In the respiratory tract, the smallest and most numerous passageways are the ___________.
a) tracheas
b) bronchioles
c) bronchi
d) larynxes
Answer: b) bronchioles
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Which of the following statements about muscles is correct?
A. Smooth muscles contract more slowly than skeletal muscles. B. Actin and myosin are arranged irregularly in cardiac and smooth muscles. C. Skeletal muscles are striated, whereas cardiac muscles are not. D. Striated muscles use actin and myosin to generate force, whereas smooth muscles do not. E. Cardiac muscles are found in the heart and the walls of the arteries.
The process of interrupted mating may be used to do which of the following?
A. Inhibit transduction B. Convert the recipient cell to F+ C. Determine the relative position of bacterial genes D. Alter the genotype of the donor cell
The BRCA2 protein functions in double-strand break repair. If a woman is heterozygous for a loss-of-function allele of BRCA2, she
A) will develop cancer because two functional copies of BRCA2 are needed in every cell. B) will not get cancer because BRCA1 can compensate for the loss of BRCA2. C) will develop cancer after several mutations occur, even if the mutations occur in different clonal populations of cells. D) may develop cancer because mutation of the wild-type BRCA2 allele could destroy an important DNA repair mechanism.
Refer to the accompanying figure. The portion of the molecule labeled as 5 is:
a. the attached amino acid.
b. a double-stranded DNA region.
c. a single-stranded DNA region.
d. the anticodon.
e. the codon.