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1 | | UV light and other ionizing radiations damage DNA molecules by... |
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| | A) | creating guanine dimmers between adjacent guanines in the DNA chain. |
| | B) | creating adenine dimmers between adjacent adenines in the DNA chain. |
| | C) | creating thymine dimmers between adjacent thymines in the DNA chain. |
| | D) | creating uracil dimmers between adjacent uracils in the DNA chain. |
| | E) | creating cytosine dimmers between adjacent cytosines in the DNA chain. |
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2 | | These dimmers weaken... |
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| | A) | hydrogen bonds. |
| | B) | sulfide bonds. |
| | C) | covalent bonds. |
| | D) | ionic bonds. |
| | E) | all of these. |
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3 | | These dimmers are repaired by... |
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| | A) | the enzyme DNA photolyase. |
| | B) | exposure to light. |
| | C) | transfer of an electron to the dimer. |
| | D) | A and B. |
| | E) | A, B and C. |
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4 | | Chemical agents can cause mutations by inducing ethylation of guanine residues in DNA. |
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| | A) | True |
| | B) | False |
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5 | | The enzyme ethylguanine-DNA ethyltransferase prevents DNA mutations from occurring. |
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| | A) | True |
| | B) | False |