Geologic time periods are divided by
A. The appearance and disappearance of life forms
B. An equal number of years
C. The amount of sediment
D. All of the above

How many chromosomes are in a gold fish?

What type of organism is a one-celled organism that functions as a single unit? a. bi-celled b. single-celled c. pre-celled d. multi-celled

During an experiment, readings for blood pressure in a persons body were found to be constant . however , when he measured by a different blood pressure cuff , the readings differed by 15 points for each reading. this difference indicates that the results are