- A A plant growth hormone that specifically triggers rapid cell division within the root cortex tissue
- B A pink oxygen-scavenging protein in root nodules that maintains anaerobic conditions for nitrogenase
- C A carbohydrate storage compound that holds fixed nitrogen in the form of starch granules
- D A diffusible signal protein released by Rhizobium that specifically triggers root hair curling
Correct answer: B. A pink oxygen-scavenging protein in root nodules that maintains anaerobic conditions for nitrogenase
Explanation: Leghemoglobin is a pink/red protein found in legume root nodules. It scavenges free O2 in the nodule, maintaining the anaerobic microenvironment required by nitrogenase (which is O2-sensitive). Its genes come from both the plant and Rhizobium.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.