True or false: Most of an ecosystem’s net primary productivity is ultimately used for the growth of primary consumers within the ecosystem.

• A. True because this is the only food source available to primary consumers.
• B. True because primary consumers are the most efficient organisms at converting their food into biomass.
• C. False because primary consumers consume most of the plant matter, but don’t convert most of it to biomass.
• D. False because primary consumers don’t consume most of the plant matter, & they do not convert most of the food they ingest into biomass.

Answer: (D)

Verified step by step guidance

1. Understand the concept of net primary productivity (NPP), which is the rate at which all the plants in an ecosystem produce net useful chemical energy. It is the energy available to the primary consumers after plants have used some for their own respiration.
2. Recognize that primary consumers are herbivores that feed on plants. They rely on the energy stored in plant biomass for their growth and survival.
3. Consider the energy transfer efficiency in ecosystems. Typically, only about 10% of the energy at one trophic level is transferred to the next level. This means that primary consumers do not convert most of the plant matter they consume into their own biomass.
4. Evaluate the statement: 'Most of an ecosystem’s net primary productivity is ultimately used for the growth of primary consumers.' Given the low efficiency of energy transfer, this statement is false.
5. Conclude that the correct reasoning is: 'False because primary consumers don’t consume most of the plant matter, and they do not convert most of the food they ingest into biomass.' This aligns with the understanding of energy flow in ecosystems.