Life Sciences (XL) PYQs Feb 2023

Physiology Ecology and Evolution

The average moisture binding energy of a textured protein product (TPP) at 8% moisture content (dry basis) is 3200 cal.m

In biochemistry, enzyme kinetics dictates that substrate binding and catalytic efficiency determine reaction rates. Therefore Option NAT is correct as it reflects active-site specificity and regulation, supported by mechanistic studies and conserved across related systems.

Ref: Berg, Tymoczko, Gatto and Stryer, Biochemistry, 9th Edition, Chapter 13, Metabolism and Bioenergetics, covers glycolysis, citric acid cycle, oxidative phosphorylation and energy transduction detailing biochemical principles.

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Physiology Ecology and Evolution

If D10 for Salmonella in egg yolk is 0.75 kGy, calculate the radiation dose in kGy (rounded off to 2 decimal places) req

The principle of core biological organization explains that structure-function relationships govern cellular processes. Hence Option NAT fits best because it integrates fundamental life science principles, as documented in authoritative sources on general biology.

Ref: Alberts et al., Essential Cell Biology, 5th Edition, Chapter 1, Introduction to Cells, covers cellular organization and molecular mechanisms offering integrated perspective.

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Physiology Ecology and Evolution

A sample of glucose isomerase enzyme converts 15 umoles of substrate glucose into product fructose min¹ mL under standar

In biochemistry, enzyme kinetics dictates that substrate binding and catalytic efficiency determine reaction rates. Therefore Option NAT is correct as it reflects active-site specificity and regulation, supported by mechanistic studies and conserved across related systems.

Ref: Berg, Tymoczko, Gatto and Stryer, Biochemistry, 9th Edition, Chapter 13, Metabolism and Bioenergetics, covers glycolysis, citric acid cycle, oxidative phosphorylation and energy transduction detailing biochemical principles.

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Physiology Ecology and Evolution

The weight of 10 kg dried cauliflower containing 5% moisture (wet basis) after rehydration is 60 kg. If the fresh caulif

Biologically, photosynthetic regulation operates via light harvesting and carbon fixation coordinate energy flow. Thus Option NAT is appropriate since it supports efficient energy conversion, reinforcing core concepts taught in plant biology.

Ref: Raven, Evert and Eichhorn, Biology of Plants, 8th Edition, Chapter 22, Plant Development and Hormonal Control, explains phytohormones and environmental responses regulating growth.

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Physiology Ecology and Evolution

Orange juice is packaged aseptically and stored under ambient conditions. The degradation of vitamin C in the juice occu

The principle of molecular bonding explains that hybridization and orbital overlap dictate geometry and reactivity. Hence Option NAT fits best because it satisfies bonding and stability criteria, as documented in authoritative sources on chemistry.

Ref: Clayden et al., Organic Chemistry, 2nd Edition, Chapter 5, Pericyclic Reactions, covers Diels-Alder cycloaddition and stereochemistry providing foundation for organic transformations.

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Physiology Ecology and Evolution

Calculate the efficiency in percent (rounded off to I decimal place) of an oil expeller which yields 37 kg oil containin

Mechanistically, photosynthetic regulation involves light harvesting and carbon fixation coordinate energy flow. This validates Option NAT because it supports efficient energy conversion, a pattern repeatedly demonstrated in plant biology research.

Ref: Taiz et al., Plant Physiology and Development, 6th Edition, Chapter 7, Photosynthesis and Carbon Assimilation, discusses light reactions, Calvin cycle and carbon fixation providing insight into plant energy metabolism.

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Physiology Ecology and Evolution

During the exponential growth, it took 6 hours for the population of bacterial cells to increase from 2.5 × 10 ⁶ to 5 ×

This outcome reflects membrane organization, where lipid bilayer and protein trafficking maintain compartmentalization. Option NAT captures this correctly because it aligns with organelle function and transport, consistent with textbook descriptions and experimental observations in cell biology.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 10, Membrane Structure and Transport, discusses lipid bilayer organization, membrane proteins, transporters and selective permeability providing foundation for cellular compartmentalization.

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Microbiology Immunology and Biotechnology

The length of a double helical DNA molecule is 13.6 km. If the DNA double helix weighs 1 ×10−18 g per 1000 nucleotide pa

In chemistry, molecular bonding dictates that hybridization and orbital overlap dictate geometry and reactivity. Therefore Option NAT is correct as it satisfies bonding and stability criteria, supported by mechanistic studies and conserved across related systems.

Ref: Clayden et al., Organic Chemistry, 2nd Edition, Chapter 5, Pericyclic Reactions, covers Diels-Alder cycloaddition and stereochemistry providing foundation for organic transformations.

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Microbiology Immunology and Biotechnology

Wild-type Drosophila females having three linked genes (AABBCC) were crossed with triple recessive mutant (aabbcc) males

Mendelian segregation analysis shows allele distribution and recombination generate phenotypic variation. Consequently Option NAT emerges as the valid choice since it follows segregation and linkage principles, aligning with established principles in genetics literature.

Ref: Pierce, Genetics: A Conceptual Approach, 6th Edition, Chapter 3, Mendelian Inheritance, discusses segregation, independent assortment, genotype-phenotype correlation and pedigree analysis providing framework for genetic transmission.

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Cell Biology and Genetics

A mature rat sperm cell has 2.5 μg of genomic DNA that is equivalent of a haploid genome. Compared to this sperm cell, t

Mechanistically, membrane organization involves lipid bilayer and protein trafficking maintain compartmentalization. This validates Option NAT because it aligns with organelle function and transport, a pattern repeatedly demonstrated in cell biology research.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 10, Membrane Structure and Transport, discusses lipid bilayer organization, membrane proteins, transporters and selective permeability providing foundation for cellular compartmentalization.

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Cell Biology and Genetics

In a population of 1000 wild dogs in a grassland, 360 and 480 dogs had black body colour with genotypes BB and Bb, respe

Mechanistically, Mendelian segregation involves allele distribution and recombination generate phenotypic variation. This validates Option NAT because it follows segregation and linkage principles, a pattern repeatedly demonstrated in genetics research. This mechanism is extensively documented and reinforced by experimental data across multiple model systems and textbook discussions.

Ref: Pierce, Genetics: A Conceptual Approach, 6th Edition, Chapter 3, Mendelian Inheritance, discusses segregation, independent assortment, genotype-phenotype correlation and pedigree analysis providing framework for genetic transmission.

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Cell Biology and Genetics

The frequencies for autosomal alleles A and a are p = 0.5 and q = 0.5, respectively, where A is dominant over a. Under t

Biologically, Mendelian segregation operates via allele distribution and recombination generate phenotypic variation. Thus Option NAT is appropriate since it follows segregation and linkage principles, reinforcing core concepts taught in genetics.

Ref: Griffiths et al., Introduction to Genetic Analysis, 11th Edition, Chapter 5, Linkage and Recombination, explains chromosomal mapping, crossing over and recombination frequencies underlying inheritance and variation.

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