If reverse transcriptase begins DNA synthesis near the 5? end of viral RNA, how is the entire viral RNA reverse transcribed?
What will be an ideal response?
Ans: Retroviral RNA ends in direct repeats called R segments. When the 5? end of viral RNA is copied to DNA, the resulting DNA R segment pairs with the R segment at the 3? end of a different viral RNA and acts a primer for the reverse transcription of the entire molecule.
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You are asked to determine if a tissue sample taken from a plant stem comes from a monocot or eudicot. How will you accomplish this?
A. Look at the ground tissue to see if it is arranged in concentric rings or in parallel bundles. B. Examine the vascular cambium and determine if it is divided into segments or is continuous throughout the stem. C. Determine if the xylem and phloem are located in separate vascular bundles or are bundled together. D. Examine the epidermis and determine the depth of the cuticle layer. E. Locate the vascular bundles and analyze their pattern.
Refer to Figure 50-4. The peak in ________ around day 21 corresponds with __________
a. luteinizing hormone; ovulation b. follicle-stimulating hormone; the development of the follicle c. estrogen; breakdown of the endometrium d. progesterone; continuing to build up the endometrium e. estrogen; ovulation
The history of life on Earth can be studied by looking at
A. microevolution. B. sexual selection. C. gene flow. D. macroevolution.