Dr. Hans von Ohain and Sir Frank Whittle are both recognized as being the co-inventors of the jet engine. Each worked separately and knew nothing of the other’s work. Hans von Ohain is considered the designer of the first operational turbojet engine. Frank Whittle was the first to register a patent for the turbojet engine in 1930. Hans von Ohain was granted a patent for his turbojet engine in 1936. However, Hans von Ohain’s jet was the first to fly in 1939. Frank Whittle’s jet first flew in 1941.

Correct Option: B

Dr. Hans von Ohain and Sir Frank Whittle are both recognized as being the co-inventors of the jet engine. Each worked separately and knew nothing of the other’s work. Hans von Ohain is considered the designer of the first operational turbojet engine. Frank Whittle was the first to register a patent for the turbojet engine in 1930. Hans von Ohain was granted a patent for his turbojet engine in 1936. However, Hans von Ohain’s jet was the first to fly in 1939. Frank Whittle’s jet first flew in 1941.

The smallpox vaccine was the first successful vaccine to be developed. The process of vaccination was first publicised by Edward Jenner in 1796, who acted upon his observation that milkmaids who caught the cowpox virus did not catch smallpox. Before the introduction of a vaccine, the mortality of the severe form of smallpox—variola major—was very high. Historical records show that a method of inducing immunity was already known. A process called inoculation, also known as insufflation or variolation was practiced in India as early as 1000 BC.

Correct Option: C

The smallpox vaccine was the first successful vaccine to be developed. The process of vaccination was first publicised by Edward Jenner in 1796, who acted upon his observation that milkmaids who caught the cowpox virus did not catch smallpox. Before the introduction of a vaccine, the mortality of the severe form of smallpox—variola major—was very high. Historical records show that a method of inducing immunity was already known. A process called inoculation, also known as insufflation or variolation was practiced in India as early as 1000 BC.

The discovery of penicillin is attributed to Scottish scientist and Nobel laureate Alexander Fleming in 1928. Penicillin is a secondary metabolite of certain species of Penicillium and is produced when growth of the fungus is inhibited by stress. It is not produced during active growth.

Correct Option: A

The discovery of penicillin is attributed to Scottish scientist and Nobel laureate Alexander Fleming in 1928. Penicillin is a secondary metabolite of certain species of Penicillium and is produced when growth of the fungus is inhibited by stress. It is not produced during active growth.

The electron microscope was invented by Max Knoll and Ernst Ruska in 1931 (Germany). An electron microscope uses condensing lenses to focus a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons. The electron microscope uses electrostatic and electromagnetic “lenses” to control the electron beam and focus it to form an image. These lenses are analogous to but different from the glass lenses of an optical microscope that forms a magnified image by focusing light on or through the specimen.

Correct Option: B

The electron microscope was invented by Max Knoll and Ernst Ruska in 1931 (Germany). An electron microscope uses condensing lenses to focus a beam of electrons to illuminate a specimen and produce a magnified image. An electron microscope (EM) has greater resolving power than a light-powered optical microscope because electrons have wavelengths about 100,000 times shorter than visible light photons. The electron microscope uses electrostatic and electromagnetic “lenses” to control the electron beam and focus it to form an image. These lenses are analogous to but different from the glass lenses of an optical microscope that forms a magnified image by focusing light on or through the specimen.

Van Leeuwenhoek discovered “protozoa” - the single-celled organisms and he called them “animalcules”. He also improved the microscope and laid foundation for microbiology. He is often cited as the first microbiologist to study muscle fibers, bacteria, spermatozoa and blood flow in capillaries. Although, he did not have much education or a scientific background, yet he defied all odds to be reckoned as a great scientist through his skillful observations, insight and unmatched curiosity. He revolutionized biological science by exposing microscopic life to the world.

Correct Option: A

Van Leeuwenhoek discovered “protozoa” - the single-celled organisms and he called them “animalcules”. He also improved the microscope and laid foundation for microbiology. He is often cited as the first microbiologist to study muscle fibers, bacteria, spermatozoa and blood flow in capillaries. Although, he did not have much education or a scientific background, yet he defied all odds to be reckoned as a great scientist through his skillful observations, insight and unmatched curiosity. He revolutionized biological science by exposing microscopic life to the world.