Viruses and Viroids
dsRNA is found in
Which one of the followings is a viral disease?
A.Wilting of cabbage
B.ANS:Leaf roll of potato
C.Red rot of sugar cane
D.Damping-off disease of seedlings
Cauliflower mosaic virus contains
ELISA is used to detect viruses where the key reagent is
Due to discovery of which of the following in 1980, the evolution was termed as RNA world
ANS:A.RNA have enzymatic property
B.In some virus RNA is genetic material
C.m-RNA, t-RNA- r-RNA synthesize proteins
D.RNA is not found in all cells
Tailed bacteriophages are
A.Motile on surface of bacteria
B.Motile on surface of plant leaves
C.Actively motile in water
One important characteristic of viruses is that they
A.Have an independent metabolism
B.Can be cultured in a cell-free medium
C.Can multiply outside a living cell
ANS:D.Do not have an independent metabolism
Virus are living, because
A.Carry metabolic activity
B.Carry anaerobic respiration
ANS:C.Multiply in host cells
DNA is not present in one of the following
ANS:B.Tobacco Mosaic Virus
Which of the following is a bacteriophage?
A.Bacteria infecting viruses
ANS:C.Virus inhabiting in bacteria
Which of the following statements is not true for retroviruses?
A.Retroviruses are causative agents for certain kinds of cancer in man
B.The genetic material in mature retroviruses is RNA
C.Retroviruses carry gene for RNA-dependent DNA polymerase
ANS:D.DNA is not present at any stage in the life cycle of retroviruses.
Viruses are no more “alive” than isolated chromosomes because
A.They both require oxygen for respiration
B.They both need food molecules
C.They require both RNA and DNA
ANS:D.Both require the environment of a cell to replicate
Which statement is correct for bacterial transduction?
A.Bacteria obtained its DNA directly
B.Transfer of some genes from one bacteria to another bacteria by conjugation
ANS:C.Transfer of some genes from one bacteria to another bacteria through virus
D.Bacteria obtained DNA from other external source
Which of the following statements is true about viruses?
ANS:A.All viruses known to man are obligate parasites
B.Viruses are capable of performing metabolic activities on their own
C.Viruses are filterable facultative parasites
D.Some viruses have cellular structure and are saprophytes
How does enveloped virus enter into host cells?
B.by contact with ceil receptor and endocytosis
C.by injecting its own nucleic acid inside the host cells
ANS:D.by fusion with the plasma membrane of host