Question 1

Which of the following best describes organelle heredity?

Accepted Answer

Transmission of genetic information through the cytoplasm, usually from one parent, involving DNA in mitochondria or chloroplasts.

Question 2

A cross is performed between a white-leafed branch and a green-leafed branch of Mirabilis jalapa. The ovule comes from the green branch. What will be the phenotype of the offspring?

Accepted Answer

All offspring will have green leaves.

Question 3

Which experimental result provided the first evidence for cytoplasmic inheritance in Chlamydomonas?

Accepted Answer

Streptomycin resistance was inherited through the parent contributing the cytoplasm, not the nucleus.

Question 4

In Saccharomyces cerevisiae, which type of petite mutation is characterized by the loss of mitochondrial DNA and is inherited cytoplasmically?

Accepted Answer

Neutral petite

Question 5

According to the endosymbiotic theory, which of the following statements is correct?

Accepted Answer

Mitochondria and chloroplasts originated from free-living bacteria engulfed by ancestral eukaryotic cells.

Question 6

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 histones.

Question 7

A woman with a mitochondrial disorder has children with a healthy man. What is the expected outcome for their children?

Accepted Answer

All children will inherit the mitochondrial disorder.

Question 8

Which of the following human diseases is associated with mutations in mitochondrial DNA?

Accepted Answer

Leber’s hereditary optic neuropathy (LHON)

Question 9

What is heteroplasmy?

Accepted Answer

The presence of a mixture of normal and mutated organelles within a cell.

Question 10

Which of the following criteria must be met for a human disease to be attributed to a mitochondrial DNA mutation?

Accepted Answer

Maternal inheritance, deficiency in organelle bioenergetic function, and mutation in a mitochondrial gene.

Question 11

In the snail Lymnaea peregra, the direction of shell coiling in the offspring is determined by:

Accepted Answer

The genotype of the mother, regardless of her phenotype.

Question 12

Which of the following best explains the maternal effect in Drosophila embryonic development?

Accepted Answer

Maternal gene products deposited in the egg establish molecular gradients that organize the embryo.

Question 13

Which of the following equations correctly represents the proportion of mutant mitochondria in a heteroplasmic cell if there are $$n$$ total mitochondria and $$m of $$them are mutant?

Accepted Answer

$$\frac{m}{n}$$

Question 14

Which of the following statements about mitochondrial gene products is correct?

Accepted Answer

Most proteins required for mitochondrial function are encoded by nuclear genes.

Question 15

A cross between a haploid petite and a haploid wild-type yeast results in all petite progeny. Which type of mutation is most likely responsible?

Accepted Answer

Suppressive petite

Question 16

Which of the following is a real-world application of mitochondrial replacement therapy (MRT)?

Accepted Answer

Preventing the transmission of mitochondrial DNA mutations from mother to child.

Question 17

Which of the following best describes the inheritance pattern of infectious heredity?

Accepted Answer

Phenotype is affected by a microorganism present in the host’s cytoplasm and inherited by offspring.

Question 18

Which ribosomal RNA genes are encoded by chloroplast DNA?

Accepted Answer

16S and 23S rRNA

Question 19

Which of the following is a consequence of the lack of histones in mitochondrial DNA?

Accepted Answer

Increased susceptibility to mutations due to lack of structural protection.

Extranuclear Inheritance: Organelle Genetics and Maternal Effects

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