Question

which of the following statements is true about the nitrogen cycle? i. bacteria are very important in the nitrogen cycle. without these bacteria, it would be very difficult for other life forms to exist. ii. nitrogen fixation occurs when bacteria take nitrogen gas out of the air and make it into ammonia. this can then be converted into nitrates that plants can use. iii. decomposition is not very important in the nitrogen cycle. iv. nitrogen is needed to make dna, proteins, atp and other important molecules for life. the nitrogen cycle makes nitrogen available to living things. a. i and iv only b. i, ii and iv only c. i, ii, iii, and iv d. ii only

Explanation:

• Statement I: Bacteria play crucial roles like nitrogen - fixing and nitrification in the nitrogen cycle, essential for other life forms.
• Statement II: Nitrogen - fixing bacteria convert atmospheric nitrogen to ammonia which can be further processed to nitrates for plants.
• Statement III: Decomposition is important as it releases nitrogen back into the environment from dead organisms. So this statement is false.
• Statement IV: Nitrogen is a key element in DNA, proteins, ATP etc., and the nitrogen cycle makes it accessible to living things.

Answer:

B. I, II and IV only