- A Mycorrhizae are sometimes thought to directly fix atmospheric nitrogen gas into ammonia within their hyphae
- B Mycorrhizal hyphae dramatically increase root surface area, especially enhancing phosphorus uptake from soil
- C Mycorrhizae mainly secrete plant growth hormones that stimulate lateral root branching activity
- D They are sometimes thought to compete directly with the host plant for water and dissolved minerals
Correct answer: B. Mycorrhizal hyphae dramatically increase root surface area, especially enhancing phosphorus uptake from soil
Explanation: Arbuscular mycorrhizal (AM) fungi form extensive hyphal networks that greatly increase the effective absorptive surface of roots. They are particularly efficient at acquiring phosphorus (poorly mobile in soil). Over 90% of land plants form mycorrhizal associations.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.