11. An individual who is heterozygous for rob(13;14) is at increased risk for having a child affected by Patau syndrome. Please briefly explain why.

because of Chromosome-13 rearranges with with other chromosome.

Explanation:

To understand and be and be able to solve or tackle this question effectively, there is need to know the meaning of the important terms in this question/problem.

- Robertsonian translocation: The term "Robertsonian translocation" simply refer to some kind of disorder in the chromosome in which a different kind of chromosome attach itself to another kind of chromosome, that is to say we have more than two fusion of chromosome that are different on chromosome 13, 14,15,21 and 22.

- Patau syndrome: The syndrome known as " Patau syndrome" is also refer to as Trisomy 13. The syndrome is a kind of abnormalities on the 13th chromosome known as chromosome 13. Patau syndrome patient will have more than two[usually three] kinds of chromosome.  

"An individual who is heterozygous for rob(13;14) is at increased risk for having a child affected by Patau syndrome. " is TRUE

A defect in  chromosome 13, that is to say the Robertsonian translocation on the 13th chromosome is what causes Patau syndrome. The Robertsonian translocation occurs by addition and subtraction of chromosomes, when there is addition on chromosome 13 or say the rearrangement of chromosome-13  with other chromosome, then, the individual's offspring has the tendency of developing Patau Syndrome.