BMAT Prep Question Analysis - Q9 & Q84
Q9 A new genetic disease is discovered. The associated family tree is shown, with disease phenotype in black and normal genotype in white.
What is the mode of inheritance of this disease?
a. X-linked recessive
b. Co-dominant
c. Autosomal dominant
d. X-linked dominant
e. Mitochonidrial
Q84 A magnetic field is directed perpendicular to a wire loop. If the magnetic field is increased steadily, which of the following is true?
a. An electromotive force will be created
b. A second magnetic field will be produced in a direction opposite to the increasing magnetic field
c. The current through the wire will be constant
d. All of the above
e. None of the above
Answer and Explanation
Q9 Answer: e. Mitochondrial
Explanation: This disease is transmitted only through mothers, so this is a mitochondrial inheritance disease. Nuclear DNA has two copies: one from the mother and one from the father. However, mitochondrial DNA is only inherited from the mother. It is not X-linked dominant because daughters of affected males aren't affected. It is not X-linked recessive because daughters of a normal father and affected mother are affected. It is not autosomal dominant because all the children of affected females are affected, and none of the children of affected males are affected. An example of mitochondrial disease is Leber's hereditary optic neuropathy.
Q84 Answer: d. All of the above
Explanation: As the magnetic field increases, a current is generated in the wire loop. The magnitude of this current will be directly proportional to the rate of increase of the magnetic field. Since the current is increased steadily (i.e. at a constant rate), the current through the wire will be constant. Since a current is induced, a second magnetic field is generated in a direction consistent with the right-hand rule for the direction of current flow. This new magnetic field will be in the opposite direction to the increasing magnetic field.
Drafted by Quincy (BMAT Prep)