During which phases of mitosis are chromosomes composed of two sister chromatids?
a. prophase only
b. prophase and metaphase
c. prophase and anaphase
d. anaphase and telophase
e. chromosomes are composed of two sister chromatids during all phases of mitosis
B
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Which of the following is not likely to be a tumor suppressor?
A) A growth factor receptor B) A checkpoint protein C) A DNA repair enzyme D) An apoptosis-promoting factor E) The negative regulator of a CDK
Biotechnology provides the technical underpinnings for rational approaches to drug design by facilitating an understanding of the molecular causes of human disease
Indicate whether the statement is true or false
Why do RNA viruses appear to have higher rates of mutation?
A) RNA nucleotides are more unstable than DNA nucleotides. B) Replication of their genomes does not involve proofreading. C) RNA viruses can incorporate a variety of nonstandard bases. D) RNA viruses are more sensitive to mutagens.
With negative pressure breathing, the muscles that move the ribs and diaphragm are distant from the absorptive alveolar surfaces. What difficulty(ies) could occur if the muscles were around each alveolus and had to expand each alveolus to suck in air?
A. Interspersed muscle tissue would take up much space and the lung-muscle volume would have to be much larger. B. Adding a third tissue to the intimate alveolar-capillary complex would increase the problems with disorders and diseases. C. Muscle tissue would get in the way of absorption of gases across the air-to-capillary border. D. Since muscle cells only contract and relax, it would be difficult for a few cells to cause alveolar expansion. E. All of the choices are correct.