Use of se in a sentence

Question

Is it wrong to not include the se in this sentence?

What are the meanings of the sentence with and without the se?

Also, why does it use hasta? Because I thought it means until

it expands UNTIL 100,000 times then stops?

Shouldn't it be se expande mas de 100.000 veces

"Y durante la germinación, la población de microbios se expande hasta 100.000 veces".

Thanks!

Answer 1

I suppose it would be ... It expands upto 100,000 times, not until.

using Se is perfect, you can't leave it out. Hasta can be upto or until

Answer 2

The 'se' is used because it comes from the pronomial verb 'expandirse'.