15433.Viroids have
DS-DNA enclosed by protein coat
SS-DNA not enclosed by protein coat
SS-RNA not enclosed by protein coat
DS-RNA enclosed by protein coat
15434.Chromosomes in a bacterial cell can be 1 - 3 in number and
can be either circular or linear, but never both within the same cell
can be circular as well as linear within the same cell
are always linear
are always circular
15435.How does enveloped virus enter into host cells?
by phagocytosis
by contact with ceil receptor and endocytosis
by injecting its own nucleic acid inside the host cells
by fusion with the plasma membrane of host
15437.Tailed bacteriophages are
Motile on surface of bacteria
Motile on surface of plant leaves
Actively motile in water
Non-motile
15438.Match the types of bacteria listed in column I with their activity given in column II. Choose the correct combination of alphabets of the two columns.
| Column - I (Types of bacteria) | Column - II (Activity) |
|---|---|
| A Streptomyces | p Food poisoning |
| B Rhizobium | q Source of Antibiotics |
| C Nitrosomonas | r Nitrogen fixation |
| D Acetobacter | s Nitrification |
| t Vinegar synthesis |
A = s, B =t, C = p, D = 1
A = t, B = p, C = r, D = S
A = q, B = r, C = p, D = t
A = q, B = r, C = s, D = t
15439.Due to discovery of which of the following in 1980, the evolution was termed as RNA world
RNA have enzymatic property
In some virus RNA is genetic material
m-RNA, t-RNA- r-RNA synthesize proteins
RNA is not found in all cells
15440.One important characteristic of viruses is that they
Have an independent metabolism
Can be cultured in a cell-free medium
Can multiply outside a living cell
Do not have an independent metabolism
15441.Which type of DNA is found in bacteria?
Helical DNA
Membrane bound DNA
Straight DNA
Circular free DNA
15442.The non-living characteristic of viruses is
ability to undergo mutation
ability to cause diseases in the host
ability to multiply only inside the host
ability to be crystallized
15443.Which of the following statements is not true for retroviruses?
Retroviruses are causative agents for certain kinds of cancer in man
The genetic material in mature retroviruses is RNA
Retroviruses carry gene for RNA-dependent DNA polymerase
DNA is not present at any stage in the life cycle of retroviruses.
15444.Which of the following is a free living nitrogen fixing bacterium present in the soil?
Azotobacter
Rhizobium
Nitrosomonas
Pseudomonas
15445.Which statement is correct for bacterial transduction?
Bacteria obtained its DNA directly
Transfer of some genes from one bacteria to another bacteria by conjugation
Transfer of some genes from one bacteria to another bacteria through virus
Bacteria obtained DNA from other external source
15446.Cell wall of Gram positive bacteria is made up of
Murein
Cellulose
Lipid and protein
Cellulose and lipid
15447.Which of the following statements is true about viruses?
All viruses known to man are obligate parasites
Viruses are capable of performing metabolic activities on their own
Viruses are filterable facultative parasites
Some viruses have cellular structure and are saprophytes
15448.Virus are living, because
Carry metabolic activity
Carry anaerobic respiration
Multiply in host cells
Cause infection
15450.In the light of recent classification of living organisms into three domains of life (bacteria, archaea and eukarya), which one of the following statements is true about archaea?
Archaea have some novel features that are absent in other prokaryotes and eukaryotes
Archaea resemble eukarya in all respects
Archaea completely differ from prokaryotes
Archaea completely differ from both prokaryotes and eukaryotes
15451.Reproduction in most of the bacteria is by a process known as
Binary fission
Budding
Sexual
Sporulation
15452.Bacteria with flagella all over the body is
Peritrichous
Amphitrichous
Monotrichous
None of these