During sex, sperm cells travel through the vagina to the uterus and fallopian tubes. In the fallopian tube, the sperm meets the egg that was released from the ovary during ovulation.
The sewing needle should float in the water if placed on a horizontal angle if I remember properly.
I hope this helps in some way.
Gradually as the result of many intermediate steps is my answer because as life on Earth for example started off with simple atoms making molecules, and as the time went past more complex compounds were be produced. And from there later on unicellular organisms started appearing. Nothing in evolution that I know of happens in a short time, at least from the human perspective.
<span>5' to 3' polymerase activity to replace the excised bases
5' to 3' exonuclease activity to remove the mismatched bases</span>
