There is no such thing as "biological women" in science. Sex and gender are separated.
Yes there is.
Biological and sociological classifications for gender are different things.
That's why we have the cis/trans terms.
Biology is not a made-up thing.
What is to be questioned are philosophical implications of "what defines a man and a woman".
Is it the reproductive organs? Their "roles" in society? Etc. Those are the things that are questioned.
Saying things like "a man can give birth" is not per se, right or wrong nowadays. BUt it is an INCOMPLETE statement, because you forget to mention that said man is a trans man, not a cis one.
And, btw, I don't care about "god's plan", or "reproductive instincts" arguments. They hold no weight in reality when:
1- not everyone follows your religion
2- the human being actively acts against its own long goal interests all the time
Having said that, while I personally don't agree with the idea of "transgender", I don't mind learning to respect basic human interactions. If you can learn someone's name, or nickname, you can learn to call someone a she/he.
And it's not like it's very hard.
Cis and Trans women are women.
Cis and trans men are men.
Really fucking easy.