During the first week of pregnancy, the most relevant event is that a zygote is formed during conception, which typically occurs shortly after an egg is released from the ovary and is fertilized by sperm. Additionally, a woman may not realize she is pregnant during this early stage, as it is too soon for typical pregnancy symptoms or a missed period to be noticeable.
However, if considering the typical menstrual cycle, fertilization occurs shortly after ovulation, which generally happens around the middle of the cycle. If conception happens, it may take a bit longer for a woman to realize she's pregnant.
So the correct responses would be:
- A zygote is formed during conception.
- A woman may realize she is pregnant (though this is less common during the very first week).
It’s important to note that a woman’s menstrual cycle is taking place until conception happens. Therefore, if the question pertains to actions before conception, then the menstrual cycle response would be appropriate. Please clarify if you're looking for specific details about one stage or another!