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CHAPTER 24 Viruses Practice Test Most scientists believe that viruses first appeared on Earth ____ living cells appeared. a. at the exact time when b. immediately before c. a very long time before d. after d Animal viruses often infect only specific host cells because a. the host cell must have specific receptors for proteins on the virus surface. b. viruses have receptors for host cell glycoproteins. c. the virus must have the same DNA as the host cell. d. the enzymes of the virus can attach only to specific host cells. a Unlike viruses, prions a. are composed only of protein. b. can be treated with antibiotics. c. are capable of reproducing outside of a host cell. d. can cause brain infections. a Which of the following is not linked to cancer? a. Epstein-Barr virus c. Ebola virus b. human papillomavirusd. hepatitis B virus c Viruses are classified according to a. the shape of their genome. b. whether they have a membrane envelope. c. whether they contain RNA or DNA. d. All of the above d A typical virus consists of a. a protein coat and a cytoplasm core. b. a polysaccharide coat and a nucleic acid core. c. a carbohydrate coat and a nucleic acid core. d. a protein coat and a nucleic acid core. d Biologists now know that viruses a. are the smallest organisms. b. all form the same crystalline shape. c. consist of a protein surrounded by a nucleic acid coat. d. contain RNA or DNA in a protein or lipidprotein coat. d Refer to the illustration above. Which structure is found outside the cell after the cell is infected? a. structure 3 c. structure 1 b. structure 4 d. structure 2 c Refer to the illustration above. Which structure could possibly be made of RNA? a. structure 2 c. structure 4 b. structure 3 d. structure 5 b All viruses have a. mitochondria. b. cytoplasm.d. d c. ribosomes. None of the above The a. b. c. d. capsid of a virus is the nucleus. cell wall and membrane complex. cell membrane. protective outer coat. d HIV causes AIDS by a. gradually destroying a person’s immune system. b. destroying the covering of a person’s nerves. c. converting a proto-oncogene to an oncogene. d. damaging a person’s blood vessels. a The a. b. c. d. study they they they they of viruses is a part of biology because are living organisms. belong to the kingdom Eubacteria. are active inside living cells. are about to become extinct. c Viruses a. have nuclei and organelles. b. are cellular organisms. c. are surrounded by a polysaccharide coat. d. reproduce only in living cells. d Which of the following contains only RNA? a. a prion c. a viroid b. a virus d. All of the above c Scientists first began to study viruses because they a. formed crystals. b. were seen through a microscope. c. were made of cells. d. could not be seen but caused disease. d Antibiotics are ineffective against viral infections because a. viruses have enzymes that inactivate the antibiotics. b. host cells protect the viruses. c. antibiotics interfere with cellular processes that viruses do not perform. d. viral protein coats block the antibiotics from entering the virus. c Which of the following is not a viral disease of humans? a. hepatitis b. shingles c. SARS d. All of the above are viral diseases of humans. d Viruses are considered nonliving because a. they cannot carry out metabolism by themselves. b. they are not made up of cells. c. they cannot reproduce by themselves. d. All of the above d Tobacco mosaic virus a. causes disease in tobacco plants. b. is able to be crystallized. c. is smaller than a bacterium. d. All of the above d Viruses that use reverse transcriptase to cause their host cells to transcribe DNA from an RNA template are called a. antibodies. c. retroviruses. b. bacteriophages. d. capsoviruses. c Viruses can vary in size and ____________________. shape An enzyme called _________________________ manufactures DNA that is complementary to a virus’s RNA. reverse transcriptase The protein coat of a virus is called a(n) ____________________. capsid The virus that causes AIDS is called _________________________. HIV (human immunodeficiency virus) The Ebola virus, the SARS virus, and hantavirus are examples of ____________________ viruses. emerging The End