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1.	Which are likely to be present in deep sea waterA. ArchaebacteriaB. EubacteriaC. Blue-green algaeD. Saprophytic fungi
Answer» Correct Answer - A (a) Archaebacteria can flourish in hot springs and deep sea hypothermal vents. Eubacteria are true bacteria, characterised by the presence of rigid cell wall and if motile a flagellum. Most fungi are heterotrophic and absorb soluble organic matter from dead substrates and heance, are called saprophyte. The cyanobacteria have chlorophyll-a similar to green plants and are photosynthetic autotrophs.

2.	Organisms which obtain energy by the oxidation of reduced inorganic compounds are called:A. homoautotrophsB. chemoautotrophsC. saprozoicD. coproheterotrophs
Answer» Correct Answer - B (b) The organisms obtaining energy by chemical reactions independent of light are called chemotrophs. The reductants obtained from the environment may be inorganic (in case of chemoautotrophs) or organic (in case of chemoheterotrophs). Photoautotrophs organisms that make their own food by photosynthesis, using the light energy. Saprozoic organisms obtain food from dead and decaying matter.

3.	What is true about archaebacteriaA. All halophilesB. All photosyntheticC. All fossilsD. Oldest living beings
Answer» Correct Answer - D (d) The archaebacteria are able to flourish in extreme conditions of environment that are believed to have existed on the primitive earth. It is believed that these represent the early forms of life. Hence, archaebacteria are called "oldest,living beings" .

4.	Which one of the following statements about viruses is correctA. Nucleic acid of viruses is known as capsiddB. Viruses possess heir own metabolic systemC. All viruses contain both RNA and DNAD. Viruses are obligate parasites
Answer» Correct Answer - D (d) Viruses are non-cellular, obligate parasites. They have DNA or RNA as genetic material (never both). Genetic material of virus is covered in protein coatm known as capsid. Viruses do not contain their own metabolic system after entrance in them.

5.	Which of the following statements is not true for retrovirusesA. DNA is not present at any stage in the life cycle of retrovirusesB. Retroviruses carry gene for RNA dependent DNA polymeraseC. The genetic material in mature retroviruses is RNAD. Retroviruses are causative agens for certain kinds of cancer in man
Answer» Correct Answer - A (a) Retroviruses are so, named because they contain enzyme reverse transcriptase or RNA dependent DNA polymerase. The genetic material of these viruses is RNA, e.g. Rous Sarcoma Virus.

6.	Tobacco Mosaic Virus (TMV) genome isA. double stranded RNAB. single stranded RNAC. polyribonucleotidesD. proteinaceous
Answer» Correct Answer - B (b) Tobacco Mosaic Virus (TMV) is elongated, rod shaped, most thoroughly studied plant virus, with 95% protein and 5% RNA by weight. RNA is genomic, i.e. genetic material which is single stranded, linear, helically coiled, 5 mu in length with 6500 nucleotides long.

7.	Interferons areA. antiviral proteinsB. antibacterial proteinsC. anticancer proteinsD. complex proteins
Answer» Correct Answer - A (a) Interferons (IFNs) are anti-viral, regulatory giycoproteins, produced in virus infected cells ofr defence. They are non-antigenic protein of molecular weight 20000 daltons, discovered by Issacs and Lindemann (1957) . These IFNs induce formation of certain enzymes that supperess viral multiplication in host cell and protect host from further viral reinfection.

8.	The main difference between Gram positive and Gram negative bacteria lies in the composition ofA. cell wallB. cell membraneC. cytoplasmD. flagella
Answer» Correct Answer - A (a) Gram stain is a differential stain that differentiates bacteria into two groups - Gram +ve and Gram -ve. The basis of this differentiation lies in the composition (lipid contents) and thickness of cell wall of these bacteria. Bacteria are called Gram +ve, if they retain the crystal violet colour even after alcohol washing. Whereas, cell wall of Gram -ve bacteria is thin, rich in lipids and decolourise the crystal violet colour of Gram stain.

9.	the main role of bacteria in the carbon cycle involvesA. photosynthesisB. chemosynthesisC. digestion or breakdown of organic compoundsD. assimilation of nitrogenous compounds
Answer» Correct Answer - C (c) Huge amount of plants, animals and human wastes are decomposed by bacteria and fungi present in environment and large quantity of `CO_(2)` necessary for photosynthesis is released into the atmosphere.

10.	Photosynthetic pigments of bacteria are located inA. leucoplastsB. chloroplastsC. chromoplastsD. chromatophores
Answer» Correct Answer - D (d) In photosynthetic bacteria, small prarticles of 60 `mum` diameter, called chromatophores, are present. These are attached to the inner surface of the cell membrane, have no limiting membrane and possess bacteriochlorophyll. Chloroplast, leucoplast and chromoplasts are plastids present in eukaryotic cells. Chromoplasts Coloured plastids except green, give different type of colour appearance to different parts of the plant. Chloroplasts Green plastids take part in the process of photosynthesis. Leucoplasts Colourless plastids, mainly function as store house of various types of food.

11.	Which one belongs to monera?A. AmoebaB. EscherichiaC. GelidiumD. Spirogyra
Answer» Correct Answer - B (b) The kingdom - Monera (Gr. Monera = simple) includes simple, prokaryotic primitive organisms. It includes bacteria, archaebacteria, Actinomycetes, Mycoplasma, spirochaetes, rickettsiae, chlamydiae and cyanobacteria. Escherichia coli is the most studied bacterium. E. coli is an enteric bacteria, found in entire colon, secretes vitamin-K, `B_(3),B_(6),B_(12)` and folic acid.

12.	A few organism are known to grow and multiply at temperature of `100-105^(@) C`. They belong toA. Marine archaebacteriaB. thermophilic sulphur bacteriaC. hot-spring blue-green algae (cyanobacteria)D. thermophilic, subaerial fungi
Answer» Correct Answer - A (a) The cell membrane of archaebacteria is consists of branched chain lipids, long chain branched alcohols, phytanals, ether linked to glycerol. This helps them to withstand extreme conditions and temperature.

13.	The plasmidA. helps in respirationB. genes found inside nucleusC. is a component of cell wall of bacteriaD. is te genetic part in addition to DNA in microorganisms
Answer» Correct Answer - D (d) Plasmids are small, self-replicating, extrachromosomal, non-essential genetic elements in bacteria. Each plasmid has a ring of circular, supercoiled, double stranded DNA. They carry genes for replication and for one or more cellular non-essential functions. These are also called minichromosomes or dispensable autonomous elements.

14.	In bacterial chromosomes, the nucleic acid polymers areA. linear DNA moleculeB. circular DNA moleculeC. of two types - DNA and RNAD. linear RNA molecule
Answer» Correct Answer - B (b) Nucleoid or chromatin body or genophore in bacteria occupies 10-20% of cell, is present near the centre of cell. It consists of a single, circular DNA molecule in which all the genes are linked. It is over a thousand times longer than the cell itself and is, therefore, highly folded. It lacks the histone proteins.

15.	What is true for cyanobacteria?A. Oxygenic with nitrogenaseB. Oxygenic without nitrogenaseC. Non-oxygenic with nitrogenaseD. Non-oxygenic without nitrogenase
Answer» Correct Answer - A (a) Cyanobacteria (Gk. Kyanos = dark blue, bakterion = a staff) also known as blue-green algae. It is a very important group of photo synthetic bacteria in the history of life on earth. The cyanobacteria fix atmospheric nitrogenase and also show oxygenic photosynthetic.