Royal jelly, a thick, milky substance secreted by young nurse honeybees to feed a bee colonyâs larvae, most notably the queen larvae, is a rich source of nutrients, as well as acetycholine, a neurotransmitter that plays a critical role in cognitive function.
The origin of the eukaryotic cell is a milestone in the evolution of life, since eukaryotes include all complex cells and almost all multicellular organisms. The timing of this series of events is hard to determine; Knoll (2006) suggests they developed approximately 1.6â2.1 billion years ago.
Prokaryotic cells were present on the earth 3.5 to 4 billion years ago, and eukaryotic cells did not appear until 1.4 to 1.5 billion years ago. Eukaryotic cells that contained mitochondria and were oxygen users, however, were not in evidence until as recently as 850 million years ago.