Question

question 20
what role does recombinant dna play in genetic engineering?
it ensures that host dna is the site of cleavage.
it causes the endonuclease to act on dna and rna.
it is responsible for altering an organisms characteristics.
it becomes the point of attachment for dna and rna in the nucleus.

Explanation:

Recombinant DNA technology combines DNA from different sources. In genetic engineering, this allows for inserting new genes into an organism. These new genes can code for proteins that change the organism's traits (characteristics). For example, inserting a pest - resistance gene into a plant (using recombinant DNA techniques) alters the plant's characteristics to make it pest - resistant. The other options are incorrect: Restriction endonucleases (not recombinant DNA) act on specific DNA sequences for cleavage (so the first option is wrong). Endonucleases act mainly on DNA (not both DNA and RNA as the second option claims). Recombinant DNA is not about being a point of attachment for DNA and RNA in the nucleus (the fourth option is incorrect).

Answer:

It is responsible for altering an organism's characteristics.