VARIETY OF LIFE
FILL IN THE BLANKS
Q.01: Fill in the blanks:
(i) C. Linneaus divided all known forms of life into two kingdoms: _______ and _______. Bacteria were placed in the kingdom ________ because they have cell walls, and protozoa were placed in the kingdom _______ because they move from place to place and ingest food. (plants/animals|plantae/animalia)
(ii) The most common system of classification used today, developed in 1969 by Robert Whittaker of Cornell University, uses five kingdoms: _______, _______, _______, _______ and ________. (Monera/Protista/Plantae/Fungi/Animalia)
(iii) Whittaker’s five kingdom system of classification recognizes two basic types of cells: ________ and ________. (prokaryotes/eukaryotes)
(iv) In five kingdom system of classification proposed by Margulis and Schwartz, organelles of symbiotic origin such as _______ and _______ were also considered. (mitochondria/chloroplasts)
(v) A bacteriophage reproduces by using the metabolic machinery of ________. (host bacteria)
(vi) The protein coat that encloses the viral genome is called: ________ It is made up of ________. (capsid/capsomeres)
(vii) Retroviruses are _________ viruses which have specific enzymes _______ by which they convert RNA to DNA. (RNA tumor/reverse transcriptase)
(viii) HIV infects ________ and the defects in these cells lead to failure in ________ system. (helper T-lymphocytes/immune)
(ix) Hepatitis is caused by ________. (viral infection)
(x) Viral Hepatitis is of ________ types. Hepatitis A and C are caused by ________ virus whereas ________ virus is the causative agent of Hepatitis B. (seven/RNA virus/DNA)
MULTIPLE CHOICE QUESTIONS
Q.02: Each question has multiple options. Encircle the correct answer.
(i) The enzymes involved in viral replication are synthesized:
(a) On the viral ribosomes
(b) On the interior surface of viral membrane
(c) By the host cell
(d) On the interior surface of viral coat
ANSWER: (c) By the host cell
EXPLANATION: Immediately after entering the host cell , the viral nucleic acid takes the control of the host’s biosynthetic machinery and induces the host cell to synthesize necessary viral components such as DNA and proteins or enzymes, and starts multiplying.
(ii) A virion is a:
(a) Virus
(b) Viral protein
(c) Viral lysozyme
(d) Viral gene
ANSWER: (a) Virus
EXPLANATION: The complete, mature and infectious particle is known as virion.
(iii) An isolated virus is not considered living, since it:
(a) Separates into two inert parts
(b) Cannot metabolize
(c) Rapidly loses it genome chemically inert
(d) Is coated with an air tight shield
ANSWER: (b) Cannot metabolize
EXPLANATION: An isolated virus, outside of a host cell, lacks the cellular machinery necessary for metabolism. It cannot carry out metabolic processes on its own. Instead, viruses depend on host cells to replicate and carry out metabolic functions. Therefore, in the absence of a host cell, a virus is considered inactive and non-living.
(iv) In the lytic cycle of a bacteriophage, the host DNA is:
(a) Replicated
(b) Turned off by a protein coat
(c) Digested into its nucleotides
(d) Turned on by removal of a protein coat
ANSWER: (c) Digested into its nucleotides
EXPLANATION: During a crucial step in the lytic cycle, the viral enzymes released by the bacteriophage break down the host DNA into its individual nucleotides.
(v) In the lysogenic cycle, the DNA of a bacteriophage:
(a) Joins the bacterial chromosome
(b) Is immediately degraded when it enters the host
(c) Attaches to the inner surface of the host membrane
(d) Goes directly to the host’s ribosomes for translation
ANSWER: (a) Joins the bacterial chromosome
EXPLANATION: In some cases, viral DNA, instead of taking over the control of host’s machinery, becomes incorporated into the bacterial chromosome. Phage in this state is called prophage and this process is known as lysogeny.
(vi) Temperate phage may exist as:
(a) Prophage
(b) Capsid
(c) Viroid
(d) Retrovirus
ANSWER: (a) Prophage
EXPLANATION: In some cases, viral DNA, instead of taking over the control of host’s machinery, becomes incorporated into the bacterial chromosome. Phage in this state is called prophage and this process is known as lysogeny. In this condition the bacterium continues to live and reproduce normally. Viral DNA being the part of bacterial chromosome passes to each daughter cell in all successive generations.
(vii) Phylogeny describes a species:
(a) Morphological similarities with other species
(b) Evolutionary history
(c) Reproductive compatibilities with other species
(d) Geographic distribution
ANSWER: (b) Evolutionary history
EXPLANATION: Phylogeny describes a species’ evolutionary history by analyzing and depicting the evolutionary relationships among different organisms. It is typically represented in a phylogenetic tree, illustrating the common ancestry and divergence of species based on shared evolutionary traits, genetic information, and common ancestors.
(viii) In the binomial system of taxonomy, developed during the 18th century by C. Linnaeus, the first word of an organism’s name (e.g., Homo sapiens) is its:
(a) Family
(b) Species
(c) Genus
(d) Race
ANSWER: (c) Genus
EXPLANATION: Linnaeus’s system of giving each species a scientific name comprising two words is known as binomial nomenclature. The first name refers to the genus (pl. genera) and is called generic name and always begins with a capital letter.
(ix) In the five-kingdom system of classification developed by Robert Whittaker, members of the kingdom Plantae are autotrophic, eukaryotic and:
(a) Multicellular
(b) Motile
(c) Either unicellular or multicellular
(d) Have sexual reproduction
ANSWER: (a) Multicellular
EXPLANATION: Kingdom Plantae contains eukaryotic, photosynthetic, multicellular, non-motile organisms which develop from embryo.
(x) Five kingdom system of classification proposed by Margulis and Schwartz is not based on:
(a) Genetics
(b) Cellular organization
(c) Nucleic Acid
(d) Mode of nutrition
ANSWER: (c) Nucleic Acid
EXPLANATION: Lynn Margulis and Karlene Schwartz (1988) modified five kingdom classification of Whittaker by considering cellular organization, mode of nutrition, cytology, genetics and organelles of symbiotic origin (mitochondria, chloroplast).
(xi) The common name of Allium cepa is:
(a) Chana
(b) Piyaz
(c) Bathu
(d) Amaltas
ANSWER: (a) Piyaz
EXPLANATION: (The scientific name of onion is Allium cepa.
(xii) Arrange the following in order of group size, beginning with the smallest: Family, kingdom, species, phylum (or division), genus, order and class.
(a) Species
(b) Genus
(c) Family
(d) Order
(e) Class
(f) Phylum (or division)
(g) Kingdom
(xiii) Pigs are reservoirs to:
(a) Hepatitis A
(b) Hepatitis B
(c) Hepatitis C
(d) Hepatitis D
(e) Hepatitis E
ANSWER: (e) Hepatitis E
EXPLANATION: Most recent work of Halbur and coworker (2001) reveals that pig could be the source of infection of hepatitis E.
(xiv) Which one of the following is false about AIDS:
(a) HIV
(b) Acquired-immune deficiency syndrome
(c) T-lymphocytes
(d) HAV
ANSWER: (d) HAV
EXPLANATION: HAV means hepatitis A virus, which is nothing to do AIDS.
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