Viroids

Q.

Silencing of mRNA has been used in producing transgenic plants resistant to?

1. Nematodes

2. Bollworms

3. Bacterial blight

4. White rusts

Q. Viruses are non-cellular entities that can replicate only after they have infected a host cell. Which of the following kingdoms do viruses belong to?

1. Protista
2. Fungi
3. Monera
4. None of the above

Q.

Which of the following is correct about viroids ?

1. They have DNA with a protein coat.

2. They have free DNA without a protein coat.

3. They have RNA with a protein coat.

4. They have free RNA without a protein coat.

Q. Who discovered infectious agents even smaller than virus with only nucleic acid and no protein coat?

1. Ivanowsky
2. M.W. Beijerinek
3. W.M. Stanley
4. T.O. Diener

Q.

Do bacteria contain nucleic acid?

Q.

Are prokaryotes gram-positive or gram-negative?

Q.

Potato spindle tuber disease is caused by?

Q.

What is the difference between viroids and prions?

Q.

Why are Viroids acellular?

Q.

Do Viroids have protein?

Q. A common feature shared by animals, plants, bacteria and viroids is the presence of

1. RNA
2. DNA
3. proteins
4. cell wall

Q.

Are viroids spherical?

Q.

What plants kill viruses?

Q.

How are viroids different from viruses?

Q. Select the incorrect about viroids.

1. Are free RNA
2. Lack protein coat
3. Were discovered by T.O. Diener
4. Have free DNA with protein coat

Q.

T.O Diener (1971) discovered a new infectious agent that was smaller than viruses. It was

1. Viroids
2. Viruses
3. Prions
4. Lichen

Q. Identify the organism with the following characteristics.
I. Simpler than viruses.
II. Genetic material is ssRNA.
III. Can cause plant diseases.
IV. Requires a host for multiplication.

1. Virions
2. Viroids
3. Prions
4. Mycoplasma

Q.

How do you cure a virus?

Q.
Name a disease caused by viroid in plants.

Q. Match the columns.

(a)	Saccharomyces cerevisiae	(i)	Production of immunosuppressive agent
(b)	Monascus purpureus	(ii)	Ripening swiss cheese
(c)	Trichoderma polysporum	(iii)	Commercial production of ethanol
(d)	Propionibacterium sharmanii	(iv)	Production of blood cholesterol lowering agents

1. a-iv, b-iii, c-ii, d-i
2. a-iii, b-iv, c-i, d-ii
3. a-iii, b-i, c-iv, d-ii
4. a-iv, b-ii, c-i, d-iii

Q.

What is the name of the casual organism of potato spindle tuber disease?

Q.

Which plant can kill a human?

Q. Proteinaceous infectious particles without nucleation acids are known as ____________.

1. Prions
2. Viroids
3. Virusoids
4. Virions

Q. Write a note on viroids?

Q. Which of the following statements in wrong for viroids?

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

Q. Read the given statements that describe certain infectious particle.
(i) It was discovered by T.O. Diener and was found to be smaller than viruses.
(ii) It causes potato spindle tuber disease.
(iii) It is a free RNA particle which lacks the protein coat.
(iv) It has low molecular weight RNA as genetic material.
Which of the following is referred to here?

1. Viroid
2. Virus
3. Virion
4. Bacteriophage

Q. Short / Long answer type questions.
Write a brief account of viroids and prions.

Q. The genetic material of a viroid is

1. DNA
2. RNA
3. Protein
4. Carbohydrate

Q. Viroids differ from viruses in having?

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

Q. Virus with nucleic acid but without protein coat is

1. Virion
2. Viroid
3. Capsid
4. Prion