Question 1

Which of the following is NOT a key property of a good model organism for genetic studies?

Accepted Answer

Complex and expensive husbandry requirements

Question 2

Why is zebrafish (Danio rerio) considered a valuable model organism for vertebrate genetics?

Accepted Answer

Fertilization and development occur externally, making observation and manipulation easier

Question 3

In a forward genetic screen, what is the primary goal?

Accepted Answer

To randomly mutagenize the genome and identify mutants affecting a process of interest

Question 4

Which of the following best describes the difference between forward and reverse genetics?

Accepted Answer

Forward genetics is an unbiased approach to identify genes involved in a process, while reverse genetics targets a specific gene for analysis

Question 5

A researcher uses a chemical mutagen to induce random mutations in mice, then screens for defects in embryonic development. What type of genetic approach is this?

Accepted Answer

Forward genetics

Question 6

Why are outcrosses performed after mutagenesis in a forward genetic screen?

Accepted Answer

To solidify individual mutations in the germline and dilute the number of mutations per genome

Question 7

Which of the following equations best represents the probability of observing a recombinant individual in a mapping cross, given a recombination frequency $$r$$?

Accepted Answer

$$P = r$$

Question 8

What is a major challenge when using whole-genome sequencing to identify a causative mutation in a mutant organism?

Accepted Answer

Distinguishing the causative mutation from background genetic variation (the 'needle in the haystack' problem)

Question 9

Which of the following is an example of a non-model organism that has become more accessible for genetic studies due to CRISPR/Cas9 and next-generation sequencing?

Accepted Answer

Planaria

Question 10

A geneticist is interested in identifying suppressor mutations that restore a wild-type phenotype in a mutant background. Which type of genetic screen is most appropriate?

Accepted Answer

Suppressor screen

Question 11

Which of the following statements about yeast (Saccharomyces cerevisiae) as a model organism is TRUE?

Accepted Answer

Yeast is very small, cheap to maintain, and has a short generation time

Question 12

Which of the following is a reason why mice (Mus musculus) are considered a good model for studying human disease?

Accepted Answer

They are genetically and anatomically closer to humans than zebrafish or flies

Question 13

In a recessive genetic screen, why is it important to produce multiple heterozygote carriers after mutagenesis?

Accepted Answer

To allow for the identification of recessive mutations in subsequent generations

Question 14

Which of the following best explains the use of polymorphic markers in mapping mutations?

Accepted Answer

They allow researchers to track recombination events and narrow down the location of a mutation

Question 15

A researcher is using Arabidopsis thaliana to study plant abscission. Which property of this model organism is most advantageous for genetic screens?

Accepted Answer

It is genetically tractable and can be bred in large numbers

Question 16

Which of the following is a plausible reason for choosing a non-model organism for genetic studies?

Accepted Answer

It possesses unique biological properties not found in model organisms

Question 17

In a forward genetic screen, which of the following best describes the process of mutagenesis?

Accepted Answer

Random introduction of mutations throughout the genome

Question 18

Which of the following is a limitation of using mice as a model organism compared to zebrafish?

Accepted Answer

Mice have lower fecundity and are more expensive to maintain

Question 19

A geneticist is interested in identifying genes that enhance a mutant phenotype. Which type of screen should they perform?

Accepted Answer

Enhancer screen

Question 20

Which of the following best describes the concept of 'requirement' in genetic analysis?

Accepted Answer

A gene is required if its loss leads to a loss of the process or phenotype of interest

Model Organisms and Forward Genetics: Oct 1

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