Question 1

Which of the following best describes the outcome of a complementation test between two pure-breeding mutants with the same phenotype, where the offspring display the wild-type phenotype?

Accepted Answer

The mutations are in different genes, and complementation has occurred.

Question 2

A female calico cat displays patches of black and orange fur. Which genetic mechanism is responsible for this mosaic pattern?

Accepted Answer

Random X chromosome inactivation during early embryonic development

Question 3

Which of the following statements about Barr bodies is correct?

Accepted Answer

A Barr body is an inactivated X chromosome found in the nuclei of female mammals.

Question 4

In a mouse, the Igf-2 gene is subject to genomic imprinting. If a mouse inherits a mutant Igf-2 allele from its father and a normal allele from its mother, what will be the phenotype of the offspring?

Accepted Answer

Dwarf, because only the paternal allele is expressed and it is mutant

Question 5

Which of the following best explains why mitochondrial diseases are inherited only from the mother in humans?

Accepted Answer

Mitochondria are transmitted through the cytoplasm of the egg, not the sperm.

Question 6

A plant with variegated leaves (green and white sectors) is crossed as the female parent with a green-leafed male. All offspring have variegated leaves. What is the most likely explanation?

Accepted Answer

Maternal inheritance of chloroplasts determines leaf color.

Question 7

Which of the following is a key feature of genomic imprinting?

Accepted Answer

Only one allele of a gene is expressed, depending on its parental origin.

Question 8

Which equation correctly represents the number of Barr bodies in a human cell with $$n X $$chromosomes?

Accepted Answer

$$n - 1$$

Question 9

A woman with a mitochondrial disease has children with a healthy man. What is the probability that her children will inherit the disease?

Accepted Answer

100%, because all mitochondria are inherited from the mother

Question 10

Which of the following best describes the endosymbiosis theory for the origin of mitochondria and chloroplasts?

Accepted Answer

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

Question 11

A geneticist performs a complementation test between two mutants and observes that the offspring all display the mutant phenotype. What conclusion can be drawn?

Accepted Answer

The mutations are in the same gene.

Question 12

Which of the following is NOT a mechanism of dosage compensation?

Accepted Answer

Genomic imprinting of autosomal genes

Question 13

Which of the following human diseases is associated with a deletion on chromosome 15 and depends on whether the deletion is inherited from the mother or the father?

Accepted Answer

Prader-Willi syndrome and Angelman syndrome

Question 14

Which of the following statements about maternal effect and maternal inheritance is correct?

Accepted Answer

Maternal effect refers to the influence of the mother's genotype on the offspring's phenotype, while maternal inheritance refers to the transmission of organellar genes from the mother.

Question 15

Which of the following is a common feature of mitochondrial and chloroplast genomes?

Accepted Answer

They are typically circular and double-stranded.

Question 16

A woman is heteroplasmic for a mitochondrial mutation. Which of the following best describes the expected outcome in her children?

Accepted Answer

Some children may be affected and others unaffected, depending on the proportion of mutant mitochondria inherited.

Question 17

Which of the following best explains why the majority of genes originally present in the mitochondrial and chloroplast genomes are now found in the nuclear genome?

Accepted Answer

Gene transfer from organelles to the nucleus occurred during evolution.

Question 18

Which of the following is a likely consequence of a mutation in a mitochondrial tRNA gene?

Accepted Answer

Impaired oxidative phosphorylation and reduced ATP production

Question 19

Which of the following best describes the inheritance pattern of a gene subject to maternal effect?

Accepted Answer

The phenotype of the offspring is determined by the genotype of the mother, regardless of the offspring's own genotype.

Non-Mendelian Inheritance, Complementation, and Organelle Genetics

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