Question 1

Which of the following best describes the original concept of a 'gene' as proposed by Wilhelm Johannsen in the early 20th century?

Accepted Answer

An abstract unit of inheritance with no assigned material attributes.

Question 2

During the classical period of genetics, what experimental evidence most strongly supported the chromosome theory of inheritance?

Accepted Answer

The observation that non-disjunction of chromosomes was associated with exceptional inheritance patterns in Drosophila.

Question 3

Which phenomenon first challenged Mendel’s law of independent assortment and led to the concept of genetic linkage?

Accepted Answer

The observation of 'coupling' in sweet pea plants

Question 4

What is the main implication of the chiasmatype theory for our understanding of genetic recombination?

Accepted Answer

Chiasmata result from the breakage and reunion of chromatids, explaining the physical basis of crossing over.

Question 5

Which of the following statements about the neoclassical period of genetics is CORRECT?

Accepted Answer

Genes were shown to have internal structure and could be dissected by recombination.

Question 6

The 'one gene—one mRNA—one polypeptide' hypothesis was undermined by which of the following discoveries?

Accepted Answer

The existence of alternative splicing and multiple promoters.

Question 7

Which process allows a single gene to produce multiple different mRNA transcripts?

Accepted Answer

Alternative splicing

Question 8

What is the significance of the phenomenon known as 'gene sharing' or 'protein moonlighting'?

Accepted Answer

It demonstrates that identical polypeptides can perform different functions in different cellular contexts.

Question 9

Which of the following best describes the impact of genome sequencing projects on the definition of a gene?

Accepted Answer

They revealed overlapping transcripts and blurred the boundaries of genes.

Question 10

Transgenerational epigenetic inheritance challenges the classical gene concept because:

Accepted Answer

It shows that inheritance can occur without changes in DNA sequence.

Question 11

Which of the following is TRUE regarding noncoding RNA genes?

Accepted Answer

They produce functional RNA molecules that are not translated into proteins.

Question 12

According to the modern perspective, why is the concept of the gene as an autonomous agent problematic?

Accepted Answer

Genes function within complex genetic regulatory networks and rarely act independently.

Question 13

Which experimental approach is illustrated by the cis-trans test diagram provided?

Accepted Answer

Determining whether two mutations affect the same functional unit (cistron) or different ones.

Question 14

In the cis-trans test, if two mutations (a and b) are in the same cistron, what is the expected phenotype of the trans-heterozygote?

Accepted Answer

Mutant

Question 15

Which of the following equations best represents the colinearity hypothesis between gene and protein structure?

Accepted Answer

$$	ext{Gene sequence} \longleftrightarrow 	ext{Amino acid sequence}$$

Question 16

Which of the following is a direct consequence of the existence of genetic regulatory networks (GRNs)?

Accepted Answer

Gene function often depends on interactions with other genes and regulatory elements.

Question 17

Which of the following best summarizes the authors’ proposed modern definition of a gene?

Accepted Answer

A gene is a DNA sequence that specifies one or more sequence-related RNAs/proteins, evoked and mediated by GRNs.

Question 18

Which real-world example illustrates the effect of genetic background on gene expression?

Accepted Answer

The variable expression of a dominant gene affecting human incisor shape and size.

The Evolving Definition of the Gene: Historical and Molecular Perspectives

Study Guide - Practice Questions