The recessive mutant allele that causes cystic fibrosis is much more frequent in Caucasians population than in other world populations. Some scientists believe heterozygotes must have had a survival advantage during plagues such as cholera that occasionally swept through this population. What concept does this illustrate?

TLS Online TPP Program

#Question id: 19707

#Unit 13. Methods in Biology

Currents caused by opening of which of the following channels contribute to the repolarization phase of the action potential ofventricular muscle fibers?

TLS Online TPP Program

#Question id: 19708

#Unit 13. Methods in Biology

In complete heart block

TLS Online TPP Program

#Question id: 24439

#Unit 13. Methods in Biology

If heart rate is 75 beats/minute, what is the R-R interval in units of milliseconds?

TLS Online TPP Program

#Question id: 24440

#Unit 13. Methods in Biology

If the R-R interval is 800 msec (0.8 sec), what is the heart rate?

TLS Online TPP Program

#Question id: 24441

#Unit 13. Methods in Biology

If the heart rate is 90 beats/min, what is the cycle length?

TLS Online TPP Program

#Question id: 24442

#Unit 13. Methods in Biology

Match the following Column I with Column II 

Column I	Column II
A. PR segment	i. Plateau portion of the ventricular action potential
B. PR interval	ii. Conduction through atrioventricular node
C. ST segment	iii. The time from initial depolarization of the atria to initial depolarization of the ventricles
D. ST interval	iv. An isoelectric portion of the QT interval