Question

it was asked to give reason why lines of longitude are known as meridians of longitude.

ans:- I have written in this that the lines of longitudes are known as Meridian of longitudes because Meridian is the word derived from Greek word meridium which mean midday or noon .

: these are known as Meridian of longitudes because they divide Earth into two parts and form a great circle.

the question was of 2 marks how much I will get on it only experts can answer......

Answer 1

I guess you colud have explained a bit more.Meridians are so called because they help us to know the mid day,thus allowing us to calculate the time of a place.
You can get 1.5 out of 2 or even 2 as well.