Explanation: Photosynthesis is the process by which green plants, algae, and some bacteria use sunlight to convert carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) and oxygen (O₂). This process takes place in the chloroplasts of plant cells, which contain the green pigment chlorophyll that captures solar energy.

Chemical Equation:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Thus, plants are known as autotrophs because they produce their own food using light energy — a process vital for sustaining all life on Earth.

Explanation: The plasma membrane in eukaryotic cells is mainly made up of a phospholipid bilayer arranged in a fluid mosaic model. Each phospholipid molecule consists of a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tails. This arrangement creates a semi-permeable barrier that regulates the movement of substances into and out of the cell. Embedded proteins, cholesterol, and carbohydrates contribute to transport, signaling, and membrane stability.

Explanation: Dialysis is a medical procedure prescribed for patients suffering from kidney failure or severe kidney disease. When the kidneys lose their ability to filter waste products, excess salts, and water from the blood, dialysis performs this function artificially. It helps maintain the body’s chemical balance and remove toxins such as urea and creatinine. There are two main types of dialysis: hemodialysis (using a dialysis machine and artificial kidney) and peritoneal dialysis (using the lining of the abdomen as a filter).

Explanation: Light from the Sun takes approximately 8 minutes and 20 seconds to reach the Earth. The average distance between the Earth and the Sun is about 149.6 million kilometers (1 Astronomical Unit). Since light travels at a speed of 3 × 10⁸ meters per second in a vacuum, it covers this distance in roughly eight minutes. This means that when we see sunlight, we are actually seeing it as it was about eight minutes earlier.

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: Oceans contain the maximum amount of carbon dioxide (CO₂) on Earth. They act as the largest carbon sink, absorbing CO₂ from the atmosphere and storing it in dissolved form or as carbonates. This helps regulate the global carbon cycle and maintain atmospheric balance.

Explanation: Cow’s milk is a nutritionally rich food containing proteins, fats, carbohydrates, minerals, and vitamins. It is particularly rich in B-group vitamins, especially Vitamin B₂ (Riboflavin) and Vitamin B₁₂ (Cobalamin). These vitamins play crucial roles in maintaining healthy skin, eyesight, and the nervous system, as well as aiding in the formation of red blood cells.

Note: While milk provides moderate amounts of Vitamin A and D, the natural content of Vitamin D is low, and milk is often fortified with Vitamin D to enhance its nutritional value.

Explanation: Groundnut (Arachis hypogaea) is a leguminous plant that exhibits geocarpy — after fertilization a downward-growing peg pushes the fertilized ovary into the soil and the pod (the fruit) matures below ground. Potato, carrot and onion are underground plant parts but are respectively a tuber (stem), root and bulb — not fruits.