Question

1. after analyzing the above diagram, what organisms are able to turn unusable nitrogen into a form usable for plants? highlight in the diagram.
2. when an organism excretes waste, can a plant directly use it as fertilizer (nitrogen source)? why or why not?
3. how does nitrogen get into the food web?
4. how does an elephant get its source of nitrogen to form its dna or proteins (like the ones you made)?
5. how does a lion get its source of nitrogen to form its dna or proteins?

complete the explanation tool on the following page, taking note of the claim already provided.

Explanation:

Step1: Identify nitrogen - fixing organisms

Nitrogen - fixing bacteria (both free - living and those in symbiotic relationships with plants) convert atmospheric nitrogen ($N_2$) into ammonia ($NH_3$) or other usable forms for plants. In the diagram, these are the bacteria.

Step2: Analyze waste utilization by plants

Organism waste contains nitrogen in the form of organic compounds like urea. Plants cannot directly use it as a nitrogen source. Microorganisms in the soil first decompose this organic nitrogen into ammonium ($NH_4^+$) and then into nitrate ($NO_3^-$) through nitrification.

Step3: Determine nitrogen entry into food - web

Plants take up nitrate ($NO_3^-$) and ammonium ($NH_4^+$) from the soil. Herbivores eat these plants, obtaining nitrogen. Carnivores then eat herbivores, passing the nitrogen along the food - web.

Step4: Explain nitrogen source for elephant

Elephants are herbivores. They get their nitrogen by eating plants. Plants have already incorporated nitrogen from the soil into their tissues in the form of amino acids, proteins, and nucleic acids.

Step5: Explain nitrogen source for lion

Lions are carnivores. They get their nitrogen by eating herbivores (such as elephants). The nitrogen in the herbivore's body, which was originally obtained from plants, is transferred to the lion.

Answer:

1. Nitrogen - fixing bacteria (highlight the bacteria in the diagram).
2. No. Microorganisms in the soil need to decompose the organic nitrogen in waste into ammonium and then nitrate for plants to use.
3. Plants take up nitrogen from the soil, herbivores eat plants, and carnivores eat herbivores, passing nitrogen along the food - web.
4. By eating plants.
5. By eating herbivores.