Answer: first : Chlorophyll
Second : bacteria
Explanation: Nitrogen is vital component of chlorophyll, that plants use to trap sunlight to produce sugar from the elements like water and carbon dioxide by photosynthesis.
Nitrogen is also present in the proteins that is used by the plants. Without proteins, plant would die.
Although nitrogen is present in atmosphere plants cannot use it until it is converted by the bacteria in a usable form.
Plants do not utilize nitrogen in the form of nitrogen gas it has to be first converted by the bacteria in the from of nitrates.