4C Viruses

A student produces a labeled drawing of a virus for a presentation. The student states that the capsid has a function similar to the nuclear membrane found in animal cells. Which of these describe the similar functions of capsids and nuclear membranes?

• both transport proteins throughout the structures

• both provide energy for activities in the structures

• both protect genetic information for the structures

• both code for the proteins needed for reproduction of the structures

In 1898 Fredrich Loeffler and Paul Frosch found evidence that the cause of a highly contagious hoof-and-mouth disease in livestock was a microscopic infectious particle. It was discovered that this particle requires a host cell to reproduce. Which pathogen is most likely responsible for causing hoof-and-mouth disease in livestock?

• a bacterium, because it is contagious

• a fungus, because it infects livestock

• a protist, because it is microscopic

• a virus, because it requires a host cell to reproduce

In the 1880's, Louis Pasteur developed a method of weakening viruses. The weakened viruses could be injected into healthy individuals. How is this method effective in fighting viral diseases?

• the immune system develops antibodies in response to the weakened viruses

• the weakened viruses attach to unaffected viruses in the host and interrupt the viral reproductive cycle

• the rate of genetic mutation in the host is decreased due to the introduction of weakened viruses

• weakened viruses are unable to enter the host organism

Which of these describes a difference between viruses and cells?

• cells contain protein, and viruses contain only carbohydrates

• viruses have flagella, and cells have only cilia

• cells reproduce independently, and viruses require a host to reproduce

• viruses have membranes made of proteins, and cells have membranes made of nucleic acid

The human immunodeficiency virus (HIV) often infects and destroys CD4 T cells. Thes CD4 T cells are one of many kinds of white blood cells that are an important part of the immune system. The most common danger related to the destruction of CD4 T cells is -

• an increase in the risk of high blood pressure

• an increase in the threat of diseases caused by microorganisms and viruses

• a decrease in the flow of blood to vital organs

• a decrease in the amount of oxygen being transported to tissues

Viruses can be transmitted through air, water, food, insect bites, and direct skin contact. Once a virus gains entry to the body, it invades a host cell in order to -

• deactivate the host cell's defenses

• synthesize antibodies for defense

• metabolize host proteins and grow

• access cellular processes for replication

The 1918 influenza epidemic killed between 50 million and 100 million people worldwide. This epidemic happened near the end of World War I. More people died from the influenza epidemic than were killed in the war. Which of the following explains why this virus was so deadly worldwide?

• infected soldiers returning from the war spread the virus when they coughed

• food was scarce because of the war, so people were undernourished, and their immune systems were weakened

• medical personnel often became ill as a result of exposure to airborne virus particles

• all of the above

The picture shows a 3-D model of a virus called a bacteriophage. Bacteriophages can infect bacteria such as E. coli. In what way are bacteriophage and E. coli alike?

• they contain antibodies

• they reproduce by mitosis

• they have identical genomes

• they lack membrane-bound organelles

Models of the human immunodeficiency virus (HIV) and an animal cell are shown below. What is the difference in the function of the glycoprotein structures of an HIV virion and the cilia of an animal cell?

• the glycoprotein structures are used for attachment, and the cilia are used to move fluids surrounding the cell

• the glycoprotein structures are used to obtain nutrition, and the cilia are used to secrete proteins

• the glycoprotein structures are used to provide physical support for the viral envelope, and the cilia strengthen the cell membrane

• the glycoprotein structures are used for defense, and the cilia are used for locomotion

H₁N₁ flu is a highly contagious viral infection caused by the influenza A (H₁N₁) virus. The symptoms of H₁N₁ flu are listed in the box. An antiviral agent administered within 48 hours of the appearance of symptoms can reduce the severity of the illness. Why is it important to administer an intiviral agent to an infected person within 48 hours of the appearance of symptoms?

• the H₁N₁ virus is dominant in cells

• the H₁N₁ virus replicates quickly

• the H₁N₁ virus does not mutate

• the H₁N₁ virus is transmitted through a vector host, such as a mosquito