Biological Classification

Mad cow disease is caused by .

1. Mycoplasma sp.
2. prions
3. viroids
4. Aspergillus sp.

Symbiotic associations between fungi and algae are called .

1. chrysophytes
2. lichens
3. sponges
4. mycorrhiza

Mad cow disease in cattle and Cr Jacob disease in humans are due to infection by .

1. Prion
2. Bacterium
3. Virus
4. Viroid

Which of the following is correct about viroids?

1. They have free RNA without protein coat
2. They have DNA with protein coat
3. They have free DNA without protein coat
4. They have RNA with protein coat

Which of the following statements is incorrect?

1. Infective constituent in viruses is the protein coat
2. Prions consist of abnormally folded proteins
3. Viroids lack a protein coat
4. Viruses are obligate parasites

Viroids differ from viruses in having

1. DNA molecules without protein coat
2. RNA molecules with protein coat
3. RNA molecules without protein coat
4. DNA molecules with protein coat

Which of the following statements is wrong for viroids?

1. They cause infections.
2. Their RNA is of high molecular weight.
3. They lack a protein coat.
4. They are smaller than viruses.

Select the wrong statement.

1. The term ' contagium vivum fluidum' was coined by M. W. Beijerinck.
2. Mosaic disease in tobacco and AIDS in human being are caused by viruses.
3. The viroids were discovered by D.J. Ivanowsky.
4. W.M. Stanley showed that viruses could be crystallised.

Which of the following shows coiled RNA strand and capsomeres?

1. Polio virus
2. Tobacco mosaic virus
3. Measles virus
4. Retrovirus

Viruses have

1. DNA enclosed in a protein coat
2. prokaryotic nucleus
3. single chromosome
4. both DNA and RNA.

A location with luxuriant growth of lichens on the trees indicates that the :

1. trees are very healthy
2. trees are heavily infested
3. location is highly polluted
4. location is not polluted

Satellite RNA are present in some :

1. Prions
2. Bacteriophages
3. Plant viruses
4. Viroids

Which statement is wrong for viruses?

1. All are parasites.
2. All of them have helical symmetry.
3. They have ability to synthesize nucleic acids and proteins.
4. Antibiotics have no effect on them.

Given below is the diagram of a bacteriophage. In which one of the options all the four parts A, B, C and D are correct? [Figure]

1. A Collar, B Tail fibres, C Head, D Sheath
2. A Tail fibres, B Head, C Sheath, D Collar
3. A Head, B Sheath, C Collar, D Tail fibres
4. A Sheath, B Collar, C Head, D Tail fibres

Virus envelope is known as

1. capsid
2. virion
3. nucleoprotein
4. core

Infectious proteins are present in –

1. Viroids
2. Geminiviruses
3. Satellite viruses
4. Prions

T.O. Diener discovered a

1. free infectious DNA
2. infectious protein
3. bacteriophage
4. free infectious RNA

The causative agent of mad-cow disease is a-

1. Virus
2. Bacterium
3. Prion
4. Worm

There exists a close association between the alga and the fungus within a lichen. The fungus

1. provides protection, anchorage and absorption for the alga
2. provides food for the alga
3. fixes the atmospheric nitrogen for the alga
4. releases oxygen for the alga

Which of the following statements is not true for retroviruses?

1. DNA is not present at any stage in the life cycle of retroviruses.
2. Retroviruses carry gene for RNA-dependent DNA polymerase.
3. The genetic material in mature retroviruses is RNA.
4. Retroviruses are causative agents for certain kinds of cancer in man.

Viruses that infect bacteria multiply and cause their lysis, are called

1. lysozymes
2. lipolytic
3. lytic
4. lysogenic

Lichens are well known combination of an alga and a fungus where fungus has

1. a saprophytic relationship with the alga
2. an epiphytic relationship with the alga
3. a parasitic relationship with alga
4. a symbiotic relationship with alga

Which one of the following statements about viruses is correct?

1. Viruses possess their own metabolic system.
2. All viruses contain both RNA and DNA.
3. Viruses are obligate parasites.
4. Nucleic acid of viruses is known as capsid.

Tobacco mosaic virus is a tubular filament of size

1. 300 10 nm
2. 300 5 nm
3. 300 20 nm
4. 700 30 nm

Viruses are no more "alive" than isolated chromosomes because

1. they require both RNA and DNA
2. they both need food molecules
3. they both require oxygen for respiration
4. both require the environment of a cell to replicate.

Cauliflower mosaic virus contains

1. ss RNA
2. ds RNA
3. ds DNA
4. ss DNA

Enzymes are not found in

1. fungi
2. algae
3. virus
4. cyanobacteria.

Which disease of man is similar to cattle's bovine spongiform encephalopathy?

1. Spongiocitis of cerebrum
2. Encephalitis
3. Spondylitis
4. Jakob–Creutzfeldt disease