Interspecific Interactions & Notation — NEET Biology
✅ Asked in NEET 2023Match List-I with List-II: (NEET 2023) List-I (Interaction) A. Mutualism B. Commensalism C. Amensalism D. Parasitism List-II (Effect) I. + (A), O (B) II. – (A), O (B) III. + (A), – (B) IV. + (A), + (B) Choose the correct option:
Match List-I with List-II: (NEET 2023) List-I (Interaction) A. Mutualism B. Commensalism C. Amensalism D. Parasitism List-II (Effect) I. + (A), O (B) II. – (A), O (B) III. + (A), – (B) IV. + (A), + (B) Choose the correct option:
Answer & NCERT explanation
Correct answer: C — -IV (B)-I (C)-II (D)-III
Mutualism: both species benefit (+,+). Commensalism: one benefits, other unaffected (+,0). Amensalism: one harmed, other unaffected (-,0). Parasitism: parasite benefits, host harmed (+,-). These are standard ecological interaction symbols used in NCERT ecology chapters for species relationships.
Read more NCERT concept on the PYQ
Interspecific interactions arise from the interaction of populations of two different species. They could be beneficial, detrimental or neutral (neither harm nor benefit) to one of the species or both. Assigning a '+' sign for beneficial interaction, '−' sign for detrimental and 0 for neutral interaction, let us look at all the possible outcomes of interspecific interactions (Table11.1).
The NTA tests your understanding of how to classify interspecific interactions (between two different species) using the +/−/0 notation system. The '+' sign indicates the interaction is beneficial to a species, '−' indicates it's harmful/detrimental, and '0' means neutral (no effect). Students often confuse this notation with the actual interaction type (predation vs competition vs symbiosis) and forget that the same interaction can have different signs for each species involved. For example, in predation, the sign is + for predator but − for prey. Always remember: the sign represents the outcome (benefit/harm/neutral) for each species individually, not the category of interaction itself.
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Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.