In humans, the yolk sac is the
site of origin for blood cells and primordial germ cells. The human yolk sac is
a membrane located outside the embryo and it is connected by a tube through the
umbilical opening to the embryo's midgut. The yolk sac serves as an early site
for the formation of blood and in time, is incorporated into the primitive gut
of the embryo.
It a rock form from extrusive rock such as the follow of lava
So the breakdown of lipids actually starts in the mouth. Your saliva has this little enzyme called lingual lipase, which breaks down these fats into something called diglycerides. These diglycyerides then make there way to the intestines, where they stimulate the pancreas to release lipase (another fat breaking enzyme!) and the pancreas to release bile. The bile and pancreatic juices both work together to break these diglycerides into fatty acids. It’s helpful to know some of the root words. Glycerol- the framework to which the fatty acids stick. Glyceride- think of this guy as several fatty acids stuck to a glycerol. Lipids- think fats, and their derivatives (our glyceride friends.) tri/di/mono- these are just number prefixes! Lipids are one glycerol molecule, and then either one, two, or three fatty acids attached, which is where you get mono(1)/di(2)/tri(3)glyceride from. I know this was long, but hopefully it helps!
A is true because they do have a true nucleus or membrane-bound organelles .
