scientist, discoveries & inventions MCQ section 4 MCQ Questions & Answers Detailed Explanation

Answer: (c)

Answer: (d)

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.

Answer: (c)

Answer: (d)

The oral polio vaccine (OPV) was developed in 1961 by Albert Sabin. Also called “trivalent oral polio vaccine” or “Sabin vaccine”, OPV consists of a mixture of live, attenuated (weakened) poliovirus strains of all three poliovirus types.

OPV produces antibodies in the blood to all three types of poliovirus. In the event of infection, these antibodies protect against paralysis by preventing the spread of wild poliovirus to the nervous system.

Answer: (c)

Answer: (a)

Araneology is a branch of zoology that deals with the study of spiders. It is a branch of Arachnology, the scientific study of spiders and related animals such as scorpions, pseudo-scorpions, and harvestmen, collectively called arachnids.