CBSE Class 10 · Science

Life Processes and Physical Phenomena

53 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 53 questions

  1. In the human digestive system, which enzyme present in saliva initiates the chemical digestion of dietary starch into maltose?
  2. During anaerobic respiration in yeast cells (fermentation), glucose is broken down into which end products?
  3. What is the basic functional and structural filtration unit of the human kidney?
  4. An object is placed at a distance of in front of a concave mirror of focal length . What is the nature and position of the image formed?
  5. If the absolute refractive indices of water and glass are and respectively, what is the refractive index of glass with respect to water ()?
  6. Which component of the human eye adjusts the focal length of the eye lens to facilitate accommodation for viewing objects at varying distances?
  7. What is the equivalent resistance when three resistors of , , and are connected in parallel across an electrical circuit?
  8. According to Joule's law of heating, the heat produced in a resistor of resistance carrying a current for a time is proportional to:
  9. What is the phenomenon responsible for the twinkling of stars observed from Earth's surface?
  10. Which component of gastric juice protects the inner stomach mucosal lining from the corrosive action of hydrochloric acid?
  11. What is the fate of pyruvate during anaerobic respiration in yeast cells?
  12. Why is the small intestine of herbivores longer than that of carnivores?
  13. What prevents backflow of blood inside the human heart during ventricular contraction?
  14. What is the structural and functional filtration unit of the human kidney?
  15. Which plant hormone promotes cell division and is present in high concentration in fruits and seeds?
  16. Which part of the human brain controls involuntary actions such as blood pressure, salivation, and vomiting?
  17. Why is the use of iodized salt recommended in human nutrition?
  18. What is the phenotypic ratio obtained in the F2 generation of a Mendelian dihybrid cross?
  19. How is sex genetically determined in human children?
  20. In which part of the female human reproductive system does fertilization normally occur?
  21. What method of asexual reproduction is observed in the freshwater organism Planaria?
  22. What is the primary role of stomatal guard cells in plant leaves?
  23. In an ecosystem, why is energy flow across trophic levels strictly unidirectional?
  24. What is the biological phenomenon where non-biodegradable pesticides accumulate in progressively higher concentrations at successive trophic levels?
  25. Which blood vessels possess thick elastic walls without valves to withstand high pulsing pressure?
  26. During inhalation in humans, which coordinated muscular movements increase the volume of the thoracic cavity?
  27. What is the function of the bile juice secreted by the liver in human digestion?
  28. In human males, why are the testes located outside the abdominal cavity in the scrotum?
  29. What is the structural feature of the small intestine that increases the surface area for nutrient absorption?
  30. What is the primary function of xylem tissue in vascular plants?
  31. Which synthetic chemical compound was primarily responsible for stratospheric ozone layer depletion before global phase-out agreements?
  32. A concave mirror produces a real, inverted image of the same size as the object. Where is the object placed?
  33. What is the magnification produced by a plane mirror?
  34. An object 4 cm in height is placed 25 cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror should a screen be placed to obtain a sharp image?
  35. The refractive index of diamond with respect to air is 2.42. What does this statement imply about the speed of light in diamond?
  36. A convex lens forms a real inverted image of a needle at a distance of 50 cm from it. Where is the needle placed if the image is equal to the size of the object?
  37. What is the power of a combination of two thin lenses of powers and placed in close contact?
  38. Why does the sky appear dark to passengers flying at very high altitudes instead of blue?
  39. What causes the apparent twinkling of stars when viewed from the surface of the Earth?
  40. Why does the Sun appear reddish early in the morning and at sunset?
  41. A person cannot see objects distinctly placed beyond 1.2 m. What type of corrective lens is required to restore normal vision?
  42. What is the equivalent resistance when three resistors of , , and are connected in parallel?
  43. How much work is done in moving a charge of 2 Coulombs across two points having a potential difference of 12 Volts?
  44. An electric lamp of resistance and a conductor of resistance are connected in series to a 6 V battery. What is the total current in the circuit?
  45. An electric heater rated 1000 W operates for 2 hours daily. What is the electrical energy consumed in kilowatt-hours (kWh) in a month of 30 days?
  46. Which of the following determines the direction of magnetic force experienced by a current-carrying conductor placed in a magnetic field?
  47. What is the magnetic field inside a long straight current-carrying solenoid?
  48. Why is an electric fuse connected in series with the live wire in domestic circuits?
  49. What is the purpose of earthing metallic electrical appliances in domestic circuits?
  50. A piece of wire of resistance is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is , what is the ratio ?
  51. Which rule gives the direction of induced electric current in a conductor moving through a magnetic field?
  52. What is the frequency of alternating current (AC) supplied in domestic circuits in India?
  53. What happens to the magnetic field strength of an electromagnet when a soft iron core is inserted inside the coil?

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