NEET UG

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Stirred-tank bioreactors have been designed for Answer: 2. availability of oxygen throughout the process A stirred-tank bioreactor has an agitator and a sparger. Stirring mixes the content... Processes of recombinant DNA technology 1 answer
A foreign DNA and plasmid cut by the same restriction endonuclease can be joined to form a recombinant plasmid using Answer: 3. ligase The same restriction enzyme gives matching sticky ends on the foreign DNA and plasmid. These ends anneal, and DNA ligase s... Processes of recombinant DNA technology 1 answer
Which of the following is not a component of downstream processing? Answer: 3. Expression Downstream processing includes separation, purification and preservation of the product after the biosynthesis stage.... Processes of recombinant DNA technology 1 answer
Which of the following restriction enzymes produces blunt ends? Answer: 1. *Eco* RV EcoRV cuts in the middle of its recognition site (GAT^ATC) and gives blunt ends. XhoI, HindIII and SalI cut with a stagg... Tools: restriction enzymes, vectors, host 1 answer
A non-proteinaceous enzyme is Answer: 1. ribozyme Almost all enzymes are proteins, but a few RNA molecules also act as catalysts. Ribozyme is a catalytic RNA (for example... Enzymes: types, properties, action, classification 1 answer
Select the mismatch. Answer: 1. Large central vacuoles—Animal cells Large central vacuoles are a feature of mature plant cells, not animal cells. Animal cells ha... Five kingdom classification 1 answer
Select the wrong statement. Answer: 1. Pili and fimbriae are mainly involved in motility of bacterial cells. Pili and fimbriae are surface structures used for attachmen... Five kingdom classification 1 answer
If an electron in a hydrogen atom jumps from the 3rd orbit to the 2nd orbit, it emits a photon of wavelength λ. When it jumps from the 4th orbit to the 3rd orbit, the corresponding wavelength of the photon will be Answer: 2. 20/7λ Use dfrac1λ=R(dfrac1n₁²-dfrac1n₂²) . 3 to 2: dfrac1λ=R(1/4-1/9)=5R/36 . 4 to 3: dfrac1λ'=R(1/9-dfrac116)=7R/144 . λ'/λ=5/36... Bohr model, energy levels, hydrogen spectrum 1 answer
The half-life of a radioactive substance is 30 minutes. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is Answer: 3. 60 Use N=N₀(1/2)^(t/T) and compare the remaining fractions. 40% decayed means 60% remains; 85% decayed means 15% remains. Ratio o... Composition and size of nucleus, atomic masses 1 answer
Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of… Answer: 3. -3 V Einstein's equation: K_max=hν-φ . 5 eV photon, K_max=2 eV, so φ=3 eV. 6 eV photon: K_max=6-3=3 eV. To stop all electrons the... Einstein's photoelectric equation, particle nature of light 1 answer
Electrons of mass m with de-Broglie wavelength λ fall on the target in an X-ray tube. The cutoff wavelength (λ_0) of the emitted X-ray is Answer: 4. λ₀=2mcλ²/h The cutoff wavelength corresponds to the whole kinetic energy K of the electron turning into one photon: λ₀=hc/K . de... Matter waves, de Broglie relation 1 answer
What is the output Y in the following circuit, when all the three inputs A, B, C are first 0 and then 1? Answer: 2. 1, 0 Gate P is an AND gate on A and B; gate Q is a NAND gate whose inputs are P's output and C. So Y=(A· B)· C . A = B = C = 0: P... Logic gates (OR, AND, NOT, NAND, NOR) 1 answer
The given circuit has two ideal diodes connected as shown in the figure below. The current flowing through the resistance R_1 will be Answer: 4. 2.5 A An ideal diode conducts only when forward biased. From the figure, the battery drives current through R₁ and then to the tw... p-n junction diode I-V characteristics 1 answer
For CE transistor amplifier, the audio signal voltage across the collector resistance of 2 kΩ is 4 V. If the current amplification factor of the transistor is 100 and the base resistance is 1 kΩ, then the input signal voltage is Answer: 1. 20 mV In a CE amplifier, V_out=I_CR_C and I_C=β I_B ; input voltage is V_in=I_BR_B . I_C=4/2000=2 mA. I_B=I_C/β=2\ mA/100=20\ μA... Semiconductors 1 answer
Two cars P and Q start from a point at the same time in a straight line and their positions are represented by x_P(t)=at+bt^2 and x_Q(t)=ft-t^2. At what time do the cars have the same velocity? Answer: 3. f-a/2(1+b) Velocity is the derivative of position; equate the two velocities. v_P=a+2bt ; v_Q=f-2t . a+2bt=f-2t⇒ 2t(b+1)=f-a . t=... Frame of reference, motion in a straight line, speed and velocity 1 answer
In the given figure, a=15 m/s^2 represents the total acceleration of a particle moving in the clockwise direction in a circle of radius R=2.5 m at a given instant of time. The speed of the particle is Answer: 2. 5.7 m/s The total acceleration has a radial (centripetal) part v²/R and a tangential part. From the figure, a makes 30^° with the... Uniform circular motion 1 answer
A rigid ball of mass m strikes a rigid wall at 60° and gets reflected without loss of speed as shown in the figure below. The value of impulse imparted by the wall on the ball will be Answer: 4. mV The wall is smooth, so only the component of velocity perpendicular to the wall changes; the parallel component stays the same... Newton's laws, force and inertia, momentum, impulse 1 answer
A linear aperture whose width is 0.02 cm is placed immediately in front of a lens of focal length 60 cm. The aperture is illuminated normally by a parallel beam of wavelength 5×10^-5 cm. The distance of the first dark band of the diffraction pattern… Answer: 3. 0.15 cm For the first dark band in single-slit diffraction, asinθ=λ . sinθ=dfrac5×10⁻⁵0.02=2.5×10⁻³ , a small angle. Distance on... Diffraction due to a single slit 1 answer
Planck's constant (h), speed of light in vacuum (c) and Newton's gravitational constant (G) are three fundamental constants. Which of the following combinations of these has the dimension of length? Answer: 4. frac√(hG)c^(3/2) Write the dimensions: [h]=ML²T⁻¹ , [c]=LT⁻¹ , [G]=M⁻¹L³T⁻² . Length has the dimension of √(Gh/c³) (the Planck le... Dimensions and dimensional analysis 1 answer
Two rotating bodies A and B of masses m and 2m with moments of inertia I_A and I_B (I_B>I_A) have equal kinetic energy of rotation. If L_A and L_B be their angular momenta respectively, then Answer: 2. L_B>L_A Express angular momentum through kinetic energy: K=L²/2I , so L=√(2IK) . The kinetic energies are equal, so L∝sqrt I . Si... Comparison of linear and rotational motion 1 answer
A bullet of mass 10 g moving horizontally with a velocity of 400 m s^-1 strikes a wooden block of mass 2 kg which is suspended by a light inextensible string of length 5 m. As a result, the centre of gravity of the block is found to rise a vertical d… Answer: 2. 120 m s ⁻¹ Use energy for the swing of the block and momentum conservation for the collision. Block after impact: v=√(2gh)=√(2×10... Elastic and inelastic collisions in one and two dimensions 1 answer
Two identical balls A and B having velocities of 0.5 m/s and -0.3 m/s respectively collide elastically in one dimension. The velocities of B and A after the collision respectively will be Answer: 1. 0.5 m/s and -0.3 m/s For an elastic head-on collision between two identical masses, the bodies simply exchange velocities. (Momen... Elastic and inelastic collisions in one and two dimensions 1 answer
A particle moves from a point (-2 i+5 j) to (4 j+3 k) when a force of (4 i+3 j) N is applied. How much work has been done by the force? Answer: 2. 5 J Work =vec F·vec d , where vec d is the displacement. vec d=(4hat j+3hat k)-(-2hat i+5hat j)=2hat i-hat j+3hat k . W=(4hat i+3... Work by constant and variable force 1 answer
A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is Answer: 2. 26 Ω The bulb rated 500 W at 100 V must carry its rated current for full power. Rated current I=P/V=500/100=5 A. Supply 230 V; bu... Electrical energy and power 1 answer

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