In tomatoes, red fruit color is dominant, R, to yellow fruit color, r. A farmer has tomatoes that produce either red or yellow tomatoes. He has signed a contract with a large seed company to provide pure, RR, and pure yellow seeds, rr. They do not want any hybrids. How could the farmer tell if his tomatoes are pure or hybrid?

He should perform a "testcross" by crossing the tomatoes in question with yellow-fruited plants.

If they are pure, all offpsring will be Red:  RR x rr = all Rr

If they are hybrids (heterozygous), half the offspring will have yellow fruits:  Rr x rr = 1:1 (red to yellow)

Explanation:

what have scientists found to be the most efficient and effective way to insert new sequences into an individual? a-scientists have created genetically altered foods that release dna during digestion. b-scientists use viruses to insert specific gene sequences. c-scientists irradiate genes so that they can be absorbed through the skin.