Question 1

HIV

Accepted Answer

HIV is a retrovirus, which means that it uses RNA as its genetic material and creates a DNA copy of itself within the host cell. This is an important characteristic of HIV and distinguishes it from other types of viruses.

Question 2

Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years,and when a patient becomes stressed the virus is released,forming cold sores on the lips.Where is the virus located while dormant in the nerve cell?

Accepted Answer

Herpes simplex virus 1 is known to establish a latent infection by integrating its genome into the chromosome of sensory neurons. This allows the virus to remain dormant in the nerve cells for years and reactivate, causing cold sores or other viral infections, when the host's immune system is weakened.

Question 3

Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years,and when a patient becomes stressed the virus is released,forming cold sores on the lips.In a cold sore,the virus is in which of the following states?

Accepted Answer

In a cold sore, the herpes simplex virus is in the lytic state, where it actively replicates and causes symptoms like sores.

Question 4

Viruses can infect all higher life forms such as plants and animals,but cannot infect bacteria.

Accepted Answer

Viruses can infect bacteria, this type of virus is called bacteriophage.

Question 5

Viruses always lack which of the following?

Accepted Answer

Viruses are acellular and do not have organelles as cells do. They consist of genetic material enclosed in a protein coat and sometimes a lipid envelope, but they do not have their own ribosomes, mitochondria, or other organelles.

Question 6

Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years,and when a patient becomes stressed the virus is released,forming cold sores on the lips.Why would the virus form a cold sore?

Accepted Answer

The herpes simplex virus 1 forms cold sores in order to spread to new hosts. The virus is highly contagious when active, and cold sores are a means for the virus to infect new hosts through direct contact.

Question 7

It has been difficult to generate drugs to treat AIDS for which reason?

Accepted Answer

HIV mutates rapidly, which creates challenges for drug development. The virus can quickly evolve resistance to drugs that are initially effective, making it difficult to maintain viral suppression with a single medication. This has led to the use of combination antiretroviral therapy (ART), which consists of multiple drugs targeted at different stages of the viral life cycle, to combat the virus.

Question 8

Since viruses have no active methods of entering plant cells,they must rely upon mechanically-caused wounds,vegetative propagation of plants,grafting,seeds,pollen,and being carried on the mouth parts of chewing insects.Tobacco mosaic virus is most commonly introduced into plants through small wounds caused by handling and by insects chewing on plant parts.What would prevent viruses from easily entering plant cells?

Accepted Answer

The cell wall on the plant acts as a barrier and prevents viruses from easily entering plant cells. The other options listed do not provide a significant barrier against virus entry. The cell wall on the virus (option A) does not play a role in virus entry as viruses do not have cell walls. The plasma membrane on the plant (option B) can be penetrated by viruses, but it is not a significant barrier. The plasma membrane on the virus (option D) is not relevant to virus entry into plant cells. The protein coat on the virus (option E) is involved in virus entry, but it is not a significant barrier when compared to the cell wall on the plant.

Question 9

Most antibiotics are not effective against viruses because they _____ and this does not affect the activity of viruses.

Accepted Answer

Antibiotics typically target bacterial cell walls or protein synthesis, which are not present in viruses. Viruses infect host cells and use the host cell machinery to replicate, so targeting these processes in the virus would also harm the host cell. Some antiviral medications can target specific viral enzymes or entry mechanisms, but antibiotics are not effective against viruses.

Question 10

Viruses are not considered to be alive,yet they share this ability with living cells:

Accepted Answer

Viruses are not considered to be living because they cannot metabolize on their own, cannot reproduce on their own, and cannot produce cell membranes. However, they can evolve through mutations and natural selection, which is a characteristic shared with living cells.

Question 11

Our most potent weapon in the fight against viruses is

Accepted Answer

Vaccinations are the most potent weapon in the fight against viruses because once a person receives a vaccine, their immune system is able to recognize and attack the virus if they come into contact with it in the future. Antibiotics and sulfa drugs are ineffective against viruses, gene therapy is still in its experimental stage, and surgery is not a treatment for viral infections.

Question 12

A highly-wound circle of RNA without a protein coat is a

Accepted Answer

A viroid is a highly-wound circle of RNA that can infect plants and cause disease, but unlike a virus, it does not have a protein coat or rely on a host cell to replicate. A virion is a complete virus particle, which includes a protein coat surrounding the genetic material. Prions are infectious proteins that cause certain neurodegenerative diseases. Prophage refers to a virus that has incorporated its genetic material into the DNA of its host cell.

Question 13

The influenza virus contains an RNA genome.Why do scientists typically have to make a new vaccine for the flu every year?

Accepted Answer

The influenza virus is known for its ability to mutate rapidly and create new strains, making it difficult to develop a long-lasting vaccine that protects against multiple strains. Therefore, scientists have to make a new vaccine every year to keep up with the constantly evolving virus.

Question 14

An infectious protein is a

Accepted Answer

Infectious proteins are called prions.

Question 15

Many viruses are inhibited by antibiotics.

Accepted Answer

Antibiotics are only effective against bacterial infections, not viral infections. It is important to differentiate between the two types of infections to ensure proper treatment.

Question 16

What is the genetic material found in HIV?

Accepted Answer

HIV contains RNA as its genetic material, not DNA. The RNA contains the instructions for viral replication and infection.

Question 17

One key reason why viruses are not considered living organisms is

Accepted Answer

Viruses cannot reproduce on their own and require a host cell to replicate. This lack of independent reproduction is one of the key reasons why viruses are not considered living organisms.

Question 18

The enzyme that HIV uses to convert its RNA into DNA is

Accepted Answer

HIV uses reverse transcriptase to convert its RNA into DNA, which is then integrated into the host cell's genome. DNA polymerase and RNA polymerase are involved in the replication of DNA and RNA, respectively, but are not used by HIV for this process. RNA integrase is used by HIV to integrate its new DNA into the host genome, but is not involved in the initial conversion of RNA to DNA. "TranslasE" is not a valid enzyme.

Question 19

The Human Immunodeficiency Virus (HIV)only affects a specific class of cells in the immune system called helper T cells,and not other types of T cells.Which is the best explanation for this observation?

Accepted Answer

The correct answer is D because HIV enters helper T cells by binding to a specific receptor called CD4, which is most abundant on the surface of helper T cells. Other types of T cells, such as cytotoxic T cells, do not have as much CD4 on their surface and are therefore not as susceptible to HIV infection.

Question 20

Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years,and when a patient becomes stressed,the virus is released,forming cold sores on the lips.While lying dormant,the virus is in which of the following states?

Accepted Answer

When a virus is lying dormant in nerve cells, it is said to be in a latent state. This means that it is not actively replicating or causing symptoms, but it has the potential to reactivate in response to stress or other triggers. The lytic state refers to the active replication and destruction of host cells by a virus, while symptomatic refers to the presence of symptoms such as cold sores. Replicative and infective are not relevant terms for describing the dormant state of a virus.

Quiz 7: DNA Structure and Gene Function

HIV