Stomata open during the day (when light is available for photosynthesis) and close at night. This reduces water loss during low photosynthetic activity periods.
Q.42Easy
Which of the following is a C4 plant commonly found in tropical regions?
Answer: C
Sugarcane is a C4 plant adapted to high light and temperature conditions. C4 plants first fix CO2 into a 4-carbon compound (oxaloacetate).
Q.43Easy
Which organelle is responsible for the synthesis of ribosomal RNA in plant cells?
Answer: B
The nucleolus within the nucleus is the site of ribosomal RNA (rRNA) synthesis and ribosome assembly in eukaryotic cells.
Q.44Easy
Which of the following statements about plasmolysis is TRUE?
Answer: D
Plasmolysis is the shrinkage of protoplasm away from the cell wall when placed in hypertonic solution. It's reversible if not prolonged.
Q.45Easy
A body is thrown vertically upward with a velocity of 40 m/s. What is the maximum height reached? (Take g = 10 m/s²)
Answer: A
Using v² = u² - 2gh, where final velocity v = 0, u = 40 m/s, g = 10 m/s². We get h = 201600 = 80 m
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Q.46Easy
Which of the following is NOT a SI base unit?
Answer: C
Newton is a derived unit (kg⋅m⋅s⁻²). Ampere, Kelvin, and Mole are SI base units
Q.47Easy
A car moving at 20 m/s suddenly applies brakes with deceleration of 5 m/s². How far does it travel before stopping?
Answer: B
Using v² = u² + 2as, where v = 0, u = 20 m/s, a = -5 m/s². We get s = 10400 = 40 m
Q.48Easy
What is the SI unit of pressure?
Answer: B
Pascal (Pa) is the SI unit of pressure, equal to 1 N/m²
Q.49Easy
Which phenomenon explains the formation of a rainbow?
Answer: A
Rainbows form due to refraction of sunlight entering water droplets and dispersion of different wavelengths
Q.50Easy
What is the angle of incidence when light ray falls on a plane mirror and the angle of reflection is 35°?
Answer: A
According to law of reflection, angle of incidence equals angle of reflection
Q.51Easy
Which of the following has the lowest refractive index?
Answer: C
Air has a refractive index of approximately 1, which is the lowest among common materials
Q.52Easy
Which of the following is NOT a vector quantity?
Answer: B
Temperature is a scalar quantity as it has only magnitude. Displacement, velocity, and acceleration are vector quantities as they have both magnitude and direction.
Q.53Easy
Which law states that the force of attraction between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance between them?
Answer: C
Newton's Law of Universal Gravitation states F = G(m₁m₂)/r². This is the fundamental law describing gravitational attraction between masses.
Q.54Easy
What is the atomic mass unit (amu) equivalent to in kg?
Answer: A
1 amu = 1.66054 × 10⁻²⁷ kg. This is used to express atomic and molecular masses.
Q.55Easy
A body falls freely from rest. What is its velocity after 2 seconds? (g = 10 m/s²)
Answer: B
Using v = u + gt, where u = 0 (at rest), t = 2s, g = 10 m/s². Therefore v = 0 + 10 × 2 = 20 m/s.
Q.56Easy
The process by which plants prepare their food using sunlight is known as:
Answer: B
Photosynthesis is the process where plants use sunlight, water, and CO₂ to produce glucose and oxygen. The equation is 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.
Q.57Easy
What is the pH of pure water at 25°C?
Answer: B
Pure water at 25°C has a pH of 7, which is neutral. This is because [H⁺] = [OH⁻] = 10⁻⁷ M, making pH = -log(10⁻⁷) = 7.
Q.58Easy
A body moving in a circular path with constant speed possesses which type of acceleration?
Answer: B
In uniform circular motion, speed is constant but direction changes continuously. This change in direction causes centripetal acceleration always directed toward the center of the circle.
Q.59Easy
Two bodies of masses 2 kg and 3 kg are dropped from the same height in vacuum. Which statement is correct?
Answer: C
In vacuum, acceleration due to gravity is independent of mass. Both bodies experience the same gravitational acceleration (g ≈ 9.8 m/s²) and fall from the same height, so they reach the ground simultaneously.
Q.60Easy
The SI unit of pressure is Pascal (Pa). How is it related to other SI units?
Answer: D
Pascal = N/m² = kg/(m·s²) = J/m³. All these expressions are dimensionally equivalent representations of pressure, showing the fundamental relationship between force, area, and SI base units.
