Biology Discoveries — Set 3

Correct Answer: D. Melvin Calvin

• **Melvin Calvin** = Discovered the biochemical pathway of carbon fixation in photosynthesis, known as the Calvin Cycle. • **1961** — The year Calvin received the Nobel Prize in Chemistry for his work on mapping the path of carbon in photosynthesis. • 💡 Wrong-option analysis: [Robert Hill]: Discovered the 'Hill reaction' in photosynthesis; [Jan Ingenhousz]: Discovered that plants produce oxygen in sunlight; [Hans Krebs]: Discovered the Citric Acid Cycle (Krebs Cycle) in cellular respiration.

Correct Answer: D. William Harvey

• **William Harvey** = Demonstrated that the heart pumps blood in a circular motion through the arteries and veins. • **quantitative methods** — He used these to prove that the blood volume was too high to be constantly consumed by the body. • 💡 Wrong-option analysis: [Galen]: An ancient Greek physician who believed in a system of blood production and consumption, not circulation as a pump; [Leonardo da Vinci]: Made detailed anatomical drawings but did not fully grasp the circulatory mechanism; [Marcello Malpighi]: Discovered capillaries, confirming Harvey's theory post-mortem.

Correct Answer: D. Christian de Duve

• **Christian de Duve** = Discovered lysosomes and peroxisomes, key organelles involved in cellular waste disposal and metabolic processes. • **1955** — The year de Duve discovered lysosomes, the cell's waste disposal units. • 💡 Wrong-option analysis: [Albert Claude]: Pioneered cell fractionation and electron microscopy; [Keith Porter]: Known for his work on the endoplasmic reticulum; [George Palade]: Discovered ribosomes.

Correct Answer: B. Alexandre Yersin

• **Alexandre Yersin** = Independently identified the bacterium Yersinia pestis as the cause of the plague. • **Hong Kong** — The location of the outbreak where Yersin made his discovery. • 💡 Wrong-option analysis: [Shibasaburo Kitasato]: Also independently identified the bacterium, but Yersin is widely credited, especially with the genus naming; [All of the mentioned]: Kitasato was involved, but Yersin often gets primary credit for linking rats to humans and the genus name; [Robert Koch]: Known for discovering the anthrax and tuberculosis bacteria.

Correct Answer: B. Barbara McClintock

• **Barbara McClintock** = Discovered 'jump genes' or transposons, demonstrating that genetic elements can change their position on the chromosome. • **1983** — The year McClintock was awarded an unshared Nobel Prize for her discovery of mobile genetic elements. • 💡 Wrong-option analysis: [Rosalind Franklin]: Made critical contributions to understanding the structure of DNA; [Nettie Stevens]: Discovered the role of X and Y chromosomes in sex determination; [Mary-Dell Chilton]: Pioneer in plant genetic engineering using Agrobacterium.

Correct Answer: D. Robert Koch

• **Robert Koch** = First isolated Bacillus anthracis and linked this specific microorganism to the disease anthrax. • **germ theory** — His discovery provided strong evidence for this fundamental concept of disease. • 💡 Wrong-option analysis: [Louis Pasteur]: Developed vaccines for anthrax and rabies, but Koch identified the specific bacterium; [Robert Hooke]: Coined the term 'cell' and made early microscopic observations; [Joseph Lister]: Pioneer of antiseptic surgery.

Correct Answer: A. George Palade

• **George Palade** = Identified ribosomes as small granules in the cytoplasm, later known as the cell's protein factories. • **electron microscope** — He used this instrument to visualize and identify ribosomes. • 💡 Wrong-option analysis: [Christian de Duve]: Discovered lysosomes and peroxisomes; [Robert Brown]: Discovered the cell nucleus; [Albert Claude]: Pioneered cell fractionation and electron microscopy, but Palade specifically identified ribosomes.

Correct Answer: B. Camillo Golgi

• **Camillo Golgi** = Discovered the Golgi apparatus, an organelle responsible for modifying, sorting, and packaging proteins. • **1898** — The year Golgi identified this organelle using his silver staining technique. • 💡 Wrong-option analysis: [Robert Hooke]: Coined the term 'cell' from observations of cork; [Anton van Leeuwenhoek]: Known for his pioneering work in microscopy and discovering microorganisms; [Santiago Ramón y Cajal]: Developed the neuron doctrine and shared the Nobel Prize with Golgi for their work on the nervous system, but Golgi specifically discovered the apparatus.

Correct Answer: A. Julius von Sachs

• **Julius von Sachs** = Proved that chlorophyll is located in distinct bodies (chloroplasts) and is essential for starch production in plants. • **sunlight energy** — His work explained how plants capture this energy for food production. • 💡 Wrong-option analysis: [Theodor Engelmann]: Determined the action spectrum of photosynthesis using a prism and bacteria; [Melvin Calvin]: Discovered the Calvin Cycle, the carbon-fixing stage of photosynthesis; [Jan Ingenhousz]: Discovered that plants release oxygen in the presence of light.

Correct Answer: C. Selman Waksman

• **Selman Waksman** = Discovered streptomycin, the first effective antibiotic for treating tuberculosis. • **1943** — The year Waksman and his students isolated streptomycin from soil bacteria. • 💡 Wrong-option analysis: [Howard Florey]: Developed penicillin for mass production and clinical use; [Alexander Fleming]: Discovered penicillin; [Edward Jenner]: Developed the smallpox vaccine.