Diversity of Life | Monera | Solution

25. (a) Anaerobic breakdown of proteins is known as putrefaction.
26. (a) The nuclear material of bacteria, consisting of naked DNA molecule, it is identified as nucleoid.
27. (c) Glycocalyx is a loose gelatinous thin sheath called loose slime layer which is secreted by protoplast and made up of polysachride and protects cell from loss of water and viral atack.
28. (d) Nitrifying bacteria such as Nitrosomonas and Nitrobacter manufacturing their organic food utilizing chemical energy in oxidation of some inorganic compound known is called chemosynthesis
29. (a) Branched chain lipids of cell membranes of archaebacteria enable them to tolerate high temperature and high acidity.
30. (d) Naked DNA is surrounded by some typical proteins (polyamines) but not histone proteins.
31. (c) During unfavourable condition highly resistant single spore is formed in the bacterial cell (e.g., Tetanus and anthrex bacteria) which known as endospore.
32. (a) Fimbriae are more in number, short thin straight bristle like appendages which function as organ of adhesion. Pili are similar to fimbriae but different in function.
33. (d) R-factor is type of plasmid which contains genes for antibiotic resistance.
34. (c) Both bacteria and cyanobacteria are prokaryotes.
35. (c) Respiratory enzyme containing infolding of plasma membrane in bacteria called chondrioid.
36. (a) In Streptococcus bacterium, various cocci or spherical bacteria are arranged in the form of chain.
37. (a) Because they used H₂S at the place of H₂O.
38. (d) The bacterium E. coli have double stranded circular DNA. Many genetical researches are carried out on E. coli for the study of genetic engineering.
39. (c) Halophiles Archaebacteria : These are facultative anaerobes, chemoorganotrophs gram negative archaebacteria found in salt lakes, salt pans, dead sea. That produce salt by solar evaporation of sea.
40. (c) In many bacteria (specially gram +ve) the plasma membrane gives rise to infoldings called mesosome. It is have respiratory enzymes like succinic dehydrogenase cytochrome oxidase for respiration.

Life cycle/Reproduction in bacteria

1. (a) The number of bacteria becomes double after each division.
2. (a) In the process of transduction, virus is used as a carrier in the transfer of DNA from one bacterial cell to other.
3. (d) 1248

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256.

11. (b) Sulphur takes part in the composition of amino acids like cystein, cystine, methionine which are the parts of protein.
12. (a) Sex factor or F–factor are extra-chromosomal DNA particles which either integrate with main DNA or remain independent of main DNA.
13. (c) Transformation experiment was first discovered by Griffith (1928) in case Diplococcus pneumoniae. But later on O.T. Avery, C.M. Macleod and M. McCarty (1944) studied transformation in detail.
14. (b) It takes place by transferring DNA from capsulated to non-capsulated.
15. (a) During conjugation two bacteria cell comes together and formed a conjugation tube. By this tube genetic material reach from donor to recipient bacteria.
16. (a) The phage l DNA attaches to the specific site of bacterial genome with the help of l integrase enzyme. The phase DNA in this lalent (non virulent) form is called provirus or prophage (integrated viral DNA with the host bacterial DNA).

Economic importance of bacteria

1. (a) This bacteria converts lactose sugar of milk into lactic acid and condenses casein protein and milk converts into curd.
2. (d) Clostridium is saprophytic, anaerobic N₂ fixing bacteria and have ability to fix atmospheric N₂ in to NH₃.
3. (c) Bacteria causes N₂ fixation.
4. (b) Clostridium dissolves the pectic material and isolate the fibers.
5. (b) Bacteria causes the curing of tea and coffee by which bitterness is removed and flavour is added.
6. (d) Mycoderma aciti convert the sugar in to acetic acid (vinegar).
7. (b) Bacillus megatherium synthesize vit–B₁₂.
8. (b) Aerobic breakdown of organic matter without release of foul gases is called Decay.
9. (d) The main role of bacteria is as a decomposer. The bacteria decompose the complex organic compounds into simple one which are reused in carbon cycle.
10. (c) Denitrifying bacteria turns NO₃ ® NO₂ ® NH₃ ® N₂.
11. (d) Some bacteria can fix atmospheric N₂ like Azotobacter and Clostridium, some bacteria can change nitrogen of ammonia into nitrate like Nitrosomonas and some bacteria help in biogeochemical cycle by braking of complex organic compound into simple inorganic compound.
12. (a) Rhizobium is symbiotic nitrogen fixing bacteria.
13. (b) NH₄NO₂NO₃.
14. (b) Non-symbiotic bacteria are also called free-living nitrogen fixing bacteria e.g. Anabaena, Nostoc, Aulosira etc. They are agriculturally important.
15. (c) They lack heterocyst. That is why, they can not take part in  fixation.
16. (d) Plasmid is used in biotechnology or genetic engineering for making the multiple copies of desired genes (DNA segment). Because plasmid has the capacity to bind with eukaryotic DNA.
17. (d) Biofertilizers include those organism, which enhance the fertility of soil.
18. (d) Lactobacillus casei and Streptococcus lactis at
19. (b) In this process bacteria decompose the pectin of the plant to liberate fibres. The process of fibre reparation is known as retting. This process is carried out by clostridium butyriam.
20. (c) Azotobacter (aerobic) is a free living N₂, fixing bacteria. it is developed in root nodules and fix atmospheric N₂ into ammonia in symbiotic association with leguminous plants.

Bacterial diseases

1. (b) On the basis of his work Pasteur proposed “germ theory of disease” which was recognised by medical scientists very soon.
2. (d) Mycobacterium tuberculosis is releases the mycolic acid called cord factor.
3. (d) DPT (Diphtheria, Tetanus vaccine) : This vaccine was prepared on the basis of theory proposed by Louis Pasteur. This is effective against three diseases like diptheria, whooping cough and tetanus.
4. (b) Crown gall is caused by Agrobacterium tumefaciens.
5. (c) Diplococcus pneumoniae bacteria.
6. (b) Bacteria Bacillus anthracis caused anthrax disease.
7. (c) Leprosy is caused by Mycobacterium leprae bacteria.

Mycoplasma

2. (b) Little leaf of brinjal : In this disease, the leaves of Brinjal remain small in size because mycoplasma inhibits leaf expansion of leaf cells.
3. (c) Mycoplasma are cell wall less cells but show multiplication like bacteria, so that they are termed as cell wall less bacteria.
4. (a) Penicillin and vancomycin inhibits the cell wall synthesis.
5. (c) Elementary bodies are related with asexual reproduction of mycoplasma. When cell of mycoplasma divides into minute bodies, these bodies are called elementary bodies.
6. (c) Cuscuta reflexa (Dodder) is parasite on angiosperms through which viruses and mycoplasma transmit.
7. (c) Mycoplasma salivarium inhibit the food as well as blood to the developing embryo in pregnant female, which cause abortion.
8. (d) Both mycoplasma and L-form bacteria are wall less.
9. (b) Mycoplasma is irregular in shape and divides by simple binary fission.
10. (a) Due to the absence of cell wall, mycoplasma are highly elastic and readily change the shape, hence the mycoplasmas are irregular and quite variable in shape. This nature is called pleomorphism.
11. (b) Because mycoplasma lacks cell wall where as penicillin acts on cell wall.
12. (d) Mycoplasma can grow out side the host cell. Thus it is clear that mycoplasma are not obligate parasite like viruses.
13. (b) Mycoplasma lacks cell wall, therefore the outermost existing layer is cell membrane.
14. (c) Mycoplasma is also known as pleuropneumonia like organisms (PPLO).

Cyanobacteria / Blue green algae

2. (c) Myxophyceae is another name of cyanobacteria which are moneran.
3. (c) Each heterocyst is connected with vegetative cells, on two sides through the prominent pores into the wall. Which later on one occupied by a refractive cynophycean granule called pollar nodule.
4. (c) Chlorophyll-b is found in eukaryotic photoautotroph.
5. (c) Nostoc help in N₂ fixation so called biofertilizers or green manure.
6. (a) Blue green algae cell is covered by a gelatenous sheath. It shows prokaryotic organisation.
7. (c) Nostoc phycocearum : Species is found in ice, or in temperate (cold) conditions due to which it is called as cryophytic alga.
8. (c) Cilia and flagella absent in blue green algae.
9. (c) Anabaena is found symbiotically in Azolla and help in N₂ fixation.
10. (c) Cyanobacteria appeared in precambrian period around 3.2 billion years ago and were the first to have oxygenic photosynthesis to evolve O₂ in photosynthesis that caused conversion of primitive reducing atmosphere to present day oxidising atmosphere (oxygen revolution).
11. (c) Because they have heterocyst for nitrogen fixation and chlorophyll for photosynthesis.
12. (c) Unicellular forms reproduce asexually by binary fission while filamentous forms are by Hormogones.
13. (c) Some cynobacteria possess heterocyst like Nostoc, Scytonema etc. Heterocyst is a site of N₂ fixation.
14. (c) Classification of algae is based on their pigments.
15. (a) Cyanobacteria is haploid so meiosis and fertilization is absent.
16. (b) Because they have photosynthetic lamellae for photosynthesis and heterocyst for -fixation.
17. (d) Spirulina is a rich source of proteins and vitamin B-complex as well.
18. (d) Blue green algae or cyanobacteria is designated as Prokaryotes.
19. (d) Sinorhizobium is a bacterium.
20. (a) Heterocysts are airtight anaerobic bodies in which enzyme nitrogenase fixes atmospheric nitrogen.
21. (c) Cynobacteria contain chlorophyll a and other photosynthetic pigment they synthesis their own carbohydrate food from CO₂ and also have water soluble pycobilin pigment c-phycocyanin.
22. (a) Nostoc possess special type of cells called heterocyst for free N₂ fixation that why nostoc is biofertliser.
23. (d) Cynobacteria have a water soluble phycobilin pigments. c-phycocyanin (blue) and c–phcoerythrin (red).

Critical Thinking Questions

2. (b) Salmonella typhi was discovered in 1880 by K.J. Eberth and isolate in pure culture in 1884 by G.Gaffky.
3. (b) Gram positive bacteria contain acid which attract the Mg ribonucleate particles, that provide stability against pH and temperature change.
4. (a) K₁₂ plasmid was first studied in E.coli, by two American scientist Lederberg and Tatum (1946).
5. (d) Since 1 ml volume of pipette = 10^–6 cubic metre.

       Diameter of 1 bacterium = 10^–3 mm = 10^–6 metre

       Hence the volume of 1 bacterium = 10^–6×10^–6×10^–6=10^–18

       Therefore number of bacterium

=.

9. (b) The cell wall of gram negative bacteria is 10–15 mm or 100–150Å thick.
10. (c) Porins is a proteins, which is found in the cell of Gram negative bacteria. Which function as channels for the entry and exist of hydrophilic low molecular weight substances.
11. (b) Marine archaebacteria cell consists of branched chain of lipids. This enables them to tolerate extremes of heat.
12. (b) Protein contain sulphur while it is not present in nucleic acid.
13. (d) As we know that bacterium divides after every 35 minutes through simple mitotic division therefore number of divisions are

Since one bacterium on division produces two cells so cell concentration after 175 minutes will be

15. (b) Dextrins are soluble polysaccharides formed by simple sugar through the bacteria like Leuconostoc mesenteroids or its enzyme called dextran sucrose.
16. (c) Protein of fresh meat is putrefied by Proteus in the absence of O₂. The process is called putrefaction.
17. (b) Bacillus thuriginensis produces a Biopesticide called thurioside. The bacterium is also sprayed as spores to control insect pests.
18. (a) Genetically modified Pseudomonas can decompose organic product like petroleum, oils etc.
19. (c) Pseudomonas sp. spoil the food stuff. Consumption of such food may caused stomach pain.
20. (b) Mycoplasma are sensitive to tetracycline and resistant to penicillin, because they lack cell wall.
21. (d) Mycoplasma fermentatus and M.hominis cause infertility in man and olitis media (inflammation of middle ear).
22. (a) The Nostoc plant is filamentous and the thrichomes are unbranched and appear moniliform.
23. (b) Myxoxanthophyll is photosynthetic pigment and found in cyanobacteria.

Assertion and Reason

1. (a) Bacterial cell is prokaryotic. It lacks true nucleus, membrane bound organelles and sexual reproduction.
2. (b) Bacteria have different shapes spherical, rod, and spiral are three important type. Cocci may be in cluster or chain form  or single and bacilli may be single, in pair in chain.
3. (b) Bacteria utilize the wavelengths longer than 700 nm for photosynthesis and the reaction centre is P-890 the reductant is NADH + H⁺. In bacteria donor may be H₂S or malate or succinate.
4. (a) Rhizobium form a symbiotic association with roots of leguminous plants producing root nodules. These bacteria reside inside the nodules and reduce atmospheric nitrogen (N₂) to ammonia. The fixed nitrogen is taken up by plant. In return the plant provides nutrients both and protection to bacteria.
5. (a) Plant cells are characterized by the presence of a rigid cell wall on the basis of which they can be differentiated from animal cells. Hence classified among plants.
6. (a) In bacterial cell, a well defined membrane-bound nucleus is not found, i.e., nuclear membrane, nucleolus and chromosomes, like a typical eukaryotic cell, are absent. It contains a single chromosome, consisting of a ringed or circular DNA filament associated with a small amount of RNA and non-histone proteins.
7. (c) The cell wall of Gram-negative bacteria contains alcohol-soluble lipid, while the cell wall of Gram-positive bacteria lacks the lipids and therefore resist decolourisation and retain the primary stain, appearing violet. Gram-negative bacteria are decolorized by organic solvents and therefore, take the counterstain, appearing red. Gram +ve bacteria does not attracted towards positive pole under influence of electric current.
8. (d) Chemosynthetic bacteria are without photosynthetic pigments. For the synthesis of their own organic food, (carbohydrates), they obtain carbon from CO₂ of the atmosphere, necessary energy from oxidation of inorganic or organic compounds, such as hydrogen sulphide (H₂S), ferrous compounds (Fe²⁺), molecular hydrogen (H₂) ammonia (NH₃) and nitrites (NO₂^—).
9. (a) Mostly pathogenic gram +ve bacteria releases exotoxins out side the cell and kills the W.B.C. and causes the disease.
10. (a) Endospore formation, a portion of cytoplasm and a copy of bacterial chromosomes dehydrate and get encased by three heavy, protective spore coats. This spores remain viable for several years and can tolerate the harshest of environments.
11. (a) Streptomyces produced broad spectrum of antibiotics by living microorganism capable of inhibiting or destroying other many types of microbes.
12. (d) Chemically bacteria consists of acetyl glycosamine, acetyl muramic acid and a peptide chain of four or five amino acids. All these chemicals together form a polymer called peptidoglycan (= murein or mucopeptide). Some other chemical substances deposited on the cell wall are – teichoic acid, protein polysaccharides lipoproteins and lipopolysaccharides.
13. (a) Anabaena found symbiotically in the root nodules of many leguminous plants which helps in N₂
14. (a) Bacillus butschli is the Gram positive bacterium and its cell wall consist of acetyl muramic acid.
15. (c) In addition to bacterial chromosomes many bacteria have accessory rings of DNA called plasmids. Plasmids are absent in eukaryotic chromosome.
16. (c) A bacterial cell such as Escherichia coil is easily cultured in an aqueous solution containing glucose and various inorganic ions. In this medium, at 37°C, the cell mass divides and doubles in about 60 minutes. The generation time can be reduced to 20 minutes if purines and pyrimidines as well as amino acids are added to the medium. E.coli is Gram –ve bacteria as it gives negative result on treatment with gram strain.

17. (e) In some bacteria, nonmotile appendages called pili or fimbriae are also present. They take part in sexual reproduction, e., conjugation.
18. (a) The cell walls of bacteria are rigid, porous, boxline structures which provide physical protection to the cell. The rigid, covalently linked framework surrounding the bacterial cell is actually on large sacline molecule, a complex polysaccharide peptide called a peptidoglycan.
19. (e) Cell secretion occurs even in the prokaryotic cells (bacteria) in relation to the production of a variety of enzyme to the medium. In certain protozoa, vacuoles similar to the contraction expel water into the medium. Golgi complex are found, which by their contraction expel water into the medium. Golgi complex and other membrane found organelle are absent in prokaryotes.
20. (c) The bacteria play an important and dual role by disposing off the dead bodies and wastes of organism and by increasing the fertility of soil.
21. (b) Myxobacteria do not have flagella and move by gliding movement.

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