Question 1

Which of the following best describes the 'genetic approach' to studying a biological process?

Accepted Answer

Identifying mutants with defective phenotypes and characterizing their genetic basis.

Question 2

In Beadle and Tatum's experiment with Neurospora, what was the primary purpose of exposing haploid spores to mutagens?

Accepted Answer

To introduce random mutations that could inactivate genes required for vitamin or amino acid synthesis.

Question 3

Which class of E. coli mutants expresses the lac operon genes constitutively, regardless of the presence of lactose?

Accepted Answer

lacC mutants

Question 4

What is the main purpose of a complementation test in genetic analysis?

Accepted Answer

To determine if two mutations are in the same gene.

Question 5

Why is Saccharomyces cerevisiae considered a valuable model organism for studying the eukaryotic cell cycle?

Accepted Answer

It is a single-celled eukaryote with basic cellular processes conserved in all eukaryotes.

Question 6

Hartwell et al. used temperature-sensitive mutants in yeast to study the cell cycle. What is the significance of a mutant that grows at 23°C but not at 36°C?

Accepted Answer

The mutation disrupts a gene required for cell cycle progression at restrictive temperature.

Question 7

The cdc genes identified in yeast are said to be 'conserved' in all eukaryotes. What does this mean?

Accepted Answer

They have homologous genes in other eukaryotes that perform similar functions.

Question 8

In the ABC model of flower development in Arabidopsis thaliana, which combination of gene expression specifies the identity of petals?

Accepted Answer

Class A and Class B genes

Question 9

If a mutant Arabidopsis flower lacks both petals and stamens, which class of genes is most likely mutated?

Accepted Answer

Class B genes

Question 10

Which equation best represents the combinatorial control of organ identity in the ABC model of flower development?

Accepted Answer

$$A + B = 	ext{petal}$$

Question 11

A double mutant in Arabidopsis thaliana affecting both class A and class C genes results in which of the following outcomes?

Accepted Answer

Neither sepals nor carpels are formed; whorls may develop as intermediate organs.

Question 12

Which of the following is a real-world application of the model system approach in genetics?

Accepted Answer

Studying cell cycle genes in yeast to understand cancer mechanisms in humans.

Question 13

Which step is NOT part of the genetic approach to studying a biological process?

Accepted Answer

Measuring protein concentration in wild-type cells only.

Question 14

In yeast, which cdc gene is associated with arrest in the G1 phase due to spindle pole body duplication failure?

Accepted Answer

cdc7

Question 15

Which of the following best explains why Arabidopsis thaliana is used as a model organism in plant genetics?

Accepted Answer

It is a small annual plant with a short life cycle and is easy to manipulate genetically.

Question 16

A yeast cell with a mutation in cdc15 fails to complete which stage of the cell cycle?

Accepted Answer

Nuclear division (mitosis)

Question 17

Which of the following statements about homologous genes is correct?

Accepted Answer

Homologous genes are present in two species because of descent from a common ancestor.

Question 18

Which of the following is a plausible outcome of mutagenesis followed by a mutant screen in a model organism?

Accepted Answer

Identification of genes required for a specific biological process.

Question 19

In the yeast cell cycle, what is the DNA content of a cell immediately after mitosis?

Accepted Answer

$$1N$$

Genetic Analysis of Biological Processes: Cell Cycle Regulation and Flower Development

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