Why is making a vaccine not a linear process???

Please help

Esther works at a large hospital where she plans food service programs she monitors an records information regarding patients diets and intake and is devoloping a new meal plan that addresses several different dietary needs for many types of patients esther enjoys her work as she feelss that she is patients develop healthier habits

What is the main structural difference between enveloped and nonenveloped viruses? a) enveloped viruses have their genetic material enclosed by a layer made only of protein.b) nonenveloped viruses have only a phospholipid membrane, while enveloped viruses have two membranes, the other one being a protein capsid.c) enveloped viruses have a phospholipid membrane outside their capsid, whereas nonenveloped viruses do not have a phospholipid membrane.d) both types of viruses have a capsid and phospholipid membrane; but in the nonenveloped virus the genetic material is between these two membranes, while in the enveloped virus the genetic material is inside both membranes.

Which food can a vegan eat? a. lasagna with cheese b. vegetable risotto c. poached eggs on toast d. chocolate milkshake e. stir-fried chicken