OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www wisedane
OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www. wisedane. com
BIOLOGY BIOLOGICAL CLASSIFICATION SET 2 MCQ’s
Q 1. The classification system proposed by linnaeus was a _____ kingdom system of classification. (a) two (b) three (c) four (d) five
ANSWER (A) EXPLANATION Ø Before 1969, all the organisms had been divided into two groups-plants and animals, mainly on the basis of presence or absence of cell wall. Linnaeus (Father of taxonomy) founded two kingdoms – kingdom Plantae and kingdom Animalia in his two kingdom system of classification.
Q 2. Which of the following characters served as the criteria for five kingdom system of classification as used by R. H. Whittaker? (a) Cell structure and thallusorgani-zation (b) Mode of nutrition and reproduction (c) Phylogenetic relationships (d) All of these
ANSWER (B) EXPLANATION Whittaker used five criteria for delimiting the kingdoms : Ø Complexity of cell structure, prokaryotic and eukaryotic Ø Complexity of body structure of structural organization, unicellular and multicellular, Ø Mode of nutrition which is divergent in multicellular kingdoms – photoautotrophy in Plantea, absorptive heterotrophy in Fungi and ingestive heterotrophy in Animalia. Photoautotrophic nutrition is also called holophytic nutrition while heterotrophy is known as holozoic nutrition. Absorptive heterotrophy is saprobiotic (saprophytic) nutrition. Ø Ecological life style like producers (Plantae). Decomposers (Fungi) and consumers (Animalia). Ø Phylogenetic relationships.
Q 3. In whittaker’s five kingdom system of classification, eukaryotes are distributed among A. Two kingdoms B. Three kingdoms C. Four kingdoms D. All the five kingdoms
ANSWER (C) EXPLANATION Ø In Whittakr’s five kingdom system of classification, eukaryotes are distributed among four kingdoms: Protista, Plantae, Fungi and Animalia. Kingdom Monera includes all prokaryotes e. g. , mycoplasma, bacteria, actinomycetes and cyanobacteria (blue green algae).
Q 4. Which one of the following is an incorrect statement regarding mycoplasma? A. They lack a cell wall. B. They are the smallest living cells. C. They cannot survive without oxygen. D. They are pathogenic in plants and animals.
ANSWER (C) EXPLANATION Mycoplasma or mollicutes are the simplest and the smallest of the free living prokaryotes classified under kingdom Monera. They were discovered in pleural fluid of cattle suffering from pleuropneumonia (Nocard and Roux, 1898). The size ranges from 0. 1 -0. 15 pm. A cell wall is absent. Plasma membrane forms the outer boundary of the cell. They mostly produce pleuropneumonia in domestic animals, a typical pneumonia and mycoplasmal urethritis in humans, little leaf disease of brinjal and witche, broom in plants. Mycoplasma can survive without o 2
Q 5. Select the pair that consists of plant or animal bacterial diseases. A. Cholera and typhoid B. Citrus canker and crown gall C. Malaria and dengue D. Both (a) and (b)
ANSWER (D) EXPLANATION Ø Pathogen of cholera is Vibrio Cholerae bacterium. Cholera is transmitted by contaminated water. Ø Typhoid or enteric Fever spreads through contaminated water in which bacterium Salmonella typhi is present. Ø Citrus canker and crown gall are bacterial diseases of plants caused by Xanthomonas citri and Agrobacterium tumefaciens respectively.
Q 6. Bacteria are grouped under four categories according to their shape. Study the given figures and select the correct option regarding this. a b c d A B C D Cocci Bacilli Spirilla Vibrio Spirilla Bacilli Vibrio Cocci Bacilli Spirilla Cocci Vibrio
ANSWER (C) EXPLANATION Ø Bacteria are grouped under four categories based on their shapes: the spherical coccus (pl. : cocci), the rodshaped and the spiral spirillum (pl. : spirilla).
Q 7. Read the following statements regarding methanogens and select the correct option. I. They are included in the group Arc-haebacteria. II. They are responsible for the produ-ction of biogas in gobar gas plants. III. They live in hot sulphur springs. IV. They are strictly anaerobic. A. Statements (i) and (ii) and are correct B. Statements (i), (ii) and (iv) are corr-ect C. Statements (ii), (iii) and (iv) are corr-ect D. All statements are correct.
ANSWER (B) EXPLANATION Ø Methanogens are a type of archaebacteria which are strict anaerobes. Nutritionally they are autotrophs which obtain both energy and carbon from decomposition products. Theyoccur in marshy areas where they convert formic acid and carbon dioxide into methane with the help of hydrogen. This capability is commercially exploited in the production of methane and fuel gas inside gobar gas plants e. g. , Methanobacterium, Methanococcus.
Q 8. Given figure is of filamentous blue green alga nostoc. Identify the parts marked as A and B and select the correct option.
ANSWER (A) EXPLANATION Ø Nostoc occurs in both aquatic and subaerial habitats. A dense mucilage covering (labeled as B in the given figure is present on the outside. Each trichome is beaded, S-shaped and consists of a large number of vegetative cells, a few terminal and intercalary large pale coloured heterocysts labeled as A in the given figure) and thick-walled resting cells called akinetes. Heterocysts are specialized to perform nitrogen fixation.
Q 9. Which of the following statements is incorrect regarding the structure of a typical bacterial cell? A. Cells possess naked circular DNA which is folded to form nucleoid. B. Cells are surrounded by a pepti-doglycan cell wall and a mucilaginous sheath C. Cells possess well developed membrane bound cell organelles. D. Ribosomes in these cells are 70 S in nature
ANSWER (C) EXPLANATION Ø In a bacterial cell, membrane bound cell organelles as found in eukaryotes are absent. Various structures present in the cytoplasm of a prokaryotic cell include mesosomes, 70 S ribosomes, nucleoid, plasmids. Gas vacuoles, food reserve, etc.
Q 10. ____ Is the most common of rep-roduction in bacteria. A. Binary fission B. Endospore formation C. Conjugation D. Sexual reproduction
ANSWER (A) EXPLANATION Ø Reproduction in bacteria occurs by three methods binary fission, sporulation and sexual reproduction. Binary fission is the most common method bacterial multiplication under favourable conditions, in which a mature bacterium divides into two equal daughter calls.
Q 11. Cyanobacteria are classified under which of following kingdoms? (a) Monera (b) Protista (c) Algae (d) Plantae
ANSWER (A) EXPLANATION Ø Cyanobacteria or blue-green are algae are Gram + photosynthetic prokaryotes which perform oxygenic photo synthesis. Photosyntheitic pigments include chlorophyll a, carotenoids and phycobilins. Cyanobacteria are classified under kingdom Monera. Ø Cyanobacterial cell structure is typically prokaryotic – one envelope organization with peptidoglycan wall, naked DNA, 70 S ribosomes and absence of membrance bound structures like endoplasmic reticulum, mitochondria, Golgi bodies, plastids, lysosomes, sap vacuoles. Ø The outer part of the protoplast, called chromoplasm, contains a number of photosynthetic thylakoids.
Q 12. A dikaryon is formed when A. Melosis is arrested B. The two haploid cells do not fuse immediately C. Cytoplasm does not fuse D. Non of the above.
ANSWER (D) EXPLANATION Ø Dikaryon is a stage/phase of a cell, in which, there are two nuclei. This condition arises, if fusion of cytoplasm (plasmogamy) is not immediately followed by fusion of nuclei (karyogamy), i. e. , there is a delay between them. Such cells are called dikaryotic cells. This conditions is found in higher fungi where karyogamy is delayed (with respect to plasmogamy) and is called dikaryophase.
Q 13. Contadium vivum fluidum was proposed by A. D. J. Ivanowsky B. M. W. Beijerinck C. Stanley D. Robert Hooke.
ANSWER (B) EXPLANATION Ø Martinus William Beijernick (a Dutch microbiologist and botanist) gave a phrase, “Contagium vivum fluidum” (Latin : “contagious living fluid”), to describe a virus. He underlined its (virus’s) ability to slip through the finest mesh filters then available, giving it almost liquid properties.
Q 14. Association between mycobiont and phycobiont are found in A. Mycorrhiza B. Root C. Lichens D. BGA.
ANSWER (C) EXPLANATION Ø Lichens are association (mutually beneficial) between fungus and alga. The fungal partner is mycobiont and algal partner is phycobiont. The mycobiont is usually an ascomycete and phycobiont is usually green algae. Lichens can grow in extremely inhospitable conditions. In many ecosystems they are the pioneer species. The role of mycobiont is providing body structure and anchorage and absorption of minerals and water. The role of phycobiont is mainly in providing food through photosynthesis.
Q 15. Difference between virus and viroid is A. Absence of protein coat in viroid but present in virus B. Presence of low molecular weight RNA in virus but absent in viroid C. Both (a) and (b) D. None of the above.
ANSWER (A) EXPLANATION Ø Viroids are smallest known agent of infectious diseases. They lack capsid as well as proteins (that are present in virus) and consist of only single stranded RNA. An example of the disease they cause is potato spindle tuber disease (PTSD).
Q 16. ______ Are important decomposers that cause decay and decomposition of dead bodies of plants and animals. A. Saprotrophic B. Saprotrophic fungi C. Plants, like Sarracenia D. Both (a) and (b)
ANSWER (D) EXPLANATION Ø Saprophytic bacteria are free living bacteria which obtain food from organic remains, e. g. , corpses, animal excreta, fallen leaves, fruits, meat, jams, jellies, bread and other products of plant and animal origin. Aerobic breakdown of organic compounds is known as decay. In nature saprophytic bacteria alongwith saprotrophic fungi are the decomposers of organic remains.
Q 17. Photosynthetic pigments of cyanobacteria (blue green algae include A. Chlorophylla B. Carotenes C. Xanthophylls D. All of these
ANSWER (D) EXPLANATION
Q 18. Cyanobacteria are used in agricultural fields for crop improvement because they cause A. N 2 fixation B. Algal blooms C. Photosynthesis D. All of these
ANSWER (A) EXPLANATION Ø Several cyanobacteria have the abllity of nitrogen fixation. The filamentous forms possess special large pale cells or heterocysts for this. Some of the fixe nitrogen comes out as excretion. After death of cyanobacteria the substraturm becomes rich in nitrogen. Such nitrogen fixing cyanobacteria are now regularly inoculated in the rice fields. This saves application of nitrogen fertilizers.
Q 19. Select the correct statement regarding heterocysts. A. These are present in some filamentous cyanobacteria such as Nostoc and Anabaena. B. These cells are specialaized to perform N 2 -fixation. C. These cells contain enzyme nitrogenise. D. Heterocyst is a large-sized pale
ANSWER (D) EXPLANATION Ø Heterocyst is a large-sized pale coloured thick-walled cell which occurs in terminal, intercalary or lateral position in filamentous cyanobacteria, e. g. , Nostoc. Ø The thick wall is impermeable to oxygen but permeable to nitrogen. Ø Mucilage sheath is absent photosystem ll is absent. Thylakoids lack phycobilisomes. Ø Therefore, photosynthesis is absent but cyclic photophosphorylation occurs. Ø Heterocyst is dependent for its nourishment on adjacent vegetative cells. Ø It has enzyme nitrogenase and so, it is specialized to perform nitrogen fixation.
Q 20. In 5 -kingdom classification system, the kingdom that includes the blue-green algae, nitrogen-fixing bacteria and methanogenic archaebacteria, is A. Plantae B. Fungi C. Protista D. Monera
ANSWER (D) EXPLANATION Ø Monera kingdom includes prokaryotes mycoplasma, bacteria, actinomycetes and cyanobacteria or blue green algae. Alongwith fungi, they are decomposers and mineralisers of the biosphere.
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