Certain types of bacteria have a relationship with certain plants where they help convert nitrogen into a usable form.
Explanation:
Nitrogen is abundant in the atmosphere, but plants cannot use it because of the absence of a necessary enzyme, nitrogenase, which converts nitrogen into a usable form. So they form a symbiotic relationship (mutually-beneficial arrangement) with nitrogen fixing soil bacteria (rhizobia) which perform biological nitrogen fixation. Biological nitrogen fixation is a process in which the symbiotic nitrogen-fixing bacteria coverts atmospheric nitrogen into ammonia and organic derivatives that plants can use to synthesize proteins. This bacteria form nodules on the roots of plants like legumes in which nitrogen fixation takes place.
Both plants and bacteria benefit from this symbiotic relationship, as the plant obtains ammonia to synthesize proteins from nitrogen in the atmosphere while bacteria obtain carbon compounds from the plant produced through photosynthesis and a secure environment to grow. As the plant roots leave behind some of the usable form of nitrogen in the soil, this process also increase soil fertility.
The fruit flys population would be less since the apples isn’t there anymore. The reasoning behind that is because it’s a fruit fly they like being around fruit.
The central element for all living things is carbon, which is why you might often hear the phrase "carbon-based" lifeforms. Another term is often "organic matter"