NEET 3 Answers PDF

**Biology (Difficult Level):** 1. **Question:** In a hypothetical experiment, if the gene encoding the enzyme RuBisCO is knocked out in a C3 plant, what is the most likely outcome during photosynthesis?\ a) Accumulation of oxygen in the stroma\ b) Inhibition of the light-dependent...

**Biology (Difficult Level):** 1. **Question:** In a hypothetical experiment, if the gene encoding the enzyme RuBisCO is knocked out in a C3 plant, what is the most likely outcome during photosynthesis?\ a) Accumulation of oxygen in the stroma\ b) Inhibition of the light-dependent reactions\ c) Complete cessation of the Calvin cycle\ d) Increased photorespiration\ **Answer:** c) Complete cessation of the Calvin cycle 2. **Question:** Which of the following is not a component of the Lac operon system in *E. coli*?\ a) Promoter\ b) Operator\ c) Terminator\ d) Structural genes (lacZ, lacY, lacA)\ **Answer:** c) Terminator 3. **Question:** Which of the following statements about the genetic code is incorrect?\ a) It is degenerate because multiple codons can code for the same amino acid.\ b) It is overlapping, meaning one nucleotide can be part of two codons.\ c) It is universal, with few exceptions across different organisms.\ d) It is unambiguous, where one codon codes for only one amino acid.\ **Answer:** b) It is overlapping, meaning one nucleotide can be part of two codons. 4. **Question:** In a plant cell, inhibition of which of the following enzymes would lead to accumulation of glycolate in the peroxisome?\ a) Glycolate oxidase\ b) Glycerate kinase\ c) Phosphoenolpyruvate carboxylase\ d) Glutamate synthase\ **Answer:** a) Glycolate oxidase 5. **Question:** If the sodium-potassium pump in neurons were to fail, what would be the immediate effect on neuronal resting membrane potential?\ a) It would become more negative.\ b) It would remain the same.\ c) It would become less negative or neutral.\ d) It would lead to an action potential.\ **Answer:** c) It would become less negative or neutral. 6. **Question:** Which of the following represents the correct sequence of developmental stages during embryogenesis in animals?\ a) Zygote → Morula → Blastula → Gastrula\ b) Zygote → Gastrula → Blastula → Morula\ c) Zygote → Blastula → Morula → Gastrula\ d) Zygote → Gastrula → Morula → Blastula\ **Answer:** a) Zygote → Morula → Blastula → Gastrula 7. **Question:** Which of the following phytohormones is primarily responsible for the maintenance of seed dormancy?\ a) Gibberellin\ b) Abscisic acid\ c) Auxin\ d) Cytokinin\ **Answer:** b) Abscisic acid 8. **Question:** In humans, the ABO blood group system exhibits codominance. Which of the following genotype-phenotype pairings is incorrect?\ a) IAIA - Blood group A\ b) IBIO - Blood group B\ c) IAIB - Blood group AB\ d) IAIB - Blood group O\ **Answer:** d) IAIB - Blood group O 9. **Question:** Which one of the following events is specifically inhibited by the herbicide atrazine in photosynthetic plants?\ a) Formation of ATP in mitochondria\ b) Transfer of electrons from PS II to plastoquinone\ c) CO₂ fixation in the Calvin cycle\ d) Formation of NADPH in photosystem I\ **Answer:** b) Transfer of electrons from PS II to plastoquinone 10. **Question:** The secondary immune response is more robust than the primary immune response because:\ a) It involves the activation of both B and T cells simultaneously.\ b) Memory cells formed during the primary response quickly recognize the antigen.\ c) There is an increase in antigen-presenting cells during the second exposure.\ d) The pathogen mutates and becomes weaker in subsequent exposures.\ **Answer:** b) Memory cells formed during the primary response quickly recognize the antigen. **Physics (Moderate Level):** 1. **Question:** A car is moving with a velocity of 20 m/s. If the brakes are applied and the car decelerates at 5 m/s², how long will it take for the car to stop?\ a) 2 s\ b) 3 s\ c) 4 s\ d) 5 s\ **Answer:** d) 4 s\ **Explanation:** Time t=va=205=4t = \\frac{v}{a} = \\frac{20}{5} = 4t=av​=520​=4 s. 2. **Question:** The escape velocity on a planet is 11.2 km/s11.2 \\, \\text{km/s}11.2km/s. If the radius of the planet is doubled while the mass remains the same, the escape velocity becomes:\ a) 11.2 km/s\ b) 22.4 km/s\ c) 7.9 km/s\ d) 5.6 km/s\ **Answer:** c) 7.9 km/s\ **Explanation:** Escape velocity ve=2GMRv\_e = \\sqrt{\\frac{2GM}{R}}ve​=R2GM​​, so if the radius doubles, the velocity becomes ve/2v\_e / \\sqrt{2}ve​/2​. 3. **Question:** A current of 2 A flows through a conductor for 5 seconds. The amount of charge passing through the conductor is:\ a) 5 C\ b) 10 C\ c) 15 C\ d) 20 C\ **Answer:** b) 10 C\ **Explanation:** Q=It=2×5=10 CoulombsQ = It = 2 \\times 5 = 10 \\, \\text{Coulombs}Q=It=2×5=10Coulombs. 4. **Question:** In an electric circuit, if three resistors of 4 ohms, 6 ohms, and 12 ohms are connected in parallel, the equivalent resistance is:\ a) 2 ohms\ b) 3 ohms\ c) 4 ohms\ d) 5 ohms\ **Answer:** b) 3 ohms\ **Explanation:** For resistors in parallel, 1Req=14+16+112\\frac{1}{R\_{eq}} = \\frac{1}{4} + \\frac{1}{6} + \\frac{1}{12}Req​1​=41​+61​+121​. 5. **Question:** Two masses, m1m\_1m1​ and m2m\_2m2​, are placed on a frictionless surface. If a force FFF is applied on m1m\_1m1​, both masses accelerate together. The net force acting on m2m\_2m2​ is:\ a) FFF\ b) F×m2F \\times m\_2F×m2​\ c) F×m2m1+m2F \\times \\frac{m\_2}{m\_1 + m\_2}F×m1​+m2​m2​​\ d) F×m1m1+m2F \\times \\frac{m\_1}{m\_1 + m\_2}F×m1​+m2​m1​​\ **Answer:** c) F×m2m1+m2F \\times \\frac{m\_2}{m\_1 + m\_2}F×m1​+m2​m2​​ 6. **Question:** A satellite revolves around Earth in a circular orbit. If the radius of the orbit is increased to 4 times the original value, the orbital speed of the satellite will:\ a) Increase by 4 times\ b) Decrease to half\ c) Decrease to one-fourth\ d) Decrease to half\ **Answer:** d) Decrease to half\ **Explanation:** Orbital speed v∝1rv \\propto \\frac{1}{\\sqrt{r}}v∝r​1​, so if rrr is quadrupled, vvv becomes half. 7. **Question:** The dimensional formula of angular momentum is:\ a) \[M1L2T−1\]\[M\^1L\^2T\^{-1}\]\[M1L2T−1\]\ b) \[M1L2T−2\]\[M\^1L\^2T\^{-2}\]\[M1L2T−2\]\ c) \[M0L1T−1\]\[M\^0L\^1T\^{-1}\]\[M0L1T−1\]\ d) \[M1L1T−2\]\[M\^1L\^1T\^{-2}\]\[M1L1T−2\]\ **Answer:** a) \[M1L2T−1\]\[M\^1L\^2T\^{-1}\]\[M1L2T−1\]\ **Explanation:** Angular momentum L=IωL = I \\omegaL=Iω, where III is moment of inertia and ω\\omegaω is angular velocity. 8. **Question:** A 10 W bulb emits light uniformly in all directions. The intensity of light at a distance of 1 m from the bulb is:\ a) 10 W/m210 \\, \\text{W/m}\^210W/m2\ b) 5 W/m25 \\, \\text{W/m}\^25W/m2\ c) 2.5 W/m22.5 \\, \\text{W/m}\^22.5W/m2\ d) 0.8 W/m20.8 \\, \\text{W/m}\^20.8W/m2\ **Answer:** c) 2.5 W/m22.5 \\, \\text{W/m}\^22.5W/m2\ **Explanation:** Intensity I=P4πr2=104×3.14×12≈2.5 W/m2I = \\frac{P}{4\\pi r\^2} = \\frac{10}{4 \\times 3.14 \\times 1\^2} \\approx 2.5 \\, \\text{W/m}\^2I=4πr2P​=4×3.14×1210​≈2.5W/m2. 9. **Question:** In a Young's double-slit experiment, the wavelength of light used is 600 nm, and the distance between the slits is 0.5 mm. If the screen is placed 1 m away from the slits, the fringe width is:\ a) 0.12 mm\ b) 0.24 mm\ c) 0.36 mm\ d) 0.48 mm\ **Answer:** b) 0.24 mm\ **Explanation:** Fringe width β=λDd=600×10−9×10.5×10−3=0.24 mm\\beta = \\frac{\\lambda D}{d} = \\frac{600 \\times 10\^{-9} \\times 1}{0.5 \\times 10\^{-3}} = 0.24 \\, \\text{mm}β=dλD​=0.5×10−3600×10−9×1​=0.24mm. 10. **Question:** A convex lens of focal length 20 cm forms an image of a real object at a distance of 60 cm from the lens. The distance of the object from the lens is:\ a) 30 cm\ b) 40 cm\ c) 45 cm\ d) 50 cm\ **Answer:** b) 40 cm\ **Explanation:** Use the lens formula 1f=1v−1u\\frac{1}{f} = \\frac{1}{v} - \\frac{1}{u}f1​=v1​−u1​, where f=20 cm,v=60 cmf = 20 \\, \\text{cm}, v = 60 \\, \\text{cm}f=20cm,v=60cm. 1. **Question:** Which of the following is the correct order of stability for carbocations?\ a) CH3+\>C6H5CH2+\>C2H5+CH\_3\^+ \> C\_6H\_5CH\_2\^+ \> C\_2H\_5\^+CH3+​\>C6​H5​CH2+​\>C2​H5+​\ b) C6H5CH2+\>CH3+\>C2H5+C\_6H\_5CH\_2\^+ \> CH\_3\^+ \> C\_2H\_5\^+C6​H5​CH2+​\>CH3+​\>C2​H5+​\ c) C6H5CH2+\>C2H5+\>CH3+C\_6H\_5CH\_2\^+ \> C\_2H\_5\^+ \> CH\_3\^+C6​H5​CH2+​\>C2​H5+​\>CH3+​\ d) C2H5+\>CH3+\>C6H5CH2+C\_2H\_5\^+ \> CH\_3\^+ \> C\_6H\_5CH\_2\^+C2​H5+​\>CH3+​\>C6​H5​CH2+​\ **Answer:** c) C6H5CH2+\>C2H5+\>CH3+C\_6H\_5CH\_2\^+ \> C\_2H\_5\^+ \> CH\_3\^+C6​H5​CH2+​\>C2​H5+​\>CH3+​ 2. **Question:** The rate of a reaction doubles when the concentration of reactant A is doubled and quadruples when the concentration of B is doubled. What is the rate law expression for this reaction?\ a) Rate = k\[A\]2\[B\]k\[A\]\^2\[B\]k\[A\]2\[B\]\ b) Rate = k\[A\]\[B\]2k\[A\]\[B\]\^2k\[A\]\[B\]2\ c) Rate = k\[A\]\[B\]k\[A\]\[B\]k\[A\]\[B\]\ d) Rate = k\[A\]1\[B\]2k\[A\]\^1\[B\]\^2k\[A\]1\[B\]2\ **Answer:** d) Rate = k\[A\]1\[B\]2k\[A\]\^1\[B\]\^2k\[A\]1\[B\]2 3. **Question:** Which of the following oxoacids of phosphorus contains P-H bonds?\ a) H₃PO₄\ b) H₃PO₃\ c) H₄P₂O₇\ d) H₃PO₂\ **Answer:** d) H₃PO₂\ **Explanation:** H₃PO₂ has one P-H bond, while the others have P-O bonds. 4. **Question:** Which of the following reactions involves the oxidation of chlorine?\ a) Cl2+H2→2HClCl\_2 + H\_2 \\rightarrow 2HClCl2​+H2​→2HCl\ b) Cl2+2NaOH→NaCl+NaOCl+H2OCl\_2 + 2NaOH \\rightarrow NaCl + NaOCl + H\_2OCl2​+2NaOH→NaCl+NaOCl+H2​O\ c) Cl2+SO2→SOCl2Cl\_2 + SO\_2 \\rightarrow SOCl\_2Cl2​+SO2​→SOCl2​\ d) Cl2+2KI→2KCl+I2Cl\_2 + 2KI \\rightarrow 2KCl + I\_2Cl2​+2KI→2KCl+I2​\ **Answer:** b) Cl2+2NaOH→NaCl+NaOCl+H2OCl\_2 + 2NaOH \\rightarrow NaCl + NaOCl + H\_2OCl2​+2NaOH→NaCl+NaOCl+H2​O\ **Explanation:** Chlorine is oxidized from 0 to +1 in NaOClNaOClNaOCl. 5. **Question:** Which of the following is an example of an ideal solution?\ a) Ethanol and water\ b) Benzene and toluene\ c) Hexane and heptane\ d) Acetone and water\ **Answer:** b) Benzene and toluene\ **Explanation:** Benzene and toluene form nearly ideal solutions due to similar intermolecular interactions. 6. **Question:** The solubility of AgCl in water is decreased in the presence of NaCl because of:\ a) The common ion effect\ b) Le Chatelier\'s principle\ c) Decrease in temperature\ d) The formation of complex ions\ **Answer:** a) The common ion effect\ **Explanation:** NaCl provides Cl−Cl\^-Cl−, which decreases the solubility of AgCl by shifting equilibrium. 7. **Question:** Which of the following pairs does not show geometrical isomerism?\ a) 1-butene\ b) 2-butene\ c) 2-pentene\ d) 1,2-dichloroethene\ **Answer:** a) 1-butene\ **Explanation:** Geometrical isomerism occurs when there is restricted rotation due to a double bond, and each carbon of the double bond must have two different groups attached. In 1-butene, this is not possible. 8. **Question:** The half-life of a first-order reaction is 100 seconds. How long will it take for the concentration of the reactant to fall to 25% of its initial value?\ a) 100 seconds\ b) 200 seconds\ c) 300 seconds\ d) 400 seconds\ **Answer:** b) 200 seconds\ **Explanation:** In first-order reactions, 25% means two half-lives. So, 2×100=2002 \\times 100 = 2002×100=200 seconds. 9. **Question:** Which of the following is the strongest Lewis acid?\ a) BF3BF\_3BF3​\ b) BCl3BCl\_3BCl3​\ c) AlCl3AlCl\_3AlCl3​\ d) GaCl3GaCl\_3GaCl3​\ **Answer:** c) AlCl3AlCl\_3AlCl3​\ **Explanation:** The smaller size and higher charge density of aluminum make it a stronger Lewis acid. 10. **Question:** Which of the following compounds shows both intramolecular and intermolecular hydrogen bonding?\ a) Ortho-nitrophenol\ b) Para-nitrophenol\ c) Acetic acid\ d) Ethanol\ **Answer:** a) Ortho-nitrophenol\ **Explanation:** Ortho-nitrophenol shows intramolecular hydrogen bonding within the molecule and can also exhibit intermolecular hydrogen bonding.