Question

Biology 12th Standard Question 3rd Chapter...
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Answer 1

Answer:

a) autosomal dominant

b) Huntington's disease

Explanation:

a) There is no skip of generation present in pedigree . Skip of generation means in all the three generation there is no individual in family that is not suffering from disease. All black coloured boxes and circles are affected individuals.

• Black coloured box represents affected male
• Black coloured circles represents affected female
• circle with dot represents carrier female
• therefore, there is no skip of generation so the trait is definitely dominant

Now assuming it to be a sex linked disorder we can see that in second generation the father is normal and mother is affected therefore the daughter must have one affected X chromosome inherited from mother and she should be carrier for the disease but she is not carrier so the trait is

definitely autosomal.

b) in Huntington's disease brain nerve cells break down.