Vasectomy causes sterility because ____
a. sperm is no longer produced
b. sperm is unable to leave the testis
c. sperm is unable to reach the vas deferens
d. sperm is unable to reach the urethra
e. semen is no longer produced
ANSWER: d
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Chemical germicides
A. may react irreversibly with proteins/enzymes. B. may react with cytoplasmic membranes or viral envelopes. C. may be disinfecting or even sterilizing. D. are sensitive to dilution factor, time of contact, and temperature of use. E. All of the choices are true.
Which statement is NOT true about the RNA-first hypothesis?
A. It says that first RNA, then DNA, and then proteins would have been necessary to interact in the chemical evolution that would have led to the development of the first cells. B. It is supported by the discovery that RNA can act as an enzyme. C. It is supported by the fact that some viruses have RNA as their genetic material. D. It suggests that there was an "RNA world" about 4 billion years ago.
Of the following, which cleft is NOT correctly matched to the structures that have failed to fuse?
A. Bilateral Cleft of Secondary Palate - Maxillary and Lateral Nasal Prominences B. Median Cleft of Lower Lip - Mandibular Prominences C. Median Cleft of Upper Lip - Medial Nasal Prominences D. Oblique Facial Cleft - Maxillary Prominences, Medial & Lateral Nasal Prominences E. Unilateral Cleft of Upper Lip - Maxillary and Medial Nasal Prominence, Unilaterally
Which answer choice lists the steps of the scientific method in the correct order?
(a). hypothesis, observation, experiment, conclusion, scientific theory (b). conclusion, hypothesis, observation, experiment, scientific theory (c). observation, hypothesis, experiment, conclusion, scientific theory (d). observation, experiment, hypothesis, conclusion, scientific theory (e). scientific theory, conclusion, hypothesis, experiment, observation