Question

1. what is true about the transfer of energy in ecosystems?

since all energy can be recycled in a food web, there are no rules about the amount of biomass at each trophic level.
since so much energy is lost at each level, a large number of producers are required provide the energy needed to maintain a stable food web.
since some energy is produced at each level, consumers must outnumber the trophic level below them to maintain a stable food web.
since very little energy is lost at each level, producers must only have more biomass than the trophic level above them to maintain a stable food web.

Explanation:

In an ecosystem, energy transfer follows the 10% rule. Only about 10% of energy is passed from one trophic level to the next, with the rest lost as heat. This means a large number of producers (which convert sunlight to energy via photosynthesis) are needed to support higher trophic levels. Producers form the base of the food web. If there weren't enough producers, there wouldn't be sufficient energy to maintain the food web. Energy is not recycled in the sense that it doesn't go back in a loop like nutrients. Also, consumers do not outnumber the trophic level below them (producers are usually more in number or biomass to support consumers). And a significant amount of energy is lost at each level (not very little).

Answer:

Since so much energy is lost at each level, a large number of producers are required provide the energy needed to maintain a stable food web.