What region of the heart acts as the heart's pacemaker?
A) sinoatrial (SA) node
B) atrioventricular (AV) node
C) semilunar valve
D) ventricle
A
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Early in mitosis chromatin condenses into the compact, rodlike structures known as chromosomes
Which of the following processes takes place more easily as a result?
a. disappearance of the nuclear envelope b. replication of DNA c. orderly distribution of DNA into the two new nuclei d. formation of the mitotic spindle e. disintegration of nucleoli
When scientists use a radioactive or fluorescent probe to label target DNA fragments and then transfer the hybridized fragments to a nylon membrane, what is this process called?
a. Southern blotting b. Northern blotting c. gel electrophoresis d. molecular cloning
The type of viral infection in which a virus enters a host cell, immediately replicates, and causes the host cell to burst is a infection.
A. systematic B. transgenic C. lytic D. lysogenic E. rare form of viral
. A severely injured animal is still able to defend itself due to the action of ____
a. dopamine b. endorphins c. endorphins d. acetylcholine e. GABA