Which of the ecological pyramids is always upright ?

Options

A. Pyramid of number
B. Pyramid of biomass
C. Pyramid of energy
D. None of these

Answer

To answer the question "Which of the ecological pyramids is always upright?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ecological Pyramids**:
- Ecological pyramids are graphical representations that show the relationship between different trophic levels in an ecosystem. They can represent the number of organisms, biomass, or energy at each trophic level.

2. **Types of Ecological Pyramids**:
- There are three main types of ecological pyramids:
- **Pyramid of Numbers**: Represents the number of individual organisms at each trophic level.
- **Pyramid of Biomass**: Represents the total biomass of organisms at each trophic level.
- **Pyramid of Energy**: Represents the flow of energy through the trophic levels.

3. **Upright vs. Inverted Pyramids**:
- An ecological pyramid can be either upright or inverted.
- **Upright Pyramid**: This occurs when the number, biomass, or energy decreases as you move up the trophic levels.
- **Inverted Pyramid**: This occurs when the number or biomass increases as you move up the trophic levels.

4. **Analyzing Each Pyramid**:
- **Pyramid of Numbers**: Can be inverted in some ecosystems (e.g., a few large trees supporting many insects).
- **Pyramid of Biomass**: Can also be inverted (e.g., aquatic ecosystems where phytoplankton biomass can be less than that of zooplankton).
- **Pyramid of Energy**: Always upright because energy decreases as it moves from one trophic level to the next due to the 10% energy transfer rule, where 90% of energy is lost as heat.

5. **Conclusion**:
- The pyramid that is always upright is the **Pyramid of Energy**. This is because energy is consistently lost at each trophic level, ensuring that the pyramid shape remains upright.

### Final Answer:
The ecological pyramid that is always upright is the **Pyramid of Energy**.