Questions

Africa is the second largest continent both by popolation and area wise. Asia being first by both popolation and area wise.

RNA is not a lipid among the given options.

A lipid is a substance of biological origin that is soluble in nonpolar solvents. It comprises a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, and phospholipids.

The one word substitute for "a person who is always dissatisfied" is malcontent.

Telnet uses TCP at layer 4. It uses IP at layer 3. We know that Telnet uses TCP/IP protocol, but in the question, it is asked specifically at layer 4 what is used in Telnet. So it is TCP at layer4 and IP at layer 3.

The persons with 'O' blood group do not have antigens in the red corpuscles. So that blood will not cause agglutination of corpuscles if mixed with any type of blood. So group 'O' persons are called universal donors.

The words do, does and did often cause confusion in the English language. They are all forms of the verb to do.

It is also common to use do, does and did as auxiliary verbs (or helping verbs) together with another verb in its base form. This is used to create negative sentences, questions, or for adding emphasis.

Examples :: 

* Russel did a great job on his debut match for team.

* Did you catch the train this morning?

* When did they arrive home?