Analyses of sulfur isotopes have been used as evidence against life on the Moon, because the sulfides in lunar rocks have
A) an isotope composition similar to marine sulfate, which is enriched in 34S.
B) an isotope composition similar to marine mud, which is depleted in 34S.
C) an isotope composition similar to igneous rocks.
D) exactly equal amounts of 34S and 32S.
Answer: C
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You are asked to give a classroom demonstration of DNA supercoiling. To do so, you take two different colored pieces of rubber tubing, twist them very tightly and excessively around each other and join the ends of the tubing appropriately. Next, you relieve the supercoiling by breaking one strand and unwinding it. In this demonstration, the breaking and unwinding to relieve the supercoiling simulates the action of
A. exonucleases. B. polymerases. C. ligases. D. topoisomerases. E. primases. Clarify Question · What is the key concept addressed by the question? · What type of thinking is required? · What key words does the question contain? Gather Content · What do you already know about supercoiling? Consider Possibilities · What other information is related to the question? Which information is most useful? Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? Reflect on Process · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
How many chromatids are found in a single human cell at the end of each of the following meiotic stages? ________ prophase I ________ anaphase I ________ prophase II ________ telophase II
What will be an ideal response?
How is a T cell receptor similar to an IgM?
A. Both are produced by T cells. B. Both can bind to a specific antigen. C. Both are organized with variable and constant segments. D. Two answer options are correct: both can bind to a specific antigen AND both are organized with variable and constant segments.
Which of the following animals has a gastrovascular cavity?
a. earthworm b. fish c. hydra d. insect e. sponge