Aedes aegypti transmits dengue virus.

Pepsinogen is an inactive precursor, or zymogen, secreted by the gastric glands in the stomach lining. It is converted into its active form, pepsin, in the presence of hydrochloric acid (HCl). This acidic environment triggers the activation process. Pepsin is a proteolytic enzyme that begins the digestion of proteins by breaking them down into smaller peptides. This process is essential for further digestion and absorption in the small intestine. The conversion of pepsinogen into pepsin is a protective mechanism. If pepsin were active inside the cells that produce it, it could digest the stomach lining itself. By secreting it in an inactive form, the body prevents self-damage. Other options are incorrect: “enzyme” is too general, proteins are the substrate, and amylase digests carbohydrates. Thus, pepsin is the correct answer. This concept is important for understanding enzyme activation and digestive physiology, commonly tested in exams.

Villi are small, finger-like projections found in the inner lining of the small intestine. Their main function is to increase the surface area for absorption of nutrients. Each villus contains blood vessels and lymphatic vessels (lacteals) that help absorb digested nutrients such as glucose, amino acids, and fatty acids. This adaptation makes nutrient absorption highly efficient. The large intestine mainly absorbs water and salts and does not have villi. The stomach is involved in digestion but not absorption at this level. The liver processes nutrients but does not contain villi. Thus, the small intestine is the correct answer. This concept highlights the importance of structural adaptations in biological systems to enhance function. Understanding villi is crucial in topics like digestion, absorption, and diseases such as celiac disease, where villi are damaged.

Max Planck, a German physicist, is known as the father of quantum theory. In 1900, he proposed that energy is emitted in discrete packets called quanta, rather than continuously. This idea explained blackbody radiation, which classical physics could not. Quantum theory revolutionized physics and led to the development of quantum mechanics. It explains the behavior of particles at atomic and subatomic levels and forms the basis of modern technologies like semiconductors and lasers. Gravitational theory is associated with Isaac Newton, while the theory of relativity was developed by Albert Einstein. “Quality theory” is not a scientific concept. Thus, the correct answer is quantum theory. Planck’s work marked the beginning of modern physics.

The Taj Mahal was constructed by Mughal Emperor Shah Jahan in memory of his wife Mumtaz Mahal. Built in Agra, India, it is one of the most famous monuments in the world and a UNESCO World Heritage Site. Construction began in 1632 and took over 20 years to complete. The monument is known for its white marble architecture and intricate design. Thus, Shah Jahan is the correct answer.