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Question 1Arts

In the Odissi repertoire, which item is a pure dance piece that opens with a salutation to the deity and is performed without narrative miming?

  1. Abhinaya
  2. Moksha
  3. Pallavi
  4. Mangalacharan Correct answer.

Explanation

Mangalacharan is the invocatory pure-dance item of Odissi, beginning with a salutation to Jagannath and moving through rhythmic patterns without interpretive storytelling. It sets the auspicious tone for the recital.

Question 2Arts

The Sangeet Natak Akademi recognises a specific number of classical dance forms of India. Which number is officially recognised?

  1. Eight Correct answer.
  2. Ten
  3. Six
  4. Four

Explanation

The Sangeet Natak Akademi currently recognises eight classical dance forms: Bharatanatyam, Kathak, Kathakali, Kuchipudi, Odissi, Manipuri, Mohiniyattam and Sattriya. Sattriya was added in 2000.

Question 3Arts

Which rhythmic cycle (tala) is most characteristic of Kathak and is divided into sixteen matras?

  1. Ektaal
  2. Trital Correct answer.
  3. Jhaptal
  4. Rupak

Explanation

Trital is the sixteen-matras cycle central to Kathak, divided into four vibhags of four beats each. It is the most frequently used tala for both nritta and gat compositions.

Question 4Arts

In Bharatanatyam, the term 'araimandi' refers to which position?

  1. A fully erect standing posture with feet together
  2. A half-sitting posture with knees bent outward Correct answer.
  3. A seated cross-legged position
  4. A jump executed on the beat

Explanation

Araimandi is the half-sitting stance in which the knees bend outward and the torso stays upright, forming the basic grounded position for much of Bharatanatyam nritta. It contrasts with the deeper muzhumandi.

Question 5Arts

Which pair correctly matches a folk theatre form with its home state?

  1. Yakshagana - Karnataka Correct answer.
  2. Tamasha - Odisha
  3. Nautanki - Kerala
  4. Bhavai - Punjab

Explanation

Yakshagana is the traditional dance-drama of coastal Karnataka, combining music, dance and elaborate costume. The other pairings are mismatched with their states.

Question 6Arts

A Kathak dancer performs a sequence of rhythmic syllables recited aloud before executing them on the feet. Which term best describes this practice?

  1. Padhant Correct answer.
  2. Tatkar
  3. Chakkar
  4. Amad

Explanation

Padhant is the recitation of bols, the spoken rhythmic syllables, which the dancer then translates into footwork. It demonstrates command over tala and is a hallmark of Kathak training.

Question 7Arts

Which hand gesture (hasta) is used to depict a bee in classical Indian dance according to the Abhinaya Darpana?

  1. Mayura
  2. Pataka
  3. Kartarimukha Correct answer.
  4. Alapadma

Explanation

Kartarimukha, with the index and little fingers extended, is used among other meanings to suggest a bee hovering near a flower. The hasta vocabulary assigns multiple meanings to each gesture.

Question 8Arts

In the Natyashastra, the nine rasas are enumerated. Which of the following is one of them?

  1. Karuna Correct answer.
  2. Matra
  3. Tala
  4. Laya

Explanation

Karuna, compassion or pathos, is one of the nine rasas listed in the Natyashastra tradition. The others are shringara, hasya, raudra, veera, bhayanaka, bibhatsa, adbhuta and shanta.

Question 9Arts

Which of these is a characteristic feature of Manipuri dance?

  1. Elaborate facial make-up with green paint
  2. Sharp percussive footwork with rapid spins
  3. Gentle, rounded movements with the body kept soft and flowing Correct answer.
  4. Vigorous jumps and high extensions

Explanation

Manipuri is distinguished by soft, rounded, almost circular body movements with minimal facial distortion, often performed in the Ras Leela tradition. It avoids the sharp, percussive attack found in some other forms.

Question 10Arts

In Kuchipudi, the dancer may perform on a brass plate while balancing a pot on the head. This item is known as which of the following?

  1. Shabdam
  2. Jatiswaram
  3. Varnam
  4. Tarangam Correct answer.

Explanation

Tarangam is the Kuchipudi item in which the dancer executes rhythmic footwork on the rim of a brass plate, sometimes with a pot balanced on the head. It demonstrates balance and control.

Question 11Arts

In Bharatanatyam, which item is the longest and most demanding composition, alternating pure dance with expressive interpretation of a lyric?

  1. Tillana
  2. Kavuthuvam
  3. Alarippu
  4. Varnam Correct answer.

Explanation

The varnam is the central and most elaborate item of a Bharatanatyam margam, weaving nritta passages around the abhinaya of a line of text. It tests stamina, rhythmic precision and interpretive depth together.

Question 12Arts

A student is asked to identify the instrument that provides the melodic accompaniment in a Kathak recital. Which instrument is traditionally most associated with this role?

  1. Harmonium Correct answer.
  2. Mridangam
  3. Pakhawaj
  4. Tabla

Explanation

In Kathak, the harmonium typically carries the melodic line while the tabla provides percussion. The sarangi has also traditionally served the melodic role.

Question 13Arts

Which statement best distinguishes nritta from nritya?

  1. Nritta is abstract rhythmic movement, while nritya conveys meaning through expressive gesture Correct answer.
  2. Nritta is performed only by men, while nritya only by women
  3. Nritta uses no music, while nritya always uses music
  4. Nritta conveys narrative, while nritya is abstract rhythm

Explanation

Nritta is pure, abstract dance movement governed by rhythm and geometry with no intended meaning. Nritya adds expressive elements such as bhava and mudra to communicate a theme.

Question 14Arts

In the Natyashastra, which sage is credited with the composition of the text on dramaturgy and dance?

  1. Jayadeva
  2. Nandikeshvara
  3. Bharata Correct answer.
  4. Abhinavagupta

Explanation

The Natyashastra is traditionally attributed to the sage Bharata, who is said to have received the art from Brahma. It remains the foundational treatise on Indian performing arts.

Question 15Arts

A choreographer wants to depict the god Krishna playing the flute. Which hasta is most appropriate for holding the flute according to classical usage?

  1. Kangula
  2. Shikhara
  3. Mrigashirsha Correct answer.
  4. Suchi

Explanation

Mrigashirsha, with the fingers held to resemble a deer's head, is used among other meanings for holding a flute or a small object. The gesture is applied in Krishna-themed abhinaya.

Question 16Arts

Which of these distinguishes Mohiniyattam from Kathakali in terms of performance convention?

  1. Mohiniyattam is solo and lasya-dominant, while Kathakali is a group dance-drama with tamasic vigour Correct answer.
  2. Both rely on the same green facial make-up
  3. Both are exclusively male solo forms
  4. Mohiniyattam is a group dance-drama, while Kathakali is solo and lasya-dominant

Explanation

Mohiniyattam is typically a solo female form emphasising lasya, grace and gentle swaying movement. Kathakali is a large-scale dance-drama performed by a group with codified make-up and vigorous, tamasic energy.

Question 17Arts

In Bharatanatyam, what does the term 'jathi' refer to in a nritta passage?

  1. A hand gesture denoting a deity
  2. A costume ornament worn at the waist
  3. A melodic mode used for the song
  4. A rhythmic syllable sequence forming a rhythmic phrase Correct answer.

Explanation

Jathi denotes a rhythmic phrase composed of sollukattu syllables, which the nattuvanar recites while the dancer executes corresponding footwork. It is a purely rhythmic unit.

Question 18Arts

Which classical dance form originated in the temples of Assam and was codified in the Vaishnava satras?

  1. Odissi
  2. Sattriya Correct answer.
  3. Manipuri
  4. Kuchipudi

Explanation

Sattriya developed in the Vaishnava monasteries, or satras, of Assam and draws on the devotional tradition of Srimanta Sankardeva. It was recognised as a classical form in 2000.

Question 19Arts

A dancer ends a Bharatanatyam recital with a tillana. What is the defining structural feature of this item?

  1. It is built on rhythmic syllables with a short concluding sahitya passage Correct answer.
  2. It narrates a full episode from the Ramayana
  3. It is performed entirely in silence
  4. It consists only of a single slow abhinaya verse

Explanation

The tillana is a brisk pure-dance composition set to rhythmic syllables, with a brief line of text appearing near the end. It showcases rhythmic virtuosity and serves as a lively finale.

Question 20Arts

Which of the following correctly states the number of beats in the tala Jhaptal?

  1. Sixteen
  2. Twelve
  3. Seven
  4. Ten Correct answer.

Explanation

Jhaptal is a ten-matras cycle divided into four vibhags of 2-3-2-3. It is common in Kathak and Hindustani music for medium-tempo compositions.

Question 21Arts

A candidate is asked to identify the correct sequence of items in a traditional Bharatanatyam margam. Which sequence is correct?

  1. Padam, Alarippu, Varnam, Tillana, Shabdam, Jatiswaram
  2. Alarippu, Jatiswaram, Shabdam, Varnam, Padam, Tillana Correct answer.
  3. Varnam, Alarippu, Tillana, Padam, Shabdam, Jatiswaram
  4. Tillana, Padam, Varnam, Shabdam, Jatiswaram, Alarippu

Explanation

The traditional margam moves from the invocatory alarippu through jatiswaram and shabdam to the central varnam, then into the expressive padams and concludes with the tillana. The order builds from pure dance to expression and back to rhythmic finale.

Question 22Arts

In Kathak, a dancer performs a composition in which the footwork gradually accelerates through three tempos. Which term describes this progression?

  1. Bol
  2. Gat
  3. Laya Correct answer.
  4. Tukra

Explanation

Laya is tempo, and the progression from vilambit through madhya to drut laya is a standard Kathak device for building tension. The dancer synchronises footwork with the increasing speed.

Question 23Arts

Which statement correctly describes the use of the Natyashastra's concept of 'pravritti'?

  1. It denotes the emotional essence evoked in the spectator
  2. It denotes the physical warm-up before a recital
  3. It denotes regional stylistic conventions of costume, speech and behaviour Correct answer.
  4. It denotes the rhythmic cycle of a composition

Explanation

Pravritti in the Natyashastra refers to regional conventions of style, including dress, language and behaviour associated with different parts of India. It is distinct from rasa, which concerns aesthetic emotion.

Question 24Arts

Which of these best explains why abhinaya is described as having four aspects in classical theory?

  1. It covers four types of percussion instruments
  2. It covers four regional styles of dance
  3. It covers four different tempos used in a recital
  4. It covers bodily, verbal, costume and emotional means of expression Correct answer.

Explanation

Abhinaya is analysed through angika (body), vachika (speech or song), aharya (costume and make-up) and sattvika (inner emotional states). Together they communicate meaning to the audience.

Question 25Arts

Which classical dance form is traditionally associated with the Ras Leela depicting Radha and Krishna?

  1. Bharatanatyam
  2. Kathakali
  3. Sattriya
  4. Manipuri Correct answer.

Explanation

Manipuri dance is closely tied to the Vaishnava Ras Leela tradition, portraying Radha, Krishna and the gopis in circular group formations. The form's soft, devotional character reflects this heritage.

Question 26CBZ (Chemistry, Botany, Zoology)

In a freshly prepared aqueous solution of glucose, the cyclic hemiacetal forms predominate over the open-chain aldehyde form. Which statement best explains this observation?

  1. The aldehyde group is oxidised by dissolved oxygen, converting it into a carboxylic acid that cannot cyclise
  2. Intermolecular hydrogen bonding between separate glucose molecules locks the open-chain form in place
  3. Glucose exists only as a cyclic structure because the open-chain form violates valence rules for carbon
  4. The intramolecular attack of a hydroxyl group on the carbonyl carbon is entropically favoured and relieves ring strain in the six-membered product Correct answer.

Explanation

Cyclisation is an intramolecular nucleophilic addition in which the C5 hydroxyl oxygen attacks the C1 carbonyl carbon, giving a six-membered pyranose ring. Because the reacting groups are tethered within one molecule, the effective concentration is high and the equilibrium lies strongly toward the cyclic hemiacetal.

Question 27CBZ (Chemistry, Botany, Zoology)

A pollen grain of a flowering plant is examined and found to contain two haploid nuclei of unequal size within the pollen tube. Which pair of structures do these nuclei represent?

  1. A generative nucleus and a tube nucleus Correct answer.
  2. Two sperm cells delivered to the egg apparatus
  3. A vegetative nucleus and an antipodal cell
  4. Two synergids released from the embryo sac

Explanation

In a mature bicellular pollen grain the generative cell divides in the tube to give two male gametes, while the vegetative (tube) nucleus remains. Before that division, the two nuclei seen are the large vegetative/tube nucleus and the smaller generative nucleus that will produce the sperm cells.

Question 28CBZ (Chemistry, Botany, Zoology)

During the cardiac cycle, the first heart sound is produced by which event?

  1. Contraction of the atrial musculature during atrial systole
  2. Closure of the atrioventricular valves at the start of ventricular systole Correct answer.
  3. Closure of the semilunar valves at the end of ventricular ejection
  4. Opening of the atrioventricular valves during ventricular filling

Explanation

The first heart sound corresponds to the closure of the mitral and tricuspid (atrioventricular) valves as ventricular pressure rises above atrial pressure at the onset of ventricular systole. This closure prevents backflow into the atria and produces the low-pitched 'lub'.

Question 29CBZ (Chemistry, Botany, Zoology)

Which of the following is the correct IUPAC name for the compound formed when ethanol is dehydrated over hot concentrated sulphuric acid?

  1. Ethyne
  2. Ethane
  3. Ethene Correct answer.
  4. Diethyl ether

Explanation

Dehydration of ethanol at about 170 °C with excess concentrated sulphuric acid removes water and forms a carbon–carbon double bond, giving ethene (ethylene). At lower temperatures around 140 °C the main product is diethyl ether instead.

Question 30CBZ (Chemistry, Botany, Zoology)

A student observes a plant tissue in which the stomata are surrounded by two subsidiary cells whose common walls lie parallel to the guard cells. This arrangement is characteristic of which stomatal type?

  1. Anomocytic
  2. Anisocytic
  3. Diacytic
  4. Paracytic Correct answer.

Explanation

Paracytic (rubiaceous) stomata have one or more subsidiary cells flanking the guard cells with their long axes parallel to the stomatal pore. This distinguishes them from diacytic stomata, where the subsidiary cells lie at right angles to the guard cells.

Question 31CBZ (Chemistry, Botany, Zoology)

Which enzyme catalyses the fixation of carbon dioxide onto ribulose-1,5-bisphosphate during the Calvin cycle?

  1. Ribulose-1,5-bisphosphate carboxylase/oxygenase Correct answer.
  2. Glyceraldehyde-3-phosphate dehydrogenase
  3. Carbonic anhydrase
  4. Phosphoenolpyruvate carboxylase

Explanation

RuBisCO catalyses the addition of CO2 to ribulose-1,5-bisphosphate, yielding two molecules of 3-phosphoglycerate, the first stable product of the Calvin cycle. The same enzyme also catalyses the competing oxygenase reaction in photorespiration.

Question 32CBZ (Chemistry, Botany, Zoology)

In a cross between two heterozygous pea plants (Tt × Tt) for a completely dominant trait, what is the expected ratio of phenotypes in the offspring?

  1. 1 dominant : 1 recessive
  2. 9 dominant : 3 recessive
  3. 1 dominant : 2 intermediate : 1 recessive
  4. 3 dominant : 1 recessive Correct answer.

Explanation

A monohybrid cross of two heterozygotes gives a genotypic ratio of 1 TT : 2 Tt : 1 tt. Since the heterozygote shows the dominant phenotype, the phenotypic ratio collapses to 3 dominant : 1 recessive.

Question 33CBZ (Chemistry, Botany, Zoology)

Which nitrogenous base is present in RNA but absent from DNA?

  1. Uracil Correct answer.
  2. Adenine
  3. Thymine
  4. Cytosine

Explanation

RNA contains uracil in place of the thymine found in DNA. Both molecules share adenine, guanine and cytosine, so uracil is the diagnostic base of RNA.

Question 34CBZ (Chemistry, Botany, Zoology)

A 0.1 M solution of acetic acid has a pH of about 2.9, whereas 0.1 M hydrochloric acid has a pH of 1.0. Which factor best accounts for this difference?

  1. Acetic acid molecules are too large to allow complete solvation in water
  2. Hydrochloric acid reacts with water to produce more hydronium ions per molecule than acetic acid can
  3. Acetic acid has a lower molar mass than hydrochloric acid
  4. Acetic acid is only partially ionised because it is a weak acid with a small dissociation constant Correct answer.

Explanation

Acetic acid is a weak acid with Ka around 1.8 × 10⁻⁵, so only a small fraction of its molecules donate a proton in dilute solution. Hydrochloric acid is strong and ionises essentially completely, giving a hydronium concentration close to the formal concentration and therefore a much lower pH.

Question 35CBZ (Chemistry, Botany, Zoology)

Which of the following pairs of species is isoelectronic with the neon atom?

  1. Na⁺ and Cl⁻
  2. Na⁺ and F⁻ Correct answer.
  3. O²⁻ and S²⁻
  4. Mg²⁺ and K⁺

Explanation

Na⁺ has lost one electron from sodium (11 → 10 electrons) and F⁻ has gained one (9 → 10 electrons). Both therefore have 10 electrons, the same configuration as neon. Isoelectronic species must have equal total electron counts.

Question 36CBZ (Chemistry, Botany, Zoology)

In the reaction of propene with HBr in the presence of organic peroxides, the major product is 1-bromopropane rather than 2-bromopropane. Which mechanistic feature explains this outcome?

  1. The peroxide converts HBr into Br₂, which adds across the double bond by an ionic mechanism
  2. The reaction proceeds by an SN2 displacement of bromide on the alkene
  3. Bromine radicals add to the terminal carbon to give the more stable secondary carbon radical, which then abstracts hydrogen from HBr Correct answer.
  4. The alkene is protonated first to give the more stable secondary carbocation, which bromide then attacks

Explanation

Peroxides generate bromine radicals, which add to the alkene so that the radical centre ends up on the more substituted carbon, giving the more stable secondary radical. That radical then abstracts a hydrogen atom from HBr, placing bromine on the terminal carbon and giving the anti-Markovnikov product.

Question 37CBZ (Chemistry, Botany, Zoology)

A plant shows a stem with collateral open vascular bundles arranged in a ring, and its root has a diarch xylem. Which group of plants is most consistent with these features?

  1. Pteridophytes
  2. Bryophytes
  3. Dicotyledons Correct answer.
  4. Monocotyledons

Explanation

Dicot stems typically have vascular bundles arranged in a ring and open bundles containing cambium, and dicot roots commonly show diarch to tetrarch xylem. Monocot stems, by contrast, have scattered closed bundles and their roots are usually polyarch.

Question 38CBZ (Chemistry, Botany, Zoology)

In the C4 pathway, the first stable product of carbon fixation in the mesophyll cell is oxaloacetate. Which combination of enzyme and substrate accounts for this?

  1. RuBisCO acting on ribulose-1,5-bisphosphate
  2. Malic enzyme acting on malate
  3. PEP carboxykinase acting on oxaloacetate
  4. PEP carboxylase acting on phosphoenolpyruvate Correct answer.

Explanation

In C4 mesophyll cells, phosphoenolpyruvate carboxylase catalyses the carboxylation of phosphoenolpyruvate to give the four-carbon acid oxaloacetate. This enzyme has a high affinity for CO2 and lacks the oxygenase activity of RuBisCO, concentrating carbon for the Calvin cycle in bundle-sheath cells.

Question 39CBZ (Chemistry, Botany, Zoology)

A woman who is a carrier of an X-linked recessive disorder marries an unaffected man. What is the probability that a son born to this couple will be affected?

  1. 50 per cent Correct answer.
  2. 25 per cent
  3. 100 per cent
  4. 0 per cent

Explanation

A son receives his Y chromosome from his father and one of the mother's X chromosomes. Since the mother is heterozygous, half her X chromosomes carry the mutant allele, so each son has a 50 per cent chance of being affected regardless of the father's genotype.

Question 40CBZ (Chemistry, Botany, Zoology)

Which statement correctly describes the role of the loop of Henle in the mammalian nephron?

  1. It filters plasma under pressure to form the primary urine
  2. It reabsorbs glucose and amino acids completely from the filtrate
  3. It secretes hydrogen ions to regulate blood pH
  4. It creates a medullary osmotic gradient by countercurrent multiplication, allowing water reabsorption from the collecting duct Correct answer.

Explanation

The descending limb is permeable to water but not solute, while the ascending limb actively pumps out sodium and chloride but is impermeable to water. This countercurrent arrangement builds a hyperosmotic gradient in the medulla, which drives water reabsorption from the collecting duct under the influence of ADH.

Question 41CBZ (Chemistry, Botany, Zoology)

A patient's blood report shows a haematocrit of 60 per cent with normal plasma protein levels. Which interpretation is most appropriate?

  1. The patient has leukaemia because the haematocrit is elevated
  2. The patient is anaemic because the haematocrit is above the reference range
  3. The patient is polycythaemic, which raises blood viscosity and increases cardiac workload Correct answer.
  4. The patient has a bleeding disorder caused by platelet deficiency

Explanation

Haematocrit is the proportion of blood volume occupied by red cells, normally about 40–50 per cent in adults. A value of 60 per cent indicates an increased red cell mass, i.e. polycythaemia, which raises viscosity and can increase resistance to blood flow and cardiac work.

Question 42CBZ (Chemistry, Botany, Zoology)

Which structure in the human male reproductive system is the site of sperm maturation and storage before ejaculation?

  1. Vas deferens
  2. Epididymis Correct answer.
  3. Seminiferous tubule
  4. Prostate gland

Explanation

Sperm produced in the seminiferous tubules pass to the epididymis, where they undergo further maturation and are stored until ejaculation. During emission they are propelled through the vas deferens and mixed with secretions of the accessory glands.

Question 43CBZ (Chemistry, Botany, Zoology)

In an angiosperm ovule, the megaspore mother cell undergoes meiosis and the functional megaspore then divides mitotically three times. Which structure results?

  1. A seven-celled, eight-nucleate embryo sac Correct answer.
  2. A two-celled pollen grain
  3. A four-celled tetrasporic embryo sac
  4. A multicellular endosperm

Explanation

The Polygonum type of embryo sac development produces eight nuclei in seven cells: three antipodals, two synergids, one egg cell and a central cell with two polar nuclei. This follows three mitotic divisions of the functional megaspore without cytokinesis after each division.

Question 44CBZ (Chemistry, Botany, Zoology)

Which statement about the enzyme-catalysed reaction rate versus substrate concentration curve is correct?

  1. The rate approaches a maximum, Vmax, when the enzyme becomes saturated with substrate Correct answer.
  2. The rate is independent of substrate concentration at all concentrations
  3. The rate increases without limit as substrate concentration rises
  4. The rate decreases steadily as substrate concentration increases

Explanation

At low substrate concentration the rate rises almost linearly, but as active sites become occupied the increase slows and the rate plateaus at Vmax. This saturation behaviour underlies the Michaelis–Menten model, in which Km is the substrate concentration giving half of Vmax.

Question 45CBZ (Chemistry, Botany, Zoology)

A plant cell is placed in a solution whose solute potential is more negative than the cell sap, and the pressure potential is initially zero. What is the immediate result?

  1. Water enters the cell and the cell becomes turgid
  2. Water leaves the cell and the protoplast shrinks away from the wall Correct answer.
  3. Solutes move actively from the cell into the external solution
  4. There is no net movement of water because the membrane is impermeable

Explanation

Water potential equals solute potential plus pressure potential. If the external solution has a more negative solute potential and the cell's pressure potential is zero, the external water potential is lower and water leaves the cell, causing plasmolysis as the protoplast pulls away from the wall.

Question 46CBZ (Chemistry, Botany, Zoology)

In the light-dependent reactions of photosynthesis, which process is directly coupled to the transfer of electrons from photosystem II to the cytochrome b6f complex?

  1. Splitting of water at the oxygen-evolving complex
  2. Pumping of protons into the thylakoid lumen Correct answer.
  3. Fixation of CO2 by RuBisCO
  4. Reduction of NADP⁺ to NADPH by ferredoxin

Explanation

As electrons pass from photosystem II through the cytochrome b6f complex to plastocyanin, protons are translocated into the thylakoid lumen. Together with protons released by water splitting, this builds the electrochemical gradient used by ATP synthase.

Question 47CBZ (Chemistry, Botany, Zoology)

Which observation would most directly support the conclusion that a given bacterial gene is under positive control by a regulatory protein?

  1. The regulatory protein binds the promoter only when the target gene is silent
  2. Deletion of the gene encoding the regulatory protein abolishes transcription of the target gene Correct answer.
  3. Addition of the regulatory protein represses transcription of the target gene
  4. Transcription of the target gene is unaffected by the presence of the regulatory protein

Explanation

In positive control the regulatory protein is required to activate transcription. Removing it by deleting its gene should therefore reduce or abolish expression of the target gene, which is the signature of an activator rather than a repressor.

Question 48CBZ (Chemistry, Botany, Zoology)

A compound with molecular formula C4H8O gives a positive 2,4-dinitrophenylhydrazine test, does not reduce Tollens' reagent, and shows a strong absorption near 1715 cm⁻¹ in its IR spectrum. Which structure is most consistent with these data?

  1. Butanal
  2. Butan-1-ol
  3. Butanoic acid
  4. Butan-2-one Correct answer.

Explanation

The DNPH test confirms a carbonyl compound, while failure to reduce Tollens' reagent indicates a ketone rather than an aldehyde. A strong carbonyl stretch near 1715 cm⁻¹ fits a saturated ketone, so butan-2-one is the consistent structure.

Question 49CBZ (Chemistry, Botany, Zoology)

Two enzymes catalyse the same reaction. Enzyme A has Km = 0.5 mM and Vmax = 100 µmol min⁻¹; enzyme B has Km = 5 mM and Vmax = 100 µmol min⁻¹. At a substrate concentration of 0.5 mM, which statement is correct?

  1. Both enzymes work at the same fraction of their Vmax because their Vmax values are equal
  2. Enzyme A works at half its Vmax while enzyme B works at about one-eleventh of its Vmax Correct answer.
  3. Enzyme B works at half its Vmax while enzyme A works at half its Vmax as well
  4. Enzyme B works at half its Vmax while enzyme A works at about one-eleventh of its Vmax

Explanation

By the Michaelis–Menten equation, v/Vmax = [S]/(Km + [S]). For enzyme A, 0.5/(0.5 + 0.5) = 0.5, so it operates at half Vmax. For enzyme B, 0.5/(5 + 0.5) ≈ 0.09, roughly one-eleventh of Vmax, showing its much lower affinity for the substrate.

Question 50CBZ (Chemistry, Botany, Zoology)

In a population at Hardy–Weinberg equilibrium, a recessive allele causing a disease has a frequency of 0.1. What proportion of the population is expected to be heterozygous carriers?

  1. 0.18 Correct answer.
  2. 0.81
  3. 0.01
  4. 0.09

Explanation

With q = 0.1, p = 0.9, and the carrier frequency is 2pq = 2 × 0.9 × 0.1 = 0.18. The affected homozygote frequency is q² = 0.01 and the homozygous dominant frequency is p² = 0.81.