Question
Why are healthy root nodules pink in colour?
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Answer
- Rhizobium has symbiotic relationship with roots of leguminous plants.
- It infects root cortex and form root nodules.
- Root nodules are the site of nitrogen fixation.
- Enzyme nitrogenase which catalyzes nitrogen fixation, gets inhibited by oxygen.
- But root nodule contain a pigment called leghaemoglobin which acts as oxygen scavanger and protects nitrogenase from getting inhibited.
- Leghaemoglobin is pink in colour.
- Hence, healthy root nodules are pink in colour.
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