Answer:
The mass number of an atom is its total number of protons and neutrons. Atoms of different elements usually have different mass numbers , but they can be the same. For example, the mass number of argon atoms and calcium atoms can both be 40.
Explanation:
There are three and they are the Atmosphere, lithosphere, and hydrosphere
The correct answer is option A, S Phase - DNA Replication
The DNA replication begin at the S phase of the cell cycle. In this phase, the cell grows and prepare itself for the DNA replication while the other components such as centro some undergo replication. The S phase occurs during the inter phase and the genetic material duplicates itself before entering the mitosis and meiosis cell division in the next stage.
The principle is called CEPHALOCAUDAL PRINCIPLE.
This principle proposed that growth follow a particular pattern in which the head and the upper part of the body grow first before the growth proceeds to other part of the body.
