when the amino acid leucine is added to the medium. This strain

A. has a mutation in the gene that encodes the leucine tRNA
B. has a mutation in the gene that encodes the enzyme that "charges" the leucine tRNA\
C. is dependent on leucine for energy
D. has a mutation affecting the biochemical pathway leading to the synthesis of leucine


Answer: D. has a mutation affecting the biochemical pathway leading to the synthesis of leucine

Biology & Microbiology

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Membrane proteins serve many functions. One of the functions is transportation of substances across the membrane. If a cell biologist placed cells into an environment in which a chemical has been added that blocks the function of only carrier proteins, the process that will be affected is

A. active transport. B. osmosis. C. simple diffusion. D. phagocytosis. E. pinocytosis.

Biology & Microbiology

The trade-off between investments in current reproduction and in growth that promotes future reproduction is referred to as the total cost of what?  

A.  adaptation B.  selection C.  reproduction D.  genetic change E.  fitness

Biology & Microbiology

Which of the following is considered an abiotic component of the ecosystem?

A) temperature B) microbes C) plants D) animals

Biology & Microbiology

Features that are useful for identification of fungal species include ________.

A. ability to produce chlorophyll a B. presence of a membrane bound nucleus C. size, shape color, and number of spores D. All of the choices are correct.

Biology & Microbiology