Blood type is a genetically determined trait. Two siblings donate blood and find out their blood types. The brother is Type A and the sister is Type B. Which of the following best explains why the siblings have different blood types?
A. The brother has a different number of blood type genes than his sister.
B. The brother's blood type gene is on a different chromosome than his sister's.
c. The brother has different alleles for the blood type gene than his sister does. D. The brother has a different number of chromosomes than his sisted does

C

Explanation:

The brother has different alleles for the blood type gene than his sister does.  Blood type is inherited from parents like many other traits that can be displayed on a punnet square.  Depending on what the parents blood type alleles were, the brother and sister could have different blood types.  

A different number of chromosomes doesn't lead to different blood types, so D is wrong.  And A is incorrect because the number genes also does not affect blood type.  And I think the blood type genes are on the same chromosome, so B is wrong.  C is correct because blood type is inherited by alleles, and different alleles can cause different traits, such as blood types.  

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion