Why are there no more than four or five links in a food chain?

The “ecological footprint” left by a citizen of a developed nation is about four times larger than that left by a citizen of a developing nation. why is this the case?

Which organism can most likely be classifild as domain bateria

The lineage of pea plants produced round seeds for four generations. the plants that fertilized these pea plants also produced round seeds. however, in the fifth generation, the plant produced to two plants with wrinkled seeds. can that be possible?