NEET UG 2026 Daily Practice Questions: Day 21 of Daily Practice Questions is here to sharpen your concepts, boost your confidence, and bring you one step closer to that white coat moment. Remember, NEET isn’t cracked in one giant leap- it’s conquered through small, consistent wins every single day. So grab your notebook, switch on your focus mode, and let’s make today’s practice count!
PHYSICS
Q.1. A block of mass m is placed on a rough horizontal surface and a horizontal force is gradually increased from zero. The block just starts sliding when . Which graph best represents the variation of frictional force with applied force ?
A. f increases linearly with and always remains equal to , even after motion starts
B. f is zero until , then suddenly jumps to and stays there
C. f increases linearly with up to , then remains constant and equal to as increases further
Join NEET News 2026 D. f is constant and equal to for all values of
Q.2. A ray of light passes from air into a glass slab. The angle of incidence is increased gradually from to . Which of the following statements about the angle of refraction is most accurate?
A. The angle of refraction first increases, then decreases, but always remains less than the angle of incidence
B. The angle of refraction decreases continuously as the angle of incidence increases
C. The angle of refraction always equals the angle of incidence
D. The angle of refraction always remains constant
Q.3. In a Young’s double-slit experiment using monochromatic light of wavelength λ, the fringe width is β. If the entire setup is immersed in a liquid of refractive index μ, keeping all distances unchanged, what will be the new fringe width β′?
A. β′=β/μ
B. β′=β/μ2
C. β′=μβ
D. β′=β
Q.4. A simple circuit consists of a battery, a resistor , and an ideal ammeter connected in series. If the resistor is replaced by another resistor of double the resistance , with the same battery, how will the ammeter reading change?
A. It will remain the same
B. It will become half of its initial value
C. It will become double its initial value
D. It will become one-quarter of its initial value
Q.5. A ray of light passes from air into glass. Which of the following will definitely occur at the boundary?
A. Only refraction
B. Only reflection
C. Neither reflection nor refraction
D. Both reflection and refraction
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CHEMISTRY
Q.6. Assertion (A): In competitive inhibition of an enzyme, the inhibitor decreases the apparent Vmax of the reaction.
Reason (R): A competitive inhibitor competes with the substrate for the active site of the enzyme and its effect can be overcome by increasing substrate concentration.
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
Q.7. A thermodynamic process is shown on a P–V diagram as a straight line connecting an initial state to a final state . The gas obeys the ideal gas equation. Which of the following statements about the work done W by the gas in this process is most appropriate?
A. W is equal to because only final pressure matters
B. W is given by the area under the straight line, which equals the average pressure times the change in volume
C. W is zero because internal energy depends only on temperature
D. W is equal to because pressure remains constant
Q.8. In an experiment, a gas is taken around a cyclic process on a P–V diagram consisting of three steps: (1) isothermal expansion, (2) isochoric cooling, and (3) isobaric compression back to the initial state. Which of the following is necessarily true for one complete cycle?
A. The net heat absorbed by the gas equals the net work done by the gas
B. The net work done by the gas in the cycle is zero
C. The change in internal energy of the gas over the cycle is negative
D. The change in internal energy of the gas over the cycle is positive
Q.9. Match the following organic reagents with the main functional group they specifically identify (classic test):
| Column 1 | Column 2 |
|---|---|
| P. Tollens’ reagent | 1. Carbonyl compounds (aldehydes and ketones) via yellow/orange precipitate |
| Q. Brady’s reagent (2,4-DNP) | 2. Aldehydes via silver mirror |
| R. Fehling’s solution | 3. Methyl ketones via iodoform formation |
| S. Sodium nitroprusside + NaOH (fresh) | 4. Sulphur-containing amino acids (e.g., cysteine) via purple/violet color |
A. P-2, Q-1, R-3, S-4
B. P-2, Q-1, R-4, S-3
C. P-2, Q-3, R-1, S-4
D. P-3, Q-1, R-2, S-4
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Q.10. In chemical kinetics, a reaction is found to follow first-order kinetics. Which of the following statements about this reaction is most appropriate?
A. The half-life is independent of the initial concentration of reactant
B. Doubling the concentration of reactant increases the rate by a factor of four
C. The rate depends on the square of the concentration of reactant
D. A plot of [A] versus time is a straight line
BIOLOGY
Q.11. A diagram of a neuron shows structure X as a long cylindrical process carrying impulses away from the cell body and structure Y as short, branched processes carrying impulses toward the cell body. Identify X and Y and their primary functions.
A. X: Dendrite – forms synaptic knobs; Y: Axon – receives impulses from synapse
B. X: Axon – stores neurotransmitters; Y: Dendrites – generate myelin sheath
C. X: Dendrite – conducts impulses away from cell body; Y: Axon – conducts impulses toward cell body
D. X: Axon – conducts impulses away from cell body; Y: Dendrites – conduct impulses toward cell body
Q.12. Match the following endocrine glands with one of their major hormones:
| Column I: | Column II: |
|---|---|
| P. Anterior pituitary | 1. Thyroxine |
| Q. Adrenal medulla | 2. Insulin |
| R. Thyroid gland | 3. Adrenaline (epinephrine) |
| S. Pancreas (Islets of Langerhans) | 4. Growth hormone (somatotropin) |
A. P-4, Q-3, R-1, S-2
B. P-4, Q-1, R-3, S-2
C. P-2, Q-3, R-1, S-4
D. P-1, Q-4, R-3, S-2
Q.13. In human physiology, which of the following changes is expected in a person who moves from sea level to high altitude and remains there for several weeks?
A. Permanent decrease in vital capacity due to reduced air pressure
B. Increased RBC count due to enhanced erythropoietin secretion
C. Reduced 2,3-BPG levels in RBCs, increasing hemoglobin’s affinity for oxygen
D. Decreased erythropoietin secretion leading to decreased RBC count
Q.14. Assertion (A): In the cardiac cycle, the second heart sound (“dup”) is produced due to closure of semilunar valves.
Reason (R): Semilunar valves close at the beginning of ventricular systole to prevent backflow of blood into the ventricles.
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. A is true, but R is false
D. Both A and R are true, and R is the correct explanation of A
Q.15. During DNA replication in prokaryotes, which enzyme is primarily responsible for relieving the supercoiling tension ahead of the replication fork?
A. DNA ligase
B. DNA gyrase (a type of topoisomerase)
C. Primase
D. DNA polymerase III
And that’s a wrap for Day 21! Every question you solve today is a brick added to the strong foundation of your NEET success. Keep showing up, keep learning from mistakes, and most importantly- keep believing in yourself. Tomorrow brings a fresh set of challenges and another chance to move closer to 650+. Until then, stay curious, stay consistent, and keep chasing that dream of becoming a doctor.
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ANSWERS & EXPLANATIONS
Ans.1. C. f increases linearly with up to , then remains constant and equal to as increases further. Before motion, static friction adjusts to match , preventing motion.
Ans.2. A. The angle of refraction first increases as the angle of incidence increases, but always remains less than the angle of incidence, and then approaches a limiting value. This behavior is a direct consequence of with .
Ans.3. A. β′=β/μ. The expression for fringe width depends linearly on wavelength, and immersion in a medium adjusts the wavelength by a factor 1/μ, leading directly to dividing β by μ.
Ans.4. B. It will become half of its initial value. The ammeter measures the same current flowing through all series elements, and this current decreases inversely as resistance increases when the supply voltage is held constant.
Ans.5. D. Both reflection and refraction. At the boundary between air and glass, a portion of the incident light is reflected back into air, while another portion enters the glass and bends due to a change in speed.
Ans.6. A. A is false, but R is true. Competitive inhibitors occupy the active site and prevent substrate binding, which means higher substrate levels are needed to achieve a given rate.
Ans.7. B. W is given by the area under the straight line, which equals the average pressure times the change in volume. In the given process, both and change, so the gas does work equal to the trapezium area between the line and the volume axis.
Ans.8. A. The net heat absorbed by the gas equals the net work done by the gas. For any thermodynamic cycle where the system returns to its initial state, the change in internal energy over one complete cycle is zero because internal energy is a state function depending only on temperature (for an ideal gas) and state variables.
Ans.9. A. P-2, Q-1, R-3, S-4 (within the context of the provided Column II). Tollens’ reagent detects aldehydes via a silver mirror, Brady’s reagent detects carbonyls via yellow/orange precipitate, and sodium nitroprusside with alkali detects sulphur-containing amino acids via a violet color.
Ans.10. A. The half-life is independent of the initial concentration of reactant. This is a key diagnostic feature of first-order kinetics, and it allows easy experimental determination of the rate constant from half-life measurements at different starting concentrations.
Ans.11. D. X: Axon – conducts impulses away from cell body; Y: Dendrites – conduct impulses toward cell body. In a typical neuron diagram, the axon is depicted as one long, often myelinated fiber, ending in synaptic terminals, while dendrites are multiple short, highly branched projections expanding around the soma to receive input.
Ans.12. A. P-4, Q-3, R-1, S-2. That combination matches each gland with an appropriate, characteristic hormone.
Ans.13. B. Increased RBC count due to enhanced erythropoietin secretion. This is a well-known acclimatization response: over days to weeks, the body adapts by producing more RBCs, so that despite low ambient oxygen, arterial oxygen content improves. This adaptation, along with increased ventilation and other changes, helps maintain tissue oxygenation at high altitude.
Ans.14. C. A is true, but R is false. The second heart sound corresponds to the closure of the aortic and pulmonary semilunar valves when the ventricles begin to relax and the pressure in them falls below that in the aorta and pulmonary artery. The valves close to prevent backflow into the ventricles during diastole.
Ans.15. B. DNA gyrase (a type of topoisomerase). DNA gyrase’s primary function is to relieve supercoiling ahead of the replication fork by transiently cleaving and rejoining the DNA, thus preventing replication machinery from stalling or causing breaks due to excessive torsional stress.
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