In multicellular organisms individual cells grow and then divide via a process called mitosis, thereby allowing the organism to grow. Cellular division and differentiation produce and maintain a complex organism, composed of systems of tissues and organs that work together to meet the needs of the whole organism.
The answer is A:
The SUGAR-PHOSPHATE CHAINS form the sides, and the BASE PAIRS form the rungs
They are said to be “denser” than air. what happens is that light slows down when it passes from the less dense air into the denser glass of water. this slowing down the ray of light also causes the ray of light to change directions. it is the change in the speed of the light that causes refraction.
This zone is called as the zone of aeration. It is present between the earth's surface and the water table, and its main constituents are the soil and rocks. The pores which are present in this zone are partly filled with water, and may mix up with air, causing aeration.