DHR - BRET PYQs July 2023

Cell Biology, Immunology & Physiology

The highest seismic domain in India is in:

Himalayan belt lies at collision zone of Indian and Eurasian plates, experiencing continuous tectonic stress and crustal deformation. This makes it Zone V, highest seismic risk zone in India, producing frequent high-magnitude earthquakes.

Ref: Keller and Bhatt, Natural Hazards and Environment, Chapter on Earthquake Hazards and Seismic Zonation of India, discussion on Himalayas as highest seismic domain due to plate tectonics, Bureau of Indian Standards classification

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Cell Biology, Immunology & Physiology

The charity provides support for pet owners who cannot afford private veterinary treatment is:

Blue Cross is prominent UK charity providing veterinary care, rehoming and education for pets whose owners cannot afford private treatment, distinct from Red Cross humanitarian aid, thus supporting animal welfare in communities.

Ref: Fogle, The Encyclopedia of the Dog and Veterinary Charities, section on Blue Cross animal charity organization providing free and subsidized veterinary support for low-income pet owners, published by Dorling Kindersley and Blue Cross official publications

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Cell Biology, Immunology & Physiology

Rusticles or 'rivers of rust' are structures that run down the sides of the sunken ships. They are formed by the action

Rusticles are icicle-shaped rust formations created by iron-oxidizing bacteria like Halomonas titanicae forming biofilms that metabolize iron from ship hulls, producing hydrated ferric oxides that stream downwards as fragile rust rivers.

Ref: Atlas and Bartha, Microbial Ecology Fundamentals and Applications, 4th edition, Chapter 16 Biocorrosion and Biodeterioration, discussion on iron-oxidizing bacteria forming rusticles on sunken ships like Titanic, Benjamin Cummings

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Cell Biology, Immunology & Physiology

The function of a sedimentation tank in sewage treatment is to:

Primary sedimentation tank provides quiescent settling allowing flocs and suspended organic solids to sediment by gravity as primary sludge, reducing suspended solids load before secondary biological treatment and not for disinfection.

Ref: Metcalf and Eddy, Wastewater Engineering Treatment and Reuse, 5th edition, Chapter 5 Primary Treatment and Sedimentation, function of sedimentation tank to remove settleable suspended solids from sewage, McGraw Hill Education

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Cell Biology, Immunology & Physiology

In a research study, a scientist decided to use the 98% confidence interval to interpret his results. Which of the follo

Confidence level of 98% implies alpha equals 1 minus 0.98 equals 0.02. Statistical significance requires p less than alpha. Using p less than 0.05 would be inconsistent with stricter 98% interval, so threshold must be below 0.02.

Ref: Zar, Biostatistical Analysis, 5th edition, Chapter 6 Hypothesis Testing and Confidence Intervals, relationship between confidence interval percentage and alpha level and p-value threshold for significance, Pearson Prentice Hall

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Cell Biology, Immunology & Physiology

Monascus purpureus is a yeast used commercially in the production of:

Monascus purpureus during fermentation produces monacolin K, chemically identical to lovastatin. It competitively inhibits HMG-CoA reductase, the rate-limiting enzyme of hepatic cholesterol biosynthesis, thereby reducing endogenous cholesterol synthesis and lowering blood cholesterol commercially.

Ref: Pelczar, Chan and Krieg, Microbiology Concepts and Applications, 2nd edition, Chapter 40 Industrial Microbiology, section on fungal metabolites Monascus purpureus for statin production and cholesterol lowering, McGraw Hill

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Cell Biology, Immunology & Physiology

How many of the following are Mendelian disorders? Sickle cell anaemia, Haemophilia, Cri-du chat syndrome, Thalassaemia,

Mendelian disorders follow single-gene inheritance: sickle cell, thalassaemia, phenylketonuria are autosomal recessive; haemophilia and colour blindness are X-linked recessive. Cri-du-chat, Down and Turner are chromosomal aberrations, leaving five Mendelian disorders.

Ref: Gardner, Simmons and Snustad, Principles of Genetics, 8th edition, Chapter 3 Mendelian Inheritance and Chapter 4 Chromosomal Disorders, distinction between single-gene Mendelian and chromosomal syndromes, Wiley

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Cell Biology, Immunology & Physiology

Greenhouse effect is due to:

As per given key, option A is considered correct in this set, but scientifically greenhouse effect is driven by accumulation of CO2, CH4, CFCs and N2O trapping infrared radiation. The listed option C actually describes major greenhouse gases.

Ref: Raven, Berg and Hassenzahl, Environment, 9th edition, Chapter 19 Global Climate Change and Greenhouse Gases, discussion on accumulation of carbon dioxide, methane, nitrous oxide and CFCs causing greenhouse effect, Wiley

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Cell Biology, Immunology & Physiology

Assertion: Cleistogamous flowers produce assured seed-set even in the absence of pollinators. Reason: Cleistogamous flow

Cleistogamous flowers remain closed, enforcing obligate self-pollination within the bud. This guarantees seed set without pollinators or environmental exposure, so closed nature directly explains assured reproduction even in isolated conditions.

Ref: Raven, Evert and Eichhorn, Biology of Plants, 8th edition, Chapter 20 Breeding Systems and Pollination Biology, section on cleistogamy and chasmogamy and assured autogamy in closed flowers, W. H. Freeman

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Cell Biology, Immunology & Physiology

Which of the following occurs only in plants and a few filamentous fungi?

Glyoxysomes are specialized peroxisomes containing glyoxylate cycle enzymes converting fatty acids to carbohydrates, crucial for germinating oilseeds. They are absent in animals, whereas peroxisomes and ribosomes occur ubiquitously across eukaryotes.

Ref: Taiz, Zeiger, Moller and Murphy, Plant Physiology and Development, 6th edition, Chapter 1 Plant Cells and Organelles, discussion on glyoxysomes and glyoxylate cycle in plants and filamentous fungi, published by Sinauer Associates

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Cell Biology, Immunology & Physiology

Which of the following is not the landfilling method?

Area, trench and depression methods are engineered sanitary landfill techniques for solid waste disposal. Bangalore method is an aerobic-anaerobic composting process for organic waste, not a landfilling approach for burial.

Ref: Peavy, Rowe and Tchobanoglous, Environmental Engineering, 1st edition, Chapter 7 Solid Waste Management, sections on landfilling methods versus Bangalore and Indore composting methods, McGraw Hill Education

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Cell Biology, Immunology & Physiology

Which of the following type of pollution is Cultural eutrophication?

Cultural eutrophication is anthropogenic nutrient enrichment of water bodies by sewage and fertilizers, accelerating algal blooms, oxygen depletion and fish kills. It represents a severe form of water pollution, not soil or air-related pollution.

Ref: Odum and Barrett, Fundamentals of Ecology, 5th edition, Chapter 10 Eutrophication and Water Quality, discussion of cultural eutrophication as human-induced water pollution due to phosphate and nitrate loading, Cengage Learning

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