Sharp claws in wild animals is an example of which type of adaptation?

What have we learned from fossil evidence about evolution? a) it is an abrupt change. b)the process is observable. c) it takes place during one lifetime only. d)the most complex traits are always selected.

How does the study of genetic disorders such as pku biologists understand normal alleles?

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain