NEET 2026 Re-Exam Prediction Paper — Set B (Medium) (Free PDF)

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NEET UG 2026 Re-Exam — Prediction Paper

Set B · Medium · Full-Length (180 Q)

For the 21 June 2026 re-exam · NTA 2026 pattern · ChapterNotes.in

Difficulty: Medium

Questions

180

Max Marks

720

Duration

3 hours

Marking

+4 / −1

About this paper (Medium tier)

The balanced central forecast: NCERT-grounded with a fair share of application and two-step reasoning. Closest to a normal NEET.

  1. 180 questions across Physics, Chemistry, Botany and Zoology — 45 each. All compulsory (no optional Section B from 2025).
  2. Each correct answer: +4. Each wrong answer: −1. Unanswered: 0. Duration: 3 hours.
  3. Syllabus: NMC-rationalised NCERT 2025 (unchanged for 2026). Standard constants: g = 10 m/s², c = 3 × 10⁸ m/s, unless stated.
  4. This is AI-built practice material for the re-exam, calibrated against the actual NEET 2026 paper. For practice only; not affiliated with NTA.

PHYSICS

Physics (Q1 to Q45)

+4 for correct, −1 for incorrect, 0 for unattempted.

Q1

The dimensional formula for X = (electric field x magnetic field)/permeability of free space is the same as that of:

(a) Energy density
(b) Pressure gradient
(c) Force per unit length
(d) Power per unit area
Q2

A quantity Z = A^2 B / sqrt(C). If percentage errors in A, B and C are 2%, 1% and 4%, the maximum percentage error in Z is:

(a) 9%
(b) 7%
(c) 5%
(d) 11%
Q3

A particle moves along the x-axis with velocity v = 8 – 2t (m/s). The distance travelled in the first 6 seconds is:

(a) 16 m
(b) 8 m
(c) 12 m
(d) 20 m
Q4

Two particles are projected from the same point with the same speed at 30 and 60 degrees. The ratio of their maximum heights is:

(a) 1 : sqrt3
(b) 1 : 3
(c) sqrt3 : 1
(d) 3 : 1
Q5

Two blocks of masses 3 kg and 2 kg are connected by a light string over a frictionless pulley; the 3 kg block hangs and the 2 kg block rests on a frictionless table. The acceleration is (g = 10 m/s^2):

(a) 6 m/s^2
(b) 4 m/s^2
(c) 5 m/s^2
(d) 3 m/s^2
Q6

A car negotiates a frictionless banked curve of radius 50 m banked at angle theta with tan(theta) = 0.5. The maximum safe speed is (g = 10 m/s^2):

(a) ~16 m/s
(b) ~10 m/s
(c) ~25 m/s
(d) ~22 m/s
Q7

A 2 kg block is pushed against a spring of force constant 500 N/m, compressing it 0.2 m. Released on a frictionless surface, its speed as it leaves the spring is:

(a) ~5.0 m/s
(b) ~3.2 m/s
(c) ~2.0 m/s
(d) ~4.5 m/s
Q8

A solid sphere of mass M, radius R rolls without slipping down an incline of height h. Its centre-of-mass speed at the bottom is:

(a) sqrt(10gh/7)
(b) sqrt(4gh/3)
(c) sqrt(6gh/5)
(d) sqrt(2gh)
Q9

A uniform rod of mass M, length L rotates about an axis through one end perpendicular to its length. Its moment of inertia is:

(a) ML^2/12
(b) ML^2/4
(c) ML^2/3
(d) ML^2/2
Q10

A dancer spins at angular velocity w. Pulling her arms in reduces her moment of inertia to one-third. Her new angular velocity and the ratio of new to old rotational KE are:

(a) 3w and 3
(b) w/3 and 1/3
(c) 3w and 1/3
(d) 9w and 9
Q11

A satellite orbits at radius 2R (R = Earth’s radius). If escape velocity from Earth’s surface is 11.2 km/s, its orbital velocity is about:

(a) ~11.2 km/s
(b) ~7.9 km/s
(c) ~4.0 km/s
(d) ~5.6 km/s
Q12

Water flows through a horizontal pipe whose area reduces from 10 cm^2 to 5 cm^2. If the speed in the wider section is 2 m/s, the speed in the narrower section is:

(a) 1 m/s
(b) 8 m/s
(c) 4 m/s
(d) 6 m/s
Q13

A capillary tube of radius 0.2 mm is dipped in water (T = 0.072 N/m, density 1000 kg/m^3, contact angle 0). The rise of water is about (g = 10 m/s^2):

(a) ~1.8 cm
(b) ~3.6 cm
(c) ~14.4 cm
(d) ~7.2 cm
Q14

One mole of an ideal monatomic gas undergoes isothermal expansion. During this process:

(a) Internal energy increases and no heat is exchanged
(b) Heat absorbed equals work done by the gas and internal energy is unchanged
(c) Work done is zero and heat is absorbed
(d) Internal energy decreases while temperature rises
Q15

A Carnot engine has efficiency 40% with the sink at 300 K. To raise the efficiency to 50% keeping the sink fixed, the source temperature must increase by:

(a) 200 K
(b) 150 K
(c) 100 K
(d) 50 K
Q16

A particle in SHM of amplitude A is at the displacement where its kinetic energy equals its potential energy. That displacement is:

(a) A sqrt2
(b) A/2
(c) A/sqrt2
(d) A
Q17

A spring-mass system has time period T. If the mass and the spring constant are both doubled, the new time period is:

(a) T sqrt2
(b) T
(c) T/sqrt2
(d) 2T
Q18

A string fixed at both ends vibrates in its third harmonic. With length 1.5 m and wave speed 120 m/s, the frequency is:

(a) 40 Hz
(b) 60 Hz
(c) 120 Hz
(d) 80 Hz
Q19

Two tuning forks give 5 beats/s. One is 256 Hz. On loading the other with wax, the beats fall to 3/s. The original frequency of the second fork is:

(a) 253 Hz
(b) 251 Hz
(c) 261 Hz
(d) 259 Hz
Q20

An electric dipole of moment p in a uniform field E is rotated from theta = 0 to theta = 90 degrees. The work done is:

(a) pE
(b) pE/2
(c) zero
(d) 2pE
Q21

A hollow conducting sphere of radius R carries charge Q. The potential at distance R/2 from the centre is:

(a) kQ/2R
(b) zero
(c) 2kQ/R
(d) kQ/R
Q22

Three capacitors of 2 uF, 3 uF and 6 uF are connected in series. The equivalent capacitance is:

(a) 2 uF
(b) 11 uF
(c) 1 uF
(d) 0.5 uF
Q23

Match Column I (quantity) with Column II (SI unit): A. Electric flux – i. weber; B. Magnetic flux – ii. volt-metre; C. Capacitance – iii. coulomb/volt; D. Inductance – iv. volt-second/ampere.

(a) A-i, B-ii, C-iii, D-iv
(b) A-ii, B-i, C-iii, D-iv
(c) A-ii, B-i, C-iv, D-iii
(d) A-iii, B-i, C-ii, D-iv
Q24

In the given circuit, a battery of EMF 12 V and internal resistance 1 ohm drives an external resistance of 5 ohm. The terminal voltage is:

(a) 11 V
(b) 10 V
(c) 12 V
(d) 2 V
Q25

In a meter bridge, the balance point is at 25 cm when the known resistance in the right gap is 9 ohm. The unknown resistance in the left gap is:

(a) 3 ohm
(b) 12 ohm
(c) 27 ohm
(d) 6 ohm
Q26

How many of these statements about a metallic conductor at constant temperature are correct? (i) Drift velocity is proportional to applied field. (ii) Resistance is independent of length. (iii) Current density is proportional to field. (iv) Mobility depends on applied field.

(a) One
(b) Two
(c) Four
(d) Three
Q27

In the given circuit, 4 ohm and 6 ohm resistors in parallel are in series with a 2.6 ohm resistor across a 10 V battery of negligible internal resistance. The current drawn is:

(a) 10 A
(b) 2 A
(c) 1 A
(d) 5 A
Q28

A proton enters a 0.2 T field at 4 x 10^6 m/s perpendicular to it. The radius of its path is (m = 1.6 x 10^-27 kg, q = 1.6 x 10^-19 C):

(a) 0.4 m
(b) 0.2 m
(c) 2 m
(d) 0.1 m
Q29

A long solenoid with 500 turns per metre carries 4 A. The field inside is (mu0 = 4pi x 10^-7):

(a) ~2.5 x 10^-3 T
(b) ~1.0 x 10^-3 T
(c) ~6.3 x 10^-3 T
(d) ~5.0 x 10^-4 T
Q30

Assertion (A): Ferromagnetic materials lose ferromagnetism above the Curie temperature. Reason (R): Above the Curie temperature, thermal agitation destroys the alignment of magnetic domains.

(a) Both A and R are true but R is NOT the correct explanation of A
(b) A is true but R is false
(c) A is false but R is true
(d) Both A and R are true and R is the correct explanation of A
Q31

A coil of inductance 0.5 H carries a current rising uniformly from 0 to 4 A in 0.2 s. The induced EMF is:

(a) 2 V
(b) 10 V
(c) 20 V
(d) 5 V
Q32

An ideal step-down transformer has 1000 primary and 100 secondary turns. The secondary delivers 5 A. The primary current is:

(a) 5 A
(b) 50 A
(c) 0.5 A
(d) 2.5 A
Q33

Statement I: In an LCR series AC circuit, the current lags the voltage when the circuit is predominantly inductive. Statement II: At resonance, the current in a series LCR circuit is minimum.

(a) Statement I is true, Statement II is false
(b) Both statements are false
(c) Statement I is false, Statement II is true
(d) Both statements are true
Q34

In a plane EM wave in vacuum the peak electric field is 30 V/m. The peak magnetic field is (c = 3 x 10^8 m/s):

(a) 1 x 10^-8 T
(b) 3 x 10^-7 T
(c) 9 x 10^-7 T
(d) 1 x 10^-7 T
Q35

A concave mirror of focal length 15 cm forms a real image 30 cm from the mirror. The object distance is:

(a) 60 cm
(b) 45 cm
(c) 15 cm
(d) 30 cm
Q36

A thin equiconvex lens has radii 20 cm each and refractive index 1.5. Its focal length in air is:

(a) 20 cm
(b) 40 cm
(c) 10 cm
(d) 15 cm
Q37

A ray passes through an equilateral prism (A = 60 degrees) at minimum deviation 30 degrees. The refractive index is:

(a) sqrt2
(b) 1.5
(c) 1.33
(d) sqrt3
Q38

In Young’s double slit experiment the fringe width is 0.4 mm. If the apparatus is immersed in water (n = 4/3), the new fringe width is:

(a) 0.53 mm
(b) 0.3 mm
(c) 0.2 mm
(d) 0.4 mm
Q39

Light of wavelength 400 nm is incident on a metal of work function 2 eV. The maximum KE of the photoelectrons is (hc = 1240 eV.nm):

(a) 1.1 eV
(b) 2.0 eV
(c) 0.5 eV
(d) 3.1 eV
Q40

An electron and a proton have the same kinetic energy. The ratio of the de Broglie wavelength of the electron to that of the proton is:

(a) sqrt(me/mp)
(b) 1
(c) mp/me
(d) sqrt(mp/me)
Q41

The energy of an electron in the second excited state (n = 3) of hydrogen is:

(a) -13.6 eV
(b) -0.85 eV
(c) -3.4 eV
(d) -1.51 eV
Q42

A radioactive sample has a half-life of 10 days. The fraction remaining after 30 days is:

(a) 1/6
(b) 1/3
(c) 1/8
(d) 1/16
Q43

Binding energy of a deuteron is 2.2 MeV and of helium-4 is 28 MeV. When two deuterons fuse to form helium, the energy released is:

(a) 25.8 MeV
(b) 23.6 MeV
(c) 30.2 MeV
(d) 2.2 MeV
Q44

In a p-n junction diode under forward bias:

(a) Only minority carriers produce the large forward current
(b) The depletion region narrows and the barrier potential is lowered
(c) Majority carriers are pushed away from the junction
(d) The depletion region widens and current is negligible
Q45

In a full-wave rectifier with input frequency 50 Hz, the fundamental ripple frequency at the output is:

(a) 100 Hz
(b) 200 Hz
(c) 25 Hz
(d) 50 Hz

CHEMISTRY

Chemistry (Q46 to Q90)

+4 for correct, −1 for incorrect, 0 for unattempted.

Q46

For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), the value of Kp is related to Kc by which expression at temperature T?

(a) Kp = Kc(RT)²
(b) Kp = Kc(RT)⁻²
(c) Kp = Kc(RT)
(d) Kp = Kc(RT)⁻¹
Q47

A 0.01 M solution of a weak monobasic acid is 5% ionised at 25°C. The dissociation constant (Ka) of the acid is approximately:

(a) 2.5 × 10⁻⁵
(b) 5.0 × 10⁻⁵
(c) 2.5 × 10⁻⁴
(d) 5.0 × 10⁻⁴
Q48

For the equilibrium CaCO₃(s) ⇌ CaO(s) + CO₂(g), which change will shift the equilibrium to the right (more decomposition)?

(a) Removing CO₂ as it forms
(b) Increasing the pressure of CO₂
(c) Adding more CaCO₃ solid
(d) Decreasing the temperature
Q49

The Ksp of Mg(OH)₂ is 1.0 × 10⁻¹¹. The molar solubility of Mg(OH)₂ in pure water is approximately:

(a) 1.4 × 10⁻⁴ M
(b) 2.2 × 10⁻⁴ M
(c) 1.0 × 10⁻⁴ M
(d) 1.0 × 10⁻⁶ M
Q50

The IUPAC name of the complex K₃[Fe(CN)₆] is:

(a) Potassium hexacyanoferrate(III)
(b) Potassium hexacyanoferrate(II)
(c) Potassium ferricyanide(III)
(d) Potassium hexacyanidoferrate(III)
Q51

The spin-only magnetic moment of the complex ion [CoF₆]³⁻ (Co³⁺, d⁶, weak-field ligand) is approximately:

(a) 2.83 BM
(b) 0 BM
(c) 4.90 BM
(d) 5.92 BM
Q52

Match List I (complex) with List II (number of unpaired electrons) and choose the correct option: List I: (A) [Fe(CN)₆]⁴⁻ (B) [Fe(H₂O)₆]²⁺ (C) [Co(NH₃)₆]³⁺ (D) [Ni(H₂O)₆]²⁺ List II: (i) 0 (ii) 2 (iii) 4

(a) A-(i), B-(ii), C-(iii), D-(i)
(b) A-(ii), B-(iii), C-(i), D-(ii)
(c) A-(iii), B-(i), C-(ii), D-(i)
(d) A-(i), B-(iii), C-(i), D-(ii)
Q53

Assertion (A): [Cu(NH₃)₄]²⁺ is square planar and shows colour. Reason (R): Cu²⁺ is a d⁹ ion and undergoes dsp² hybridisation, with d-d transitions giving colour.

(a) Both A and R are true but R is NOT the correct explanation of A
(b) A is false but R is true
(c) Both A and R are true and R is the correct explanation of A
(d) A is true but R is false
Q54

Among CH₃CH₂CH₂⁺ (n-propyl), (CH₃)₂CH⁺ (isopropyl) and CH₂=CH–CH₂⁺ (allyl), the correct order of stability is:

(a) isopropyl > allyl > n-propyl
(b) n-propyl > isopropyl > allyl
(c) allyl > isopropyl > n-propyl
(d) isopropyl > n-propyl > allyl
Q55

The number of structural (chain + positional) isomers possible for the molecular formula C₅H₁₂ is:

(a) 3
(b) 5
(c) 2
(d) 4
Q56

Which of the following is the strongest acid?

(a) ClCH₂COOH
(b) Cl₂CHCOOH
(c) FCH₂COOH
(d) CH₃COOH
Q57

For a first-order reaction, 75% of the reactant is consumed in 60 minutes. The half-life of the reaction is:

(a) 30 min
(b) 20 min
(c) 15 min
(d) 40 min
Q58

The rate constant of a first-order reaction is 2.303 × 10⁻³ s⁻¹. The time required for the concentration to fall to 1/10 of its initial value is:

(a) 100 s
(b) 500 s
(c) 1000 s
(d) 2303 s
Q59

The activation energy of a reaction can be determined from the slope of the Arrhenius plot. If ln k is plotted against 1/T, the slope equals:

(a) Ea/R
(b) Ea/2.303R
(c) −Ea/R
(d) −Ea/2.303R
Q60

The correct decreasing order of basicity in aqueous solution is:

(a) C₂H₅NH₂ > (C₂H₅)₂NH > (C₂H₅)₃N > C₆H₅NH₂
(b) (C₂H₅)₂NH > C₂H₅NH₂ > (C₂H₅)₃N > C₆H₅NH₂
(c) C₆H₅NH₂ > (C₂H₅)₃N > C₂H₅NH₂ > (C₂H₅)₂NH
(d) (C₂H₅)₃N > (C₂H₅)₂NH > C₂H₅NH₂ > C₆H₅NH₂
Q61

In the carbylamine test, which class of amine gives a foul-smelling isocyanide?

(a) Both primary and secondary amines
(b) Only secondary amines
(c) Only tertiary amines
(d) Only primary amines
Q62

Aniline is treated with NaNO₂/HCl at 273–278 K, and the product is then warmed with water. The final product is:

(a) Nitrobenzene
(b) Benzene
(c) Phenol
(d) Chlorobenzene
Q63

According to MO theory, the bond order and magnetic nature of the N₂ molecule are:

(a) 3, paramagnetic
(b) 2.5, paramagnetic
(c) 3, diamagnetic
(d) 2, diamagnetic
Q64

The shape and hybridisation of the IF₇ molecule (central I, 7 bond pairs, no lone pair) are:

(a) Pentagonal bipyramidal, sp³d³
(b) Capped trigonal prismatic, sp³d²
(c) Square antiprismatic, sp³d³
(d) Octahedral, sp³d²
Q65

Which of the following statements about hydrogen bonding is/are correct? (I) H₂O has a higher boiling point than H₂S due to intermolecular H-bonding. (II) o-nitrophenol has a higher boiling point than p-nitrophenol. (III) HF is a weaker acid than HCl partly due to strong H-bonding.

(a) I, II and III
(b) I and III only
(c) II and III only
(d) I and II only
Q66

For a reaction at 300 K, ΔH = +30 kJ/mol and ΔS = +100 J/K/mol. The value of ΔG (in kJ/mol) is:

(a) +30
(b) 0
(c) −60
(d) +60
Q67

Using Hess’s law: given enthalpies of formation of CO₂(g) = −393 kJ/mol and CO(g) = −110 kJ/mol, the enthalpy of the reaction CO(g) + ½O₂(g) → CO₂(g) is:

(a) −283 kJ/mol
(b) −503 kJ/mol
(c) +283 kJ/mol
(d) −110 kJ/mol
Q68

For an ideal gas, which of the following is true for an adiabatic process?

(a) ΔT = 0 always
(b) ΔU = 0, so q = −w
(c) q = 0, so ΔU = w
(d) w = 0, so q = ΔU
Q69

Which of the following correctly describes the structure of white phosphorus (P₄)?

(a) Square planar with 90° bond angles
(b) Tetrahedral P₄ with P–P–P bond angle of 60°
(c) Linear chain of P atoms
(d) Layered sheet structure
Q70

Match List I (interhalogen/species) with List II (shape) and choose the correct option: List I: (A) ClF₃ (B) BrF₅ (C) ICl (D) IF₇ List II: (i) Linear (ii) Bent T-shape (iii) Square pyramidal (iv) Pentagonal bipyramidal

(a) A-(ii), B-(iv), C-(i), D-(iii)
(b) A-(ii), B-(iii), C-(i), D-(iv)
(c) A-(iii), B-(ii), C-(i), D-(iv)
(d) A-(i), B-(iii), C-(ii), D-(iv)
Q71

Which of the following statements about Group 15 hydrides is correct?

(a) Basic character increases down the group: NH₃ < PH₃ < AsH₃
(b) Bond angle increases down the group: NH₃ < PH₃ < AsH₃
(c) Thermal stability decreases down the group: NH₃ > PH₃ > AsH₃ > SbH₃
(d) NH₃ has the lowest boiling point among the hydrides
Q72

In the aldol condensation, which of the following aldehydes cannot undergo self-aldol condensation?

(a) Propanal (CH₃CH₂CHO)
(b) Acetaldehyde (CH₃CHO)
(c) Benzaldehyde (C₆H₅CHO)
(d) Butanal (CH₃CH₂CH₂CHO)
Q73

Match List I (reagent/reaction) with List II (transformation) and choose the correct option: List I: (A) Clemmensen reduction (B) Wolff–Kishner reduction (C) Tollens’ reagent (D) Fehling’s solution List II: (i) >C=O → >CH₂ using Zn-Hg/HCl (ii) >C=O → >CH₂ using NH₂NH₂/KOH (iii) oxidises aldehyde, silver mirror (iv) oxidises aliphatic aldehyde, red ppt

(a) A-(i), B-(ii), C-(iv), D-(iii)
(b) A-(iii), B-(iv), C-(i), D-(ii)
(c) A-(ii), B-(i), C-(iii), D-(iv)
(d) A-(i), B-(ii), C-(iii), D-(iv)
Q74

The correct order of acidic strength among the following carboxylic acids is: HCOOH, CH₃COOH, C₆H₅COOH, ClCH₂COOH

(a) ClCH₂COOH > HCOOH > C₆H₅COOH > CH₃COOH
(b) HCOOH > ClCH₂COOH > CH₃COOH > C₆H₅COOH
(c) CH₃COOH > HCOOH > C₆H₅COOH > ClCH₂COOH
(d) ClCH₂COOH > C₆H₅COOH > HCOOH > CH₃COOH
Q75

Which of the following is a reducing sugar?

(a) Trehalose
(b) Sucrose
(c) Maltose
(d) Methyl α-D-glucoside
Q76

Which of the following statements about proteins is/are correct? (I) The secondary structure (α-helix, β-sheet) is stabilised by hydrogen bonds. (II) The peptide bond is an amide linkage (–CO–NH–). (III) Denaturation destroys the primary structure of a protein.

(a) I and III only
(b) II and III only
(c) I and II only
(d) I, II and III
Q77

For the cell reaction with E°cell = +0.46 V at 298 K and n = 2, the equilibrium constant (use 2.303RT/F = 0.059) is of the order:

(a) 10¹⁶
(b) 10²³
(c) 10⁸
(d) 10⁻⁸
Q78

The limiting molar conductivity (Λ°ₘ) of CH₃COOH can be obtained from Kohlrausch’s law using:

(a) Λ°(CH₃COONa) + Λ°(HCl) − Λ°(NaCl)
(b) Λ°(CH₃COONa) − Λ°(HCl) + Λ°(NaCl)
(c) Λ°(HCl) + Λ°(NaCl) − Λ°(CH₃COONa)
(d) Λ°(CH₃COONa) + Λ°(NaCl) − Λ°(HCl)
Q79

An aqueous solution contains a non-volatile solute. The relative lowering of vapour pressure is 0.2. If the solution contains 1 mole of solute, the number of moles of solvent is:

(a) 4
(b) 5
(c) 10
(d) 8
Q80

0.5 m aqueous solution of NaCl shows a van’t Hoff factor i = 1.9. The percentage dissociation of NaCl is:

(a) 80%
(b) 85%
(c) 90%
(d) 95%
Q81

On reductive ozonolysis of an alkene, the products are acetone and acetaldehyde. The alkene is:

(a) 3-methyl-1-butene
(b) 2-pentene
(c) 2-methyl-1-butene
(d) 2-methyl-2-butene
Q82

When propene reacts with HBr in the presence of benzoyl peroxide, the major product is:

(a) 2-bromopropane
(b) 1-bromopropane
(c) 2-bromo-1-propene
(d) 1,2-dibromopropane
Q83

The acidic character of the following compounds increases in the order: phenol, p-nitrophenol, p-cresol (p-methylphenol)

(a) p-cresol < p-nitrophenol < phenol
(b) p-cresol < phenol < p-nitrophenol
(c) phenol < p-cresol < p-nitrophenol
(d) p-nitrophenol < phenol < p-cresol
Q84

In the Williamson synthesis, the best combination to prepare tert-butyl methyl ether without significant elimination is:

(a) methyl bromide + sodium tert-butoxide
(b) tert-butyl bromide + sodium methoxide
(c) tert-butyl bromide + methanol
(d) methyl iodide + tert-butyl alcohol
Q85

An optically active 2-bromobutane undergoes hydrolysis. Under purely SN1 conditions the product is largely racemised, whereas under SN2 conditions the product shows inversion of configuration. The reason racemisation accompanies the SN1 pathway is:

(a) 2-bromobutane cannot form a carbocation
(b) The planar carbocation intermediate is attacked from both faces with near-equal probability
(c) The nucleophile attacks from the back side only
(d) SN1 always proceeds with complete retention of configuration
Q86

Assertion (A): Lanthanoid contraction causes the atomic radii of Zr and Hf to be nearly the same. Reason (R): The poor shielding of 4f electrons leads to a steady decrease in size across the lanthanoid series.

(a) Both A and R are true but R is NOT the correct explanation of A
(b) Both A and R are true and R is the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Q87

A sample of pure iron weighing 11.2 g reacts completely with excess dilute H₂SO₄ to form FeSO₄ and H₂. What is the volume of H₂ liberated at STP and the mass of FeSO₄ formed? (Fe = 56, S = 32, O = 16)

(a) 8.96 L H₂ and 30.4 g FeSO₄
(b) 4.48 L H₂ and 30.4 g FeSO₄
(c) 4.48 L H₂ and 15.2 g FeSO₄
(d) 2.24 L H₂ and 15.2 g FeSO₄
Q88

Consider the orbitals 3p, 3d and 4s. The number of radial nodes in each, respectively, is:

(a) 1, 0, 1
(b) 1, 0, 3
(c) 0, 1, 2
(d) 2, 1, 0
Q89

In the balanced reaction MnO₄⁻ + C₂O₄²⁻ + H⁺ → Mn²⁺ + CO₂ + H₂O (acidic medium), the number of moles of C₂O₄²⁻ oxidised per mole of MnO₄⁻ is:

(a) 1
(b) 2/5
(c) 2
(d) 5/2
Q90

Arrange the following species in the correct order of increasing atomic/ionic radius: Na⁺, Mg²⁺, F⁻, O²⁻ (all isoelectronic with Ne).

(a) F⁻ < O²⁻ < Na⁺ < Mg²⁺
(b) Na⁺ < Mg²⁺ < O²⁻ < F⁻
(c) O²⁻ < F⁻ < Na⁺ < Mg²⁺
(d) Mg²⁺ < Na⁺ < F⁻ < O²⁻

BOTANY

Botany (Q91 to Q135)

+4 for correct, −1 for incorrect, 0 for unattempted.

Q91

In a cross between two pea plants, the F1 generation was self-pollinated to give an F2 of 480 plants. If the trait shows a 9:3:3:1 dihybrid ratio, approximately how many plants would be expected to show both recessive characters?

(a) 120
(b) 90
(c) 270
(d) 30
Q92

A woman with blood group AB marries a man with blood group O. What are the possible blood groups of their children?

(a) A and B only
(b) Only AB
(c) A, B, AB and O
(d) AB and O only
Q93

Assertion (A): In Mirabilis jalapa, a cross between red and white flowered plants gives pink F1 flowers. Reason (R): This is a case of incomplete dominance in which the heterozygote shows an intermediate phenotype because neither allele can completely mask the other.

(a) A is false but R is true
(b) Both A and R are true and R is the correct explanation of A
(c) A is true but R is false
(d) Both A and R are true but R is not the correct explanation of A
Q94

Match Column I (Chromosomal disorder) with Column II (Chromosomal constitution): Column I: A. Down syndrome B. Turner syndrome C. Klinefelter syndrome D. Normal human female Column II: i. 44 + XXY ii. Trisomy of 21 iii. 44 + XX iv. 44 + XO

(a) A-iii, B-iv, C-i, D-ii
(b) A-ii, B-iii, C-i, D-iv
(c) A-ii, B-i, C-iv, D-iii
(d) A-ii, B-iv, C-i, D-iii
Q95

A carrier woman for a sex-linked recessive condition marries a normal man. How many of the following statements are correct? 1. Half of the sons will be affected. 2. All daughters will be either carrier or normal. 3. None of the daughters will be affected. 4. Half of the daughters will be carriers.

(a) Four
(b) One
(c) Three
(d) Two
Q96

Two genes A and B are located 20 map units apart on the same chromosome. In a test cross of an AaBb (cis-configuration) individual, what percentage of the offspring are expected to be recombinant?

(a) 20%
(b) 80%
(c) 10%
(d) 40%
Q97

A transcription unit in DNA has three regions. In which direction does RNA polymerase synthesise RNA, and which strand serves as the template?

(a) RNA synthesised 3’→5′; the 5’→3′ strand is the template
(b) RNA synthesised 5’→3′; the strand with polarity 3’→5′ acts as template
(c) RNA synthesised 5’→3′; the 5’→3′ strand is the template
(d) RNA synthesised 3’→5′; the template equals the coding strand
Q98

In the lac operon of E. coli, how many of the following are correct? 1. The repressor is synthesised by the i gene. 2. Lactose acts as an inducer. 3. In the presence of inducer, the repressor cannot bind the operator. 4. The z gene codes for beta-galactosidase.

(a) Two
(b) Three
(c) Four
(d) One
Q99

Meselson and Stahl grew E. coli in 15N medium and then shifted to 14N medium. After two generations in 14N medium, what is the ratio of hybrid (15N/14N) to light (14N/14N) DNA molecules?

(a) 3:1
(b) 1:1
(c) 1:0
(d) 1:3
Q100

Statement I: The genetic code is degenerate, meaning some amino acids are coded by more than one codon. Statement II: AUG codes for methionine and also acts as the initiator codon.

(a) Both Statement I and Statement II are correct
(b) Statement I is correct, Statement II is incorrect
(c) Statement I is incorrect, Statement II is correct
(d) Both statements are incorrect
Q101

During eukaryotic RNA processing, which sequence correctly describes the maturation of hnRNA into mRNA?

(a) Capping → tailing → no splicing
(b) Splicing → tailing → capping
(c) Tailing → capping → splicing
(d) Capping → splicing (intron removal) → tailing
Q102

Match Column I (Group) with Column II (Characteristic): Column I: A. Dinoflagellates B. Euglenoids C. Slime moulds D. Diatoms Column II: i. Cell wall of indestructible silica ii. Cellulose plates in wall; cause red tides iii. Pellicle, no cell wall iv. Saprophytic with aggregating plasmodium

(a) A-ii, B-iv, C-iii, D-i
(b) A-ii, B-iii, C-iv, D-i
(c) A-iii, B-ii, C-iv, D-i
(d) A-i, B-iii, C-iv, D-ii
Q103

How many of the following groups store their reserve food as a starch-type carbohydrate (true starch or floridean starch)? 1. Chlorophyceae 2. Phaeophyceae 3. Rhodophyceae 4. Cyanobacteria

(a) One
(b) Four
(c) Three
(d) Two
Q104

In the life cycle of a moss (bryophyte), which statement about alternation of generations is correct?

(a) Both generations are independent and free-living
(b) The dominant photosynthetic gametophyte (n) bears the dependent sporophyte (2n)
(c) The dominant sporophyte (2n) bears a dependent gametophyte (n)
(d) The gametophyte is diploid and the sporophyte is haploid
Q105

Assertion (A): Gymnosperms are called naked-seeded plants. Reason (R): Their ovules are not enclosed by an ovary wall, so the seeds remain exposed.

(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Q106

A flower has the following features: (5) fused sepals, 5 petals, 5 epipetalous stamens, and a bicarpellary syncarpous superior ovary with axile placentation and an obliquely placed septum. To which family does it belong?

(a) Fabaceae
(b) Brassicaceae
(c) Liliaceae
(d) Solanaceae
Q107

Match Column I (Family) with Column II (Characteristic feature): Column I: A. Fabaceae (aestivation) B. Solanaceae C. Liliaceae D. Fabaceae (stamens) Column II: i. Vexillary (papilionaceous) aestivation ii. Tepals (3+3), axile placentation iii. Diadelphous stamens (9)+1 iv. Berry fruit, oblique ovary

(a) A-iii, B-iv, C-ii, D-i
(b) A-i, B-iv, C-ii, D-iii
(c) A-i, B-ii, C-iv, D-iii
(d) A-iv, B-i, C-ii, D-iii
Q108

How many of the following terms are correctly defined? 1. Gamosepalous – sepals united 2. Epipetalous – stamens attached to petals 3. Polypetalous – petals free 4. Gamopetalous – petals free

(a) One
(b) Three
(c) Four
(d) Two
Q109

In a flower, the aestivation in which margins of sepals or petals overlap one another but not in any particular direction is called:

(a) Vexillary
(b) Twisted
(c) Valvate
(d) Imbricate
Q110

In C4 plants, the primary CO2 acceptor and the first stable product formed in the mesophyll cells are respectively:

(a) PEP and malic acid
(b) RuBP and 3-PGA
(c) RuBP and OAA
(d) PEP and oxaloacetic acid (OAA)
Q111

Assertion (A): Photorespiration in C3 plants does not produce ATP or NADPH. Reason (R): In photorespiration, RuBisCO acts as an oxygenase and no sugar is synthesised, so there is no energy yield.

(a) Both A and R are true and R is the correct explanation of A
(b) A is true but R is false
(c) A is false but R is true
(d) Both A and R are true but R is not the correct explanation of A
Q112

In the Calvin cycle, when 3 molecules of CO2 are fixed, how many molecules of RuBP are regenerated and how many ATP are used specifically in the regeneration step?

(a) 3 RuBP using 9 ATP
(b) 3 RuBP using 6 ATP
(c) 3 RuBP regenerated using 3 ATP
(d) 6 RuBP using 6 ATP
Q113

In aerobic respiration, the complete oxidation of one molecule of glucose through glycolysis, the link reaction and the Krebs cycle releases how many molecules of CO2, and at which stages?

(a) 6 CO2 in total: 2 in glycolysis and 4 in the Krebs cycle
(b) 6 CO2 in total: none in glycolysis, 2 in the link reaction, and 4 in the Krebs cycle
(c) 2 CO2 in total, all released in the Krebs cycle
(d) 4 CO2 in total: 2 in the link reaction and 2 in the Krebs cycle
Q114

Statement I: The respiratory quotient (RQ) of fats is less than 1. Statement II: During fat oxidation, more oxygen is consumed relative to the CO2 released.

(a) Statement I is incorrect, Statement II is correct
(b) Both statements are incorrect
(c) Statement I is correct, Statement II is incorrect
(d) Both Statement I and Statement II are correct
Q115

Match Column I (Plant growth regulator) with Column II (Effect): Column I: A. Gibberellin B. Abscisic acid C. Ethylene D. Cytokinin Column II: i. Promotes fruit ripening and senescence ii. Bolting in rosette plants iii. Stress hormone, stomatal closure iv. Cell division, delays senescence

(a) A-ii, B-i, C-iii, D-iv
(b) A-ii, B-iii, C-i, D-iv
(c) A-iv, B-iii, C-i, D-ii
(d) A-i, B-iii, C-ii, D-iv
Q116

Assertion (A): A short-day plant flowers when the night length exceeds a critical period. Reason (R): The duration of the dark period is the decisive factor in photoperiodic induction of flowering.

(a) A is false but R is true
(b) Both A and R are true but R is not the correct explanation of A
(c) Both A and R are true and R is the correct explanation of A
(d) A is true but R is false
Q117

How many of the following effects are correctly attributed to auxins? 1. Promotion of apical dominance. 2. Induction of parthenocarpy. 3. Promotion of rooting in stem cuttings. 4. Breaking of seed dormancy in cereals.

(a) Four
(b) One
(c) Three
(d) Two
Q118

In a mature angiosperm embryo sac, the central cell, the two synergids, and the three antipodal cells contain respectively how many nuclei (before fertilisation)?

(a) 2 polar nuclei in central cell; 1 in each synergid; 1 in each antipodal
(b) 2 in central cell; 2 in each synergid; 2 in each antipodal
(c) 3 in central cell; 1 synergid; 3 antipodals
(d) 1 in central cell; 2 in each synergid; 1 in each antipodal
Q119

During double fertilisation in angiosperms, the two fusion events produce respectively:

(a) Haploid zygote and diploid endosperm
(b) Diploid zygote (syngamy) and triploid primary endosperm nucleus (triple fusion)
(c) Triploid zygote and diploid endosperm
(d) Diploid zygote and diploid endosperm
Q120

How many of the following statements about pollination are correct? 1. Geitonogamy involves transfer of pollen between two flowers of the same plant. 2. Xenogamy brings genetically different pollen to the stigma. 3. Autogamy in chasmogamous flowers requires synchrony of anther dehiscence and stigma receptivity. 4. Cleistogamous flowers are always cross-pollinated.

(a) Two
(b) One
(c) Three
(d) Four
Q121

Statement I: In meiosis, crossing over occurs during the pachytene stage of prophase I. Statement II: Synapsis of homologous chromosomes occurs during zygotene.

(a) Both statements are incorrect
(b) Statement I is correct, Statement II is incorrect
(c) Statement I is incorrect, Statement II is correct
(d) Both Statement I and Statement II are correct
Q122

How many of the following are correct differences between mitosis and meiosis? 1. Mitosis produces two diploid cells; meiosis produces four haploid cells. 2. Crossing over occurs in meiosis I but not in mitosis. 3. Homologous chromosomes pair only in meiosis. 4. DNA replicates twice in meiosis (once before each division).

(a) Two
(b) One
(c) Four
(d) Three
Q123

Assertion (A): Cytokinesis in plant cells occurs by cell-plate formation. Reason (R): The rigid cell wall of plant cells prevents division by a cleavage furrow.

(a) Both A and R are true and R is the correct explanation of A
(b) A is false but R is true
(c) A is true but R is false
(d) Both A and R are true but R is not the correct explanation of A
Q124

Match Column I (Cell organelle) with Column II (Function): Column I: A. Rough ER B. Golgi apparatus C. Lysosome D. Mitochondria Column II: i. Intracellular digestion ii. Protein synthesis (membrane-bound ribosomes) iii. Site of oxidative phosphorylation iv. Packaging and modification of proteins

(a) A-ii, B-i, C-iv, D-iii
(b) A-ii, B-iv, C-iii, D-i
(c) A-iv, B-ii, C-i, D-iii
(d) A-ii, B-iv, C-i, D-iii
Q125

For an enzyme-catalysed reaction, if the Km of an enzyme is low, what does it indicate about the enzyme’s affinity for its substrate?

(a) No relationship with affinity
(b) Low affinity for the substrate
(c) High affinity for the substrate
(d) The enzyme is denatured
Q126

How many of the following biomolecules are polysaccharides? 1. Cellulose 2. Glycogen 3. Inulin 4. Insulin

(a) One
(b) Four
(c) Three
(d) Two
Q127

In a PCR cycle, the three steps occur in the correct order as:

(a) Denaturation → extension → annealing
(b) Denaturation → annealing of primers → extension by Taq polymerase
(c) Extension → denaturation → annealing
(d) Annealing → denaturation → extension
Q128

Match Column I (Biotech tool/application) with Column II (Role/feature): Column I: A. Ti plasmid B. RNA interference C. Bt cotton D. Gel electrophoresis Column II: i. Separation of DNA fragments by size ii. Vector from Agrobacterium for plant transformation iii. Silencing of nematode mRNA iv. Cry protein-mediated insect resistance

(a) A-iii, B-ii, C-iv, D-i
(b) A-ii, B-iv, C-iii, D-i
(c) A-ii, B-iii, C-iv, D-i
(d) A-ii, B-iii, C-i, D-iv
Q129

How many of the following statements about restriction endonucleases are correct? 1. They recognise specific palindromic sequences. 2. They cut DNA at specific sites producing fragments. 3. They are also called ‘molecular scissors’. 4. They join DNA fragments by forming phosphodiester bonds.

(a) Three
(b) Two
(c) Four
(d) One
Q130

In an ecological pyramid of energy, if the producers contain 20,000 kJ of energy, approximately how much energy is available at the third trophic level (secondary consumers)?

(a) 2000 kJ
(b) 20 kJ
(c) 2 kJ
(d) 200 kJ
Q131

Statement I: Gross primary productivity (GPP) minus respiration equals net primary productivity (NPP). Statement II: NPP is the biomass available for consumption by heterotrophs.

(a) Both Statement I and Statement II are correct
(b) Statement I is correct, Statement II is incorrect
(c) Both statements are incorrect
(d) Statement I is incorrect, Statement II is correct
Q132

Assertion (A): A logistic growth curve is sigmoid (S-shaped). Reason (R): Resources become limiting as the population approaches the carrying capacity (K).

(a) A is false but R is true
(b) Both A and R are true and R is the correct explanation of A
(c) A is true but R is false
(d) Both A and R are true but R is not the correct explanation of A
Q133

Match Column I (Population interaction) with Column II (Effect on the two species): Column I: A. Mutualism B. Competition C. Predation D. Commensalism Column II: i. +/0 ii. +/+ iii. -/- iv. +/-

(a) A-i, B-iii, C-iv, D-ii
(b) A-ii, B-iv, C-iii, D-i
(c) A-ii, B-iii, C-iv, D-i
(d) A-ii, B-iii, C-i, D-iv
Q134

According to the species-area relationship on a log-log scale (log S = log C + Z log A), the slope Z (regression coefficient) for most taxa over relatively small areas lies in the range:

(a) 0.1 to 0.2
(b) 1.0 to 1.5
(c) 0.001 to 0.01
(d) 0.6 to 1.2
Q135

How many of the following are examples of in-situ conservation? 1. National parks 2. Biosphere reserves 3. Zoological parks 4. Sacred groves

(a) One
(b) Two
(c) Four
(d) Three

ZOOLOGY

Zoology (Q136 to Q180)

+4 for correct, −1 for incorrect, 0 for unattempted.

Q136

EcoRI is a restriction endonuclease that recognises a specific palindromic sequence. At which position does it cleave the DNA backbone?

(a) Between G and A on the 5′-GAATTC-3′ strand, leaving 5′ overhangs (sticky ends)
(b) Exactly at the centre between the two A residues, leaving blunt ends
(c) Between T and C, leaving blunt ends
(d) Between G and A on the 5′-GAATTC-3′ strand, leaving 3′ overhangs
Q137

In the cloning vector pBR322, the recognition site for the restriction enzyme PstI lies within the ampicillin-resistance gene. If a foreign DNA fragment is inserted at this PstI site, the resulting recombinant bacteria will be:

(a) Resistant to tetracycline but sensitive to ampicillin
(b) Resistant to both ampicillin and tetracycline
(c) Sensitive to both antibiotics
(d) Resistant to ampicillin but sensitive to tetracycline
Q138

Arrange the three steps of one PCR cycle in the correct order: (i) Annealing of primers (ii) Denaturation (iii) Extension by Taq polymerase.

(a) (ii) → (i) → (iii)
(b) (ii) → (iii) → (i)
(c) (i) → (ii) → (iii)
(d) (iii) → (ii) → (i)
Q139

In agarose gel electrophoresis of DNA, the separated fragments are visualised by staining with ethidium bromide and exposing to:

(a) X-rays
(b) UV radiation
(c) Visible white light only
(d) Infrared radiation
Q140

How many of the following statements regarding the Ti plasmid and bioreactors are CORRECT? (i) The Ti plasmid of Agrobacterium tumefaciens can be used as a vector to deliver genes into plant cells. (ii) A stirred-tank bioreactor allows mixing and oxygen availability throughout the culture. (iii) Bacteriophages and plasmids both serve as cloning vectors because they can replicate independently within bacterial cells. (iv) Downstream processing includes separation, purification and quality control of the product.

(a) One
(b) Four
(c) Two
(d) Three
Q141

Genetically engineered human insulin (Humulin) is produced by inserting genes for the A and B polypeptide chains separately into E. coli. After production, the mature insulin is assembled by:

(a) Methylating the B chain only
(b) Cleaving a single proinsulin chain by trypsin
(c) Adding a C-peptide that joins A and B chains
(d) Linking A and B chains by disulphide bonds
Q142

Bt cotton expresses a cry gene whose protein toxin is initially produced as an inactive protoxin. This protoxin becomes an active toxin in the insect gut because:

(a) Stomach proteases of the cotton plant cleave it
(b) The alkaline pH of the insect gut solubilises and activates the crystal protoxin
(c) The toxin is activated by the acidic pH of the gut
(d) It binds directly to the midgut without modification
Q143

In the strategy to develop nematode-resistant tobacco against Meloidogyne incognita, host cells were transformed using Agrobacterium vectors to produce both sense and antisense RNA. This silenced the parasite’s gene by:

(a) RNA interference (formation of dsRNA)
(b) Increased translation of the parasite mRNA
(c) Point mutation of the nematode DNA
(d) Gene amplification
Q144

How many of the following are TRUE about enzyme classification and action? (i) Oxidoreductases catalyse oxidation-reduction reactions between two substrates. (ii) Ligases catalyse the joining of two compounds with hydrolysis of ATP. (iii) Lyases catalyse transfer of a group from one substrate to another. (iv) An enzyme lowers the activation energy of a reaction.

(a) Three
(b) Four
(c) One
(d) Two
Q145

A cofactor that is tightly and permanently bound to the apoenzyme by covalent bonds is called a:

(a) Free vitamin
(b) Metal-ion activator
(c) Prosthetic group
(d) Coenzyme
Q146

During the catabolism of a pure fat substrate, the respiratory quotient (RQ = CO2 released / O2 consumed) is approximately:

(a) 0.5
(b) 0.7
(c) 0.9
(d) 1.0
Q147

Which of the following correctly describes the secondary structure of a protein?

(a) The right-handed helix or pleated sheet stabilised by hydrogen bonds
(b) The overall three-dimensional folding into a globular shape
(c) The linear sequence of amino acids joined by peptide bonds
(d) The aggregation of multiple polypeptide subunits
Q148

Match List I (Biomolecule type) with List II (Example) and select the correct option: List I A. Nucleotide B. Amino acid C. Secondary metabolite D. Reducing sugar List II I. Glucose II. Adenylic acid III. Alkaloid (morphine) IV. Tyrosine

(a) A-IV, B-II, C-III, D-I
(b) A-I, B-IV, C-III, D-II
(c) A-II, B-III, C-IV, D-I
(d) A-II, B-IV, C-III, D-I
Q149

How many of the following animals possess a true coelom (eucoelomate condition)? Ascaris, Earthworm (Pheretima), Planaria, Cockroach, Hydra, Starfish

(a) Five
(b) Three
(c) Two
(d) Four
Q150

Match List I (Phylum) with List II (Diagnostic feature) and choose the correct option: List I A. Porifera B. Ctenophora C. Aschelminthes D. Echinodermata List II I. Water vascular system II. Canal system & choanocytes III. Comb plates for locomotion IV. Complete digestive tract, pseudocoelom

(a) A-III, B-II, C-IV, D-I
(b) A-I, B-III, C-IV, D-II
(c) A-II, B-IV, C-III, D-I
(d) A-II, B-III, C-IV, D-I
Q151

Which of the following is the correct combination of characters for Phylum Chordata that distinguishes it from non-chordates?

(a) Notochord, ventral solid nerve cord, ventral heart
(b) Notochord, dorsal hollow nerve cord, paired pharyngeal gill slits
(c) Solid dorsal nerve cord, pharyngeal slits, ventral notochord
(d) Absence of notochord, dorsal heart, closed circulation
Q152

Statement I: All members of Phylum Echinodermata are exclusively marine and show radial symmetry in the adult. Statement II: Echinoderm larvae are bilaterally symmetrical. In light of the above, choose the correct option.

(a) Statement I is incorrect but Statement II is correct
(b) Both Statement I and Statement II are correct
(c) Statement I is correct but Statement II is incorrect
(d) Both Statement I and Statement II are incorrect
Q153

During human spermatogenesis, one primary spermatocyte ultimately gives rise to four sperms, whereas in oogenesis one primary oocyte gives rise to only one functional ovum. The difference is mainly because in oogenesis:

(a) Meiosis does not occur at all
(b) Cytokinesis is unequal, producing polar bodies that degenerate
(c) Crossing over is completely absent
(d) Only mitosis occurs in the ovary
Q154

Which hormone surge is directly responsible for triggering ovulation in the human menstrual cycle?

(a) Sudden fall of estrogen
(b) Peak of progesterone
(c) Sharp peak of FSH
(d) Rapid surge of LH
Q155

Arrange the following events of early human development in the correct chronological order: (i) Implantation (ii) Fertilisation in ampulla (iii) Formation of blastocyst (iv) Cleavage to morula

(a) (ii) → (iii) → (iv) → (i)
(b) (iv) → (ii) → (iii) → (i)
(c) (ii) → (iv) → (iii) → (i)
(d) (ii) → (iv) → (i) → (iii)
Q156

Which of the following contraceptive methods works primarily as a copper-releasing intra-uterine device that suppresses sperm motility and makes the uterus unsuitable for implantation?

(a) Tubectomy
(b) Combined oral pills
(c) Diaphragm
(d) Copper-releasing IUDs (e.g., Cu-T)
Q157

Match List I (Assisted Reproductive Technology) with List II (Procedure) and select the correct answer: List I A. IVF B. ZIFT C. GIFT D. ICSI List II I. Transfer of ovum from a donor into the fallopian tube of another female II. Injection of a single sperm directly into the ovum III. Fertilisation outside the body, then early embryo transferred to fallopian tube IV. Embryo formed in lab and transferred (test-tube baby programme)

(a) A-III, B-IV, C-I, D-II
(b) A-IV, B-III, C-I, D-II
(c) A-IV, B-I, C-III, D-II
(d) A-II, B-III, C-I, D-IV
Q158

In a large randomly-mating population at Hardy-Weinberg equilibrium, the frequency of a recessive allele (a) is 0.2. What percentage of the population is expected to be heterozygous (Aa)?

(a) 16%
(b) 32%
(c) 4%
(d) 64%
Q159

The forelimbs of a whale, a bat and a human have a similar basic skeletal plan but perform different functions. This is an example of:

(a) Analogous organs showing convergent evolution
(b) Vestigial organs
(c) Homologous organs showing divergent evolution
(d) Adaptive convergence
Q160

Arrange the following in the correct sequence of human evolution from earliest to most recent: (i) Homo erectus (ii) Australopithecus (iii) Homo habilis (iv) Homo sapiens

(a) (iii) → (ii) → (i) → (iv)
(b) (iii) → (i) → (ii) → (iv)
(c) (ii) → (iii) → (i) → (iv)
(d) (ii) → (i) → (iii) → (iv)
Q161

At the tissue level, the oxygen-haemoglobin dissociation curve shifts to the right, favouring unloading of O2. How many of the following factors cause this rightward shift? (i) Increase in pCO2 (ii) Decrease in pH (more H+) (iii) Rise in temperature (iv) Decrease in pO2

(a) Three
(b) Four
(c) Two
(d) One
Q162

The largest fraction of carbon dioxide is transported in human blood in the form of:

(a) Carbonic acid bound to plasma proteins
(b) Bicarbonate ions (HCO3-)
(c) Carbaminohaemoglobin
(d) Dissolved CO2 in plasma
Q163

If a person’s Tidal Volume is 500 mL, Inspiratory Reserve Volume is 3000 mL and Expiratory Reserve Volume is 1100 mL, what is the Vital Capacity (assuming these are the relevant volumes)?

(a) 4100 mL
(b) 4600 mL
(c) 3500 mL
(d) 3600 mL
Q164

In the cardiac cycle, the QRS complex of an ECG represents:

(a) Ventricular depolarisation
(b) Atrial repolarisation
(c) Ventricular repolarisation
(d) Atrial depolarisation
Q165

Assertion (A): A person with AB blood group is called a universal recipient. Reason (R): The plasma of an AB individual has no anti-A or anti-B antibodies.

(a) A is true but R is false
(b) A is false but R is true
(c) Both A and R are true but R is NOT the correct explanation of A
(d) Both A and R are true and R is the correct explanation of A
Q166

If the daily glomerular filtrate is 180 litres and the daily urine output is 1.8 litres, what percentage of the filtrate is reabsorbed by the nephrons?

(a) 99%
(b) 99.9%
(c) 90%
(d) 95%
Q167

Assertion (A): The counter-current mechanism in the kidney helps to maintain a high osmolarity gradient (interstitial concentration increasing towards the inner medulla). Reason (R): The loop of Henle and vasa recta together act as a counter-current system.

(a) Both A and R are true but R is NOT the correct explanation of A
(b) A is true but R is false
(c) Both A and R are true and R is the correct explanation of A
(d) A is false but R is true
Q168

According to the sliding filament theory, during muscle contraction which of the following statements is CORRECT regarding the sarcomere?

(a) A-band, I-band and H-zone all shorten equally
(b) I-band and H-zone shorten while A-band length remains constant
(c) A-band shortens, I-band remains constant
(d) The length of actin and myosin filaments decreases
Q169

In a relaxed sarcomere the distance from one Z-line to the next is 3.2 μm. During contraction each half-sarcomere shortens by 0.4 μm. What is the length of the contracted sarcomere?

(a) 2.8 μm
(b) 2.0 μm
(c) 2.4 μm
(d) 1.6 μm
Q170

Match List I (Joint) with List II (Type/Location) and choose the correct option: List I A. Between atlas and axis B. Between carpals C. Knee joint D. Between skull bones List II I. Hinge joint II. Pivot joint III. Fibrous (immovable) joint IV. Gliding joint

(a) A-III, B-IV, C-I, D-II
(b) A-II, B-IV, C-I, D-III
(c) A-II, B-I, C-IV, D-III
(d) A-I, B-IV, C-II, D-III
Q171

Assertion (A): In acquired immunity, the secondary immune response is faster and stronger than the primary response. Reason (R): Memory B and T cells generated during the first encounter recognise the pathogen on re-exposure.

(a) Both A and R are true and R is the correct explanation of A
(b) A is true but R is false
(c) A is false but R is true
(d) Both A and R are true but R is NOT the correct explanation of A
Q172

The malarial parasite Plasmodium enters the human body as which infective stage, released from the salivary glands of the female Anopheles mosquito?

(a) Sporozoites
(b) Trophozoites
(c) Merozoites
(d) Gametocytes
Q173

During the propagation of a nerve impulse, the rising phase (depolarisation) of the action potential is mainly due to:

(a) Activity of the Na+-K+ ATPase pump
(b) Opening of voltage-gated Na+ channels and Na+ influx
(c) Opening of voltage-gated K+ channels and K+ efflux
(d) Closing of Cl- channels
Q174

In the human eye, the region of the retina where the photoreceptors converge to leave as the optic nerve, and which is devoid of rods and cones, is the:

(a) Blind spot
(b) Iris
(c) Fovea (yellow spot)
(d) Ciliary body
Q175

Match List I (Endocrine gland/hormone) with List II (Disorder due to abnormal secretion) and choose the correct option: List I A. Thyroid (deficiency in adult) B. Insulin (deficiency) C. Growth hormone (excess in adult) D. Parathyroid (deficiency) List II I. Diabetes mellitus II. Acromegaly III. Myxoedema IV. Tetany

(a) A-IV, B-I, C-II, D-III
(b) A-III, B-II, C-I, D-IV
(c) A-I, B-III, C-II, D-IV
(d) A-III, B-I, C-II, D-IV
Q176

Steroid hormones differ from protein hormones in their mechanism of action because steroid hormones:

(a) Bind to membrane receptors and activate cyclic AMP
(b) Easily cross the plasma membrane and bind intracellular receptors to regulate gene expression
(c) Cannot enter the cell and act via second messengers
(d) Are always faster-acting than peptide hormones
Q177

Which of the following animal tissues has cells that are tall, with the nucleus at the base, and is found lining the inner surface of the stomach and intestine where it performs secretion and absorption?

(a) Cuboidal epithelium
(b) Columnar epithelium
(c) Ciliated epithelium of trachea
(d) Squamous epithelium
Q178

Match List I (Microbe) with List II (Product/Role) and choose the correct option: List I A. Lactobacillus B. Saccharomyces cerevisiae C. Aspergillus niger D. Trichoderma polysporum List II I. Bread/ethanol production II. Cyclosporin A (immunosuppressant) III. Curd formation IV. Citric acid

(a) A-III, B-I, C-II, D-IV
(b) A-I, B-III, C-IV, D-II
(c) A-IV, B-I, C-III, D-II
(d) A-III, B-I, C-IV, D-II
Q179

In sewage treatment, the BOD (Biochemical Oxygen Demand) of the effluent indicates:

(a) The number of pathogens present per litre
(b) The amount of dissolved oxygen produced by aquatic plants
(c) The amount of oxygen consumed if all organic matter in one litre of water is oxidised by bacteria
(d) The total nitrogen content of the water
Q180

Phenylketonuria is an inborn error of metabolism inherited as an autosomal recessive trait. The biochemical defect is the lack of an enzyme that converts:

(a) Glucose into glycogen
(b) Tyrosine into melanin
(c) Homogentisic acid into maleylacetoacetate
(d) Phenylalanine into tyrosine

PHYSICS — Answer Key (Q1–Q45)

Q1. (d) E x B / mu0 is the Poynting vector, representing power per unit area (intensity), i.e. W/m^2.
Q2. (b) dZ/Z = 2(2%) + 1% + 0.5(4%) = 4% + 1% + 2% = 7%.
Q3. (d) v=0 at t=4 s. 0-4 s gives 16 m, 4-6 s gives 4 m. Total distance = 20 m.
Q4. (b) H proportional to sin^2(theta). sin^2(30)/sin^2(60) = (1/4)/(3/4) = 1/3, so 1:3.
Q5. (a) Driving force = 30 N, total mass = 5 kg, a = 6 m/s^2.
Q6. (a) v^2 = rg tan(theta) = 250, v = sqrt(250) ~ 16 m/s.
Q7. (b) PE = 0.5(500)(0.2)^2 = 10 J = 0.5(2)v^2, v = sqrt(10) ~ 3.2 m/s.
Q8. (a) I = (2/5)MR^2. Mgh = (7/10)Mv^2, v = sqrt(10gh/7).
Q9. (c) ML^2/12 + M(L/2)^2 = ML^2/3.
Q10. (a) Iw conserved gives w’=3w. KE’=0.5(I/3)(3w)^2 = 3 times original. Ratio = 3.
Q11. (d) v = sqrt(gR/2). sqrt(gR) = 11.2/sqrt2 ~ 7.92, v = 7.92/sqrt2 ~ 5.6 km/s.
Q12. (c) A1 v1 = A2 v2, 10×2 = 5xv2, v2 = 4 m/s.
Q13. (d) h = 2T/(rho g r) = 0.144/2 = 0.072 m = 7.2 cm.
Q14. (b) Isothermal: change in U = 0, so Q = W.
Q15. (c) T1 = 300/0.6 = 500 K; new T1 = 300/0.5 = 600 K. Increase = 100 K.
Q16. (c) 0.5k(A^2 – x^2) = 0.5k x^2 gives x = A/sqrt2.
Q17. (b) T = 2pi sqrt(m/k); doublings cancel, so T unchanged.
Q18. (c) f = nv/2L = 3×120/(2×1.5) = 120 Hz.
Q19. (c) Loading lowers frequency; the beat decreased, so the fork was 261 Hz (moving toward 256).
Q20. (a) W = pE(cos0 – cos90) = pE.
Q21. (d) Inside a conductor the potential is constant equal to the surface value kQ/R.
Q22. (c) 1/C = 1/2 + 1/3 + 1/6 = 1, C = 1 uF.
Q23. (b) Electric flux V.m; magnetic flux weber; capacitance C/V; inductance V.s/A.
Q24. (b) I = 12/6 = 2 A; V = IR = 10 V.
Q25. (a) X/9 = 25/75 = 1/3, X = 3 ohm.
Q26. (b) (i) and (iii) correct; (ii) and (iv) wrong. So 2 correct.
Q27. (b) Parallel = 2.4 ohm; total = 5 ohm; I = 10/5 = 2 A.
Q28. (b) r = mv/qB = 6.4e-21/3.2e-20 = 0.2 m.
Q29. (a) B = mu0 n I = 4pi x 10^-7 x 2000 ~ 2.51 x 10^-3 T.
Q30. (d) Thermal agitation disrupts domain alignment, making the material paramagnetic; R explains A.
Q31. (b) EMF = L dI/dt = 0.5 x 20 = 10 V.
Q32. (c) Ip = Is x Ns/Np = 5 x (100/1000) = 0.5 A.
Q33. (a) I true (XL > XC means current lags). II false (at resonance current is maximum).
Q34. (d) B0 = E0/c = 30/(3e8) = 1 x 10^-7 T.
Q35. (d) 1/15 = 1/30 + 1/u gives 1/u = 1/30, u = 30 cm.
Q36. (a) 1/f = 0.5 x (2/20) = 0.05, f = 20 cm.
Q37. (a) n = sin45/sin30 = sqrt2.
Q38. (b) beta’ = beta/n = 0.4/(4/3) = 0.3 mm.
Q39. (a) E = 1240/400 = 3.1 eV; KE_max = 3.1 – 2.0 = 1.1 eV.
Q40. (d) lambda proportional to 1/sqrt(m) for equal KE, so lambda_e/lambda_p = sqrt(mp/me).
Q41. (d) E3 = -13.6/9 ~ -1.51 eV.
Q42. (c) 3 half-lives gives (1/2)^3 = 1/8.
Q43. (b) 28 – 2(2.2) = 23.6 MeV.
Q44. (b) Forward bias reduces the barrier and depletion width, letting majority carriers cross.
Q45. (a) Full-wave gives two pulses per cycle, ripple frequency = 100 Hz.

CHEMISTRY — Answer Key (Q46–Q90)

Q46. (b) Kp = Kc(RT)^Δn where Δn = (moles gaseous products) − (moles gaseous reactants) = 2 − (1+3) = −2. Hence Kp = Kc(RT)⁻².
Q47. (a) α = 0.05, C = 0.01 M. Ka ≈ Cα² = 0.01 × (0.05)² = 0.01 × 0.0025 = 2.5 × 10⁻⁵.
Q48. (a) By Le Chatelier’s principle, removing the product gas CO₂ drives the forward reaction. Adding/removing pure solids does not change equilibrium; the reaction is endothermic so lowering T shifts left.
Q49. (a) Mg(OH)₂ ⇌ Mg²⁺ + 2OH⁻; Ksp = s(2s)² = 4s³ = 1.0×10⁻¹¹. s³ = 2.5×10⁻¹², s = (2.5×10⁻¹²)^(1/3) ≈ 1.36×10⁻⁴ ≈ 1.4×10⁻⁴ M.
Q50. (d) Anion: hexacyanido (current IUPAC uses ‘cyanido’) ligands on Fe. Charge: K₃ gives +3, six CN⁻ give −6, so Fe is +3 → ferrate(III). Correct: potassium hexacyanidoferrate(III).
Q51. (c) F⁻ is a weak-field ligand → high spin d⁶: t2g⁴ eg² gives 4 unpaired electrons. μ = √[n(n+2)] = √[4×6] = √24 = 4.90 BM.
Q52. (d) (A) Fe²⁺ d⁶ with strong CN⁻ → low spin, 0 unpaired. (B) Fe²⁺ d⁶ with weak H₂O → high spin, 4 unpaired. (C) Co³⁺ d⁶ with strong NH₃ → low spin, 0 unpaired. (D) Ni²⁺ d⁸ → 2 unpaired. So A-i, B-iii, C-i, D-ii.
Q53. (c) [Cu(NH₃)₄]²⁺ is square planar (dsp²) for Cu²⁺ (d⁹). The partially filled d-orbitals permit d-d transitions giving the deep-blue colour. R correctly explains A.
Q54. (c) Allyl cation is resonance-stabilised (most stable). Isopropyl is secondary (stabilised by hyperconjugation + inductive), more stable than the primary n-propyl. Order: allyl > isopropyl(2°) > n-propyl(1°).
Q55. (a) C₅H₁₂ (pentane) has three chain isomers: n-pentane, isopentane (2-methylbutane), and neopentane (2,2-dimethylpropane).
Q56. (b) Electron-withdrawing groups increase acidity by stabilising the carboxylate. Two Cl atoms (Cl₂CHCOOH, dichloroacetic acid) exert a stronger combined −I effect than a single F or Cl, making it the strongest acid here.
Q57. (a) 75% consumed means 2 half-lives elapsed (100→50→25). So 2 t½ = 60 min → t½ = 30 min.
Q58. (c) t = (2.303/k) log(a/a−x) = (2.303 / 2.303×10⁻³) log10 = 1000 × 1 = 1000 s.
Q59. (c) Arrhenius equation in log form: ln k = ln A − Ea/RT. Plotting ln k vs 1/T gives a straight line of slope = −Ea/R.
Q60. (b) In aqueous solution for ethyl amines, the order is secondary > primary > tertiary (combined inductive + solvation effects): (C₂H₅)₂NH > C₂H₅NH₂ > (C₂H₅)₃N. Aniline (aromatic) is weakest due to lone-pair delocalisation into the ring.
Q61. (d) The carbylamine (isocyanide) test, RNH₂ + CHCl₃ + 3KOH → RNC + 3KCl + 3H₂O, is given only by primary amines (aliphatic and aromatic). It is used to distinguish 1° amines.
Q62. (c) Aniline forms benzenediazonium chloride at 0–5 °C. On warming with water, the diazonium group is replaced by –OH, giving phenol (with N₂ evolution).
Q63. (c) N₂ has 14 electrons. Bond order = (10−4)/2 = 3. All electrons are paired, so N₂ is diamagnetic.
Q64. (a) IF₇: central I has 7 bond pairs and no lone pair. Seven electron domains → sp³d³ hybridisation and pentagonal bipyramidal geometry.
Q65. (b) (I) True: H₂O’s strong intermolecular H-bonds raise its bp above H₂S. (II) False: o-nitrophenol has intramolecular H-bonding (chelation), lowering its bp below p-nitrophenol which has intermolecular H-bonds. (III) True: strong H–F bonding/short strong H–F bond contributes to HF being weaker than HCl. So I and III.
Q66. (b) ΔG = ΔH − TΔS = 30 − 300×(0.100) = 30 − 30 = 0 kJ/mol. The reaction is at equilibrium at 300 K.
Q67. (a) ΔH = ΔHf(CO₂) − ΔHf(CO) − ½ΔHf(O₂) = (−393) − (−110) − 0 = −283 kJ/mol.
Q68. (c) In an adiabatic process there is no heat exchange (q = 0), so by the first law ΔU = q + w = w. (An isothermal ideal-gas process, by contrast, has ΔU = 0 and hence q = −w.)
Q69. (b) White phosphorus exists as discrete tetrahedral P₄ molecules; each P is bonded to three others with a strained P–P–P bond angle of 60°, accounting for its high reactivity.
Q70. (b) ClF₃ (AX₃E₂) → bent T-shape; BrF₅ (AX₅E) → square pyramidal; ICl (diatomic) → linear; IF₇ (AX₇) → pentagonal bipyramidal. So A-ii, B-iii, C-i, D-iv.
Q71. (c) Down Group 15 the E–H bond weakens, so thermal stability decreases: NH₃ > PH₃ > AsH₃ > SbH₃ > BiH₃. (NH₃ has the highest bp due to H-bonding; basicity decreases down; bond angle decreases down.)
Q72. (c) Aldol condensation requires at least one α-hydrogen. Benzaldehyde (C₆H₅CHO) has no α-hydrogen, so it cannot undergo self-aldol (it instead gives the Cannizzaro reaction).
Q73. (d) Clemmensen uses Zn-Hg/HCl (i); Wolff–Kishner uses hydrazine/base (ii); Tollens’ gives a silver mirror with aldehydes (iii); Fehling’s gives a red Cu₂O ppt with aliphatic aldehydes (iv). So A-i, B-ii, C-iii, D-iv.
Q74. (a) Chloroacetic acid (strong −I effect, pKa ≈ 2.85) is the most acidic, then formic acid HCOOH (pKa ≈ 3.75) > benzoic acid C₆H₅COOH (pKa ≈ 4.2) > acetic acid CH₃COOH (pKa ≈ 4.76). So the order is ClCH₂COOH > HCOOH > C₆H₅COOH > CH₃COOH.
Q75. (c) Maltose has a free anomeric (hemiacetal) carbon on one glucose unit, so it is a reducing sugar. Sucrose and trehalose have both anomeric carbons locked in the glycosidic linkage, and in methyl α-D-glucoside the anomeric carbon is fixed as a glycoside; all three are non-reducing.
Q76. (c) (I) True: secondary structure is H-bond stabilised. (II) True: peptide bond is –CO–NH– amide. (III) False: denaturation destroys 2°/3° structure but the primary structure (peptide sequence) remains intact. So I and II.
Q77. (a) log K = nE°cell/0.059 = (2 × 0.46)/0.059 = 0.92/0.059 ≈ 15.6 ≈ 16. So K ≈ 10¹⁶.
Q78. (a) Λ°(CH₃COOH) = Λ°(CH₃COO⁻) + Λ°(H⁺). Combining strong electrolytes: Λ°(CH₃COONa) + Λ°(HCl) − Λ°(NaCl) cancels Na⁺ and Cl⁻, leaving CH₃COO⁻ + H⁺.
Q79. (a) Relative lowering of VP = mole fraction of solute = n_solute/(n_solute + n_solvent). 0.2 = 1/(1 + n). 1 + n = 5, so n_solvent = 4.
Q80. (c) For NaCl (n=2): i = 1 + α(n−1) = 1 + α. So 1.9 = 1 + α → α = 0.9 = 90%.
Q81. (d) Reductive ozonolysis cleaves C=C into two carbonyls. Acetone (CH₃)₂C=O and acetaldehyde CH₃CHO rejoin as (CH₃)₂C=CH–CH₃, i.e. 2-methyl-2-butene.
Q82. (b) With peroxide, HBr adds by a free-radical mechanism (anti-Markovnikov, peroxide effect), placing Br on the terminal carbon to give 1-bromopropane.
Q83. (b) Electron-donating –CH₃ (p-cresol) decreases acidity; electron-withdrawing –NO₂ (p-nitrophenol) increases acidity. Order: p-cresol < phenol < p-nitrophenol.
Q84. (a) In Williamson synthesis the alkyl halide should be the less hindered one (1° or methyl) to favour SN2 over elimination. So use CH₃Br (methyl) with bulky tert-butoxide. Using tert-butyl halide would give elimination (isobutylene).
Q85. (b) SN1 proceeds through a planar (sp²) carbocation intermediate; the nucleophile can attack either face with roughly equal probability, giving both enantiomers and hence (partial) racemisation. SN2, by contrast, is a back-side single-step attack giving inversion (Walden inversion).
Q86. (b) The poor shielding by 4f electrons (R, true) causes a gradual size decrease across the 4f series (lanthanoid contraction), which makes Hf nearly equal in radius to the lighter Zr (A, true). R correctly explains A.
Q87. (b) Moles Fe = 11.2/56 = 0.2. Fe + H₂SO₄ → FeSO₄ + H₂; 0.2 mol Fe gives 0.2 mol H₂ → 0.2 × 22.4 = 4.48 L at STP, and 0.2 mol FeSO₄ (molar mass 152) = 0.2 × 152 = 30.4 g.
Q88. (b) Radial nodes = n − l − 1. For 3p (n=3, l=1): 3−1−1 = 1. For 3d (n=3, l=2): 3−2−1 = 0. For 4s (n=4, l=0): 4−0−1 = 3. So 1, 0, 3.
Q89. (d) MnO₄⁻ gains 5 e⁻ (Mn⁷⁺→Mn²⁺); each C₂O₄²⁻ loses 2 e⁻ (2C³⁺→2C⁴⁺). Balancing electrons: 2 MnO₄⁻ react with 5 C₂O₄²⁻, so per mole MnO₄⁻, 5/2 moles oxalate are oxidised.
Q90. (d) For isoelectronic species (all 10 electrons), radius decreases as nuclear charge (Z) increases. Z: O(8) < F(9) < Na(11) < Mg(12). So increasing radius means decreasing Z: Mg²⁺ < Na⁺ < F⁻ < O²⁻.

BOTANY — Answer Key (Q91–Q135)

Q91. (d) In a 9:3:3:1 ratio, the both-recessive class is 1/16. 1/16 of 480 = 30 plants.
Q92. (a) AB (I^A I^B) parent gives gametes I^A or I^B; O (ii) parent gives i. Offspring are I^A i (group A) or I^B i (group B). Hence only A and B are possible.
Q93. (b) In Mirabilis jalapa the red x white cross gives pink F1, a classic case of incomplete dominance. The heterozygote (Rr) is pink because neither allele is fully dominant, so the phenotype is intermediate. R correctly explains why the F1 is pink.
Q94. (d) Down = trisomy 21 (ii); Turner = 44+XO (iv); Klinefelter = 44+XXY (i); normal female = 44+XX (iii).
Q95. (a) Carrier mother (X^A X^a) x normal father (X^A Y). Sons: 1/2 normal, 1/2 affected (1 correct). Daughters: 1/2 normal, 1/2 carrier; none affected (2,3,4 correct). All four correct.
Q96. (a) Map distance in centimorgans equals the percentage of recombinant offspring. 20 map units = 20% recombinants.
Q97. (b) RNA polymerase synthesises RNA in the 5’→3′ direction, reading a template strand of opposite polarity (3’→5′).
Q98. (c) i gene makes repressor (1); lactose/allolactose is inducer (2); inducer binds repressor preventing operator binding (3); z gene codes beta-galactosidase (4). All four correct.
Q99. (b) After one generation all DNA is hybrid. After two generations, of 4 molecules: 2 hybrid and 2 light. Ratio = 1:1.
Q100. (a) Degeneracy is a real feature of the code (I correct). AUG codes Met and serves as start codon (II correct). Both correct.
Q101. (d) hnRNA undergoes capping (5′ methyl guanosine cap), splicing to remove introns, and polyadenylation (tailing) at the 3′ end to become mature mRNA.
Q102. (b) Dinoflagellates: cellulose plates, red tides (ii); euglenoids: pellicle, no wall (iii); slime moulds: saprophytic plasmodium (iv); diatoms: silica wall (i).
Q103. (d) Chlorophyceae store true starch and Rhodophyceae store floridean starch (2). Phaeophyceae store mannitol/laminarin; cyanobacteria are Monera (not an algal class here). Two correct.
Q104. (b) In bryophytes the haploid gametophyte is the dominant, photosynthetic, free-living phase; the diploid sporophyte is smaller and dependent on it.
Q105. (a) Gymnosperm ovules are not enclosed in an ovary; after fertilisation the seeds remain exposed/naked. R correctly explains A.
Q106. (d) Gamosepalous calyx, epipetalous stamens, bicarpellary syncarpous superior ovary with axile placentation and oblique septum are diagnostic of Solanaceae.
Q107. (b) Fabaceae: vexillary aestivation (i) and diadelphous (9)+1 stamens (iii). Solanaceae: berry, oblique ovary (iv). Liliaceae: tepals 3+3, axile placentation (ii).
Q108. (b) Gamosepalous = united sepals; epipetalous = stamens fused to petals; polypetalous = free petals (all correct). Gamopetalous means united petals, not free (wrong). Three correct.
Q109. (d) Imbricate aestivation has overlapping margins with no definite direction. Valvate = margins just touch; twisted = regular overlap; vexillary = papilionaceous.
Q110. (d) In C4 mesophyll cells, PEP accepts CO2 (via PEP carboxylase) to form the 4-carbon oxaloacetic acid (OAA) as the first stable product.
Q111. (a) In photorespiration RuBisCO acts as an oxygenase rather than a carboxylase; this pathway does not fix carbon into sugar and consequently yields no ATP or NADPH. The oxygenase activity with no sugar synthesis is precisely why there is no energy gain, so R correctly explains A.
Q112. (c) For every 3 CO2 fixed, 3 RuBP molecules are regenerated, using 3 ATP (one per RuBP) in the regeneration step. (Whole cycle uses 9 ATP and 6 NADPH per 3 CO2.)
Q113. (b) Glycolysis releases no CO2. Each glucose yields 2 pyruvate; the link reaction (pyruvate → acetyl-CoA) releases 1 CO2 per pyruvate = 2 CO2, and each turn of the Krebs cycle releases 2 CO2 (×2 turns) = 4 CO2. Total = 6 CO2 per glucose, matching its 6 carbons.
Q114. (d) Fats have RQ < 1 (about 0.7) because their oxidation consumes more O2 than CO2 released. Both statements correct, II explains I.
Q115. (b) Gibberellin causes bolting (ii); ABA is the stress hormone causing stomatal closure (iii); ethylene promotes ripening/senescence (i); cytokinin promotes cell division and delays senescence (iv).
Q116. (c) Short-day plants flower when continuous darkness exceeds a critical length; experiments show the dark period length is decisive (a light flash during the night prevents flowering). R correctly explains A.
Q117. (c) Auxins cause apical dominance (1), induce parthenocarpy (2), and promote root initiation in cuttings (3). Breaking cereal seed dormancy is gibberellin (4 wrong). Three correct.
Q118. (a) The 7-celled, 8-nucleate embryo sac: central cell has 2 polar nuclei; 2 synergids and 3 antipodal cells each have 1 nucleus; plus the egg = 8 nuclei in 7 cells.
Q119. (b) Syngamy: male gamete + egg = diploid zygote. Triple fusion: second male gamete + two polar nuclei = triploid primary endosperm nucleus.
Q120. (c) Geitonogamy is between flowers of the same plant (1); xenogamy brings genetically different pollen (2); autogamy in open flowers needs synchrony (3). Cleistogamous flowers are invariably self-pollinated (4 wrong). Three correct.
Q121. (d) Synapsis (pairing into bivalents) occurs in zygotene (II correct); crossing over occurs at pachytene (I correct). Both correct.
Q122. (d) Mitosis: 2 diploid cells; meiosis: 4 haploid (1). Crossing over only in meiosis (2). Pairing of homologues only in meiosis (3). DNA replicates only once, before meiosis I (4 wrong). Three correct.
Q123. (a) Plant cells divide by a cell plate growing outward to the wall; the rigid existing cell wall prevents the furrowing/constriction method used by animal cells. R correctly explains A.
Q124. (d) Rough ER bears ribosomes for protein synthesis (ii); Golgi packages/modifies (iv); lysosome does intracellular digestion (i); mitochondria carry out oxidative phosphorylation (iii).
Q125. (c) Km is the substrate concentration at half Vmax. A low Km means half-maximal velocity is reached at low substrate concentration, indicating high affinity.
Q126. (c) Cellulose, glycogen and inulin are polysaccharides (3). Insulin is a protein hormone, not a polysaccharide. Three correct.
Q127. (b) Each PCR cycle: denaturation (strand separation at high temperature), annealing (primers bind), then extension (thermostable Taq polymerase synthesises new strands).
Q128. (c) Ti plasmid = Agrobacterium vector (ii); RNAi silences mRNA, used against nematodes (iii); Bt cotton uses Cry protein for insect resistance (iv); gel electrophoresis separates DNA by size (i).
Q129. (a) Restriction enzymes recognise palindromes (1), cut at specific sites (2), and are molecular scissors (3). Joining is done by DNA ligase (4 wrong). Three correct.
Q130. (d) Using the 10% law: producers 20,000 kJ → primary consumers 2000 kJ → secondary consumers (third trophic level) 200 kJ.
Q131. (a) NPP = GPP – respiratory losses (I correct); NPP is the biomass available to herbivores and decomposers (II correct). Both correct.
Q132. (b) Logistic growth is S-shaped because as N approaches K, resource limitation slows growth, flattening the curve. R correctly explains A.
Q133. (c) Mutualism +/+ (ii); competition -/- (iii); predation +/- (iv); commensalism +/0 (i).
Q134. (a) For relatively small areas, the slope Z of the species-area relationship lies between 0.1 and 0.2, regardless of taxonomic group or region.
Q135. (d) In-situ (on-site) conservation: national parks, biosphere reserves, sacred groves (3). Zoological parks are ex-situ. Three correct.

ZOOLOGY — Answer Key (Q136–Q180)

Q136. (a) EcoRI recognises the palindrome 5′-GAATTC-3′ and cuts between G and the adjoining A on both strands. Because the cut is staggered, it leaves single-stranded 5′ protruding overhangs (AATT) called sticky/cohesive ends.
Q137. (a) Insertion at PstI inactivates the ampicillin-resistance (ampR) gene by insertional inactivation, so recombinants become ampicillin-sensitive. The tetracycline-resistance gene stays intact, so they remain tetracycline-resistant.
Q138. (a) A PCR cycle proceeds as Denaturation (~94°C, strands separate) → Annealing (~50-55°C, primers bind) → Extension (~72°C, Taq polymerase synthesises new strands). Hence (ii)→(i)→(iii).
Q139. (b) DNA fragments stained with ethidium bromide fluoresce as bright orange bands when exposed to UV radiation. DNA itself is colourless and not visible in visible light without the dye+UV.
Q140. (b) All four are correct: the Ti plasmid is the natural vector engineered for plant transformation; stirred-tank bioreactors provide aeration and mixing; plasmids and phages both replicate autonomously and act as vectors; downstream processing covers separation, purification and QC.
Q141. (d) In the recombinant process, chains A and B are produced separately in E. coli and then combined in vitro by forming disulphide bonds between them to make the functional insulin. The natural C-peptide is not required in this assembly approach.
Q142. (b) The Cry crystal protein is an inactive protoxin. In the insect’s gut, the alkaline pH solubilises the crystals, converting the protoxin into the active toxin, which then binds to the midgut epithelium and creates pores, killing the insect.
Q143. (a) Complementary sense and antisense RNAs form a double-stranded RNA, which triggers RNA interference (RNAi). This silences the specific transcript essential to the nematode, so the parasite cannot survive in the transgenic host.
Q144. (a) (i) correct; (ii) correct (ligases link molecules, e.g. C-C, C-O, C-N bonds); (iv) correct (enzymes lower activation energy). (iii) is WRONG — that describes transferases; lyases catalyse removal of groups leaving double bonds (without hydrolysis). So three are correct.
Q145. (c) Prosthetic groups are organic cofactors tightly bound (often covalently) to the apoenzyme, e.g. haem in peroxidase/catalase. Coenzymes, in contrast, associate transiently and dissociate readily during catalysis.
Q146. (b) Fats contain little oxygen relative to carbon and hydrogen, so more O2 is consumed per CO2 produced. The RQ for fats is about 0.7. (Carbohydrate = 1.0, protein ≈ 0.9.) A common 2026 trap.
Q147. (a) Secondary structure refers to regular local folding such as the α-helix and β-pleated sheet, stabilised by hydrogen bonds. The sequence is primary, the 3-D fold is tertiary, and subunit assembly is quaternary.
Q148. (d) Adenylic acid is a nucleotide (A-II); tyrosine is an amino acid (B-IV); morphine is an alkaloid, a secondary metabolite (C-III); glucose is a reducing sugar (D-I).
Q149. (b) Eucoelomates among these: Earthworm (Annelida), Cockroach (Arthropoda) and Starfish (Echinodermata) = three. Ascaris is pseudocoelomate; Planaria (Platyhelminthes) and Hydra (Cnidaria) are acoelomate.
Q150. (d) Porifera — canal system and choanocytes (A-II); Ctenophora — comb plates/ctenes for locomotion (B-III); Aschelminthes — complete gut with pseudocoelom (C-IV); Echinodermata — water vascular system (D-I).
Q151. (b) The three fundamental chordate characters are a notochord, a dorsal hollow (tubular) nerve cord, and paired pharyngeal gill slits. Chordates also have a ventral heart and a post-anal tail, but the listed trio is the defining set.
Q152. (b) Echinoderms are exclusively marine and the adults show radial (pentamerous) symmetry, while their larvae are bilaterally symmetrical (an evolutionarily significant point). Both statements are correct.
Q153. (b) In oogenesis the cytoplasmic divisions are unequal, so the bulk of cytoplasm goes to one cell while the others become tiny polar bodies that degenerate. Hence one primary oocyte forms a single ovum, unlike the four spermatids from a spermatocyte.
Q154. (d) A rapid surge of luteinising hormone (LH), the LH surge, around the middle of the cycle induces rupture of the Graafian follicle and release of the ovum (ovulation).
Q155. (c) Fertilisation occurs in the ampullary region (ii); the zygote undergoes cleavage to form a morula (iv); the morula develops into a blastocyst (iii); the blastocyst then implants in the uterine wall (i).
Q156. (d) Copper-releasing IUDs such as Cu-T release Cu ions that suppress sperm motility and the fertilising capacity of sperms, and make the uterus unsuitable for implantation. Pills act on hormones, tubectomy is surgical, and the diaphragm is a barrier method.
Q157. (b) IVF — fertilisation in lab, embryo transferred (test-tube baby) (A-IV); ZIFT — zygote/early embryo (up to 8 blastomeres) transferred to fallopian tube (B-III); GIFT — transfer of ovum from a donor into the fallopian tube (C-I); ICSI — single sperm injected directly into ovum (D-II).
Q158. (b) q = 0.2, so p = 0.8. Heterozygote frequency = 2pq = 2 × 0.8 × 0.2 = 0.32 = 32%.
Q159. (c) Same fundamental structure but different functions = homologous organs, indicating divergent evolution from a common ancestor. (Analogous organs have different structure but similar function = convergent evolution.)
Q160. (c) The accepted sequence is Australopithecus → Homo habilis (first tool-maker, ~2 mya) → Homo erectus (~1.5 mya) → Homo sapiens. Hence (ii)→(iii)→(i)→(iv).
Q161. (b) All four favour the rightward shift and O2 unloading at tissues: high pCO2, low pH (Bohr effect), increased temperature, and low pO2 all reduce haemoglobin’s affinity for O2. So four are correct.
Q162. (b) About 70% of CO2 is carried as bicarbonate ions in plasma (formed via carbonic anhydrase in RBCs). About 20-25% travels as carbamino-haemoglobin and only ~7% remains dissolved in plasma.
Q163. (b) Vital Capacity = TV + IRV + ERV = 500 + 3000 + 1100 = 4600 mL. (Residual volume is excluded as it cannot be exhaled.)
Q164. (a) The QRS complex marks ventricular depolarisation, which initiates ventricular contraction (systole). The P wave is atrial depolarisation and the T wave is ventricular repolarisation.
Q165. (d) An AB individual has both A and B antigens on RBCs but no anti-A or anti-B antibodies in plasma, so transfused A, B, AB or O cells are not agglutinated — making them a universal recipient. R correctly explains A.
Q166. (a) Reabsorbed volume = 180 − 1.8 = 178.2 L. Percentage reabsorbed = (178.2/180) × 100 = 99%. Nearly all filtrate is reabsorbed.
Q167. (c) The proximity and flow arrangement of the loop of Henle and the vasa recta (counter-current) builds and maintains the increasing medullary osmotic gradient, enabling concentrated urine formation. R correctly explains A.
Q168. (b) During contraction, thin filaments slide over thick filaments without changing filament length. Therefore the A-band (length of myosin) stays constant, while the I-band and H-zone shorten and the sarcomere narrows.
Q169. (c) Each half-sarcomere shortens by 0.4 μm, so total shortening = 2 × 0.4 = 0.8 μm. Contracted sarcomere = 3.2 − 0.8 = 2.4 μm.
Q170. (b) Atlas-axis = pivot joint (A-II); between carpals = gliding joint (B-IV); knee = hinge joint (C-I); between skull bones = fibrous, immovable joint (D-III).
Q171. (a) Memory cells formed in the primary response enable a rapid, intense secondary response on re-exposure. R correctly explains A — this is the basis of vaccination.
Q172. (a) Sporozoites are the infective stage injected by the bite of an infected female Anopheles. They first multiply in liver cells, then enter RBCs where they form merozoites; gametocytes are picked up by the mosquito.
Q173. (b) At threshold, voltage-gated Na+ channels open and Na+ rushes in, reversing the membrane potential (depolarisation/rising phase). Subsequent K+ efflux causes repolarisation; the pump only restores ionic gradients gradually.
Q174. (a) The blind spot is the point where the optic nerve leaves the retina; it lacks rods and cones, so no image is formed there. The fovea (in the macula lutea) is the point of highest visual acuity, densely packed with cones.
Q175. (d) Adult hypothyroidism → myxoedema (A-III); insulin deficiency → diabetes mellitus (B-I); GH excess in adults → acromegaly (C-II); parathyroid hormone deficiency → low blood Ca2+ → tetany (D-IV).
Q176. (b) Being lipid-soluble, steroid hormones diffuse across the plasma membrane, bind to intracellular (cytoplasmic/nuclear) receptors, and the hormone-receptor complex regulates gene transcription. Protein/peptide hormones bind surface receptors and act via second messengers like cAMP.
Q177. (b) Columnar epithelium consists of tall cells with basally placed nuclei; it lines the stomach and intestine and is specialised for secretion and absorption.
Q178. (d) Lactobacillus → curd (A-III); Saccharomyces cerevisiae → bread and ethanol (B-I); Aspergillus niger → citric acid (C-IV); Trichoderma polysporum → cyclosporin A immunosuppressant (D-II).
Q179. (c) BOD measures the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria. A higher BOD means greater polluting organic load; treated effluent has low BOD.
Q180. (d) In phenylketonuria, the enzyme that converts phenylalanine to tyrosine is absent, so phenylalanine and its derivatives accumulate, causing mental retardation. It is an autosomal recessive Mendelian disorder.
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