If a birth defect were said to be caused by a teratogen, it was caused by:
a. an abnormal gene
b. an environmental factor
c. an unusual number of chromosomes
d. both A and C above
b. an environmental factor
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Which type of innervation causes reduced blood flow to the digestive tract?
A. Parasympathetic B. Sympathetic
The vertebrate heart muscle is known as
A) Pericardium. B) Epicardium. C) Myocardium. D) Endocardium.
Answer the following statement(s) true (T) or false (F)
1. Several muscles of facial expression are stimulated by the facial nerve. In other words, these muscles are innervated by the facial nerve. 2. Most athletic injuries can be prevented by conditioning, stretching, and warm-up exercise. 3. Injury to the deep fibular nerve would cause inability to extend one's toes. 4. As axon diameter increases, the conduction speed of an action potential decreases. 5. The nervous system employs exclusively electrical means to send messages, whereas the endocrine system communicates by means of chemical messengers.
Interferon
a. is released from viruses b. triggers the production of viral-blocking enzymes by cells that have not yet been invaded by viruses c. directly breaks down viral messenger RNA d. inhibits protein synthesis, both of which are essential for viral replication e. have characteristics b and d