AP BIOLOGY

Detailed explanation-1: -Prokaryotes play several roles in the nitrogen cycle. Nitrogen-fixing bacteria in the soil and within the root nodules of some plants convert nitrogen gas in the atmosphere to ammonia. Nitrifying bacteria convert ammonia to nitrites or nitrates.

Detailed explanation-2: -Organisms that are involved in nitrogen cycles are nitrogen fixers, nitrifying bacteria, and denitrifying bacteria. Example: Nitrosomonas, Rhizobium, Pseudomonas, and Thiobacillus, etc.

Detailed explanation-3: -Plants take up nitrogen compounds through their roots. Animals obtain these compounds when they eat the plants. When plants and animals die or when animals excrete wastes, the nitrogen compounds in the organic matter re-enter the soil where they are broken down by microorganisms, known as decomposers.

Detailed explanation-4: -Simply by eating, all living things take in these molecules and break them down in their own bodies in order to use them. When animals die, they contribute to the nitrogen cycle as well. Nitrogen-rich compounds from bodies of animals are decomposed, and nitrogen is returned to the soil to be recycled and re-used.

Detailed explanation-5: -Neither plants or animals can obtain nitrogen directly from the atmosphere. Instead, they depend on a process known as nitrogen fixation. Key players in this process are legumes and the symbiotic bacteria which are associated with the legume’s root nodules. These bacteria are known as nitrogen-fixing bacteria.