Question

In some viruses, RNA is present instead of DNA indicating that:
A. Their nucleic acid must combine with host DNA before replication.
B. They cannot replicate.
C. There is no hereditary information.
D. RNA can act to transfer heredity.

Answer 1

Hint: Nucleic acids serve in storage of genetic data. It is very important for the genetic information to be stored especially in an orderly sequence, since these codes are further transcribed and translated to form proteins. These proteins play various structural and functional (enzymatic) roles.

Complete Step by Step Answer:
The RNA or Ribonucleic acid does not require the host's DNA (Deoxyribonucleic acid) to replicate. Although to infect the host or enter its genetic component, it uses the process of reverse transcription to convert its RNA to DNA for its DNA to be inserted into the host’s DNA.
It can either replicate itself by RNA dependent RNA synthesis. Since the sequence of complementary strands depend on RNA and RNA is to be synthesised from it, it is called RNA dependent RNA synthesis. Another way of replication that is seen in retroviruses is Reverse Transcription. This method uses messenger RNA or mRNA to make its complementary DNA strand. Hence, this method is called RNA dependent DNA synthesis.
The viruses that have RNA as their genetic material are called retroviruses. It is hard to make vaccines against such viruses as these keep mutating. These can use RNA or DNA or sometimes even both alternatingly as a tool to store hereditary information. Infact, many primitive organisms had RNA for transmitting hereditary information and manufacturing proteins.
Therefore, the correct answer is option:D -RNA can act to transfer heredity.

Note: The method of Reverse Transcription is now used by scientists to detect such viruses in the carrier’s body. It helps in amplifying the genetic sequence which makes it easy to detect viruses. Therefore, these techniques were also used to detect SARS-CoV-2 virus.