Q: The endosymbiosis theory explains the origin of mitochondria and chloroplasts. According to this theory, which equation best describes the relationship?

$$\text{Eukaryotic cell} = \text{Prokaryotic cell} + \text{Endosymbiotic bacterium}$$

Q: A mother with mild mitochondrial DNA mutations can have children with severe disease due to the 'bottleneck effect.' Which equation best represents the proportion of mutant mitochondria in offspring?

$$P_{mutant} = \frac{\text{number of mutant mitochondria in egg}}{\text{total mitochondria in egg}}$$

Question 1

Which of the following best describes organelle (maternal) heredity?

Accepted Answer

Inheritance of traits determined by DNA in mitochondria or chloroplasts, usually from the maternal parent.

Question 2

A child is diagnosed with a mitochondrial disorder affecting ATP production. Which inheritance pattern is most likely responsible?

Accepted Answer

Maternal inheritance

Question 3

In the Japanese Four o’clock plant, variegated leaves are observed. Which statement best explains the inheritance of this phenotype?

Accepted Answer

The phenotype is determined by chloroplast DNA and inherited only from the maternal parent.

Question 4

Which equation best represents the probability of a child inheriting a mitochondrial disorder if the mother is affected and the father is unaffected?

Accepted Answer

$$P = 1$$

Question 5

A reciprocal cross between Chlamydomonas strains (sr mt+ x ss mt- and ss mt+ x sr mt-) shows all offspring inherit streptomycin resistance from the maternal parent. What does this demonstrate?

Accepted Answer

Uniparental inheritance of non-chromosomal genes

Question 6

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

Accepted Answer

Rhabdovirus Sigma in Drosophila causing CO2 sensitivity

Question 7

In yeast, petite colonies can arise due to mutations in mitochondrial DNA. Which inheritance pattern is observed for suppressive petites?

Accepted Answer

Non-Mendelian inheritance where all offspring are petite

Question 8

The endosymbiosis theory explains the origin of mitochondria and chloroplasts. According to this theory, which equation best describes the relationship?

Accepted Answer

$$	ext{Eukaryotic cell} = 	ext{Prokaryotic cell} + 	ext{Endosymbiotic bacterium}$$

Question 9

Which of the following best describes maternal effects on phenotype?

Accepted Answer

Phenotype is influenced by gene products (such as mRNA) stored in the egg cytoplasm before fertilization.

Question 10

In Limnaea snails, the direction of shell coiling is determined by a maternal developmental gene. Which process does this gene control?

Accepted Answer

Orientation of the spindle in the second mitotic division of the zygote

Question 11

A mother with mild mitochondrial DNA mutations can have children with severe disease due to the 'bottleneck effect.' Which equation best represents the proportion of mutant mitochondria in offspring?

Accepted Answer

$$P_{mutant} = \frac{	ext{number of mutant mitochondria in egg}}{	ext{total mitochondria in egg}}$$

Question 12

Which statement about sperm contribution to the zygote is correct?

Accepted Answer

Sperm contributes virtually no cytoplasm to the zygote.

Question 13

Which scenario best illustrates heteroplasmy?

Accepted Answer

A cell contains more than one clonal line of mitochondrial DNA.

Question 14

Which of the following is NOT a type of extranuclear inheritance?

Accepted Answer

Autosomal dominant inheritance

Question 15

A flour moth's eye pigment is determined by maternal genotype. If a mutant female (aa) is crossed with a wild-type male (Aa), what is the expected phenotype of the offspring?

Accepted Answer

All offspring will have red eyes.

Question 16

Which of the following best explains why mitochondrial disorders often affect multiple organ systems?

Accepted Answer

Mitochondria are present in nearly all cells and are essential for ATP production.

Question 17

Which equation best represents the inheritance of chloroplast DNA in plants?

Accepted Answer

$$	ext{Offspring chloroplast DNA} = 	ext{Maternal chloroplast DNA}$$

Question 18

Which of the following is a permanent maternal effect?

Accepted Answer

Shell coiling in Limnaea snails

Question 19

Which of the following best describes the effect of bacterial endosymbionts in insects?

Accepted Answer

They are inherited through the egg cytoplasm and can affect the phenotype of the offspring.

Extranuclear Inheritance: Organelle, Infectious, and Maternal Effects

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