Zoology & Ecology

Zoology & Ecology

Which of the following is true?

Nutrient broth is simple undefined basal medium containing peptone, beef extract and sodium chloride supporting growth of non-fastidious organisms without selective or differential additives. Agar lacks nutrients, chocolate medium is enriched not selective, and selective substances added create selective media not enrichment.

Ref: Cappuccino and Sherman, Microbiology: A Laboratory Manual, 11th Edition, Chapter Culture Media Types, defines nutrient broth as basal medium, agar as solidifying agent, chocolate enriched media and selective versus enrichment media, published by Pearson Education.

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Zoology & Ecology

Definitive host of guinea worm is

Guinea worm Dracunculus medinensis has humans as definitive host where adult females reside subcutaneously and release larvae. Cyclops copepod acts as intermediate host ingesting larvae. Snail hosts schistosomes and liver flukes, while ticks transmit protozoa but not guinea worm.

Ref: Neva and Brown, Basic Clinical Parasitology, 6th Edition, Chapter Nematodes Dracunculus medinensis, defines human as definitive host for guinea worm and Cyclops copepod as intermediate host life cycle, published by Prentice Hall Appleton Lange.

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Zoology & Ecology

Phenol co-efficient indicates

Phenol coefficient or Rideal-Walker test compares disinfectant killing power to phenol against Salmonella Typhi and Staphylococcus aureus under standard conditions. Higher coefficient indicates greater efficacy than phenol. It measures antimicrobial efficacy, not purity, dilution or quantity of disinfectant preparation.

Ref: Rutala and Weber, Disinfection, Sterilization and Antisepsis, Chapter Phenol Coefficient Tests, explains Rideal-Walker method measuring disinfectant efficacy relative to phenol killing of test organisms, published by Association for Professionals in Infection Control.

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Zoology & Ecology

Which of the following is not transmitted by soil?

Brucella spreads via direct contact with infected reproductive tissues, milk and ingestion, not via soil persistence. Coccidioidomycosis inhaled arthroconidia from arid soils, Clostridium tetani spores persist in soil causing tetanus, and Bacillus anthracis spores survive long in soil causing anthrax.

Ref: Gordon and Jordan, Soil Microbiology Ecology, Chapter Pathogens in Soil, discusses soil-borne diseases coccidioidomycosis tetanus anthrax from spores and non soil-borne Brucella transmission via contact, published by Academic Press Elsevier.

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Zoology & Ecology

Which of the following organism is an obligate aerobe?

Pseudomonas aeruginosa is strictly aerobic non-fermentative rod utilizing oxygen as terminal electron acceptor with cytochrome oxidases, unable to grow anaerobically without nitrate. Escherichia coli and Staphylococcus are facultative anaerobes, while Acinetobacter is also strictly aerobic but less classic obligate textbook example.

Ref: Madigan, Martinko et al., Brock Biology of Microorganisms, 15th Edition, Chapter 17 Diversity of Bacteria, classifies Pseudomonas aeruginosa as obligate aerobe non-fermentative, aerobic respiration, cytochrome oxidase positive, published by Pearson Education.

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Zoology & Ecology

Which of the following is not an occupational zoonotic disease?

Occupational zoonoses affect veterinarians, abattoir workers and livestock handlers through animal contact. Brucellosis, anthrax and salmonellosis are classic occupational risks from infected tissues or products. Plague caused by Yersinia pestis transmits via flea vectors, not primarily occupational livestock exposure.

Ref: Acha and Szyfres, Zoonoses and Communicable Diseases Common to Man and Animals, 3rd Edition, Volume 1 Bacterioses, differentiates occupational zoonoses brucellosis anthrax salmonellosis from plague flea borne transmission, published by Pan American Health Organization.

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Zoology & Ecology

Yolk sac route inoculation should be done on

Yolk sac inoculation targets rapidly dividing embryonic endoderm for growth of Chlamydia and some viruses. Optimal yolk sac size and embryo susceptibility occur in 6-8 days old embryonated eggs. Older eggs 10-14 days are preferred for allantoic or amniotic routes.

Ref: Mahy and Van Regenmortel, Encyclopedia of Virology, 3rd Edition, Chapter Viral Cultivation in Embryonated Eggs, details yolk sac inoculation protocol using six to eight day old eggs for chlamydia growth, published by Academic Press Elsevier.

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Zoology & Ecology

Kennel cough in dogs is caused by

Kennel cough is highly contagious canine infectious tracheobronchitis causing harsh dry cough. Bordetella bronchiseptica, often with canine parainfluenza virus and adenovirus, is principal bacterial pathogen. Brucella melitensis causes abortions, Corynebacterium renale causes urinary infection and Bacillus anthracis causes anthrax.

Ref: Greene, Infectious Diseases of the Dog and Cat, 4th Edition, Chapter Respiratory Infections Bordetella, discusses kennel cough infectious tracheobronchitis caused by Bordetella bronchiseptica and parainfluenza virus, published by Elsevier Saunders.

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Zoology & Ecology

Tuberculosis lesions are prominent in digestive tract rather than in respiratory tract in

Avian tuberculosis caused by Mycobacterium avium primarily localizes in liver, spleen and intestine leading to prominent digestive tract granulomas in poultry. In contrast, cattle develop respiratory lesions due to Mycobacterium bovis aerosol transmission. Route of infection determines lesion distribution in species.

Ref: Swayne et al., Diseases of Poultry, 13th Edition, Chapter Mycobacterial Infections, describes Mycobacterium avium infection in poultry with digestive tract granulomas versus bovine tuberculosis respiratory lesions, published by Wiley Blackwell.

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Zoology & Ecology

Rumen Gas largely consists of Carbon Dioxide and methane in the proportion of

Ruminal fermentation by anaerobic microbes generates gases predominantly carbon dioxide about sixty-five percent and methane about thirty-five percent along with traces of hydrogen. This 65:35 ratio reflects carbohydrate fermentation and methanogenesis. Eructation expels these gases; bloat prevents expulsion causing distress.

Ref: Dukes, Physiology of Domestic Animals, 13th Edition, Chapter Ruminant Digestion, explains rumen fermentation gases, carbon dioxide sixty five percent and methane thirty five percent ratio, methanogenesis and eructation, published by Cornell University Press.

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Zoology & Ecology

Elicitors are molecules that:

Elicitors are biotic or abiotic molecules such as oligogalacturonides, chitin or salicylic acid that trigger plant innate immunity. They activate phytoalexin synthesis, PR proteins and hypersensitive response. They do not primarily induce cell division, hairy roots or general growth stimulation.

Ref: Taiz, Zeiger et al., Plant Physiology and Development, 6th Edition, Chapter 13 Biotic Interactions, defines elicitors, pathogen associated molecular patterns triggering defense responses, phytoalexins and PR proteins, published by Sinauer Associates Oxford.

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Zoology & Ecology

Which one of the following is caused by a fungus?

Powdery mildew is fungal disease caused by Erysiphales like Erysiphe producing white mycelial patches. Sandal spike is due to phytoplasma, crown gall by bacterium Agrobacterium tumefaciens, and citrus canker by bacterium Xanthomonas axonopodis. Therefore only powdery mildew is fungal.

Ref: Agrios, Plant Pathology, 5th Edition, Chapter Plant Diseases Caused by Fungi, covers powdery mildew caused by Erysiphales, white powdery growth, bacterial diseases crown gall and citrus canker, published by Academic Press Elsevier.

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