which of the follwing pyramids is not used in ecology? pyramid of

Analyze the question: You're asked which of the four is NOT a type of ecological pyramid.

Concept: Ecological pyramids show how living things are arranged across the trophic levels (feeding levels) of a food chain. The three standard types are:

1. Pyramid of numbers shows how many individual organisms are at each trophic level.
2. Pyramid of biomass shows the total dry mass of living material at each trophic level.
3. Pyramid of energy shows how much energy flows through each trophic level, usually in kJ/m²/year.

Solution:

• A. Energy: a recognised ecological pyramid.
• B. Numbers: a recognised ecological pyramid.
• C. Biomass: a recognised ecological pyramid.
• D. "Organisms": not a standard type. Organisms are what the pyramids describe, and "numbers of organisms" is already covered by the pyramid of numbers. "Pyramid of organisms" is not a recognised term in ecology.

Answer: D

Tip: Remember the three ecological pyramids as N-B-E: Numbers, Biomass, Energy. If an option isn't one of these, it's probably the odd one out. Also remember that the pyramid of energy is always upright, while numbers and biomass can sometimes be inverted, such as numbers on a single big tree supporting many insects.