There are two main stages in the cell cycle. The first stage is interphase during which the cell grows and replicates its DNA. The second phase is the mitotic phase (M-Phase) during which the cell divides and transfers one copy of its DNA to two identical daughter cells.
This question is incomplete. However, the answer to this question is Continental Drift. Approximately 300 million years ago, there were not separate continents, only one giant super continent that we call Pangaea. Over time, scientists realised that the Earth's outer shell slides over the inner mantle through plate tectonics. Around 200 million years ago, Pangaea began to break up through the process of continental drift. Gondwana, incorporating present-day <span>Africa, South America, Antarctica, India and Australia, split from Laurasia (Eurasia and North America). Approximately 150 million years ago, Gondwana started to break up into the present day continents</span>
Answer:
Chlorophyll is a green pigment found in chloroplast in plants. It absorbs sunlight during the process of photosynthesis. It is a chelate molecule. In a chelate molecule a central metal ion forms bonds with a large organic molecule made of carbon, hydrogen and other elements like nitrogen or oxygen.
In chlorophyll, magnesium is the central metal ion and it is bonded to a large organic molecule called as porphyrin. Porphyrin constitutes four nitrogen atoms to which the central magnesium is bonded in square planar arrangement. Since chlorophyll is responsible for the green color of the leaves, more the green color more the chlorophyll content and more is the nitrogen content. Hence, chlorophyll meter measures this green light and finds out if the plant needs more or less nitrogen.
