[Campbell Biology P.869] Both rhizobacteria and mycorrhizae play crucial roles in plant nutr... | Practice Question

Both rhizobacteria and mycorrhizae play crucial roles in plant nutrition. Which of the following statements accurately distinguishes the primary contribution of mycorrhizae from that of nitrogen-fixing rhizobacteria to plants?

  • A: Mycorrhizae absorb water and minerals for the plant, while nitrogen-fixing rhizobacteria convert atmospheric N₂ into usable nitrogen compounds.
  • B: Mycorrhizae provide antibiotics to the plant, while nitrogen-fixing rhizobacteria absorb water.
  • C: Both mycorrhizae and nitrogen-fixing rhizobacteria are primarily involved in breaking down humus.
  • D: Mycorrhizae fix nitrogen from the atmosphere, while rhizobacteria enhance mineral absorption.

Explanation

The text states that "Mycorrhizae are mutualistic associations of fungi and roots. The fungal hyphae of mycorrhizae absorb water and minerals, which they supply to their plant hosts." For rhizobacteria, it mentions "Nitrogen-fixing bacteria convert atmospheric N₂ to nitrogenous minerals that plants can absorb as a nitrogen source for organic synthesis." This clearly distinguishes their primary roles.