Explanation: Lysosomes are known as the ‘suicidal bags’ or ‘disposal units’ of the cell because they contain powerful hydrolytic enzymes capable of breaking down worn-out cell organelles, foreign substances, and even the entire cell when it becomes damaged or diseased.

Graphite is used in pencils. It is a soft form of carbon that leaves a dark mark on paper due to its layered structure, where carbon atoms are arranged in sheets that slide easily over each other. Though commonly called “lead,” pencils actually contain graphite mixed with clay to adjust hardness.

• Silicon: Used in electronics, not pencils.
• Charcoal: Used in art drawing but not regular pencils.
• Phosphorous: Used in safety matches and fertilizers, not pencils.

Explanation: The Sun is seen a few minutes before actual sunrise and after actual sunset due to the refraction of light by the Earth's atmosphere. The atmosphere bends the Sun’s rays towards the Earth, making the Sun appear slightly above the horizon even when it is below it.

Sound waves from a loudspeaker are produced by vibrations of its diaphragm. When an electric current passes through the speaker coil, it causes the diaphragm to move back and forth, creating compressions and rarefactions in the air. These pressure variations travel as sound waves to our ears.

• Frequency: Determines pitch but does not create sound.
• Pitch: A property of sound, not its cause.
• Amplitude: Determines loudness but not the origin of sound.

Explanation: When a bus starts suddenly, the passengers tend to lean backward due to the inertia of rest. Inertia is the tendency of a body to resist any change in its state of motion or rest. The lower part of the passenger’s body moves forward with the bus as it starts, but the upper part of the body tends to remain at rest momentarily. This makes the passenger appear to fall backward relative to the bus. It is a clear example of Newton’s First Law of Motion.

Explanation: Animals that live in or on trees are called arboreal animals. They are adapted to climbing and moving about among branches. Examples include monkeys, squirrels, chameleons, and tree frogs. Their adaptations may include grasping limbs, prehensile tails, claws, or adhesive pads that help them cling to tree surfaces and move efficiently among branches.

Tuberculosis (TB) is commonly known as the "White Plague". It earned this name because it causes extreme paleness and weight loss in affected individuals. Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis, primarily affecting the lungs but can also spread to other parts of the body. It spreads through airborne droplets when an infected person coughs or sneezes.

Other options (for context)

• Typhoid: Caused by Salmonella typhi, affects the intestine and causes high fever.
• Malaria: Caused by Plasmodium parasite transmitted through mosquito bites.
• Plague: Caused by Yersinia pestis, historically known as the “Black Death,” not the white plague.

The pale yellow colour of urine is due to the presence of the pigment Urochrome. Urochrome is a waste product formed from the breakdown of hemoglobin in red blood cells. It is produced when hemoglobin is metabolized into urobilin and then excreted through urine. The intensity of the yellow color can vary depending on hydration levels — darker urine indicates dehydration, while pale urine indicates proper hydration.

Other options (for context)

• Urophyll: No such pigment exists in human physiology.
• Chlorophyll: Green pigment found in plants, not in urine.
• Chloroplast: Cell organelle in plants where photosynthesis occurs, not a pigment.

Explanation: PROLOG (Programming in Logic) is a high-level programming language widely used in the field of Artificial Intelligence (AI) and computational linguistics. It is based on formal logic and is especially useful for solving problems involving pattern matching, rule-based reasoning, and natural language processing.