Which of the following best describes a "species"?
a. a group of individuals producing similar vestigial structures
b. a group of individuals developed through selective breeding
c. a group of populations with homologous structures
d. a group of populations that evolved independently
e. a group of similar fossils
Ans: c. a group of populations with homologous structures
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Tamryn has a son who has Duchenne muscular dystrophy, which is inherited as an X-linked recessive trait. At a molecular level, the disease is due to lack of the protein dystrophin. Tamryn participates in a study that looks at dystrophin levels in various muscles. The study samples cells from 10 different muscles. The study finds that some cells make dystrophin and some do not. An explanation for this finding is that
A) the mutation is only in some muscle cells. B) Tamryn is making less dystrophin as she gets older. The study should be repeated at different ages. C) the X chromosome that bears the mutation is turned on in some cells but off in others. D) Tamryn does not have a Y chromosome.
Polarized cells are characterized by
A) random orientation within a tissue. B) being surrounded on all sides by a basement membrane. C) junctions only to ECM and not to other cells. D) distinct apical and basolateral ends of the cell. E) formation of several connected layers of cells.
Which statement is NOT true about mutations?
(a) A mutation is a change in the DNA that can generate offspring less fit for survival than their parents. (b) A mutation can be a result of imperfect DNA duplication. (c) A mutation is a result of sexual reproduction. (d) A mutation is a change in the DNA that can generate offspring that are as fit for survival as their parents are.
Which of the following statements about PCR is not true?
A. The amount of DNA doubles with each replication cycle. B. PCR can create millions of copies of a segment of DNA in a test tube. C. PCR stands for "polymerizing copies of RNA." D. The target is repeatedly replicated. E. PCR uses DNA polymerase.