Final answer:
Nodules enable plants to utilize nitrogen through a symbiotic relationship with soil bacteria.
Step-by-step explanation:
Nodules are specialized structures that form on the roots of certain plants, such as legumes, due to symbiotic interaction with soil bacteria. These nodules enable the plants to utilize nitrogen through a process called nitrogen fixation.
Soil bacteria, known as rhizobia, interact with legume roots to form nodules where nitrogen fixation takes place. This process converts atmospheric nitrogen into ammonia, which the plant can use as a nutrient.
The symbiotic relationship between the plant and the bacteria is mutually beneficial. The plant receives a continuous supply of nitrogen, while the bacteria receive carbon compounds generated through photosynthesis and a protected place to grow.