Describe the hypothesis of viruses occurring before living cells and how DNA might have evolved. What is the current hypothesis about the evolutionary relationships between RNA, DNA, viruses, and cellular life?
What will be an ideal response?
Answer: One hypothesis on the origin of viruses states they developed prior to the living cells they infect. RNA viruses likely were the first to come about, and when host cells evolved ribonucleases to combat infection by RNA viruses, DNA might have evolved in viruses and a way to circumvent this defense. Because DNA is more stable than RNA, its evolution would also be advantageous and maintained in the cellular hosts.
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A. Subcutaneous mycoses B. Systemic mycoses C. Superficial mycoses D. Intramuscular mycoses
In females, estrogen and progesterone (select all correct choices):
A. direct development of female reproductive structures during embryogenesis. B. direct development of female secondary sexual characteristics during puberty. C. regulate the menstrual cycle and support pregnancy. D. maintain adult health. E. None of these choices are correct.
The cheesy coating that prevents the fetus' skin from chafing is called
a. vernix caseosa. b. fossa ovalis. c. chorionic villus. d. lanugo. e. colostrum.
Which of the following designates a human female with Turner’s Syndrome?
a. XXY b. XY c. XX d. XYY e. XO