Question 1

Which of the following best describes extranuclear inheritance?

Accepted Answer

Inheritance of traits determined by genes found in organelles such as mitochondria and chloroplasts.

Question 2

A woman affected by a mitochondrial disease has children with an unaffected man. What is the expected pattern of inheritance for her children?

Accepted Answer

All children will inherit the disease, regardless of sex.

Question 3

Which of the following is NOT a reason why mitochondrial DNA (mtDNA) is more susceptible to mutations than nuclear DNA?

Accepted Answer

mtDNA is protected by histone proteins.

Question 4

In Mirabilis jalapa (the four o'clock plant), leaf variegation is determined by chloroplast DNA. If a variegated female plant is crossed with a green male plant, what is the expected phenotype of the offspring?

Accepted Answer

Offspring will show variegation, as chloroplasts are inherited maternally.

Question 5

Which equation best represents the probability $P$ that a child will inherit a mitochondrial disorder from an affected mother?

Accepted Answer

$P = 1$

Question 6

Which of the following statements about organelle heredity is TRUE?

Accepted Answer

Organelle heredity involves DNA found in mitochondria and chloroplasts, which is inherited independently of nuclear chromosomes.

Question 7

Which of the following best explains why traits determined by mitochondrial DNA do not follow Mendelian inheritance?

Accepted Answer

Mitochondrial DNA is inherited exclusively from the mother, bypassing segregation and independent assortment.

Question 8

A researcher observes that a certain trait in yeast is inherited through the cytoplasm and not the nucleus. Which type of inheritance is most likely responsible?

Accepted Answer

Extranuclear inheritance

Question 9

Which of the following organisms has the largest mitochondrial genome size according to the provided data?

Accepted Answer

Arabidopsis thaliana

Question 10

Which of the following is a real-world example of infectious heredity?

Accepted Answer

Inheritance of a phenotype affected by the presence of a microorganism in the cytoplasm of host cells.

Question 11

Which statement about chloroplast DNA (cpDNA) inheritance is correct?

Accepted Answer

cpDNA is often inherited maternally or biparentally, and controls photosynthesis-related traits.

Question 12

Which of the following is NOT a feature of non-Mendelian inheritance patterns?

Accepted Answer

Traits always segregate in Punnett square patterns.

Question 13

If a plant inherits all its chloroplasts from the egg cell, which type of inheritance is this?

Accepted Answer

Maternal inheritance

Question 14

Which of the following best explains why sperm contributes little or no mitochondria to the zygote?

Accepted Answer

Sperm mitochondria are excluded or destroyed by the egg cell after fertilization.

Question 15

A cell contains thousands of mitochondria. If a mutation occurs in the mtDNA of one mitochondrion, what is the most likely outcome for the cell?

Accepted Answer

The cell may remain functional due to the presence of many normal mitochondria.

Question 16

Which of the following is a key difference between mitochondrial and nuclear DNA?

Accepted Answer

Mitochondrial DNA is circular and found in multiple copies per cell, while nuclear DNA is linear and typically diploid.

Question 17

Which of the following equations represents the total number of mitochondrial genomes in a human cell if each mitochondrion contains $n$ copies of mtDNA and the cell contains $m$ mitochondria?

Accepted Answer

$N = m 	imes n$

Question 18

Which of the following statements about cytoplasmic inheritance is FALSE?

Accepted Answer

Cytoplasmic inheritance always follows Mendelian ratios.

Question 19

A patient presents with symptoms of a mitochondrial disorder. Which of the following would be the most likely explanation for the inheritance of this disorder?

Accepted Answer

The disorder was inherited from the mother due to mutations in mtDNA.

Question 20

Which of the following best describes the role of reactive oxygen species (ROS) in mitochondrial DNA mutation?

Accepted Answer

ROS generated by cell respiration increase the mutation rate in mtDNA.

Extranuclear Inheritance: Mitochondrial and Chloroplast Genetics

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