Human BiOlogy.

[iluvme]

There;s this Question,
Which chromosomes are present in an ovum?
A. X only
B. Y only
C. XX
D. XY

Why is C wrong?

[elemis]

Is the answer A ?

[iluvme]

Yup. Why?

[elemis]

Yup. Why?

I dont do Biology and whatever you read from now on is due to the knowledge I got from the Discovery Channel

I know that the eggs of a woman have only an X chromosome. Its the male sperm that provides the other chromosome whether it be X or Y.

So in short, a stand alone egg has only an X chromosome and a stand alone male Sperm has either an X or a Y.

[Deadly_king]

I dont do Biology and whatever you read from now on is due to the knowledge I got from the Discovery Channel

I know that the eggs of a woman have only an X chromosome. Its the male sperm that provides the other chromosome whether it be X or Y.

So in short, a stand alone egg has only an X chromosome and a stand alone male Sperm has either an X or a Y.

Good job Ari..........you know many things for someone who do not do biology.

Indeed the egg is a gamete and it carries only one sex chromosome. In all it will have the number of chromosomes that is only 23.

[iluvme]

Thanks Ari and Deadly King.
I must be mad to do Human Bio. This sucks.

[Deadly_king]

Thanks Ari and Deadly King.
I must be mad to do Human Bio. This sucks.

Nan......you are wrong. It's not that difficult. Just demands a bit of concentration and understanding.

Don't worry.....you'll get it with time 

[iluvme]

Thanks Deadly King.

Whats the difference between gametes and chromosome?

[Deadly_king]

Thanks Deadly King.

Whats the difference between gametes and chromosome?

I don't think you need to know that for O-level. It's in AS syllabus.
This question does not really arise. Anyway let me get this clear for you.

A gamete is a cell consisting half the number of chromosomes than a normal cell.

Chromosomes are thread-like structures which contain the genes and is found in the nucleus of a cell. A normal human cell consist of 46 chromosomes, while a gamete has only 23 chromosomes.

Don't get too much engrossed in that.......you'll learn it if you take biology for AS in the following years  

[iluvme]

I AM doing Bio for AS. Which'll be next May InshaAllah.

Well, what confused me was when drawing crosses, we do this right,
    Gametes- X X and X Y
Which means women have XX but when asked about the chromosome in an ovum there's only an X. 
I still don't get it.

[Deadly_king]

I AM doing Bio for AS. Which'll be next May InshaAllah.

Well, what confused me was when drawing crosses, we do this right,
    Gametes- X X and X Y
Which means women have XX but when asked about the chromosome in an ovum there's only an X.  
I still don't get it.

Ameen

Gametes : 1.X   2.X   3.X    4.Y

This means from a woman's normal cell, 2 gametes each having one X chromosome can be formed while a man can provide two gametes, one having an X chromosome while the other contains a Y chromosome.

[iluvme]

Thank you Deadly King. 
+ rep.

[Deadly_king]

Thank you Deadly King. 
+ rep.

hey that's alright. I just hope you understood

Seems you returned me my +rep

[iluvme]

Lol, yeah maybe.

Though apparently I gotta spread it after 2 hours.

[iluvme]

Please explain, the four types of immunity

Active artificial immunity,
Active natural immunity,
Passive artificial immunity,
Passive natural immunity.

Or is there more? These were the four mentioned in the past papers.