Partial answer.
According to Merriam-Webster, these is the plural form of this, and those is the plural form of that.
this
1 a (1) : the person, thing, or idea that is present or near in place, time, or thought or that has just been mentioned
that
2
a : the one farther away or less immediately under observation or discussion
So those ones refers to things away from you; these ones refers to things close to you.
Let's suppose ones are apples, and there are some apples next to you, and there are some apples away from you.
You point to the apples close to you and say
I like these apples.
You point to the apples away from you and say
I do not like those apples.
Next, it should be
Those/these who want to get more marks should know a bonus chapter in the book
I cannot explain why. I think it is because the students are sitting away from you, or that you are referring to people away from you.
If you had a cage full of students and you were standing next to the cage and you point to the students in the cage, it might make sense to say
these who want to get more marks should know a bonus chapter in the book
But I admit, this sounds very strange.