Answer:
Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die.
Yes it is the only empire that existed in the history of Africa
Answer:
This is an example of a Cross-sectional Design.
Explanation:
A Cross-sectional design or study occurs when a researcher observers <em>various subjects of different aspects</em> such as age in a specific point in time, in order to observe the differences within the subjects.
In this case, we can clearly see it is this type of design since the researcher interviews children from ages 5, 9 and 13 in one specific moment in time.
