Radioisotopes are used to preserve food because radioisotopes:

dry out the food and make the food less susceptible to bacteria and mold infestation

can kill the bacteria, mold, insect eggs and yeast that cause food to spoil quickly

make the food radioactive so no bacteria or mold can grow on the food

can keep the food from spoiling indefinitely

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.