Inventors and Scientific Discoveries

Ivan Pavlov is famous for his experiments on classical conditioning, which involves the formation of conditioned reflexes in dogs.

Sir Alexander Fleming, a Scottish researcher, is credited with the discovery of penicillin in 1928.

Penicillin is a group of antibiotics derived from Penicillium fungi. The discovery of penicillin is attributed to Alexander Flemming in 1928.
Salman Waksman discovered streptomycin
Burkholder discovered Pfiesteria, which is a genus of heterotrophic dinoflagellates
Eugene Dubois was the first person to ever deliberately search for fossils of human ancestors
So, the correct answer is 'Fleming'

Selman Waksman, the microbiologist who discovered streptomycin, first used the word "antibiotic" in 1943. 

While Alexander Fleming discovered penicillin, Howard Florey and Ernest Chain were responsible for isolating and purifying it, and demonstrating its clinical potential as an effective drug.

• Sutton deduced that chromosomes are the basis of heredity and that the reduction of chromosomes in meiosis is directly related to Mendel's laws of inheritance.
• Thomas Hunt Morgan described the phenomenon of linkage and crossing over. Morgan imagined that genes on chromosomes were similar to pearls on a string, in other words, they were physical objects. The closer two genes were to one another on a chromosome, the greater their chance of being inherited together. In contrast, genes located farther away from one another on the same chromosome were more likely to be separated during recombination. Therefore, Morgan correctly proposed that the strength of linkage between two genes depends upon the distance between the genes on the chromosome. This proposition became the basis for construction of the earliest maps of the human genome.
• James Dewey Watson discovered the structure of DNA in 1953 with Francis Crick.
• Scottish bacteriologist Alexander Fleming accidentally discovered the antibiotic in 1928, when he came back from a vacation and found that a green mold called Penicillium notatum had contaminated Petri dishes in his lab and were killing some of the bacteria he’d been growing.

Selman Waksman, the microbiologist who discovered streptomycin, first used the word "antibiotic" in the medical sense in 1943. 

Penicillin was discovered in London in September of 1928 by Dr. Alexander Fleming, the bacteriologist on duty at St. Mary’s Hospital. The discovery of penicillin has often been described as a miracle drug because prior to the discovery of penicillin, death could occur in very trivial injuries and diseases.

The term germplasm was first used by the German biologist August Weismann. His germplasm theory states that multicellular organisms consist of germ cells that contain and transmit heritable information and somatic cells which carryout ordinary bodily functions. In the germplasm theory, inheritance in a muticellular organism only takes place by means of the germ cells: the gametes, such as egg cells and sperm cells. Other cells of the body do not function as agents of heredity.

Hammerling began growing acetabularia in laboratories in the 1930s. There he discovered that the plant had one cell and the nucleus was always located in the rhizoid. Then he began studying the roles of the nucleus and cytoplasm by experimenting with the acetabularia. He demonstrated that nucleus has the genetic material which regulates the inheritance of characters.

So, the correct answer is option C.

Mendel, during his hybridization experiments on pea plant, proposed presence of unit factors for each trait as heredity material that is faithfully transmitted from one generation to next. He called them “factors”. Sutton and Boveri recognized parallelism between inheritance of Mendel's factors and behavior of the chromosome in meiosis and fertilization. This led them to propose the chromosomal theory of inheritance states that genes are linearly arranged on chromosomes at specific loci. Darwin proposed the theory of natural selection to explain the process of evolution. Khorana extended the experiment of Nirenberg and Holley to reveal that polycytidylate encodes a polypeptide containing only proline and polyadenylate encodes polylysine. M. Nirenberg, Khorana, and Holley were awarded Nobel Prize for in vitro synthesis of polypeptides using artificially synthesized mRNA. Thus, the correct answer is option C.

Cell theory was proposed by a German botanist, Matthias Schleiden and English zoologist, Theodor Schwann in the year 1839. Cell theory was considered as most acceptable theory which, elucidated the functioning of a cell. The cell theory includes the following points -
1) All living things are made up of cells.
2) The cell is the smallest living thing that can perform all the functions of life.   
Later on, in year 1855 Rudolf Virchow added a new point in cell theory that all cells must come from pre-existing cells, which was also known as "Omnis cellula e cellula".
So, the correct answer is option B.

Sir Hans Adolf Krebs was a German born British physician and biochemist. He was the pioneer scientist in study of cellular respiration, a biochemical pathway in cells for production of energy.