Am amniotic egg is first developed in the reptiles.
The membrane and shell make a protective membrane that can provide a safe environment for the cells to divide, and embryo to develop. Animals having an amniotic shell are called as amniotes. The other body parts develop later on.
The scientist who is said to have discovered all the four nitrogenous bases present in the DNA of all organisms is, Erwin Chargaff, an Austro-Hungarian biochemist who immigrated to the United States. Hope this helps!
A control group in a scientific experiment is a group separated from the rest of the experiment, where the independent variable being tested cannot influence the results. This isolates the independent variable's effects on the experiment and can help rule out alternative explanations of the experimental results.