Red Blood Corpuscles (RBCs), also known as erythrocytes, are formed in the bone marrow. Specifically, they are produced in the red bone marrow of large bones through a process called erythropoiesis. The hormone erythropoietin, secreted mainly by the kidneys, regulates this process. Mature RBCs are responsible for transporting oxygen from the lungs to body tissues using the pigment hemoglobin.

Other options (for context)

• Heart: Pumps blood but does not produce blood cells.
• Liver: In adults, it does not form RBCs (though it does in the fetal stage).
• Kidney: Produces erythropoietin hormone but not RBCs directly.

Explanation: Mars is known as the Red Planet because its surface contains a large amount of iron oxide (rust), which gives it a reddish appearance. It is the fourth planet from the Sun and has two moons — Phobos and Deimos.

Explanation: Sound waves are not electromagnetic waves; they are mechanical waves that require a material medium (like air, water, or solids) for propagation. In contrast, radio waves, X-rays, and visible light are electromagnetic waves that can travel through a vacuum.

Explanation: Liquid Natural Gas (LNG) predominantly contains methane (CH₄) in liquid form. It is produced by cooling natural gas to about −162°C, which reduces its volume for easier storage and transportation. LNG is a clean fuel with high energy efficiency and low emissions.

The Yellow Revolution in India refers to the significant increase in the production of oilseeds. It was initiated to make India self-sufficient in edible oils such as mustard, sunflower, groundnut, and soybean oils. The revolution gained momentum under the Technology Mission on Oilseeds (TMO) launched in the 1980s. The key figure associated with the Yellow Revolution is Sam Pitroda.

Other options (for context)

• Cereals: Their production growth is linked with the Green Revolution.
• Milk: Related to the White Revolution led by Dr. Verghese Kurien.
• None of these: Incorrect — the Yellow Revolution specifically concerns oilseeds.

William Harvey, an English physician, discovered the process of blood circulation in 1628. He demonstrated that the heart acts as a pump to circulate blood continuously throughout the body via a closed system of arteries and veins. His work, published in "De Motu Cordis" (On the Motion of the Heart and Blood), laid the foundation for modern cardiovascular physiology.

Other options (for context)

• Mary Anderson: Invented the windshield wiper, not related to medicine.
• Virginia Apgar: Developed the Apgar score for assessing newborn health.
• Robert Feulgen: Discovered a staining technique for DNA, not blood circulation.

Explanation: SONAR (Sound Navigation and Ranging) is a system used in ships and submarines to determine the depth of the ocean or to locate underwater objects. It works by sending sound waves into the water and measuring the time taken for the echo to return after reflecting from the seabed or any object.

Explanation: Proteins are complex organic compounds composed of smaller units called amino acids. Each amino acid contains an amino group (–NH₂), which contributes nitrogen to the molecular structure. This makes nitrogen an essential element in all proteins. Carbohydrates and fats lack nitrogen, while only some vitamins contain it.