▶️ Answer/Explanation
A pyramid of energy always takes a true upright shape (Diagram $3$) because energy is lost at each trophic level (the $10\%$ rule), so it can never be inverted or “top-heavy.” For the pyramid of numbers, the food chain is: Grass $\rightarrow$ Zebra $\rightarrow$ Insects $\rightarrow$ Birds. While there is plenty of grass, there are fewer zebras. However, many insects live on a single zebra, causing the third level to widen significantly. Finally, there are fewer birds than insects. This creates a partially inverted shape where a narrow level (zebras) supports a wider level (insects), matching Diagram $1$.
✅ Answer: (C)
✅ Answer: (C)
▶️ Answer/Explanation
To find the percentage of energy lost, first identify the energy levels: producers have $1000$ units and secondary consumers have $10$ units. The amount of energy transferred is only $1\%$, calculated as $(\frac{10}{1000}) \times 100$. However, the question asks for the energy lost during this transition. The energy lost is the initial energy minus the final energy: $1000 – 10 = 990$ units. To find the percentage lost, use the formula: $\text{Percentage Lost} = (\frac{\text{Energy Lost}}{\text{Initial Energy}}) \times 100$. This gives $(\frac{990}{1000}) \times 100 = 99\%$. This massive loss occurs because energy is dissipated as heat and used for metabolic processes at each trophic level.
✅ Answer: (D)
✅ Answer: (D)
▶️ Answer/Explanation
Decomposers, such as bacteria and fungi, obtain their energy by breaking down organic matter from dead organisms and waste products. Since all living things eventually die, every level of a food web—including producers (plants), herbivores (primary consumers), and carnivores (secondary/tertiary consumers)—serves as a source of energy for decomposers. This process is essential for recycling nutrients back into the ecosystem. Therefore, the correct row must show a “yes” (✓) for all three categories.
✅ Answer: (A)
✅ Answer: (A)