Sex determination: A boy or a girl

Introduction:

A sex determination system is a biological system that determines the development of sexual characters in an organism.The world of determining the sex of upcoming babies are unbelievable.Lets have a look on some of the ways to determine the sex of  some dynamic creatures.

Sex determination in humans:

In humans the sex of a baby is determined by two sets of chromosomes i.e X and Y.Female parent contains only X chromosome to give to the child while the male parent have both X and Y chromosome.

If the X chromosome containing sperm fertilises the egg ,then the upcoming child will be a girl and if Y chromosome containing sperm fertilises the egg,then the upcoming child will be a baby boy.

Sex determination in birds:

Birds and some reptiles have also a chromosomal sex determination system but with a different set of chromosomes which are W and Z.In case of birds,the world is different,here females dominate the world and decides the sex of their upcoming babies.

 Here the male parent will always contribute the Z chromosome and the female can give both W or Z chromosome.If Z chromosome comes from the mother than the offspring will be male and if W chromosome comes from the mother then the offspring will be female.

Sex determination in ants:

In this case ,the world is totally different & the sex determination does not depend upon the chromosomes.

Here the female ants lay eggs and if the eggs get fertilised by a male then there is 100% chance of that the fertilised egg will become a female ant but if the egg doesn't get fertilised then still it will grow and become a male ant ,which is known as haplodiploid system & are also seen in bees and wasp. 

Sex determination through temperature (TSD):

Sex determination in crocodiles,tortoise and some other animal is unbelievable because here sex of the upcomimg baby is determined by the temperature of the egg during a critical period of embryonic development.

Here ,generally males are grown in lower temperature and females are grown in hotter temperature that's why perhaps we call it hot chicks and cool dudes . But in some species males are born in between a particular temperature but females are born above or below the critical temperature.

A bonus for you:

You will be surprised to know that in case of lizards (except some species) ,there are only females. Here sex determination is not even a question.

In this case there are only females,the egg hatches ,they grow ,they cross over their own chromosomes to produce eggs.

Amazing fact right! The nature never hesitate to amaze us.