question_answer 19)

  If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is (a) autosomal dominant                                               (b) autosomal recessive (c) sex-linked dominant                                                (d) sex-linked recessive

Answer:

                  (d) Most sex-linked (X-linked) conditions are recessive. This means that in a person with two X-chromosomes (females), both copies of a gene I.e., one on each X-chromosome),must have a change or mutation whereas in a person with one X-chromosomes(males), only one copy of a gene must have a mutation. A female with a mutation in one copy of a gene on the X-chromosome is said to be a 'carrier' for an X-linked condition.   For X-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the X-chromosome can transmit either the X-chromosome with this mutation or a normal X-chromosome to her children. Autosomal dominant inheritance refers to the pattern of inheritance of a condition directly or indirectly due to a dominant faulty gene located on auto some. Autosomal recessive inheritance is the condition caused directly or indirectly due to are cessive faulty gene copy on auto some, Sex-linked dominant is a rare trait that is caused by a single abnormal gene on the X-chromosome.