When does cell differentiation occur?

a) when cells do not express genes
b) when cells express all genes
c) when cells express the same genes
d) when cells express different genes

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?

Matched chromosomes carrying information about the same characteristics in the organism are called

The human body needs energy in order to carry out life processes such as breathing. where does the body get this energy? a. from eating food b. from learning about new things c. from lying in the sun d. from sleeping