What is the difference between a scientific theory and an opinion?

Which is not a characteristic of the animal kingdom? a. they include both vertebrates and invertebrates b. their skin is covered with hair or fur c. they are heterotrophs d. they are eukaryotic

To determine if a particular plant is homozygous or heterozygous, you would have to test cross with a

This is the interaction of two organisms where one is and the other is neither nor harmed.