Prokaryotes and Viruses

A typical virus consists of

• a protein coat and a cytoplasm core

• a carbohydrate coat and a nucleic acid core

• a protein coat and a nucleic acid core

• a polysaccharide coat and a nucleic acid core

Which of these is the best description of a virus?

• a noncellular living organism

• one of the smallest bacteria known

• a member of the kingdom Virusae

• chemical complexes of RNA or DNA protected by protein

In order to infect a cell, a virus must

• inject its protein into the cell while the nucleic acid remains attached to the host cell surface.

• have a special protein on its surface that can interact with a protein on the surface of the host cell.

• actively burrow through the cell wall or cell membrane of the host cell to reach the cell's nucleus.

• produce a special extension of its cytoplasm when it comes into contact with the appropriate host cell.

The viral infection cycle that will most rapidly cause cell destruction is called the _______ cycle.

• lysogenic

• lysozyme

• lytic

• lysol

Which statement is true about prokaryotes?

• They contain a single circular DNA molecule as the genetic material.

• They lack ribosomes.

• They usually lack a cell wall.

• They divide by mitosis.

Which definition of a relationship between bacteria and other organisms is NOT correct?

• A parasitic bacterium is one that can cause disease in a plant or animal.

• A symbiotic relationship is one in which the bacterium is usually free-living, but may become associated as a parasite in an animal under certain conditions.

• A mutualistic relationship is one in which each of the associated organisms derives benefit.

• A commensalistic bacterium lives on or in another organism without doing it any harm or any good, but the bacterium derives a benefit.

Methanogens and halophiles are

• members of the bacteria domain.

• members of the achaea domain.

• immunoviruses.

• members of the eukarya domain.

Prokaryotic cells are characterized by

• the lack of an organized nucleus (true nucleus).

• cells that can move by flagella.

• the lack of membrane-bound organelles.

• All of the choices are correct.

To be sure you have sterilized water, you must boil it for a long time in a pressure cooker because

• some bacteria produce very resistant endospores.

• bacteria are facultative anaerobes.

• peptidoglycan is resistant to boiling water.

• bacteria can otherwise regenerate living cells from nonliving.

Many animal parasites and bacterial disease agents infect a fairly broad range of hosts, but viruses are often very specific to one type of tissue in one or a few species because

• a virus must be recognized and "taken in" by a host cell.

• viral proteins must match host cell proteins in order to adhere to the cell.

• some viruses may have evolved from nucleic acids from these host cell genomes.

• All of the choices are correct.