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.
(Or, can the endosymbiont theory explain the origin of eukaryotic cells?) Eukaryotic cells, such as yeast and those of animals and plants, have a membrane-bound nucleus, chromosome structures and organelles such as mitochondria and chloroplasts, whereas prokaryotic cells, such as bacteria, lack these features.