Some couples practice natural family planning (also known as the rhythm method of birth control), which involves abstaining from sexual intercourse during the time that a woman can become pregnant in her menstrual cycle. The egg only survives in the Fallopian tube for 24 hours after ovulation, so conception can only happen during a 24-hour period each month. However, this form of contraception is very unreliable and is not recommended for couples who are actively trying to avoid pregnancy.  

 

Which of the following is NOT a reason why this form of birth control is unreliable?

Select one:

Women always ovulate on the same day of their menstrual cycle every month.

Sperm can survive in the Fallopian tubes for 3 to 5 days.

It is difficult to predict exactly when in her cycle a woman ovulates.

 Ovulation can be affected by stress or illness.

 

 

A gastrulation does NOT

Select one:

consist of endoderm, mesoderm, and ectoderm

include the differentiation of cells into tissues and organs

involve the formation of germ layers

result in the formation of a third layer in the embryonic disk