Answer:
Despite its abundance in the atmosphere, nitrogen is often the most limiting nutrient for plant growth. This problem occurs because most plants can only take up nitrogen in two solid forms: ammonium ion (NH4+ ) and the ion nitrate (NO3- ).
Explanation:
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D: Macromolecules
Macromolecules are very large molecules, made up of many smaller sub units.
Carbohydrates (also called saccharides) are molecular compounds made from just three elements: carbon, hydrogen and oxygen. Monosaccharides (e.g. glucose) and disaccharides (e.g. sucrose) are relatively small molecules. They are often called sugars.
is the Earth's atmosphere that protects us from radiation and the vacuum of space it also protects us from UV radiation from the sun which can be very dangerous