Question 1

In Sia and Dawson's 1931 experiment:

Accepted Answer

Sia and Dawson's experiment demonstrated that the transformation of bacteria could occur in vitro, without the need for a living host like mice, thus showing that mice play no direct role in the transforming principle.

Question 2

Which large organic molecules are essential chromosome components?

Accepted Answer

Chromosomes are composed of proteins and nucleic acids. The nucleic acids in chromosomes are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), and the proteins are primarily histones and non-histones. These large organic molecules play critical roles in the structure, organization, and function of chromosomes. Lipids and polysaccharides are not major components of chromosomes.

Question 3

Why were some geneticists reluctant to accept the idea of nucleic acids as genetic material even after the discovery of the structure of DNA in 1953?

Accepted Answer

Before the acceptance of DNA as the genetic material, many scientists believed proteins, with their greater complexity and variability, were more likely to carry the vast amount of genetic information necessary for life. Nucleic acids were thought to be too simple in structure to perform such a complex function.

Question 4

After Griffiths 1928 experiments leading to the discovery of the Transforming Principle,subsequent experimentation demonstrated that:

Accepted Answer

Subsequent experimentation demonstrated that DNAse treatment eliminates all transforming activity, supporting the idea that the transforming principle was DNA.

Question 5

Hershey and Chase used radiolabeled T2 phages to identify which component of the phage entered E.coli during infection.Which of the following matches the radiolabel with the appropriate phage component?

Accepted Answer

Hershey and Chase used radioactive phosphorus (³²P) to label the DNA of T2 phages because DNA contains phosphorus but no sulfur. This allowed them to track the DNA into the E. coli cells, demonstrating that DNA is the genetic material that is injected into the host cell during infection.

Question 6

RNA was first identified as the genetic material of the tobacco mosaic virus (TMV)through an experiment in which:

Accepted Answer

The experiment that identified RNA as the genetic material of the tobacco mosaic virus (TMV) involved exchanging the protein coats and RNA from two distinctive TMV strains. This demonstrated that the RNA, not the protein coat, determined the characteristics of the resulting virus, thus identifying RNA as the genetic material in TMV.

Question 7

Which of the following are essential functions that the genetic material must perform?

Accepted Answer

The essential functions of genetic material include replication (to ensure genetic continuity across generations), mutation (to introduce genetic variability), and gene expression (to produce the proteins necessary for life).

Question 8

How does mutation allow an organism to evolve? 1.Changes in the genetic material allow organisms to adapt to modifications in the environment
2)Changes in the genetic material allow organisms to survive in limited types of environment
3)Mutations do not allow an organism to evolve

Accepted Answer

Mutations introduce genetic variability, which can lead to adaptations that allow organisms to better survive and reproduce in changing environments, thus contributing to evolution.

Question 9

Which of the following materials was used by Avery,McLeod,and McCarty in their experimentation to identify the transforming agent?

Accepted Answer

Avery, McLeod, and McCarty used DNAse, RNAse, and Protease in their experiments to determine that DNA was the transforming agent. These enzymes were used to selectively degrade DNA, RNA, and proteins, respectively, to see which component was essential for transformation.

Question 10

Which of the following is a genotypic function that the genetic material must be able to perform?

Accepted Answer

Replication is the process by which the genetic material makes a copy of itself. This is essential for the transmission of genetic information from one generation to the next.

Question 11

Infectious agents that contain small circular pieces of RNA that are not packaged in a protein coat are known as:

Accepted Answer

Viroids are small infectious agents that contain a short single-stranded RNA molecule without a protein coat. They are smaller than viruses and can cause disease in some plants. Prions (A) are infectious proteins that can cause neurological diseases in animals, but they do not contain RNA. Viruses (B) are infectious agents that have small pieces of RNA or DNA packaged in a protein coat. Bacteria (C) are microorganisms that have a cell wall, cytoplasm, and genetic material, but they do not contain RNA alone. Protists (E) are a diverse group of eukaryotic organisms, and not all of them are infectious agents.

Question 12

Which of the following is a phenotypic function that genetic material must be able to perform?

Accepted Answer

Gene expression is the phenotypic function that genetic material must be able to perform as it is responsible for the production of proteins that determine observable traits. Replication, mutation, adaptation, and translation are all processes involved in the function of genetic material, but not necessarily for its phenotypic expression.

Question 13

Infectious agents that contain only altered forms of protein and no nucleic acid are known as:

Accepted Answer

Prions are infectious agents that only contain abnormal forms of a protein called prion protein (PrP). They do not contain any nucleic acid, such as DNA or RNA.

Question 14

The genetic information in most organisms,excluding viruses,viroids,and prions,is encoded in what molecule?

Accepted Answer

The genetic information in most organisms is encoded in DNA. RNA is involved in the transcription and translation of the genetic information, but the actual genetic code is stored in DNA. Protein, lactose, and lactase are not the molecules that store genetic information.

Question 15

The pathogenic effects of viroids are thought to result from:

Accepted Answer

Viroids are small RNA molecules that infect plants and are responsible for causing many plant diseases. They do not have the ability to directly mutate DNA or stop gene expression. However, they can alter normal patterns of gene expression in the host plant, resulting in a variety of pathogenic effects.

Question 16

The work carried out by Hershey and Chase had one flaw: a high degree of ³?S was found inside the cells.This flaw was later addressed by:

Accepted Answer

Protease treatment was later used to remove any phage protein that may have remained inside the bacterial cells, therefore correcting the flaw of a high degree of ³?S found inside the cells during Hershey and Chase's experiment.

Question 17

Before direct proof of DNA being the genetic material,indirect evidence suggesting DNA as the appropriate macromolecule,included

Accepted Answer

All of the given options suggest indirect evidence for DNA as the genetic material. Gametes having half the amount of DNA indicates that it is involved in inheritance. The molecular composition of DNA being the same in different cells implies its important role in cellular processes. The correlation between DNA content and the number of chromosome sets per cell suggests a connection between DNA and genetic material. Finally, DNA's stability hints at its essential role in genetic material.

Question 18

Which of the following is a type of nucleic acid?

Accepted Answer

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are both nucleic acids, essential for genetic information storage and transfer in living organisms. DNAse and RNAse are enzymes that degrade DNA and RNA, respectively, not types of nucleic acids.

Question 19

The first direct evidence indicating that DNA,rather than RNA or protein,is the genetic material in bacteriophages was performed by:

Accepted Answer

Hershey and Chase provided the first direct evidence that DNA was the genetic material in bacteriophages in 1952 through their experiments with radioactively labeled viruses infecting bacteria. They found that when the bacteriophage transferred its genetic material into the host cell, it was the DNA - not the protein coat - that was passed on to the next generation of viruses.

Question 20

The first direct evidence indicating that DNA,rather than RNA or protein,is the genetic material in bacteria was gathered by:

Accepted Answer

Avery, McLeod, and McCarty conducted experiments in 1944 that provided the first direct evidence indicating that DNA, rather than RNA or protein, is the genetic material in bacteria. They showed that when DNA was extracted from a virulent strain of bacteria and added to a non-virulent strain, the non-virulent strain became virulent. When RNA or protein was extracted and added, the non-virulent strain did not become virulent.

Quiz 9: DNA And The Molecular Structure Of Chromosomes