Question

many farmers grow crops that have been altered by scientists to be resistant to pests. how are restriction enzymes used to make these alterations? they are used by the plant cells to break down the membranes of pest cells. they are used to destroy the dna of the plant cells in order to create new genes. they are used by the plant cells to strengthen their cell walls and discourage pests. they are used to cut plant cell dna so that genes can be inserted into the genome. question 19 the following question has two parts. first, answer part a. then, answer part b. part a plasmid dna samples are taken from four bacteria species and treated with the same restriction enzyme. the treated dna is then analyzed using gel electrophoresis. the results of the gel electrophoresis are shown in the diagram. gel electrophoresis results species species species species marker dna

Explanation:

Restriction enzymes are used in genetic engineering. Their main function is to cut DNA at specific sequences. In the context of modifying crops for pest resistance, they cut the plant cell DNA so that new genes (like those for pest resistance) can be inserted into the genome.

• Option A: Restriction enzymes are not used by plant cells to break down pest cell membranes. That is not their function.
• Option B: They do not destroy plant cell DNA to create new genes. New genes are usually obtained from other sources (like bacteria in Bt - corn case) and inserted.
• Option C: Strengthening cell walls is not the role of restriction enzymes.
• Option D: This is correct as it aligns with the function of restriction enzymes in genetic engineering (cutting DNA for gene insertion).

Answer:

D. They are used to cut plant cell DNA so that genes can be inserted into the genome.