Question

pedigree worksheet
name

1. which members of the family above are afflicted with huntington’s disease?
2. there are no carriers for huntington’s disease- you either have it or you don’t.

with this in mind, is huntington’s disease caused by a dominant or recessive trait?

1. how many children did individuals i-1 and i-2 have?
2. how many girls did ii-1 and ii-2 have? how many have huntington’s disease?
3. how are individuals iii-2 and ii-4 related? i-2 and iii-5?

Explanation:

1. Identify filled symbols per the key.
2. Dominant traits appear in every generation, no carriers (only present/absent).
3. Count direct offspring of I-1 and I-2 (row II, 3-8).
4. Count female offspring of II-1 and II-2, then count affected ones.
5. Trace family lines: III-2's parent is II-2, sibling of II-4; I-2 is the grandparent of II-4, great-grandparent of III-5.

Answer:

1. I-1, II-2, II-3, II-7, III-3
2. Dominant trait
3. 5
4. 2; 1
5. Cousins; Great-grandparent and great-grandchild