NEET

Q 90. Person with blood group AB is considered as universal recipient because he has: Option A Both A and B antibodies in the plasma. Option B No antigen on the RBC and no antibody in the plasma. Option C Both A and B antigens in the plasma but no antibodies. Option D Both A and B antigens on the RBC but no antibodies in the plasma.

Correct Option: D Solution: A person with blood group AB have both A and B antigens on the RBC but no antibodies in the plasma are considered as universal recipient.

read more

Q 87. Select the correct option describing gonadotropin activity in a normal pregnant female: Option A High level of FSH and LH facilitate implantation of the embryo. Option B High level of hCG stimulates the synthesis of estrogen and progesterone. Option C High level of hCG stimulates the thickening of endometrium. Option D High level of FSH and LH stimulates the thickening of endometrium

Correct Option: B Solution: In a normal pregnant female high level of hCG (human chorionic gonadotropin) stimulates the synthesis of estrogen and progesterone

read more

Q 83. Given below is the representation of the extent of global diversity of invertebrates. What groups do the four portions (A-D) represent respectively? A B C D Option A Crustaceans Crustaceans Molluscs Other animal group Option B Molluscs Other animal group Crustaceans Insects Option C Insects Molluscs Crustaceans Other animal group Option D Insects Crustaceans Other animal group Molluscs

Correct Option: C Solution: In the animal kingdom, phylum Arthropoda is the largest with its largest group of insects. The second-largest population is of phylum Mollusca. In the third place is...

read more

Q 81. Which one of the following is wrongly matched? Option A Translation – Using information in m-RNA to make protein. Option B Repressor protein-Binds to operator to stop enzyme synthesis. Option C Operon – Structural genes, operator and promoter. Option D Transcription – Writing information from DNA to t-RNA

Correct Option: D Solution: Transcription is the process of formation of m-RNA from DNA during protein synthesis. It is not writing information from DNA to t-RNA. Thus this statement is incorrectly...

read more

Q 72. Dr.F. Went noted that if coleoptile tips were removed and placed on agar for one hour, the agar would produce a bending when placed on one side of freshly cut coleoptile stumps. Of what significance is this experiment? Option A It is the basis for quantitative determination of small amounts of growth promoting substances. Option B It supports the hypothesis that IAA is auxin. Option C It demonstrated polar movement of auxins. Option D It made possible the isolation and exact identification of auxin.

Correct Option: A Solution: The significance of the experiment is that It is the basis for the quantitative determination of small amounts of growth-promoting substances.

read more

Q 66. How do parasympathetic neural signals affect the working of the heart? Option A Heart rate is increased without affecting the cardiac output. Option B Both heart rate and cardiac output increase. Option C Heart rate decreases but cardiac output increases. Option D Reduces both heart rate and cardiac output.

Correct Option: D Solution: Post-ganglionic fibers of the parasympathetic nervous system secrete acetylcholine. This in return decreases the heart rate and cardiac output.

read more

Q 64. Geitonogamy involves: Option A Fertilisation of a flower by the pollen from the same flower. Option B Fertilisation of a flower by the pollen from a flower of another plant in the same population. Option C Fertilisation of a flower by the pollen from another flower of plant belonging to a distant population. Option D Fertilisation of a flower by the pollen from another flower of the same plant.

Correct Option: D Solution: Geitonogamy involves fertilization of a flower by the pollen from another flower of the same plant

read more

Q 59. Fight-or-flight reactions cause activation of: Option A The kidney, leading to suppression of renin angiotensin-aldosterone pathway. Option B The adrenal medulla, leading to increased secretion of epinephrine and norepinephrine. Option C The pancreas, leading to a reduction in the blood sugar levels. Option D The parathyroid glands, leading to an increased metabolic rate.

Correct Option: B Solution: The adrenal medulla, leading to increased secretion of epinephrine and norepinephrine is activated because of the Fight-or-flight reactions. Epinephrine (adrenaline) and...

read more

Q 48. Match the following and select the correct answer: a. Centriole I Infoldings in mitochondria b. Chlorophyll Ii Thylakoids c. Cristae Iii Nucleic acids d. Ribozymes Iv Basal body cilia or flagella a b c d Option A i. ii. iv. iii. Option B i. iii ii. iv. Option C iv. iii. i. ii. Option D iv. ii. i. iii.

Correct option: D Solution: Centriole is a basal body. Chlorophyll contains thylakoids. Cristae are infoldings present in the inner layer of mitochondria Ribozymes is a catalytic RNA.

read more

Q 28. At which stage of HIV infection does one usually show symptoms of AIDS? Option A When the infected retro virus enters the host cells. Option B When HIV damages large number of helper T – lymphocytes. Option C When the viral DNA is produced by reverse transcriptase. Option D Within 15 days of sexual contact with an infected person.

Correct Option: B Solution: The helper T-lymphocytes are targeted by the HIV in the blood, causing a decrease in the number of helper T-lymphocytes in the body of the infected person. The infected...

read more

Q 15. Select the option which is not correct with respect to enzyme action: Option A Addition of a lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate. Option B A non-competitive inhibitor binds the enzyme at a site distinct from that which binds the substrate. Option C Malonate is a competitive inhibitor of succinic dehydrogenase. Option D Substrate binds with the enzyme at its active site.

Correct option: A Explanation: competitive inhibitor of succinic dehydrogenase is malonate. Malonate competes with the substrate for the substrate-binding site of the enzyme. Similarly, the...

read more

Q 11. Identify the hormone with its correct matching of source and function. Option A Melatonin – Pineal gland – regulates the normal rhythm of sleep-wake cycle. Option B Progesterone – corpus luteum – secondary sex organs. Option C Atrial natriuretic factor –ventricular wall – increases the blood pressure. Option D Oxytocin – posterior pituitary – growth and maintenance of mammary glands.

Correct option: A Explanation: Melatonin hormone is secreted by the pineal gland, whose function is to regulate the normal rhythm of the sleep-wake cycle.

read more

Q 6. Just as a person moving from Delhi to Shimla to escape the heat for the duration of hot summer, thousands of migratory birds from Siberia and other extremely cold northern regions move to: Option A Meghalaya Option B Corbett National Park Option C Keoladeo National Park Option D Western Ghat

Correct option: C Explanation: thousands of migratory birds from Siberia and other extremely cold northern regions move to Keoladeo National Park, located in Bharatpur Rajasthan. Presently it is...

read more

Q 4. Choose the correctly matched pair: Option A Moist surface of buccal cavity – Glandular epithelium Option B Tubular parts of nephrons – Cuboidal epithelium Option C Inner surface of bronchioles – Squamous epithelium Option D Inner lining of salivary ducts – Ciliated epithelium

Correct option: B Explanation: Single layer of cube cells make up the cuboidal epithelium. It is present in the tubular part of the nephron in the kidneys. Its main functions are absorption and...

read more

In the product

$ \vec{F}=q(\vec{v}\times \vec{B}) $ $ \vec{F}=q\vec{v}(B\hat{i}+B\hat{j}+{{B}_{0}}\hat{k}) $ $ For\,q=1\,and\,\vec{v}=2\hat{i}+4\hat{j}+6\hat{k}\,and\, $ $ \vec{F}=4\hat{i}-20\hat{j}+12\hat{k} $ $...

read more

A convex lens ‘A’ of focal length 20 cm and a concave lens ‘B’ of focal length 5 cm are kept along the same axis with a distance ‘d’ between them. If a parallel beam of light falling on ‘A’ leaves ‘B’ as a parallel beam, then the distance ‘d’ in cm will be

(1) 25                                              (2) 15 (3) 50                                              (4) 30 Solution: Answer (2) After refraction by a convex lens, parallel beams of light...

read more

The stress-strain curves are drawn for two different materials X and Y. It is observed that the ultimate strength point and the fracture point are close to each other for material X but are far apart for material Y. We can say that materials X and Y are likely to be (respectively), (1) Plastic and ductile (2) Ductile and brittle (3) Brittle and ductile (4) Brittle and plastic

Answer (3) Sol. As given that fracture point and ultimate strength point is close for material $\mathrm{X}$, So, $\mathrm{X}$ is brittle in nature and both points are far apart for material $Y$...

read more

Two bullets are fired horizontally and simultaneously towards each other from roof tops of two buildings 100 \mathrm{~m} apart and of same height of 200 \mathrm{~m}, with the same velocity of 25 \mathrm{~m} / \mathrm{s}. When and where will the two bullets collide? \left(\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}\right) (1) They will not collide (2) After 2 \mathrm{~s} at a height of 180 \mathrm{~m} (3) After 2 \mathrm{~s} at a height of 20 \mathrm{~m} (4) After 4 \mathrm{~s} at a height of 120 \mathrm{~m}

Answer (2) Sol. Let bullets collide at time t $ \begin{array}{l} x_{1}+x_{2}=100 \mathrm{~m} \\ 25 t+25 t=100 \\ t=2 s \\ \begin{array}{r} y=\frac{1}{2} g t^{2}=\frac{1}{2} \times 10 \times 2^{2} \\...

read more

A mass falls from a height ‘ h ‘ and its time of fall ‘t’ is recorded in terms of time period \mathrm{T} of a simple pendulum. On the surface of earth it is found that \mathrm{t}=2 \mathrm{~T}. The entire set up is taken on the surface of another planet whose mass is half of that of earth and radius the same. Same experiment is repeated and corresponding times noted as ‘ \mathrm{t}^{\prime} and ‘ \mathrm{T}^{\prime}. Then we can say (1) t^{\prime}=2 \mathrm{~T}^{\prime} (2) \mathrm{t}^{\prime}=\sqrt{2} \mathrm{~T}^{\prime} (3) \mathrm{t}^{\prime}>2 \mathrm{~T}^{\prime} (4) \mathrm{t}^{\prime}<2 \mathrm{~T}^{\prime}

Answer (1) Sol. For surface of earth time taken in falling $\mathrm{h}$ distance. $ \begin{array}{l} t=\sqrt{\frac{2 h}{g}} \\ \text { and } \quad T=2 \pi \sqrt{\frac{1}{g}} \end{array} $ Given...

read more

A truck is stationary and has a bob suspended by a light string, in a frame attached to the truck. The truck suddenly moves to the right with an acceleration of a. The pendulum will tilt (1) to the left and angle of inclination of the pendulum with the vertical is \tan ^{-1}\left(\frac{\mathbf{g}}{\mathbf{a}}\right) (2) to the left and angle of inclination of the pendulum with the vertical is \sin ^{-1}(\underline{\mathbf{g}}{\mathrm{a}})(3) to the left and angle of inclination of tha pendulum with the vertical is \tan ^{-1}\left(\frac{\mathbf{a}}{\mathbf{g}}\right) (4) to the left and angle of inclination of the pendulum with the vertical is \sin ^{-1}\left(\frac{\mathbf{a}}{\mathbf{g}}\right)

Answer (3) Sol. From the frame of truck $ \begin{array}{l} \operatorname{Tsin} \theta=\mathbf{m a} \\ T \cos \theta=\mathrm{mg} \end{array} $ $\theta=\tan...

read more

Two small spherical metal balls, having equal masses, are made from materials of densities \rho_{1} and \rho_{2}\left(\rho_{1}=8 \rho_{2}\right) and have radii of 1 \mathrm{~mm} and 2 \mathrm{~mm}, respectively, they are made to fall vertically (from rest) in a viscous medium whose coefficient of viscosity equals \eta and whose density is 0.1 \rho_{2} . The ratio of their terminal velocities would be, (1) \frac{79}{36} (2) \frac{79}{72} (3) \frac{19}{36} (4) \frac{39}{72}

Answer (1) Solution: As $V_{T}=\frac{2 a^{2}}{9 \eta}(\rho-\sigma) g$ $ \begin{array}{l} V_{T_{1}}=\frac{2 \times(1)^{2}}{9 \eta}\left(\rho_{1}-0.1 \rho_{2}\right) g \\ V_{T_{1}}=\frac{2 \times 1}{9...

read more

A deep rectangular pond of surface area A, containing water (density =\rho ), specific heat capacity =\mathrm{s} ), is located in a region where the outside air temperature is at a steady value of -26^{\circ} \mathrm{C}. The thickness of the frozen ice layer in this pond, at a certain instant is \mathrm{x}. Taking the thermal conductivity of ice as K, and its specific latent heat of fusion as L, the rate of increase of the thickness of ice layer, at this instant, would be given by (1) 26 \mathrm{~K} / \rho \times(\mathrm{L}+4 \mathrm{~s}) (2) 26 \mathrm{~K} / \rho \times(\mathrm{L}-4 \mathrm{~s}) (3) 26 K /\left(\rho x^{2} L\right) (4) 26 \mathrm{~K} /(\rho \times \mathrm{L})

Answer (4) Sol. Assume at any instant thickness of ice is $\mathrm{x}$. And time taken to form additional thickness. $(\mathrm{dx})$ is $\mathrm{dt}$. $\mathrm{mL}=\frac{\mathrm{KA}[26-0] \mathrm{d}...

read more

 In a potentiometer circuit a cell of EMF 1.5 V gives balance point at 36 cm length of wire. If another cell of EMF 2.5 V replaces the first cell, then at what length of the wire, the balance point occurs?

(1) 60 cm                                         (2) 21.6 cm (3) 64 cm                                         (4) 62 cm Solution: Answer (1) From the application of potentiometer to compare two...

read more

The radius of the first permitted Bohr orbit, for the electron, in a hydrogen atom equals 0.51 \AA and its ground state energy equals -13.6 \mathrm{eV}. If the electron in the hydrogen atom is replaced by muon \left(\mu^{-}\right)[charge same as electron and mass \left.207 \mathrm{~m}_{\mathrm{e}}\right], the first Bohr radius and ground state energy will be, (1) 2.56 \times 10^{-13} \mathrm{~m},-13.6 \mathrm{eV} (2) 0.53 \times 10^{-13} \mathrm{~m},-3.6 \mathrm{eV} (3) 25.6 \times 10^{-13} \mathrm{~m},-2.8 \mathrm{eV} (4) 2.56 \times 10^{-13} \mathrm{~m},-2.8 \mathrm{keV}

The correct answer is (4) Sol. $r_{n} \propto \frac{1}{m}$ $ \begin{array}{l} \mathrm{r}_{\mu}=\frac{0.51}{207}=2.56 \times 10^{-13} \mathrm{~m} \\ \mathrm{E} \propto \mathrm{m}_{\mathrm{e}} \\...

read more

A beam of light consisting of red, green and blue colours is incident on a right angled prism. The refractive index of the material of the prism for the above red, green and blue wavelengths are 1.39,1.44 and 1.47 respectively. The prism will: (1) Separate the red colour part from the green and blue colours (2) Separate the blue colour part from the red and green colours (3) Separate all the three colours from one another. (4) Not separate the three colours at all

Solution: (1) For $\mathrm{TIR} I>\mathrm{I}_{\mathrm{c}}$ so $\operatorname{Sin} \mathrm{i}>\sin \mathrm{I}_{\mathrm{c}}$ $ \operatorname{Sin} 45^{\circ}>\frac{1}{\mu} \Rightarrow \mu...

read more

A photoelectric surface is illuminated successively by monochromatic light of wavelength \lambda and \frac{\lambda}{2}. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is: (h = Planck’s constant, c= speed of light) (1) \frac{h c}{3 \lambda} (2) \frac{h c}{2 \lambda} (3) \frac{h c}{\lambda} (4) \frac{2 h c}{\lambda}

Solution: (2) $ \begin{array}{l} k_{1}=\frac{h c}{\lambda}-\psi \\ k_{2}=3 k_{1}=\frac{2 h c}{\lambda}-\psi=\frac{3 h c}{\lambda}-3 \psi \end{array} $ So $2 \psi=\frac{h c}{\lambda}$ So...

read more

Water rises to a height ‘ h ‘ in capillary tube. If the length of capillary tube above the surface of water is made less than ‘ \mathrm{h} ‘, then: (1) Water does not rise at all (2) Water rises upto the tip of capillary tube and then starts overflowing like a fountain (3) Water rises upto the top of capillary tube and stays there without overflowing (4) Water rises upto a point a little below the top and stays there

Solution: (3) Water will not overflow, but its radius of curvature will vary. Explanation: It won't overflow. That should be obvious since doing so would create a constant flow, constantly using...

read more

On a frictionless surfaces, a block of mass M moving at speed v collides elastically with another block of same mass M which is initially at rest. After collision the first block moves at an angle \theta to its initial direction and has a speed \frac{\mathrm{v}}{3}. The second block’s speed after the collision is: (1) \frac{\sqrt{3}}{2} v (2) \frac{2 \sqrt{2}}{3} v (3) \frac{3}{4} v (4) \frac{3}{\sqrt{2}} v

Solution: (2) $\overrightarrow{\mathrm{P}}_{1}=\overrightarrow{\mathrm{P}_{\mathrm{f}}}$ $\Rightarrow\left|\mathrm{P}_{\mathrm{i}}\right|=\left|\mathrm{P}_{\mathrm{f}}\right| \Rightarrow...

read more

Two stones of masses ma and 2 \mathrm{~m} are whirled in horizontal circles, the heavier one in a radius \frac{\mathrm{r}}{2} and the lighter one in radius r. the tangential speed of lighter stone is n times that of the value of heavier stone when they experience same centripetal forces. The value of n is: (1) 1 (2) 2 (3) 3 (4) 4

The Solution is (2) $ \mathrm{F}_{\mathrm{C}}=\frac{\mathrm{mv}_{1}^{2}}{\mathrm{r}}=\frac{2 \mathrm{mv}_{2}^{2}}{\left(\frac{\mathrm{r}}{2}\right)}=\frac{4 \mathrm{mv}_{2}^{2}}{\mathrm{r}} $...

read more

A plank with a box on it at one end is gradually raised about the other end. As the angle of inclination with the horizontal reaches 30^{\circ}, the box starts to slip and slides 4.0 \mathrm{~m} down the plank in 4.0 \mathrm{~s}. The coefficients of static and kinetic friction between the box and the plank will be, respectively: (1) 0.4 and 0.3 (2) 0.6 and 0.6 (3) 0.6 and 0.5 (4) 0.5 and 0.6

The Solution is (3) $ \begin{array}{l} \mu_{s}=\tan 30^{\circ}=\frac{1}{\sqrt{3}}=0.5 \\ \mu_{s}=0.57=0.6 \\ \mathrm{~S}=\mathrm{ut}+\frac{1}{2} \mathrm{at}^{2} \\ 4=\frac{1}{2} a(4)^{2} \Rightarrow...

read more

A screw gauge gives the following readings when used to measure the diameter of a wire Main scale reading : 0 mm Circular scale reading : 52 divisions Given that 1 mm on main scale corresponds to 100 divisions on the circular scale. The diameter of the wire from the above data is

(1) 0.52 cm                           (2) 0.026 cm (3) 0.26 cm                           (4) 0.052 cm Solution: Answer (4) According to the question, the pitch of the screw gauge, P = 1 mm The...

read more