How and why does a DNA molecule replicate itself?

DNA makes a copy of itself during cell division.  The separation of the two single strands of DNA creates a 'Y' shape called a replication 'fork'. The two separated strands  act as templates for making the new strands of DNA.

Explanation:

answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation:

this age may represent the age of the earth's accretion, of core formation, or of the material from which the earth formed. this dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.