What is the slow, wavelike contraction that moves food through the digestive system?

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

What are the most explosive events that occur on the sun? umbras solar flares solar winds prominences

The response is the basis for vaccination. primary secondary tertiary none of the above