Biology · Plant Kingdom · NEET
Both are special roots of gymnosperms, but the partner organism is different. Coralloid roots are found in Cycas and hold nitrogen-fixing cyanobacteria (blue-green algae, like Nostoc/Anabaena). Mycorrhiza is found in Pinus and is a partnership between the root and a fungus. So the easy split is: coralloid root = root + cyanobacteria (bacteria), mycorrhiza = root + fungus. NEET loves to swap these two, so lock the pair to the plant.
Cycas has coralloid roots. Pinus has mycorrhiza. NCERT says it plainly: mycorrhiza in Pinus, and small specialised roots called coralloid roots in Cycas. If you mix them up in the exam you lose an easy mark, so remember Cycas and Coralloid both start with 'C'.
Nitrogen-fixing cyanobacteria (blue-green algae) live inside the coralloid roots. These cyanobacteria, such as Nostoc and Anabaena, take nitrogen gas (N2) from the air and change it into a form the plant can use. This is why coralloid roots grow near the soil surface and look coral-like and green.
Mycorrhiza involves a FUNGUS, not a bacterium. The word means fungus (myco) + root (rhiza). The fungus wraps around or enters the root of Pinus. The fungus helps the plant absorb water and minerals (like phosphorus), and the plant gives the fungus sugar. This give-and-take is called a symbiotic (mutual) relationship.
No. The root itself does not fix nitrogen. The cyanobacteria living inside the coralloid root do the nitrogen fixing. The root only gives the cyanobacteria a place to live. So the correct statement is: coralloid roots are associated with nitrogen-fixing cyanobacteria. Do not write that the root or the plant fixes nitrogen on its own.
No, this is a common trap. Mycorrhiza does NOT fix nitrogen. Only the coralloid roots (with cyanobacteria) do nitrogen fixation. The fungus in mycorrhiza helps the plant absorb water and minerals from the soil, especially phosphorus. Keep nitrogen fixation tied to Cycas coralloid roots only.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Because they are small, branched, and grow near the soil surface in a shape that looks like coral. 'Coralloid' means coral-like. Inside them live nitrogen-fixing cyanobacteria.
Yes. Both are symbiotic (mutual benefit) associations. In coralloid roots, the plant and cyanobacteria both benefit. In mycorrhiza, the plant and fungus both benefit. This is why NEET groups them as special roots of gymnosperms.
No. Mycorrhiza (fungus + root) is found in many plants, including angiosperms. But for the Plant Kingdom chapter, NCERT gives Pinus as the example of a gymnosperm with mycorrhiza. Know the Pinus example for the exam.
Commonly Nostoc and Anabaena. These are blue-green algae (cyanobacteria) that fix atmospheric nitrogen. NCERT only says 'N2-fixing cyanobacteria', so knowing they are cyanobacteria is enough, but the named genera help in match-type questions.
Yes, often as a match-the-column or 'select the correct pair' question, like Cycas - coralloid roots or Pinus - mycorrhiza. Memorise the two pairs and their partner organism (cyanobacteria vs fungus) to answer fast.
