What does "pruning" the brain mean?
a) more brain connections are made
b) the brain gets rid of some of the less effective connections
c) the brain grows new cells
d) all of the above

Explain the purpose and function of the icd-10-pcs coding system, include reasons for the transition from icd-9 vol. 3.

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.

Most of the phosphorus on earth comes from ?