An herbivore eats food that provides 1,000 kJ of energy, of which 500 kJ is lost in faeces, 350 kJ is used in cellular respiration, and 150 kJ is used for growth. The percent production efficiency of the herbivore is:

Correct option is C

The production efficiency of an organism is the percentage of energy that is converted into new biomass (growth) relative to the Assimilated energy. It can be calculated using the formula:

$$\text{Production efficiency} = \left( \frac{\text{Energy used for growth}}{\text{Assimilated energy}} \right) \times 100$$

In this case:

• Energy ingested = 1,000 kJ

• Energy used for growth = 150 kJ

Step 1: Find assimilated energy

Assimilated energy = Ingested energy − Energy lost in faeces
= $1000\text{kJ}-500\text{kJ}=500\text{kJ}$

Step 2: Energy used for growth

Growth = 150 kJ

​$$\text{Efficiency} = \left( \frac{150}{500} \right) \times 100 = 30\%$$​​

Information Booster:

1. Production efficiency indicates how much energy consumed by an organism is converted into biomass (growth) rather than being used for other processes like respiration or being lost.

2. The remaining energy after respiration and faeces loss contributes to growth in the organism, which is used for reproduction and survival.

3. Energy efficiency is typically lower in herbivores compared to carnivores due to their less efficient digestion and energy utilization.

Additional Knowledge:

• 50 (option 1) is incorrect because it overestimates the growth efficiency.

• 35 (option 2) is incorrect; it doesn’t align with the calculation based on the provided data.

• 15 (option 4) underestimates the energy efficiency of the herbivore.

Production efficiency=(1501000)×100=30%\text{Production efficiency} = \left(\frac{150}{1000}\right) \times 100 = 30\%