Biology · Organisms and Populations · NEET
They overlap but are not exactly the same word. Symbiosis means two species living together in close contact. Mutualism means both species BENEFIT from that contact. Lichens and mycorrhizae are symbiotic AND mutualistic. For NEET, the sign you write for mutualism is always (+/+). If both partners gain, call it mutualism.
In a lichen, the alga makes food by photosynthesis and shares it, while the fungus gives shelter, water and minerals. Because BOTH the fungus and the alga gain, it is (+/+) mutualism. Commensalism would be (+/0), where only one gains and the other is unaffected. Since neither partner is 'unaffected' here, it is not commensalism.
Mycorrhizae are MUTUALISM (+/+). The fungus helps the plant root absorb minerals and water from soil, and the plant gives the fungus energy-rich carbohydrates. Both benefit, so it cannot be parasitism, which is (+/-) where one is harmed. This exact idea was asked in NEET 2017.
Mutualism is (+/+): both species benefit (lichens, mycorrhizae, fig-fig wasp). Commensalism is (+/0): one benefits and the other is neither harmed nor helped (orchid on a mango tree, cattle egret with cattle). The trap: change one sign from + to 0 and the answer flips.
It is obligate MUTUALISM (+/+). The fig gets pollinated by the wasp, and the wasp uses the developing fig seeds to raise its larvae. Both gain, so it is NOT commensalism. NEET has tested this exact confusion (2023 Odisha and 2025 asked it directly).
Mycorrhizae are the example of
Plants offer rewards to animals in the form of pollen and nectar and the animals facilitate the pollination process. This is an example of:
Statement I: Fig fruit is a non-vegetarian fruit as it has enclosed fig wasps in it. Statement II: Fig wasp and fig tree exhibit a mutual relationship, as the fig fruit provides the wasp a place to lay eggs and the fig gets pollinated by the fig wasp. Choose the most appropriate answer.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Mutualism is a relationship between two different species where both of them benefit. In NEET sign language it is written as (+/+).
Lichens (fungus + alga), mycorrhizae (fungus + plant roots), the fig-fig wasp pollination pair, and the Yucca plant-moth pair. All are (+/+).
It can be both. In obligate mutualism neither partner can complete its life cycle alone (fig-fig wasp, Yucca-moth). In some cases it is looser, but for NEET the fig-wasp and Yucca-moth are the obligate examples to remember.
Count the benefits. Mutualism = both benefit (+/+). Commensalism = only one benefits, the other is unaffected (+/0). If you can name a gain for BOTH species, it is mutualism.
Mutualism is (+/+). Compare: competition (-/-), predation and parasitism (+/-), commensalism (+/0), amensalism (-/0).
