The structure of the hormone thyroxine is given below. The percentage of iodine in thyroxine is $..........\%$. ($nearest$ $integer$)
($Given$ $molar$ $mass$ $in$ $g \ mol^{-1}: C: 12, H: 1, O: 16, N: 14, I: 127$)

How many isoprene units are present in abscisic acid?

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

Assertion : $DNA$ as well as $RNA$ molecules are found in the nucleus of a cell.
Reason : On heating,the enzymes do not lose their specific activity.

During the process of aerobic respiration,acetyl co-enzyme $A$ is formed from which of the following?

Which of the following statements are correct?
a) In maltose,$C-1$ of one $\alpha-D$-glucose is linked to $C-4$ of second $\alpha-D$-glucose.
b) Quaternary structure of protein represents spatial arrangement of two or more polypeptide chains with respect to each other.
c) Nucleotide units in a nucleic acid are joined to each other through a phosphodiester linkage.
d) Abnormally low level of thyroxine leads to hypothyroidism.