What comes next: 3, 7, 13, 21, 31, ?

The enzyme that unwinds the DNA double helix during replication is:

Complete series: AB, CD, EF, GH, ?

Pointing to a man, a woman said he is the son of my mother\'s only daughter. How is the man related to the woman?

Enzymes are biological catalysts made of:

Five houses in a row are painted different colors. The green house is immediately to the left of the white house. The red house is at one end. The blue house is between the yellow and red houses. The yellow house is at the other end from red. What color is the middle house?