Which would cause a plant to stop growing

Ialready know the answers to these questions and they are on the attachment. but i just need to know why that answer is the correct one. plz asap! this is for a report that i need to email by 10!

Hershey and chase confirmed that dna, not protein, was the genetic material. how do the results of their two experiments support this conclusion?

1. isogamy 1 organisms with gametes of the same size and shape 2. anisogamy organisms with gametes of different sizes and shapes 3. oogamy 2 organisms with gametes of the same shape but different sizes 4. gonads gamete-producing organs in lower plants 5. gametangia gamete-producing organs in animals