B4C

A photograph of a virus is shown below. The projections on the surface of this virus allow the virus to -

• move inside a host cell

• attach to a host cell

• control a host cell's DNA

• signal other viruses to infect a host cell

Cold sores are caused by the herpes simplex virus type 1. A company that wants to develop antiviral drugs would ask a research immunologist to study -

• the mechanism used by the virus to infect cells

• how closely related the virus is to cold viruses

• the metabolism of the virus

• meiosis in the virus

A person infected with the human immunodeficiency virus (HIV) may not have any symptoms for a period of time. During this period the virus affects the body by doing which of the following?

• the virus produces toxins that weaken immune cells and prevent them from reproducing

• the virus damages immune cells while using their machinery to produce copies of itself

• the virus uses nutrients meant for immune cells to fuel its own cellular respiration

• the virus changes the identity of the nucleotides of immune cells to prevent the immune system from functioning normally

Severe acute respiratory syndrome (SARS) is an illness caused by a coronavirus. Symptoms including a high fever, headaches, and body aches typically occur two to seven days after infection by the virus. SARS is more serious in elderly patients. This information suggests that the reproductive cycle of the SARS virus is -

• lysogenic, because the virus is a coronavirus

• lytic, beause the virus causes respiratory illness

• lysogenic, beause the virus primarily affects older people

• lytic, because of the quick onset of symptoms after infection

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 flue is a highly contagious viral infection caused by the influenza A (H1N1) virus. The symptoms of H1N1 flu are listed in the box below. 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 antiviral agent to an infected person within 48 hours of the appearance of the symptoms?

• The H1N1 virus is dormant 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

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 water. 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 water, so people were undernourished, and their immune systems were weakened

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

• all of the above

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

• they contain antibodies

• they reproduce by mitosis

• they have identical genomes

• they lack membrane bound organelles

The human immunodeficiency virus (HIV) often infects and destroys CD4 T cells. These 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 cells defenses

• synthesize antibodies for defense

• metabolize host proteins and grow

• access cellular processes for replication