Microbiology MCQs with Answer and Explnation | Chapter 2

Answer: Busch

Busch was a German physicist who worked on the development of electron microscopes. He realized that magnetic fields could be used to focus electron beams, and he developed a theoretical model for magnetic lenses. He also built a prototype magnetic lens that was able to focus electron beams with high precision.

Busch’s work on magnetic lenses was essential for the development of the electron microscope. Electron microscopes use magnetic lenses to focus electron beams onto a specimen, and they can produce images with much higher resolution than light microscopes.

Answer: Both Mercury lamp and Tungsten metal

The source of electrons in an electron microscope is a tungsten filament.

The tungsten filament is heated to a high temperature, which causes electrons to be emitted from its surface. These electrons are then accelerated through a vacuum by a high voltage.

The accelerated electron beam is then focused by magnetic lenses onto the specimen. The interaction of the electron beam with the specimen produces secondary electrons, which are detected by a detector and used to create an image.

Mercury lamps are used in some electron microscopes to produce electrons, but they are not the primary source of electrons. Mercury lamps are typically used to produce a beam of electrons that is used to heat the tungsten filament.

Answer: 2,00,000 X

Electron microscopes use a beam of electrons to magnify objects, instead of light. This allows them to achieve much higher magnifications than light microscopes, which are limited by the wavelength of light. Electron microscopes are used to study a wide range of objects, including viruses, bacteria, cells, and materials.

Answer: 1.0

The numerical aperture (NA) of a microscope objective is calculated using the following formula:

NA = n * sin(α)

where:

• n is the refractive index of the medium between the lens and the specimen
• α is the angular aperture of the lens

In air, the refractive index is approximately 1.0. Therefore, the NA of a 10x objective and a 40x objective with air as the medium can be calculated as follows:

10x objective:

NA = 1.0 * sin(α)

Assuming an angular aperture of 10 degrees, the NA of a 10x objective with air as the medium is approximately 0.17.

40x objective:

NA = 1.0 * sin(α)

Assuming an angular aperture of 65 degrees, the NA of a 40x objective with air as the medium is approximately 0.91.

10x objective: 0.17

40x objective: 0.91

Answer: Resolving power

Resolving power is a measure of the smallest distance between two objects that can be distinguished as separate objects. It is limited by the wavelength of light and the numerical aperture (NA) of the microscope objective.

The shorter the wavelength of light and the higher the NA of the objective, the higher the resolving power of the microscope.

Resolving power is important for observing small objects and structures, such as cells and bacteria

Answer: Air borne disease

Tuberculosis is an airborne disease. It is caused by the bacterium Mycobacterium tuberculosis, which spreads through the air when an infected person coughs, sneezes, or speaks. The bacteria can remain suspended in the air for several hours, and anyone who inhales them can become infected.

Waterborne diseases are caused by pathogens that are transmitted through contaminated water. Foodborne diseases are caused by pathogens that are transmitted through contaminated food. Arthropod-borne diseases are caused by pathogens that are transmitted through the bites of infected insects or ticks.

Answer: Antony von

The inventor of the microscope is “Antonie van Leeuwenhoek.” He was a Dutch scientist who, in the 17th century, developed and improved the microscope, pioneering the field of microscopy and making significant advancements in our understanding of the microscopic world.

Answer: MLD

MLD stands for Minimum Lethal Dose. It is the minimum number of bacteria or other microorganisms required to produce clinical evidence of death in a susceptible animal under standard conditions. MLD is a measure of the virulence of a microorganism.

• LD50 stands for Lethal Dose, 50%. It is the dose of a substance that is lethal to 50% of a population of test animals. LD50 is a measure of the toxicity of a substance.
• ID stands for Infectious Dose. It is the minimum number of microorganisms required to cause infection in a susceptible host. ID is a measure of the infectivity of a microorganism.

Answer: Milstein kohler

César Milstein and Georges Köhler developed the hybridoma technique in 1975, which allowed them to produce monoclonal antibodies. This technique involves fusing a myeloma cell with a B cell that has been immunized against a specific antigen. The resulting hybridoma cell is immortal and can produce large quantities of monoclonal antibodies.

Monoclonal antibodies have revolutionized the field of immunology and have been used to develop a wide range of diagnostic and therapeutic tools. They are used to diagnose and treat cancer, autoimmune diseases, and infectious diseases. They are also used in research to study the immune system and to develop new drugs.

The other scientists you mentioned have also made important contributions to the field of immunology, but they are not specifically associated with monoclonal antibodies:

• Frank Macfarlane Burnet and Peter Medawar developed the clonal selection theory of antibody production.
• Ray Owen discovered the Bursa of Fabricius, which is an important organ in the development of the immune system.

Answer: Klein Berger

Klieneberger was a German-British microbiologist who worked at the Lister Institute in London. She was studying pleuropneumonia-like organisms (PPLOs), which are now known as mycoplasmas, when she discovered L-forms.

Klieneberger observed that some of the PPLOs in her cultures had lost their cell walls. These cell wall-deficient bacteria were able to grow and reproduce, but they were much smaller and more fragile than the normal bacteria.

The other scientists you mentioned also made important contributions to the field of microbiology, but they are not specifically associated with the discovery of L-forms:

• Louis Pasteur is best known for his work on pasteurization and his development of the rabies vaccine.
• Robert Koch is considered to be the father of bacteriology.
• Antoni van Leeuwenhoek is best known for his invention of the microscope and his discovery of bacteria and protozoa.

Answer: Edward Jenner

The smallpox vaccine was first discovered by Edward Jenner, an English physician who lived from 1749 to 1823. Jenner was aware of the observation that milkmaids who had contracted cowpox, a mild disease similar to smallpox, were immune to smallpox. In 1796, he conducted an experiment in which he inoculated a young boy with cowpox and then exposed him to smallpox. The boy did not contract smallpox, demonstrating that cowpox could be used to protect against smallpox.

• Jenner’s discovery was a major breakthrough in the fight against smallpox, which was a major cause of death at the time. His work led to the development of the first effective vaccine, and it is considered to be one of the most important achievements in the history of medicine.
• Robert Koch, Louis Pasteur, and Lister were also important figures in the history of medicine, but they were not involved in the development of the smallpox vaccine. Koch is known for his work on the germ theory of disease, Pasteur is known for his work on pasteurization and vaccination, and Lister is known for his work on antiseptic surgery.

Answer: Magnetic coils

Electron microscopes use electromagnetic lenses to focus the electron beam. These lenses are made of coils of wire that generate a magnetic field when an electric current is passed through them. The magnetic field deflects the electrons in the beam, causing them to converge and focus on a point.

Superfine glass, aluminum foils, and electrons are not used as objective lenses in electron microscopes. Superfine glass is not able to focus electrons, aluminum foils would scatter the electrons, and electrons themselves cannot be used to focus other electrons.

Answer: Koch

Robert Koch is widely regarded as the father of medical microbiology. He made significant contributions to the field, including his work on the etiology of anthrax, tuberculosis, and cholera. Koch formulated Koch’s postulates, a set of criteria used to establish the causative relationship between a microorganism and a disease. His work laid the foundation for understanding how specific microbes cause diseases, leading to the development of the field of medical microbiology.

Answer: 1ìm

The resolution of the eye is limited by the wavelength of light. The wavelength of visible light is about 0.5 μm, so the eye cannot resolve any objects that are smaller than this wavelength.

For example, the human eye cannot see individual bacteria, because bacteria are typically less than 1 μm in size.

The other options are all larger than 1 μm, so they can be resolved by the eye.

Answer: Paul Ehrlich

Ehrlich was a German physician and immunologist who is considered to be one of the founders of modern chemotherapy. He was the first person to propose that it was possible to develop drugs that could kill specific types of cells without harming the rest of the body.

In 1908, Ehrlich developed the first chemotherapy drug, arsphenamine, which was used to treat syphilis. Arsphenamine was a major breakthrough in the treatment of syphilis, and it helped to reduce the mortality rate of the disease by more than 90%.

Ehrlich’s work on chemotherapy laid the foundation for the development of modern cancer chemotherapy drugs. Chemotherapy drugs are now used to treat a wide range of cancers, and they have saved the lives of millions of people.

The other scientists you mentioned also made important contributions to the field of medicine, but they are not specifically associated with the development of modern chemotherapy:

• Joseph Lister was an English surgeon who developed the antiseptic method, which helped to reduce the mortality rate from surgery.
• Elie Metchnikoff was a Russian zoologist and microbiologist who discovered the role of phagocytes in the immune system.

Answer: F.W. Twort

Viral infection of bacteria was discovered by Frederick William Twort. In 1915, Twort observed that the bacteria in his cultures were being killed by a mysterious agent. He identified this agent as a virus, and he showed that the virus could be filtered out of the culture and then used to infect new bacteria.

Twort’s discovery was the first evidence that viruses could infect bacteria. He named the virus that he had discovered the “bacteriophage.” Twort’s work on bacteriophages was not widely recognized at the time, but it was later confirmed by Félix d’Hérelle in 1917.

The discovery of viral infection of bacteria was a major breakthrough in the field of microbiology. It showed that viruses could infect both plants and animals, and it helped to establish the field of phage therapy. Phage therapy is the use of bacteriophages to treat bacterial infections.

The other scientists you mentioned did not make significant contributions to the discovery of viral infection of bacteria:

• Martinus Willem Beijerinck was a Dutch microbiologist who is best known for his discovery of viruses.
• Dimitry Ivanovsky was a Russian botanist and microbiologist who is best known for his discovery of tobacco mosaic virus.

Answer: 0.2 micron

Micron is a unit of length equal to one millionth of a meter, or 0.001 millimeters. Angstrom units are even smaller, equal to one ten-billionth of a meter, or 0.00000001 millimeters. Centimeters are much larger, equal to one hundredth of a meter.

Answer: Elie Metchikoff

Metchnikoff was a Russian zoologist and microbiologist who is considered to be one of the founders of modern immunology. He was the first person to describe the process of phagocytosis, in which white blood cells engulf and destroy foreign invaders such as bacteria and viruses.

Metchnikoff made his discovery of phagocytosis in the late 1870s while he was studying starfish larvae. He observed that certain cells in the larvae would engulf and digest other cells. Metchnikoff hypothesized that these cells were playing a role in the defense of the larvae against infection.

The other scientists you mentioned also made important contributions to the field of immunology, but they are not specifically associated with the discovery of phagocytosis.

• Paul Ehrlich is considered to be one of the founders of modern chemotherapy.
• Joseph Lister is best known for his development of the antiseptic method.
  Louis Pasteur is best known for his work on pasteurization and his development of the rabies vaccine.

Answer: Tungsten metal

Electrons in an electron microscope are produced by a heated tungsten filament. The filament is typically shaped like a hairpin and is surrounded by a cathode cap. A negative voltage is applied to the cathode cap, which creates an electric field that accelerates the electrons away from the filament.

Mercury lamps are not used as a source of electrons in electron microscopes.

Answer: Absence of nuclear envelope

The main feature of prokaryotic organisms is the absence of a nuclear envelope. This means that their genetic material is not enclosed within a membrane-bound nucleus. Instead, it is located in a region of the cytoplasm called the nucleoid.

Prokaryotic organisms do have nuclear material, protein synthesis, and some are capable of locomotion. However, the absence of a nuclear envelope is a defining characteristic of prokaryotic cells.

Answer: 1000x – 2000x

The magnification range of a light microscope is typically “1000x – 2000x.” Light microscopes use visible light to magnify specimens, and this range represents the maximum magnification achievable with these microscopes. It’s important to note that specialized light microscopes may offer slightly higher magnifications, but 1000x – 2000x covers the general range.

Answer: A.V Leeuwenhock

The title of “Father of Microbiology” is generally attributed to Antonie van Leeuwenhoek, a Dutch scientist who lived from 1632 to 1723. Leeuwenhoek was a pioneer in the development of microscopy, and he was the first person to observe and describe bacteria and other microorganisms. His observations were groundbreaking and helped to establish microbiology as a scientific discipline.

Louis Pasteur, Joseph Lister, and Robert Koch were also important figures in the history of microbiology.

• Pasteur is known for his work on pasteurization and vaccination.
• Lister is known for his work on antiseptic surgery.
• Koch is known for his work on the germ theory of disease.

Answer: Koch

The title of “Father of Medical Microbiology” is generally attributed to Robert Koch , a German physician and microbiologist who lived from 1843 to 1910. Koch made significant contributions to the understanding of infectious diseases, and he is best known for his work on the germ theory of disease and the development of Koch’s postulates.

Koch’s postulates are a set of four criteria that must be met to establish a causal relationship between a microbe and a disease. These postulates are still used today to identify the cause of infectious diseases.

Koch also developed several important techniques for culturing and identifying bacteria, and he discovered the bacteria that cause tuberculosis and cholera. His work on tuberculosis earned him the Nobel Prize in Physiology or Medicine in 1905.

Louis Pasteur, Edward Jenner, and Antonie van Leeuwenhoek were also important figures in the history of microbiology.

• Pasteur is known for his work on pasteurization and vaccination.
• Jenner is known for his work on the smallpox vaccine.
• Leeuwenhoek is known for his pioneering work in microscopy.

However, Koch’s contributions to the field of medical microbiology are considered to be more fundamental, and he is therefore generally recognized as the “Father of Medical Microbiology”.

Answer: Hugo devries

The term “mutation” was coined by Hugo de Vries, a Dutch botanist and geneticist who lived from 1848 to 1935. De Vries was studying the evening primrose plant when he noticed that some of the plants had unusual characteristics that were not present in the parent plants. He called these sudden changes in the plant’s characteristics “mutations”.

• De Vries’s work on mutations was a major contribution to the field of genetics, and it helped to lay the foundation for the modern understanding of evolution. His work was also influential in the development of the field of mutagenesis, which is the study of how mutations are caused and how they can be used to improve crops and other organisms.
• Pasteur, Darwin, and Lamarck were also important figures in the history of biology, but they did not coin the term “mutation”. Pasteur is known for his work on pasteurization and vaccination, Darwin is known for his theory of evolution by natural selection, and Lamarck is known for his theory of inheritance of acquired characteristics.

Answer: Fruit juices

In the early 1850s, Pasteur was investigating the process of fermentation, which is the conversion of sugars into alcohol and other products by yeast or bacteria. He was particularly interested in the role of microorganisms in fermentation, and he wanted to determine whether microorganisms were essential for the process.

To test this, Pasteur conducted a series of experiments in which he fermented fruit juices in the presence and absence of microorganisms. He found that fermentation only occurred when microorganisms were present. This led him to conclude that microorganisms are essential for fermentation.

Pasteur’s experiments on fermentation were groundbreaking, and they helped to establish the germ theory of disease. This theory states that diseases are caused by microorganisms, and it revolutionized the field of medicine.

Answer: Mercury lamp

Mercury lamps emit a wide spectrum of light, including ultraviolet (UV) light. UV light is necessary to excite fluorophores, which are molecules that emit light when they are exposed to UV light.

• Sunlight also contains UV light, but it is not as intense as the UV light emitted by a mercury lamp. For this reason, sunlight is not typically used as a source of light in fluorescence microscopy.

Answer: Non-sense mutation

A nonsense mutation is a type of mutation that changes a codon that codes for an amino acid into a stop codon. This premature stop codon results in the production of a shortened protein that is likely non-functional.

• Mis-sense mutations change a codon that codes for one amino acid into a codon that codes for a different amino acid. This can change the structure and function of the protein.
• Neutral mutations do not change the amino acid sequence of the protein.
• Reverse mutations are mutations that change a mutant allele back to its original wild-type allele.

Answer: Johnsen & Hans

The compound microscope was not invented by a single person, but rather it was developed over time by a number of different people. The earliest compound microscopes were made in the Netherlands in the late 16th century, and they are generally attributed to Hans and Zacharias Janssen, a father-and-son team of spectacle makers.

• The Janssens’ microscopes were simple devices that used two lenses to magnify objects. They were not very powerful, but they were a significant advance over the simple magnifying glasses that were used at the time.
• In the early 17th century, Galileo Galilei made significant improvements to the compound microscope. He developed a way to grind lenses more precisely, and he also designed a new type of microscope that used a combination of lenses to achieve higher magnification.
• In the late 17th century, Antonie van Leeuwenhoek made further improvements to the compound microscope. He developed a method for making very small lenses, which allowed him to build microscopes with much higher magnification than had been possible before. Leeuwenhoek’s microscopes were so powerful that he was able to observe bacteria and other microorganisms for the first time.

Answer: Virulence

Virulence is the ability of a microorganism to cause disease. It is determined by a number of factors, including the microorganism’s ability to invade and damage host tissues, its ability to produce toxins, and its ability to evade the host immune system.

• Pathogens are microorganisms that can cause disease, but not all pathogens are virulent. Some pathogens, such as the bacteria that live in our gut, are harmless to us. However, other pathogens, such as the bacteria that cause food poisoning or the viruses that cause the flu, are highly virulent.
• Infection is the process by which a microorganism invades and establishes itself in a host organism. Infection does not always lead to disease, but it can if the microorganism is virulent enough.

Answer: Chondroids

Mesosomes are also known as chondrioids. They are invaginations of the plasma membrane of bacteria that were once thought to be organelles. However, it is now known that mesosomes are artifacts of the chemical fixation process used to prepare bacterial cells for electron microscopy.

Mitochondria are organelles found in eukaryotic cells that are responsible for cellular respiration. Endoplasmic reticulum is a network of membranes in eukaryotic cells that is involved in protein synthesis and transport. Plasmids are small, circular pieces of DNA that are found in bacteria and some other organisms.

Answer: Janssen and Hans

Janssen was a spectacle maker from Middelburg, Netherlands. He and his son, Zacharias, were experimenting with lenses when they invented the compound microscope. The compound microscope uses two lenses to magnify objects, which allows for much higher magnifications than a simple microscope, which uses only one lens.

The Janssens’ microscope was crude and had a magnification of only about 9x, but it was a major breakthrough in the history of science. It allowed scientists to see the world around them in a new way and to make discoveries about the natural world that would not have been possible without it.

The other scientists you mentioned did not invent the compound microscope:

• Antonie van Leeuwenhoek was a Dutch scientist who used simple microscopes to make many important discoveries, including bacteria and protozoa.
• Louis Pasteur was a French chemist and microbiologist who is best known for his work on pasteurization and his development of the rabies vaccine.
• Robert Koch was a German physician and microbiologist who is considered to be the father of bacteriology.

Answer: Knoll and Ruska

Ruska and Knoll were German scientists who were working on ways to improve the resolution of microscopes. They realized that electrons could be used to create images with much higher resolution than light could.

Ruska and Knoll developed the first electron microscope in 1931. The microscope was able to magnify objects up to 100,000 times, which was much higher than the magnification of any optical microscope at the time.

The electron microscope has revolutionized the field of biology. It has allowed scientists to see the inner workings of cells and tissues in unprecedented detail. The electron microscope has also been used to make important discoveries in a variety of other fields, including physics, chemistry, and materials science.

Answer: Conjunction

Conjugation is a type of bacterial sex in which two bacteria cells come into contact and exchange genetic material. It is a mechanism for horizontal gene transfer, which means that it allows bacteria to share genes with each other that are not present in their own genomes.

Lederberg and Tatum’s discovery of conjugation was a major breakthrough in the field of microbiology. It showed that bacteria were capable of exchanging genetic material with each other, which could lead to the rapid emergence of new strains of bacteria with new traits.

The other options you mentioned are all related to bacteria, but they are not specifically related to conjugation.

• Transformation is a process by which bacteria take up DNA from the environment.
• Mutation is a change in the DNA of a cell.
• Plasmids are small, circular pieces of DNA that can be transferred between bacteria.

Answer: Both Howard Ricketts and da Rocha-lima

Ricketts was an American pathologist who worked at the University of Chicago. In 1906, he was sent to study an outbreak of Rocky Mountain spotted fever in Montana. Ricketts was able to identify the causative organism of the disease, which he named Rickettsia rickettsii. Ricketts also showed that the disease was transmitted by ticks.

Da Rocha-lima was a Brazilian physician who also studied Rocky Mountain spotted fever. He independently discovered R. rickettsii in 1916, but Ricketts is credited with the first discovery of the organism.

The other scientists you mentioned did not make significant contributions to the discovery of the causative organism of Rocky Mountain spotted fever.

• Robert Koch was a German physician and microbiologist who is considered to be the father of bacteriology. He discovered the causative agents of tuberculosis and cholera.

Answer: Pandemic

A pandemic is an epidemic of an infectious disease that has spread across a large region, typically multiple continents or worldwide, affecting a substantial number of people. A disease or condition is not a pandemic merely because it is widespread or kills many people; it must also be infectious. For instance, cancer is responsible for many deaths but is not considered a pandemic because the disease is not contagious.

Here are the definitions of the other terms:

• Sporadic refers to a disease that occurs infrequently and irregularly.
• Epidemic refers to a disease that spreads rapidly among a large number of people in a community at the same time.
• Endemic refers to a disease that is constantly present in a certain region or population.

Answer: Oxysomes

The stalked particles on the cristae of mitochondria are called oxysomes. They are also known as ATP synthase complexes, as they are responsible for the synthesis of ATP, the cell’s primary energy currency. These complexes are embedded in the inner mitochondrial membrane and consist of two main parts: F0 and F1. The F0 portion is embedded in the membrane and acts as a proton channel, while the F1 portion protrudes into the mitochondrial matrix and is responsible for ATP synthesis.

Glyoxysomes, peroxisomes, and spherosomes are different types of organelles found in eukaryotic cells. Glyoxysomes are involved in the conversion of fatty acids to carbohydrates, peroxisomes are involved in the breakdown of fatty acids and detoxification of harmful substances, and spherosomes are involved in the storage of lipids.

Answer: None of these

Jenner was an English physician who developed the first vaccine for smallpox in 1796. He coined the term “vaccine” from the Latin word “vacca,” which means “cow.” This is because Jenner used cowpox virus to develop his vaccine for smallpox. Smallpox was a deadly disease that killed millions of people each year, but Jenner’s vaccine helped to eradicate the disease.

The other scientists you mentioned also made important contributions to the field of microbiology, but they are not specifically associated with the term “vaccine”:

• Robert Koch was a German physician and microbiologist who is considered to be the father of bacteriology. He discovered the causative agents of tuberculosis and cholera, and he developed many important techniques for studying bacteria.
• Louis Pasteur was a French chemist and microbiologist who is best known for his work on pasteurization and his development of the rabies vaccine.
• John Needham was an English priest and scientist who was one of the first people to propose that microorganisms could arise spontaneously from non-living matter.

Answer: Lord Lister

The antiseptic method was first demonstrated by Lord Joseph Lister, a Scottish surgeon who lived from 1827 to 1912. Lister was inspired by the work of Louis Pasteur, who had shown that microorganisms were responsible for causing fermentation and disease. Lister hypothesized that if microorganisms could be killed or prevented from entering wounds, then the risk of infection could be reduced.

In 1865, Lister began using carbolic acid, a powerful antiseptic, to clean surgical instruments and wounds. He also developed a method of spraying carbolic acid into the air around the operating table to create an antiseptic environment. Lister’s methods were remarkably successful in reducing the rate of postoperative infections, and they revolutionized the practice of surgery.

Edward Jenner was an English physician who is known for his work on vaccination, particularly the development of the smallpox vaccine. Lwanowski and Beijerinck were not involved in the development of antiseptic methods.

Answer: Metchnikof

The phagocytic phenomenon was discovered by Élie Metchnikoff, a Russian zoologist and immunologist. In 1882, while studying starfish larvae, he observed specialized cells engulfing and destroying foreign particles, a process he termed phagocytosis.

This discovery revolutionized the understanding of the immune system, revealing a crucial defense mechanism against invading pathogens. Metchnikoff’s work laid the foundation for cellular immunology and earned him a Nobel Prize in 1908, along with Paul Ehrlich, for their contributions to understanding immunity.

Answer: All of these

Cholera is an acute diarrheal illness caused by the bacterium Vibrio cholerae. It is transmitted through contaminated water or food, and it can cause severe dehydration and death if left untreated.

The following measures can be taken to prevent cholera.

• Protected water supply: Ensuring access to safe drinking water is essential for preventing cholera. This can be achieved by treating water with chlorine or other disinfectants, boiling water before drinking, or using a water filter.
• Environmental sanitation: Proper sanitation practices, such as proper sewage disposal and handwashing with soap and water, can help to prevent the spread of cholera.
• Immunization with killed vaccines: There are several oral cholera vaccines available that can provide protection against cholera. These vaccines are not 100% effective, but they can significantly reduce the risk of getting cholera.

Answer: Numerical Aperture

NA is a measure of the amount of light that can be collected by a lens. It is a function of the refractive index of the medium between the lens and the specimen, and the angle of the cone of light that enters the lens.

A higher NA means that the lens can collect more light, which results in a brighter image. This is important for observing specimens that are faint or difficult to see.

Angular aperture is also a measure of the light-gathering capacity of a lens, but it is not as commonly used as NA.

Answer: De’Herelle

d’Hérelle was a French-Canadian microbiologist who discovered bacteriophages in 1917. He was studying dysentery in France when he observed that the bacteria in his cultures were being killed by a mysterious agent. d’Hérelle identified this agent as a virus, and he named it bacteriophage, which means “bacteria eater”.

d’Hérelle was the first person to describe the lytic cycle of bacteriophages, in which the virus infects a bacterium and then destroys it. He also showed that bacteriophages could be used to treat bacterial infections.

d’Hérelle’s work on bacteriophages was groundbreaking, and it helped to establish the field of phage therapy. Phage therapy is the use of bacteriophages to treat bacterial infections. Phage therapy is now being used to treat a variety of bacterial infections, including antibiotic-resistant infections.

The other scientists you mentioned did not make significant contributions to the discovery of bacteriophages:

• Frederick William Twort was an English bacteriologist who independently discovered bacteriophages in 1915, but d’Hérelle is credited with the first discovery of the organisms.
• Martinus Willem Beijerinck was a Dutch microbiologist who is best known for his discovery of viruses.
• Dimitry Ivanovsky was a Russian botanist and microbiologist who is best known for his discovery of tobacco mosaic virus.

Answer: Lord Lister

Antiseptic methods were first introduced by Lord Lister. He was a British surgeon who pioneered the use of antiseptics to prevent infection in surgical wounds. Lister was inspired by the work of Louis Pasteur, who had shown that microorganisms were responsible for causing fermentation and disease. Lister hypothesized that if microorganisms could be killed or prevented from entering a wound, then infection could be prevented.

In 1865, Lister began using carbolic acid (phenol) to sterilize surgical instruments and dressings. He also sprayed carbolic acid solution over the surgical field during operations. Lister’s methods were met with skepticism at first, but they soon proved to be effective in reducing the rate of post-surgical infections. Lister’s work revolutionized surgery and paved the way for the development of modern antiseptic techniques.

Answer: Condensor

The condenser is a lens system that focuses light from the light source onto the specimen. This helps to ensure that the specimen is evenly illuminated and that the image is clear and bright.

The other components of a light microscope are.

• Objective: The objective lens is the lens that is closest to the specimen. It is responsible for magnifying the specimen.
• Ocular: The ocular lens is the lens that is closest to the eye. It is responsible for magnifying the image from the objective lens

Answer: 12,000x

The magnification power of the electron microscope developed by Ernst Ruska and Max Knoll in 1931 was 12,000x.

This was a significant improvement over the magnification power of light microscopes at the time, which was typically limited to around 1,000x. The electron microscope allowed scientists to see smaller objects and structures in unprecedented detail, which led to many important discoveries in biology, chemistry, and physics.

Knell and Ruska’s electron microscope was the first practical electron microscope, and it paved the way for the development of more sophisticated electron microscopes that are used today in research and industry.

Answer: Pneumococci

Frederick Griffith’s experiment in 1928 was a landmark study that demonstrated the phenomenon of bacterial transformation. He observed that a non-virulent strain of Streptococcus pneumoniae could be transformed into a virulent strain by exposure to heat-killed virulent bacteria. This suggested that some substance from the dead bacteria was able to change the genetic makeup of the living bacteria. This substance was later identified as DNA.

Answer: Kohler and Milstein

The hybridoma technique was first discovered by César Milstein and Georges Köhler in 1975. They were awarded the Nobel Prize in Physiology or Medicine in 1984 for their discovery. The hybridoma technique is a method for producing monoclonal antibodies, which are antibodies that are all identical and specific to a particular antigen. This technique has revolutionized the field of immunology and has had a major impact on the development of diagnostic and therapeutic agents.

• Robert Koch was a German physician and microbiologist who is best known for his work on tuberculosis. He was awarded the Nobel Prize in Physiology or Medicine in 1905 for his discovery of the bacterium that causes tuberculosis.
• Félix d’Herelle was a French-Canadian microbiologist who is best known for his discovery of bacteriophages, which are viruses that infect bacteria. He was a pioneer in the field of phage therapy, which is the use of bacteriophages to treat bacterial infections.
• Karl Landsteiner was an Austrian physician and biologist who is best known for his discovery of the blood groups. He was awarded the Nobel Prize in Physiology or Medicine in 1930 for his discovery.

Answer: Joseph Lister

Antiseptic surgery was pioneered by Joseph Lister, a British surgeon who revolutionized surgical practice by introducing antiseptic techniques to prevent post-surgical infections. Inspired by Louis Pasteur’s work on germ theory, Lister hypothesized that microorganisms were responsible for wound infections and sought ways to eliminate them.

In 1865, Lister began using carbolic acid (phenol) to sterilize surgical instruments, dressings, and the surgical field. This practice significantly reduced post-surgical infection rates and marked a turning point in surgical history. While Lister’s methods evolved over time, his contributions laid the foundation for modern antiseptic surgery.

Answer: Prions

Kuru disease in humans is caused by prions. Prions are infectious, misfolded proteins that can cause other normal proteins to misfold, leading to neurodegenerative diseases. Kuru is a rare and fatal neurodegenerative disorder that was formerly common among the Fore people of Papua New Guinea. It was transmitted through the ritualistic consumption of human brain tissue.

Bacteria, viroids, and mycoplasma are all different types of microorganisms that can cause disease. However, they are not the cause of kuru disease.

Answer: Pili

During conjugation, the genetic material is transferred through pili. Pili are thin, tube-like structures that extend from the surface of donor bacteria. They attach to recipient bacteria and form a bridge through which the genetic material can pass.

The cell wall, medium, and capsule are not involved in the transfer of genetic material during conjugation. The cell wall is a rigid structure that surrounds the bacterial cell, the medium is the environment in which the bacteria are growing, and the capsule is a slimy layer that surrounds some bacteria.