The enzyme pepsin functions with a very low pH of around 2. It is found in the stomach, with the acidity coming from the hydrochloric acid present there. it breaks proteins into amino acids.
Yes, The energy source for all stars is nuclear fusion.
The scientific term of a fat cell is an adipoctye.
The term rare amino acids is misleading in some respects. It refers to all those amino acids that are not incorporated into proteins. We already got to know some of them like ornithine or citrulline that are rather common intermediates of the basic metabolism. Roughly 220 different structures are known, most of which occur in plant cells in a free state though glutamate-, oxalate- or acetyl- derivatives can also sometimes be found.
Source: https://s10.lite.msu.edu/res/msu/botonl/b_online/e20/20e.htm
Hope this helps!
This is the depiction of a solar eclipse
