Which of the following is the correct order of events in the control of the heartbeat?
1. activation of the SA node
2. contraction of the atria
3. contraction of the ventricles
4. activation of the AV node
5. transmission of the action potential through a set of modified muscle fibers
A. 1, 2, 4, 5, 3
B. 1, 4, 2, 5, 3
C. 1, 3, 4, 2, 5
D. 1, 5, 4, 2, 3
E. 1, 2, 5, 4, 3
A
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Hip dysplasia is a common ailment in large dog breeds including Rottweilers in the United
States. One breeder decides to import several females from Germany where the disease is less common to mate with his male dogs. This introduction of new alleles into his dog population is an example of __________.
a. natural selection b. adaptation c. gene flow d. dispersal
The main source of fuel for more than 30 minutes of
muscle contraction is a. fatty acids. b. glucose. c. glycogen. d. creatine phosphate. e. glycerol.
A mutation in the DNA-binding domain of a steroid hormone receptor is most likely to affect what aspect of receptor function?
A. The binding of the hormone to the receptor B. The cellular response to the hormone C. The translocation of the receptor to the nucleus D. The conformational change of the receptor
What makes each amino acid unique?
A. the central carbon B. the R group C. the carboxyl group D. the carbon ring E. the amino group