The sum total of all the roles an organism plays in a habitat is referred to as its

Step 1: Analyze the question The question asks for the term describing the sum total of all the roles an organism plays in its habitat. The key phrase is "roles an organism plays."

Step 2: Explain the concept Let's define each option:

• Ecology: The study of the relationships between organisms and their environment.
• Ecosystem: A community of living organisms interacting with each other and with the non-living environment.
• Habit: A regular or repeated behaviour of an organism.
• Habitat: The place where an organism lives (its "address").
• Niche: The role or function of an organism in its habitat, including what it eats, what eats it, where it nests, how it reproduces, and how it interacts with other organisms (its "profession").

Step 3: Solve The question asks about the roles an organism plays, not the place where it lives or the study of it. This is the definition of a niche.

• Habitat is the place, so D is not correct.
• Ecosystem is the whole system, so B is not correct.
• Ecology is the field of study, so A is not correct.
• Habit is behaviour, so C is not correct.

Step 4: Answer The correct option is E. niche.

Tip: Remember "Habitat = Address, Niche = Occupation." The habitat is where the organism lives, while the niche is what it does there. For example, in a pond, a tadpole's habitat is the water, while its niche includes feeding on algae and serving as food for fish.