Questions

That 8 letter word is Whatsapp (a messenger app)

First four letters:   WHAT a question
 
Letters 2,3,4:     HAT protects our head

Letters 5,6,7:   SAP an IT company

Letters 7,8:    PP same.

Yeast used in making bread is a Fungus.

Enzymes are protein macromolecules. Enzymes are almost always made of proteins only. Proteins are large biopolymer molecules that are made up of repeating monomer units called amino acids. There are 20 different common amino acids that make up proteins like enzymes. Of these, nine amino acids are essential, which means you must get them from your diet.

Enzymes catalyze chemical reactions in biological systems. This means that they speed up the rate of the reaction.

 It is a strange sequence. Each number describes the resemblance of the previous one, except the first one.

11 describes the previous '1' which contains one '1'

21 describes the previous '11' which contains two '1'

1211 describes the previous '21' which contains one '2' and one '1'

111221 describes the previous '1211' which contains one '1', one '2' and two '1'.

So the next sequence will be 312211, that is the previous '111221' contains three '1', two '2' and one '1'.