Hyperkeratosis is caused due to the excess of which vitamin?

The given structure represents a low molecular weight organic compound found in living tissues. Identify the category and the missing component $X$ in the structure.
Category $-$ Component

What does a bomb calorimeter measure?

$99 \%$ of living systems are made up of four elements:

From what you have learnt,can you tell whether enzymes are bigger or $DNA$ is bigger in molecular size? How did you know?

Identify and list $10$ interesting small molecular weight biomolecules. Determine if there are industries that manufacture these compounds through isolation and identify their primary buyers.