Inventors and Scientific Discoveries

The stethoscope was invented in France in 1816 by Rene Laennec in Paris. 

In the year 1829, Johann Wolfgang Dobereiner, a German scientist, was the first to classify elements into groups based on John Dalton's assertions. He grouped the elements with similar chemical properties into clusters of three called 'Triads'. The distinctive feature of a triad was the atomic mass of the middle element. When elements were arranged in order of their increasing atomic mass, the atomic mass of the middle element was approximately the arithmetic mean of the other two elements of the triad.

Charles Darwin used cut tip of canary grass seedlings to demonstrate the sensitivities of the stem apex to light mediated movements. 

A tropism is a growth movement by plant part in the direction of the stimulus. According to Boysen-Jensen, the stimulus for phototropism, growth in response to light, is a diffusible chemical that passes from the tip of the coleoptile. He cut the tip of the coleoptile and the severed tip was reattached through a gelatin disc. The recapitated coleoptile showed bending of stem towards light. Paal continued with Boyse-Jensen work. He said that the tip of coleoptile produces some chemical which travels down and stimulates growth. The light causes the accumulation of that chemical on the shaded side of the coleoptile. 

• Secretin was the first hormone to be identified. In 1902, William Bayliss and Ernest Starling were studying how the nervous system controls the process of digestion.
•  It was known that the pancreas secreted digestive juices in response to the passage of food (chyme) through the pyloric sphincter into the duodenum. Hence, The scientist who found secretion of gastric juice to be under control of the nervous system was Ernest Starling.

in 1932, James Chadwick discovered neutron.

In 1952, Selman Abraham Waksman was awarded the Nobel prize in physiology or medicine in recognition for his discovery of streptomycin, the first antibiotic active against tuberculosis

The Nobel prize in Physiology or Medicine 1945 was awarded jointly to Sir Alexander Fleming, Ernst Boris Chain and Sir Howard Walter Florey for the discovery of penicillin and its curative effect in various infectious diseases. 

Ross Granville Harrison was an American biologist and anatomist credited as the first to work successfully with artificial tissue culture.

To produce Dolly, sheep a cloned animal where the fin Dorset mammary cell nucleus is injected into the Scottish Blackface ewe oocyte with the help of electricity. The new fused cell is them implanted into a surrogate mother, another Scottish Blackface ewe which develops sheep a clone of fin Dorset sheep. Thus, the correct answer is option B.

Recombinant DNA technology was pioneered by Stanley Cohen and Herbert Boyer in 1973.

Karl Ereky coined the word biotechnology in Hungary. This discovery and the naming was done in the year 1917. The term biotechnology is the branch of science which deals with the application of biological techniques for human welfare. It involves the modification of genes by the enzymatic action which leads to the production of some biological entity like antibodies, vaccines etc which benefits the mankind. 

The imbibition theory of ascent of sap was proposed by Unger.

Scientist Christian Wolf proposed the theory of capillary force for the ascent of sap. He proposed that when water is present in fine tubes then a force develops which causes ascent of sap which is known as capillary force.

An oncogene is a gene that has the potential to cause cancer. In tumor cells, oncogenes were first discovered in certain retroviruses and were identified as cancer-causing agents in many animals. In the mid 1970s, the American microbiologists, John Michael Bishop and Harold Varmus tested the theory that healthy body cells contain dormant viral oncogenes that, when triggered, cause cancer. 
Thus, the correct answer is option (D), 'J.M. Bishop and H.E. Vermus'.