Seth and Zack are twin brothers; Seth is tall with blue eyes and brown hair and Zack is short with brown eyes and red hair. How were they most likely conceived?
a. One sperm fertilized one egg, which then split into two, early on in development.
b. Two sperm fertilized one egg, which split into two, early on in development.
c. One sperm fertilized two separate eggs.
d. Two sperm fertilized two separate eggs.
Question 2
What is a typical change that occurs in the circulatory system during pregnancy?
a. A woman's blood volume decreases up to 50.
b. A woman's blood volume increases up to 50.
c. The speed of blood flow decreases up to 50.
d. The speed of blood flow increases up to 50.
The hair cycle
the blue of the deeper reef.
A Tibetan wolf killed in 1938. Note the proportionately short legs
A white squirrel. Note the non-pink eyes.
Twin buildings