What essential criteria must be met in order to execute a successful mapping cross? check all the statements that apply. a. the genotypes of the offspring must be readily determined from their phenotypes. b. one parent should be homozygous dominant and the other homozygous recessive for all the genes being mapped. c. one parent should be heterozygous and the other homozygous recessive for all the genes being mapped. d. recombination must occur in the sex that displays genetic heterogeneity.

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.