When a large number of organisms share limited resources, the result is?

Step 1: Analyze the question The question asks what happens when many organisms share limited resources such as food, water, space, light or mates.

Step 2: Explain the concept When resources are limited and many organisms need them, they struggle against one another to get them. This struggle is called competition. It can be:

• Intraspecific: between members of the same species (e.g., two cockerels fighting over food).
• Interspecific: between different species (e.g., grasses and weeds competing for sunlight and soil nutrients).

Step 3: Check each option

• A. Mutualism: both organisms benefit (e.g., nitrogen-fixing bacteria in legume roots). This is not about a struggle for resources.
• B. Extinction: the complete disappearance of a species. Competition may contribute to it over time, but it is not the immediate result of sharing limited resources.
• C. Commensalism: one organism benefits while the other is neither helped nor harmed (e.g., an epiphyte growing on a tree). Resources are not being fought over here.
• D. Competition: the correct term for organisms struggling over limited resources.

Step 4: Answer The correct option is D. competition.

Exam tip: Link the keywords to the term. "Limited resources" and "many organisms" point to competition. "Both benefit" points to mutualism. "One benefits, the other unaffected" points to commensalism. "One benefits, the other harmed" points to parasitism.