Which of the following represents a nucleoside?

Identify the statement which is not correct from the following.
$(i)$ Carbohydrates are stored as glycogen in animals.
$(ii)$ In glycylalanine,the carbonyl group of peptide bond belongs to alanine.
$(iii)$ Base - sugar - phosphate unit is known as nucleoside.
$(iv)$ Obesity is due to hypothyroidism.
The correct answer is

The number of chiral centres in penicillin is

Which of the following is the most important biological molecule containing $Mg$ found in living organisms?

The artificial sweetener $X$ contains a glycosidic linkage and $Y$ contains amide and ester linkages. $X$ and $Y$ respectively are:

Which is correct about saccharin?