The smallest parts of these that retain their original properties are called

element , atom

Explanation:

An atom is the smallest part of all the elements found on this planet. An atom is the basic unit just like a cell is the basic unit of life. As a cell has all the original properties of life , an atom also has all the original properties of element.

For example - A single atom of iron will show magnetic properties just like an an iron rod.

Like wise all all chemical properties of an atom are exactly similar to its element.

the answer would be 2, if crossing over doesn’t occur 2 out of 4 of the daughter cells will have that allele.

hope this : )