Test: Biological Classification - Viruses Viroids and Lichens (April 5) - NEET MCQ

• Lichens exist in symbiotic associations with algae and fungi.
• The algal and fungal components in Lichens are known as Phycobiant and Mycobiant respectively.

Hence, the correct option is A
NCERT Reference: Page no. 27 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.

• Virus, infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria.
• The name is from a Latin word meaning “venom” or “poisonous fluid.”

Hence, the correct option is D.
NCERT Reference: Page no. 26 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.

• Viruses are ultramicroscopic disease-producing organisms. They have two fundamental characteristics of the living system i.e. presence of nucleic acid as genetic material and the ability to produce their own copies.
• They have no cellular organization and no metabolic machinery of their own.
• They are obligatory intracellular parasites as they are completely inactive outside the host.
• They can be crystallized and even in their crystalline form, they retain their infectivity. Wendall Stanley was the first to purify and crystallize a plant virus called Tobacco Mosaic Virus (TMV) and he showed that even in crystalline form the virus retains it's infectivity. This showed the non living nature of the virus.

Hence, the correct option is D
NCERT Reference: Page no. 27 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2

• The co-existence of algae with fungus is called lichens.
• Lichens are the best examples of the symbiotic association.
• They are also good indicators of pollution as they don’t grow in polluted regions.

Hence, the correct option is B
NCERT Reference: Page no. 27 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.

• Viruses are made up of nucleic acid, which is DNA/RNA with protein. Cell membrane, protoplasm, ribosomes, etc., are absent. Since it lacks metabolism, it lacks enzymes.
• Fungi, algae, and cyanobacteria, on the other hand, have a variety of enzymes as it is made up of the cell.

Hence, the correct option is B
NCERT Reference: Page no. 26 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.

• Characters of living nature of viruses are: Viruses have genetic material (DNA or RNA). They can mutate.
• They can grow, once inside the host cell. They can be transmitted from one host to another. They are capable of multiplication within a host.
• They react to heat, radiation and chemicals. They show irritability.
• They bring about enzymatic changes in vitro. They are able to infect and cause the disease to living beings.
• The DNA and proteins of viruses are similar in composition and structure to those of higher organisms.

Hence, the correct option is D
NCERT Reference: Page no. 25 of chapter “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.

• Viruses don’t contain cell and instead have genetic material made of nucleic acids and a protein sheath covering it which is made of proteins.
• This protein sheath is called capsid and is made of basic units called capsomeres.

Hence, the correct option is B.
NCERT Reference: Page no. 27 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.

A virus is a small infectious agent that  replicates only inside the living cells of other organisms.

• Option A: Viruses can undergo replication by lytic and lysogenic cycles.
• Option B: The feature of viruses to perform viral genetic change in their own genome is a process of virus mutation.
• Option C: The energy production and liberation process are absent in viruses, as this process is not required by viruses. 

Hence, the correct option is C
NCERT Reference: Page no. 25 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.

• Viroids are the smallest infectious pathogens known.
• They are composed solely of a short strand of circular, single- stranded RNA that does not encode a protein. This viroid is called Potato Spindle Tuber Viroid (PSTV).

Hence, the correct option is C
NCERT Reference: Page no. 27 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.

• The outer protein coat of a virus is known as the capsid.
• It consists of several oligomeric structural subunits made of a protein called protomers which cover the nucleic acid which is present in the virus and protects it when virus inserts itself into the host.
• The capsid proteins also help the virus attach and penetrate the host cells thereby infecting the host.

Hence, the correct option is B.

NCERT Reference: Page no. 26 of topic “2.6 VIRUSES, VIROIDS, PRIONS AND LICHENS” of chapter 2.