Symbionts which help plants in uptake of phosphorous and trace metals such as zinc and copper.

Explanation

Mycorrhizal fungi form symbiotic associations with plant roots and extend fungal hyphae through the soil, increasing the area from which phosphorus and trace metals such as zinc and copper can be absorbed. The plant supplies carbohydrates to the fungus in return. Students may choose bacteria because some bacteria are plant symbionts, but the classic symbionts responsible for this mineral uptake are fungi.