Important Practice Questions For NEET UG 2026 (Day 31)

Important Practice Questions For NEET UG 2026 Day 31: Ready to level up your preparation game? Day 31 of Important Practice Questions for NEET UG 2026 is here to challenge your concepts, sharpen your accuracy, and boost your confidence one question at a time!

Whether you’re mastering tricky Biology diagrams, decoding Physics numericals, or untangling Chemistry reactions, today’s practice set is designed to push you a step closer to your dream medical college. So grab your notebook, set a timer, and let’s turn practice into progress!

PHYSICS

Q.1. A block of mass $2\text{kg}$ is pushed along a horizontal frictionless surface with a constant force of $10\text{N}$. What is the work done by this force when the block moves $5\text{m}$?

A. 10J

B. 5J

C. 25J

D. 50J

Q.2. A ball is thrown vertically upwards with an initial speed of $20{\text{m s}}^{-1}$. Neglecting air resistance and taking $g=10{\text{m s}}^{-2}$, what is the maximum height reached by the ball?

A. 40m

B. 20m

C. 30m

D. 10m

Q.3. Which statement correctly describes the behavior of light when it passes from air into a denser medium like glass at an angle other than ${90}^{\circ }$?

A. Its wavelength increases while its speed decreases

B. Its frequency decreases while its speed remains constant

C. Its speed increases and it bends away from the normal

D. Its speed decreases and it bends towards the normal

Q.4. A ray of light passes through the optical centre of a thin convex lens. How will it emerge after refraction by the lens (neglecting any slight thickness)?

A. It will pass undeviated, continuing in the same straight line

B. It will retrace its path back along the incident direction

C. It will bend and pass through the principal focus on the other side

D. It will reflect completely from the lens surface

Q.5. A 2 $\mathrm{\Omega }$ resistor and a 4 $\mathrm{\Omega }$ resistor are connected in parallel across a 12 V battery. What is the total current drawn from the battery?

A. 2 A

B. 6 A

C. 1 A

D. 3 A

CHEMISTRY

Q.6. A radioactive sample has a half-life of 5 years. What fraction of the original radioactive nuclei will remain undecayed after 15 years?

A. $\frac{1}{8}$

B. $\frac{1}{4}$

C. $\frac{1}{2}$

D. $\frac{1}{3}$

Q.7. Which statement correctly describes the effect of increasing temperature on the rate of a reversible chemical reaction according to Le Chatelier’s principle, if the reaction is exothermic in the forward direction?

A. Increasing temperature increases both forward and backward rates equally but does not change equilibrium

B. Increasing temperature shifts the equilibrium towards products, increasing forward reaction yield

C. Increasing temperature shifts the equilibrium towards reactants, decreasing forward reaction yield

D. Temperature has no effect on the equilibrium position of an exothermic reaction

Q.8. An element $X$ forms a chloride ${\text{XCl}}_2$ and an oxide $\text{XO}$. To which group of the modern periodic table does $X$ most likely belong?

A. Group 2

B. Group 13

C. Group 17

D. Group 1

Q.9. Which functional group is present in all amino acids that form proteins in living organisms?

A. Only a carboxyl group $(-\text{COOH})$

B. Only an amino group $(-{\text{NH}}_2)$

C. A phosphate group $(-{\text{PO}}_4^{3-})$ attached to the side chain

D. Both an amino group and a carboxyl group attached to the same α-carbon

Q.10. Which of the following changes will definitely increase the rate of a chemical reaction according to collision theory?

A. Increasing the concentration of reactants in solution

B. Decreasing temperature while keeping concentration constant

C. Increasing the activation energy of the reaction

D. Decreasing the frequency of effective collisions

Read Also: Important NEET UG Diagrams Day 12

BIOLOGY

Q.11. In a healthy nephron, which process is primarily responsible for the selective reabsorption of glucose from the filtrate back into the blood?

A. Osmosis in the Bowman’s capsule

B. Facilitated diffusion in the descending limb of loop of Henle

C. Simple diffusion along the length of the collecting duct

D. Active transport in the proximal convoluted tubule

Q.12. Which of the following statements best explains why enzymes are highly specific in the reactions they catalyse in living cells?

A. They are nonspecific catalysts that speed up all biochemical reactions equally

B. Their active site is complementary in shape and chemical properties to specific substrates

C. Their active site has a fixed shape that fits only one substrate and never changes

D. They are made of DNA, which directly binds only one type of substrate

Q.13. In human reproduction, which event directly triggers ovulation from the mature Graafian follicle?

A. A rapid decline in follicle-stimulating hormone (FSH) levels

B. A sudden surge of luteinizing hormone (LH) from the anterior pituitary

C. The release of gonadotropin-releasing hormone (GnRH) from the hypothalamus at puberty

D. A progressive rise in progesterone throughout the follicular phase

Q.14. Which of the following best explains why genetic recombination is greater in sexually reproducing organisms than in asexually reproducing ones?

A. Asexual reproduction always occurs without DNA replication

B. Sexual reproduction always produces polyploid offspring

C. Sexual reproduction involves mutation but asexual reproduction does not

D. Sexual reproduction involves meiosis and fusion of gametes, creating new allele combinations

Q.15. Which process in cellular respiration directly generates the majority of ATP molecules in aerobic conditions?

A. Glycolysis in the cytoplasm

B. Krebs cycle (citric acid cycle) in the mitochondrial matrix

C. Link reaction (pyruvate to acetyl-CoA) in mitochondria

D. Oxidative phosphorylation via electron transport chain and chemiosmosis

Q.16. In the context of the Hardy-Weinberg principle, which factor would most likely disrupt genetic equilibrium in a large, randomly mating population?

A. Random mating with no selection

B. Large population size and no migration

C. Strong natural selection favoring a particular genotype

D. Absence of mutation

Q.17. Which of the following best explains why the left ventricle of the human heart has a thicker muscular wall than the right ventricle?

A. It pumps blood to the entire body at a higher pressure

B. It pumps blood only to the lungs, which are nearby

C. It needs to maintain a lower pressure to protect capillaries

D. It receives deoxygenated blood from the venae cavae

Q.18. In a typical neuron, which event directly triggers the release of neurotransmitter into the synaptic cleft at a chemical synapse?

A. Opening of sodium channels at the axon hillock

B. Passive diffusion of neurotransmitter back into the presynaptic neuron

C. Binding of neurotransmitter to receptors on the postsynaptic membrane

D. Arrival of an action potential opening voltage-gated calcium channels at the axon terminal

Q.19. In an aquatic ecosystem, which of the following best explains why phytoplankton are placed at the first trophic level?

A. They have the highest biomass among all organisms

B. They are primary consumers that feed directly on zooplankton

C. They are decomposers that recycle nutrients back to water

D. They are primary producers that convert solar energy into chemical energy

Q.20. Which of the following best illustrates stabilizing selection in a natural population?

A. Human birth weight tending to cluster around an intermediate range

B. Beetles evolving much larger bodies over many generations

C. Moths shifting from light-colored forms to dark-colored forms in polluted areas

D. Finch populations splitting into two groups with very small and very large beaks

And that’s a wrap for Day 31! Remember, every question you solve today adds one more brick to your NEET success story. Consistency beats cramming, and daily practice is your secret weapon for cracking NEET UG 2026 with confidence.

Keep revising, keep practicing, and most importantly, keep believing in yourself. See you tomorrow with another power-packed set of questions!

Share Your Scores Below!!

Read Also: NEET UG 2026 Important Practice Questions (Day 30)

ANSWERS & EXPLANATIONS

Ans.1. D. 50J. To find work, we only need the magnitude of the constant force and the displacement in its direction. The expression is $W=Fs\cos \theta$, where $\theta$ is the angle between force and displacement. Here, $F=10\text{N}$, $s=5\text{m}$, and $\theta =0^{\circ }$, so $W=10\times 5\times 1=50\text{J}$ 

Ans.2. B. 20m. Another way to solve the problem is by using energy conservation. The initial kinetic energy is $\frac{1}{2}m{u}^2$, and at maximum height this is converted into gravitational potential energy $mgh$. Equating, $\frac{1}{2}m{u}^2=mgh$. The mass $m$m cancels out, giving $\frac{1}{2}{u}^2=gh$. Substituting $u=20{\text{m s}}^{-1}$ and $g=10{\text{m s}}^{-2}$, we get $\frac{1}{2}(20{)}^2=10h$ so $200=10h$ and $h=20\text{m}$.

Ans.3. D. its speed decreases and it bends towards the normal. When light passes from air into glass, the refractive index increases, causing the speed of light to decrease according to $n=\frac{c}{v}$. Since the frequency $f$ stays the same, the wavelength $\lambda$ in the new medium must change as $v=f\lambda$. Snell’s law $n_1\sin {\theta }_1=n_2\sin {\theta }_2$ shows that entering a denser medium makes the ray bend towards the normal. 

Ans.4. A. it will pass undeviated, continuing in the same straight line. In a thin lens, the optical centre is a point where the principal rays can be considered to pass without deviation. A ray directed through this point emerges from the lens parallel to its original direction, assuming the lens is thin and aligned symmetrically.

Ans.5. B. 6 A. The right way to find the total current in this parallel circuit is to first find the current through each branch.

Ans.6. A. 1/8. The concept of half-life means that in each half-life period, half of the remaining nuclei decay. After one half-life (5 years), $\frac{1}{2}$ of the original sample remains. After two half-lives (10 years), half of that $(\frac{1}{2}\times \frac{1}{2}=\frac{1}{4})$remains. After three half-lives (15 years), half again $(\frac{1}{4}\times \frac{1}{2}=\frac{1}{8})$ remains. Thus, the remaining fraction after 15 years is ${\left(\frac{1}{2}\right)}^3=\frac{1}{8}$.

Ans.7. C. increasing temperature shifts the equilibrium towards reactants, decreasing forward reaction yield in an exothermic reaction. From a kinetic perspective, both directions speed up with temperature, but from an equilibrium perspective, the relative rates adjust until a new equilibrium is established. For an exothermic forward reaction, the equilibrium constant decreases with increasing temperature, leading to a composition richer in reactants.

Ans.8. A. Group 2. The formulas given, ${\text{XCl}}_2$ and $\text{XO}$, indicate that $X$ behaves as a metal with a $+2$ oxidation state, forming ionic compounds with chloride and oxide ions.

Ans.9. D. both an amino group and a carboxyl group attached to the same $\alpha$α-carbon. The general structure of an $\alpha$-amino acid includes a central $\alpha$-carbon atom bonded to four different groups: an amino group $(-{\text{NH}}_2)$, a carboxyl group $(-\text{COOH})$, a hydrogen atom, and a variable side chain or $R$-group.

Ans.10. A.  increasing the concentration of reactants in solution. In collision theory, only collisions with energy equal to or greater than the activation energy and with proper orientation are effective. If the activation energy is increased, a smaller fraction of molecules will possess sufficient energy at a given temperature, so fewer effective collisions occur per unit time. This leads to a slower reaction. 

Ans.11. D. Active transport in the proximal convoluted tubule. After filtration at the glomerulus, the filtrate entering Bowman’s capsule contains glucose at a concentration similar to plasma, but it is the proximal convoluted tubule that actively reclaims glucose. Carrier proteins use energy to transport glucose back into the blood, thereby preventing its loss.

Ans.12. B. their active site is complementary in shape and chemical properties to specific substrates. Enzyme specificity is explained by models such as the lock-and-key and induced-fit models. In the lock-and-key model, the active site has a shape that is complementary to the substrate, allowing only certain molecules to bind. The induced-fit model refines this by suggesting that the active site is flexible and can adjust its shape slightly when the substrate binds, improving the fit. 

Ans.13. B.  a sudden surge of luteinizing hormone (LH) from the anterior pituitary. FSH levels are important earlier in the cycle for stimulating the growth and maturation of ovarian follicles, which in turn secrete estrogen. As estrogen levels rise, they eventually switch from exerting negative to positive feedback on the hypothalamus and pituitary, resulting in a surge of LH secretion. 

Ans.14. D. sexual reproduction involves meiosis and fusion of gametes, creating new allele combinations. In asexual reproduction, DNA replication occurs followed by mitotic division, producing genetically similar daughter cells. There is no crossing over or independent assortment, so genetic recombination is minimal.

Ans.15. D. oxidative phosphorylation via electron transport chain and chemiosmosis. The link reaction prepares pyruvate for entry into the Krebs cycle, generating reduced coenzymes that later donate electrons to the electron transport chain. However, ATP yield from this step is minimal compared to the massive ATP production during oxidative phosphorylation.

Ans.16. C. strong natural selection favoring a particular genotype. Random mating ensures that individuals pair regardless of their genotypes, so allele combinations occur purely by chance, preserving the relationships $p^2$, $2pq$, and $q^2$ for genotype frequencies under equilibrium. In the absence of selection, all genotypes have equal fitness, meaning they contribute equally to the next generation. 

Ans.17. A. t pumps blood to the entire body at a higher pressure. Capillary networks are protected from extreme pressures by the elastic and muscular properties of arteries and arterioles, which regulate blood flow and pressure. The left ventricle must produce a high initial pressure to ensure that blood reaches even distant tissues efficiently.

Ans.18. D. arrival of an action potential opening voltage-gated calcium channels at the axon terminal. Neurotransmitter release is an active, calcium-dependent process that occurs before removal mechanisms like reuptake. Once released, neurotransmitter molecules may be taken back into the presynaptic neuron via transporter proteins, degraded by enzymes (e.g., acetylcholinesterase for acetylcholine), or diffuse away. 

Ans.19. D. They are primary producers that convert solar energy into chemical energy. Zooplankton are typical primary consumers that graze on phytoplankton. Phytoplankton, by contrast, use sunlight to manufacture organic food via photosynthesis, forming the energetic foundation of the aquatic ecosystem. 

Ans.20. A. Human birth weight tending to cluster around an intermediate range. In stabilizing selection, selective pressures favor individuals who are closest to the average phenotype and act against extremes at both ends. This keeps the population stable and reduces overall variability, in contrast to directional selection, which pushes the population mean towards one extreme.