Plant cells have what is perhaps the most complex outer coverings. Plant cell walls are made largely of cellulose which forms strong, highly rigid, almost indigestible coverings that protect the cell and gives it shape.
The central nervous system by sending messages from the brain through the nerves that go to your spine.
The flow of energy in an ecosystem is best described as energy moving in one direction from the sun to the producers then to the consumers.
Explanation;
Energy flow is the amount of energy that moves through successive trophic levels of a food chain in an ecosystem. Ecosystem maintain themselves by cycling energy and nutrients.
The energy from sunlight is taken up by producers which use it to produce organic compounds through photosynthesis. The energy is then passed successively to the trophic levels, that is from the producers to the consumers ( primary, secondary, tertiary and quotienary consumers). During this transfer some energy is lost at each trophic level in form of heat.
They are thus known as the "supporting cells" of the nervous system. The four main functions of glial cells are: to surround neurons and hold them in place, to supply nutrients and oxygen to neurons, to insulate one neuron from another, and to destroy and remove the carcasses of dead neurons (clean up).
Pre-embryonic cleavages make use of the abundant cytoplasm of the conceptus as the cells rapidly divide without changing the total volume.