Answer:
exposure to ultraviolet radiation is a correct answer.
Explanation:
Ultraviolet light exposure results in the formation of pyrimidine dimers. Ultraviolet radiation damage the DNA by resulting in chemical changes.
Ultraviolet radiation is absorbed by the pyrimidine bases( cytosine and thymine in DNA) and result in the formation of covalent bonds between the succeeding bases.
The formation of the pyrimidine dimers results in the distortions of DNA helix and disrupt the base-pairing during the replication of DNA which results in a mutation.
<span>Causes Of Melanoma. Ultraviolet rays Most skin cancers are caused by too much exposure to the sun's ultraviolet (UV) rays. The two types of UV rays that cause melanoma are UV-A and UV-B rays.</span>
<u>Answer</u>: Large collection of stars, gas, and dust held together by gravity.
<u>Explanation:</u>
- The name <em>galaxy</em> has been derived from the word <em>galaxies</em> which is a Greek word meaning milky.
- In simple words a galaxy is a collection of a large number of stars, however, to be more precise <em>a galaxy is a gravity-bound collection of stars, dust, gas, dark matter and stellar remnants. </em>
- There are different types of galaxies found in various shapes and size, some of the most common shapes being elliptical, irregular and spiral.
- An example is the milky way galaxy that contains our solar system.
