Virus Bellwork

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

• move inside a host cell
• attach to a host cell
• control the host cell's DNA
• signal other viruses to infect the host cell

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, because the virus causes respiratory illness
• lysogenic, because 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.

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

viruses can replicate either they lytic cycle or lysogenic cycle. which of the following describes the lysogenic cycle?

• during the lysogenic cycle, the virus incorporates its genetic material into the host cell and converts the host cell into a pathogenic bacterial cell

• during the lysogenic cycle, the virus attaches externally to the host cell and remains attached for several years until it is ready to become active

• during the lysogenic cycle, the viral nucleic acids (DNA) incorporate into the host cell's genetic material and remain in a dormant state for a long period of time

• during the lysogenic cycle, the viral nucleic acids (DNA) hijack the genetic material's host cell and direct the cell to make new viral cells over a short period of time that will erupt from the cell

Some viruses replicate via the lytic cycle by-

• altering the genetic material of the host cell to make the host cell use its own enzymes to assemble new viruses. these viruses break out of the cell, resulting in cell death, and then spread the newly formed viruses to other cells

• undergoing meiosis to create genetically diverse cells. these cells are capable of passing along the fittest traits from one generation to the next

• incorporating their genetic material into the genetic material of the host cell. these viruses are called proviruses and may remain dormant for several days, weeks, or years

• regenerating through the process of mitosis, where each new cell contains a piece of genetic information from the provirus. this genetic material leaves the cell after a few weeks

Viruses and cells are different in many ways. In which of these ways are viruses and cells most similar?

• composition of outer covering

• stages of life cycle

• composition of genetic material

• stages of reproduction

What characteristic of viruses distinguishes them from cells?

• They do not have genetic material.

• They are not separated from their environments by a coat or membrane.

• They lack an independent metabolism.

• Their traits do not evolve in response to selection pressures.

Which of the following is effective in reducing the number of viral infections?

• antibodies

• vaccines

• innoculation

• none of the above

Scientists are designing new medicines to fight infectious diseases caused by viruses. One of the most effective ways these medicines could limit the spread of the virus within the body would be to –

• prevent viruses from dividing

• burst cells infected with viruses

• stop viruses from attaching to cells

• make it easier for viruses to leave cells