If the following graph represents the decay of strontium-90 in an igneous rock, what event occurred at 0 years on the horizontal axis ?

The first signs of cellular differentiation occur in the blastocyst. why is cellular differentiation important for the development of a fully formed human infant?

The reactions that occur in the ribosome, where amino acids are combined to form proteins are anabolic or catabolic?

Which sentence best describes the relationship between chlorophyll and the chloroplast? a.)chlorophyll is a chemical found in a chloroplast. b.) chloroplast is a chemical found in a chlorophyll. c.) both chlorophyll and chloroplasts are found in animals. d.) both chlorophyll and chloroplasts make carbon dioxide.