Who conquered England in 1066 when the English king died without an heir but was required to defeat two Harolds to clear the way?

Cystic fibrosis is caused by a defect in a:

Cells produced by meiosis are called: 

Crossing-over occurs during which stage of meiosis?

Which was the most common occupation of the nobility during the Middle Ages?

Where is this taking place?

Which type of receptor responds to chemical substances such as taste and smell?

The SRY gene is located on the:

Independent alignment of chromosomes occurs during:

Nondisjunction is the failure of chromosomes to: