In viruses called retroviruses, the genetic information is contained in RNA; these viruses have no DNA. These viruses also have an enzyme called reverse transcriptase. What is its function?

It catalyses the synthesis of complementary DNA copies from RNA.

Explanation:

The reverse transcriptase is an enzyme that allows strands of DNA molecules to be synthesized from a single strand RNA template. The enzyme, also known as RNA directed DNA polymerase is usually used by retroviruses to synthesize complementary DNA sequence from an RNA template, a process that is an opposite of transcription.

An organism will evolve by natural selection, or the ability to adapt to an environment in the best possible way. For example, if carbon pollution continues to occur on a mass scale, the lungs of many land animals may evolve to filter out carbon from the air they breathe in. With this knowledge, humans may continue to be negligent about the environment. Factories may raise the amount of CO2 they release into the atmosphere at a rate in which evolution of the animals' lungs may not catch up to. This could inevitably lead to the mass extinction of hordes of animals.