Viruses are considered nonliving because

a. they can't reproduce by themselves

b. they aren't made up of cells

c. they can't carry out metabolism by themselves

d. all of the above

The study of viruses is a part of biology because

a. they belong to the kingdom eubacteria

b. they are about to become extinct

c. they are living organisms

d. they are active inside living cells

biologists now know that viruses

a. are the smallest organisms

b. consist of protein surrounded by a nucleic acid coat

c. contain RNA or DNA in a protein or lipid protein coat

d. all form the same crystalline shape

the capsid of a virus is the

a. protective outer coat

b. cell membrane

c. nucleus

d. cell wall and membrane complex

viruses are classified according to

a. whether they contain RNA or DNA

b. the shape of their genome

c. whetehr they have a membrane envelope

d. all of the above

all viruses have

a. cytoplasm

b. ribosomes

c. mitochondria

d. none of the above

Tobacco mosaic virus

a. is able to be crystallized

b. causes disease in tobcco plants

c. is smaller than a bacterium

d. all of the above

scientists first began to study viruses because they

a. were seen through a microscope

b. could not be seen but caused disease

c. formed crystals

d. were made of cells

Viruses that use reverse transcriptase to cause their host cells to transcribe DNA from an RNA template are called

a. bacteriophages

b. antibodies

c. retroviruses

d. capsoviruses

Which of the following contains only RNA

a. a prion

b. a virus

c. a viroid

d. all of the above

unlike viruses, prions

a. are capable of reproducing outside a host cell

b. are composed only of protein

c. can cause brain infections

d. can be treated with antibiotics

a typical virus consists of

a. a protein coat and cytoplasm core

b. a carbohydrate coat and nucleic acid core

c. a protein coat and nucleic acid core

d. a polysaccaride coat and nucleic acid core

viruses

a. are cellular organisms

b. reproduce only in living cells

c. have nuclei and organelles

d. are surrounded by a polysaccaride coat

animal viruses often infect only specific host cells because

a. the virus must have the same DNA as the host

b. the host must have specific receptors for proteins on the virus surface

c. viruses have receptors for host cell glycoproteins

d. the enzymes of the virus can attach only to specific host cells

in which cell cycles does viral DNA become integrated into the host cell's DNA

a. lytic

b. lysogenic

c. neither

d. both

Antibiotics are ineffective against viral infections because

a. host cells protect the viruses

b. viruses have enzymes that inactivate the antibiotics

c. antibiotics interfere with cellular processes that the viruses don't perform

d. viral protein coats block the antibiotics from entering the virus

which is not a virus of humans

a. hepatitis

b. sars

d. shingles

d. all of the above are human viruses

which of the following is not linked to cancer

a. ebola virus

b. human papillomavirus

c. hepatitis B

d. epstein barr virus

which of the following human activities is most closely associated with the emergence of viruses previously not seen in humans?

a. absence of vaccination program

b. crowded living conditions

c. clearing of forests for houses

d. eating uncooked meat

most scientists think that early viruses originated from

a. other viruses

b. existing cell parts

c.animals

d. sponaneous generation

HIV causes AIDS by

a. converting proto-oncogene into an oncogene

b. damaging a person's blood vessels

c. destroying the covering of a person's nerves

d. gradually destroying a person's immune system

which of the following isn't a vector of viral diseases

a. mosquitoes

b. ticks

c. prions

d. humans

which of the following has been the most successful at fighting viral diseases

a. vaccination

b. vector control

c. drug therapy

d. both a and b

most scientists believe that viruses first appeared on earth _____ living cells appeared.

a. after

b. a very long time before

c. at the exact time when

d. immediatly before