Asystematic error in data is called
a. bias.
b. control.
c. dependence.
d. variation.

Which of the following does not cause blindness? a. cataractsb. glaucomac. osteoarthritisd. diabetes

Which action is most likely to contribute to a positive self-image?

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.