Assertion: Restriction endonuclease cuts DNA and isolated mostly from bacteria. Reason: Restriction endonuclease is a type of nuclease.
Explanation
Both the assertion and reason are true, but the reason is not the correct explanation of the assertion. The assertion states that restriction endonuclease cuts DNA and is isolated mostly from bacteria. The context confirms that restriction enzymes 'act as scissors to cut the molecules of DNA' and were discovered by scientists working with bacterial systems like E. coli. The reason correctly states that restriction endonuclease is a type of nuclease. However, being a nuclease only explains WHY restriction endonucleases cut DNA (nucleases are enzymes that cleave nucleic acids). It does NOT explain why they are isolated mostly from bacteria. The bacterial origin of restriction enzymes is due to their natural role as a defense mechanism in bacteria, which is unrelated to simply being classified as a nuclease. Therefore, while both statements are true, the reason does not correctly explain the assertion.
Solution Steps
Step 1: Verify if assertion is true - Context confirms restriction enzymes 'act as scissors to cut the molecules of DNA' and work involves bacteria like E. coli.
Step 2: Verify if reason is true - Restriction endonuclease is indeed a type of nuclease (enzyme that cleaves nucleic acids).
Step 3: Check if reason explains assertion - Being a nuclease explains the DNA-cutting function but NOT the bacterial origin.
Step 4: Conclude that both are true but reason is not the correct explanation - Option B is correct.