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AP Biology에서 Nitrogen이 중요해지는 부분이 2번 있는데요

첫번째, 

토양, 환경, 농업 같은 얘길 하면서

2 elements that are often the limiting agents of plant growth :

phosphorus and nitrogen.

phosphorus because it's part of a rock cycle which takes millions of years to replensh in soil

nitrogen because it's usually gas, which means bacteria is needed to convert N2 gas into ammonia found in soil.

그래서 비료 같은 성분이 rich in phosphorus, nitrogen, which allows better growth of plants.

두번째, 

생명체들이 매일 대사활동을 하면서 breakdown of proteins, nucleic acids in cells

results in creation of 'nitrogenous waste' which requires excretion from the body.

강의에서 언급했다시피, there are 3 main ways animals can get rid of nitrogen from their bodies

ammonia, urea, and uric acid.

6번 문제의 경우 nitrogen influx에 대해서 지문이 나오는데

이거 2가지를 합쳐서 얘기를 하고 있죠?

salmon are living organisms, so of course they contain nitrogen in their bodies.

when bears and salmon are found together, there is increase of nitrogen compounds in the environment

(which acts as fertilizer and promotes better growth of plants)

d 보기가 틀린 이유는

bear urine is not a source of nitrogen for the salmon

salmon gain nitrogen via food sources (and bear urine is definitely not a food source)

그에 비해 salmon is a source of nitrogen for the bear

so bears gain nitrogen by eating the migrating salmon,

some parts of salmon that are not eaten by bears will remain near the river and decompose

resulting in the "nitrogen influx" as shown in the graph.

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열공하시고 혹시 또 질문이 생기면 게시판에서 만나요! :D