Microbiology MCQs with Answer and Explnation | Chapter 9

Answer: Salmonella typhi

It is a selective and differential medium that is used to isolate and identify Salmonella typhi from clinical specimens such as stool, blood, and vomitus. The medium contains bismuth sulphite, which inhibits the growth of most other types of bacteria. Salmonella typhi is able to grow on the medium and produces black colonies.

The other options are incorrect:

• Shigella dysenteriae is a Gram-negative bacterium that causes shigellosis, a type of bacillary dysentery. It can be isolated on a variety of media, including MacConkey agar and Hektoen enteric agar.
• Vibrio cholerae is a Gram-negative bacterium that causes cholera, a serious diarrheal disease. It can be isolated on a variety of media, including alkaline peptone water and thiosulphate-citrate-bile salts sucrose agar.
• E. coli is a Gram-negative bacterium that is found in the intestines of humans and other animals. It is a common cause of food poisoning and other infections. E. coli can be isolated on a variety of media, including MacConkey agar and blood agar.

Answer: Moller’s staining

Moeller’s staining is a differential staining method used to identify bacterial spores. It is based on the principle that spores have a thick, impermeable coat that prevents most dyes from penetrating. However, if the spores are heated, the coat becomes permeable and the dyes can penetrate.

Moeller’s staining is performed as follows:

A smear of the bacteria is made on a slide and allowed to dry.
The slide is heated over a flame until the smear begins to smoke.
The slide is flooded with malachite green stain and allowed to stain for 5 minutes.
The slide is rinsed with water.
The slide is flooded with safranin stain and allowed to stain for 1 minute.
The slide is rinsed with water and dried.
Bacterial spores will appear green, while vegetative cells will appear red.

The other options are incorrect:

• Albert’s staining is a differential staining method used to identify Mycobacterium tuberculosis.
• Lugol’s staining is a simple staining method used to stain glycogen and starch.
• Indian ink preparation is a simple staining method used to stain fungi and other microorganisms.

Answer: All of these

• Micrography: This involves using a microscope to take pictures of the virus. The size of the virus can then be estimated by measuring the size of the virus particles in the pictures
• Ultra-centrifugation at high speed: This involves spinning a sample of the virus in a centrifuge at very high speeds. The virus particles will be separated from each other by their size. The size of the virus particles can then be determined by measuring the distance that they travel in the centrifuge.
• Ultra-filtration: This involves passing a sample of the virus through a filter with pores of a known size. The virus particles that are larger than the pores in the filter will be blocked, while the virus particles that are smaller than the pores in the filter will pass through. The size of the virus particles can then be estimated by measuring the size of the pores in the filter that block the virus particles.

Each of these methods has its own advantages and disadvantages. Micrography is a relatively inexpensive method, but it can be difficult to accurately measure the size of virus particles from microscope pictures. Ultra-centrifugation at high speed is a very accurate method, but it is also a relatively expensive and time-consuming method. Ultra-filtration is a relatively inexpensive and easy-to-perform method, but it is not as accurate as ultra-centrifugation at high speed.

Answer: All of these

• Microscopy: This involves examining a sample of sputum or other bodily fluid under a microscope to look for the presence of Mycobacterium tuberculosis, the bacteria that causes tuberculosis.
• Emulator: This is a newer method that uses a device called an emulator to detect the presence of M. tuberculosis in a sample of sputum. The emulator is a small, portable device that can be used in clinics and hospitals.
• Antiformin method: This is an older method that is still used in some laboratories. It involves using a chemical called antiformin to kill all of the bacteria in a sample of sputum, except for M. tuberculosis. The M. tuberculosis bacteria can then be identified using microscopy.
• Petroff’s method: This is a variation of the antiformin method. It uses a different chemical to kill the bacteria, and it also includes a step to concentrate the M. tuberculosis bacteria.
• Concentration method: This is a newer method that uses a variety of techniques to concentrate the M. tuberculosis bacteria in a sample of sputum. This makes it easier to identify the bacteria using microscopy.

Answer: All of these

• Microscopic exam: D. pneumoniae colonies on blood agar are typically small, gray, and translucent. They may also have a mucoid appearance. Gram staining of D. pneumoniae colonies shows Gram-positive diplococci.
• Culture of sputum/blood: D. pneumoniae can be isolated from sputum or blood cultures. Sputum cultures are typically incubated for 5-7 days, while blood cultures are typically incubated for 7-10 days.
• Animal inoculation: D. pneumoniae can be identified by animal inoculation. Mice are typically used for animal inoculation. A small amount of D. pneumoniae is injected into the mouse’s peritoneal cavity. If the mouse develops pneumonia, then the bacteria is identified as D. pneumoniae.

Of the above methods, culture of sputum/blood is the most common method used to identify D. pneumoniae

Answer: All of these

• Glucose broth is a general-purpose medium that can be used to cultivate a variety of bacteria, including D. pneumoniae.
• Serum broth is a nutrient-rich medium that is used to cultivate fastidious bacteria, such as D. pneumoniae.
• Agar and blood agar are solid media that can be used to isolate and cultivate D. pneumoniae. Blood agar contains blood, which provides additional nutrients for the bacteria and also helps to differentiate between different types of bacteria.
• Chocolate agar is a solid medium that contains blood that has been heated, which denatures the hemoglobin and turns the medium a chocolate brown color. Chocolate agar is a good medium for cultivating D. pneumoniae because it provides the bacteria with nutrients from the blood and also inhibits the growth of some other types of bacteria.

Answer: All of these

Heat kills microorganisms by denaturing their proteins and disrupting their cell membranes. The most common way to heat sterilize fermentation equipment is to use steam. Steam is a very effective way to kill microorganisms because it is very hot and can penetrate all areas of the equipment.

Other methods of sterilization, such as radiation and chemicals, are also effective, but they are not as commonly used in fermentation because they can be more expensive and/or time-consuming.

Here is a brief overview of each method:

• Heat: Heat is the most common method of sterilization for fermentation equipment. It can be applied using steam, dry heat, or a combination of both.
• Radiation: Radiation can be used to sterilize fermentation equipment, but it is not as commonly used as heat. Radiation can be applied using gamma rays, ultraviolet light, or electron beams.
• Chemicals: Chemicals can be used to sterilize fermentation equipment, but they are not as commonly used as heat. Chemicals such as bleach and formaldehyde can be used to sterilize fermentation equipment, but they must be used carefully to avoid damaging the equipment.

Answer: Sabouraud’s medium

Sabouraud’s medium is a selective and diagnostic medium that is used to isolate and cultivate fungi. It contains a high concentration of glucose, which is a good source of carbon for fungi. It also contains an acidic pH, which inhibits the growth of many bacteria.

Sabouraud’s medium is typically used to isolate fungi from clinical specimens such as skin, nails, hair, and sputum. It is also used to isolate fungi from food and environmental samples.

The other options are incorrect:

• Nutrient agar and nutrient broth are general-purpose media that can be used to grow a variety of bacteria and fungi. However, they are not selective for fungi, so they are not ideal for isolating fungi from mixed cultures.
• Minimal agar medium is a medium that contains only the essential nutrients that are required for bacterial growth. It is not suitable for growing fungi, which require a more complex medium.

Answer: Blastospore

Blastospores are asexual spores that are produced by budding. Budding is a type of cell division in which a new daughter cell emerges from a parent cell. Blastospores are typically round or oval in shape and are produced by a variety of fungi and yeasts.

The other options are incorrect:

• Chlamydospores are thick-walled asexual spores that are produced by some fungi. They are resistant to harsh environmental conditions and can help the fungus to survive for long periods of time.
• Arthrospores are asexual spores that are produced by fragmentation of the hyphae (filaments) of some fungi.
• Conidia are asexual spores that are produced by many fungi. They are typically small, lightweight, and easily dispersed by the wind.

Answer: NNN medium

NNN medium, also known as Novy-MacNeal-Nicolle medium, is a complex medium that is used to isolate and cultivate Leishmania parasites. It contains a variety of nutrients, including blood, serum, and peptone, that are essential for Leishmania growth.

NNN medium is typically used to isolate Leishmania from clinical specimens such as blood, skin lesions, and lymph node aspirates. It is also used to maintain Leishmania cultures in the laboratory.

The other options are incorrect:

• Sabouraud’s medium is a selective medium that is used to isolate fungi.
• Wilson-Blair medium is a selective and differential medium that is used to isolate Salmonella typhi.
• Czapek-Dox medium is a minimal medium that is used to cultivate fungi.

Answer: Staphylococcus

Salt agar, also known as Mannitol Salt Agar (MSA), is a selective and differential medium commonly used for the cultivation of Staphylococci, particularly Staphylococcus aureus. The medium contains a high concentration of salt (7.5% sodium chloride), which inhibits the growth of most bacteria but allows for the selective growth of staphylococci, which are more salt-tolerant.

Answer: 7-10 days

The average incubation period of tetanus is 7-10 days. However, it can range from 3-21 days, depending on the severity of the wound and the distance from the central nervous system.

The tetanus toxin is produced by Clostridium tetani, a bacterium that lives in the soil and in the intestines of animals. The bacteria can enter the body through a puncture wound, such as a cut from a nail, or through a burn. Once inside the body, the bacteria produce a toxin that travels to the central nervous system, where it causes muscle spasms.

Tetanus is a serious and potentially life-threatening infection. If you suspect that you may have tetanus, it is important to seek medical attention immediately. Treatment typically involves tetanus immunoglobulin (TIG), which helps to neutralize the tetanus toxin, and antibiotics, which kill the bacteria.

Answer: 8-12 hours

During this time, the bacteria multiply and produce toxins in the intestines. The toxins cause damage to the lining of the intestines, leading to symptoms such as diarrhea, abdominal pain, and nausea.

In some cases, the incubation period can be shorter (as little as 2 hours) or longer (up to 24 hours). This depends on a number of factors, including the amount of bacteria ingested, the age and health of the individual, and the type of food that was contaminated.

If you suspect that you have Cl. welchii food poisoning, it is important to seek medical attention immediately. Early diagnosis and treatment can help to prevent complications.

Here are some tips to help prevent Cl. welchii food poisoning:

• Cook food thoroughly to an internal temperature of at least 145 degrees Fahrenheit (63 degrees Celsius).
• Refrigerate food promptly after cooking.
• Do not reheat food more than once.
• Avoid eating raw or undercooked meat, poultry, and seafood.
• Practice good hand hygiene, especially when handling food.

Answer: Lecithinase

Lecithinase is an enzyme that is produced by some bacteria, including Clostridium welchii (also known as Clostridium perfringens). Lecithinase breaks down lecithin, a phospholipid that is found in cell membranes. This can lead to cell damage and lysis.

Nagler’s reaction is a simple test that can be used to detect the presence of lecithinase in a bacterial culture. The test involves incubating the culture with a mixture of egg yolk and lecithin. If lecithinase is present, it will break down the lecithin, resulting in a turbidity or precipitation in the egg yolk.

Nagler’s reaction is a useful test for identifying Clostridium welchii, which is a common cause of food poisoning and gas gangrene. It can also be used to test for the presence of other lecithinase-producing bacteria.

The other options are incorrect:

• Coagulase is an enzyme that is produced by some bacteria, including Staphylococcus aureus. Coagulase clots fibrinogen, a protein that is found in blood.
• Hyaluronidase is an enzyme that is produced by some bacteria, including Streptococcus pyogenes. Hyaluronidase breaks down hyaluronic acid, which is a component of the extracellular matrix.

Answer: Nagler’s test

The Nagler’s test is a biochemical test that is used to detect the presence of lecithinase C, an enzyme that is produced by Clostridium welchii. Lecithinase C is responsible for the characteristic necrosis and gas gangrene that is associated with clostridial infections.

To perform the Nagler’s test, a sample of the bacteria is incubated with a mixture of lecithin and bile salts. If the bacteria produce lecithinase C, it will break down the lecithin, resulting in a milky white precipitate.

The other options are incorrect:

• Elek’s gel precipitation test is used to detect the presence of toxins produced by Corynebacterium diphtheriae.
• Weil-Felix test is used to detect the presence of antibodies to Rickettsiae.
• Bacitracin test is used to differentiate between Gram-positive bacteria.

Answer: Robertson’s cooked meat medium

RCM medium is a selective and enriched medium that is specifically designed for the growth of Clostridium spp. It contains a variety of nutrients that are essential for Clostridium spp. growth, as well as substances that inhibit the growth of other bacteria.

RCM medium is used in clinical microbiology laboratories to isolate and identify Clostridium spp. from clinical specimens such as feces, blood, and wounds. It is also used to test for drug susceptibility of Clostridium spp. isolates.

The other options are incorrect:

• 76 Lower Stein Jensen’s medium is a general-purpose medium that can be used to grow a variety of bacteria, including Clostridium spp. However, it is not as selective as RCM medium, so it is not as good for isolating Clostridium spp. from other bacteria.
• MacConkey’s medium is a selective and differential medium that is used to isolate and differentiate Gram-negative bacteria. It is not selective for Clostridium spp., which are Gram-positive bacteria.

Answer: Foot pad of mice

Lepra bacillus is a slow-growing bacterium that is difficult to culture in the laboratory. The foot pad of mice is a good culture medium for lepra bacillus because it provides a warm and moist environment that is conducive to its growth.

Armadillo’s brain and liver of guinea pig can also be used to culture lepra bacillus, but they are not as reliable as the foot pad of mice.

It is important to note that lepra bacillus is a highly infectious bacterium, so all precautions must be taken when culturing it in the laboratory.

Here is a brief overview of the different culture media that can be used to culture lepra bacillus:

• Foot pad of mice: This is the most reliable culture medium for lepra bacillus. The mice are injected with the lepra bacillus in the foot pad. After a few months, the foot pad is swollen and the lepra bacillus can be isolated from it.
• Armadillo’s brain: Armadillos are naturally infected with lepra bacillus. The brain of an infected armadillo can be used to culture lepra bacillus. However, this method is not as reliable as the foot pad of mice method.
• Liver of guinea pig: Guinea pigs can be infected with lepra bacillus. The liver of an infected guinea pig can be used to culture lepra bacillus. However, this method is not as reliable as the foot pad of mice method.

Answer: LJ medium

LJ medium is a selective and enriched medium that is specifically designed for the growth of M. tuberculosis. It contains a variety of nutrients that are essential for M. tuberculosis growth, as well as substances that inhibit the growth of other bacteria.

LJ medium is used in clinical microbiology laboratories to isolate and identify M. tuberculosis from clinical specimens such as sputum, urine, and lymph node aspirates. It is also used to test for drug susceptibility of M. tuberculosis isolates.

The other options are incorrect:

• MacConkey’s medium is a selective and differential medium that is used to isolate and differentiate Gram-negative bacteria. It is not selective for M. tuberculosis, which is a Gram-positive bacterium.
• Wilson-Blair medium is a selective and differential medium that is used to isolate and differentiate Salmonella typhi. It is not selective for M. tuberculosis.

Answer: Potassium tellurite medium

Potassium tellurite medium is a selective and differential medium that is used to isolate and differentiate Corynebacterium diphtheriae, the causative agent of diphtheria. It contains potassium tellurite, which is a toxic substance that inhibits the growth of most other bacteria. C. diphtheriae is resistant to potassium tellurite, so it can grow on this medium.

The other options are incorrect:

• LJ medium is a general-purpose medium that can be used to grow a variety of bacteria, including C. diphtheriae. However, it is not as selective as potassium tellurite medium, so it is not as good for isolating C. diphtheriae from other bacteria.
• MacConkey’s medium is a selective and differential medium that is used to isolate and differentiate Gram-negative bacteria. It is not selective for C. diphtheriae, which is a Gram-positive bacterium.
• PDA medium is a general-purpose medium that is used to grow a variety of fungi. It is not selective for C. diphtheriae.

Answer: Pink coloured colonies

MacConkey’s medium is a selective and differential medium that is used to isolate and differentiate Gram-negative bacteria. It contains lactose, which is a sugar that can be fermented by many Gram-negative bacteria. When lactose is fermented, it produces acid, which lowers the pH of the medium. MacConkey’s medium also contains a pH indicator called neutral red, which turns pink at low pH.

E. coli is a lactose-fermenting bacteria, so it will lower the pH of the medium and turn the colonies pink.

The other options are incorrect:

• Colorless colonies are typically produced by non-lactose fermenting bacteria.
• Greenish pigmentation is typically produced by Pseudomonas aeruginosa.
• Medusa head appearance is typically produced by Proteus spp.

Answer: Salmonella spp.

The Kauffmann-White scheme is a serological typing scheme that is used to identify different strains of Salmonella bacteria. It is based on the detection of O (somatic), H (flagellar), and Vi (capsule) antigens on the surface of the bacteria.

O antigens are lipopolysaccharide antigens that are found on the outer membrane of the bacteria. H antigens are protein antigens that are found on the flagella of the bacteria. Vi antigens are polysaccharide antigens that are found on the capsule of some strains of Salmonella bacteria.

The Kauffmann-White scheme is a very useful tool for identifying Salmonella bacteria. It is used in clinical microbiology laboratories to diagnose Salmonella infections and to track the spread of Salmonella outbreaks.

The other options are incorrect:

• Shigella spp. are Gram-negative bacteria that are closely related to Salmonella spp. However, they do not have the same O, H, and Vi antigens as Salmonella spp., so they cannot be identified using the Kauffmann-White scheme.
• Escherichia coli is a Gram-negative bacteria that is also closely related to Salmonella spp. However, it does not have the same O, H, and Vi antigens as Salmonella spp., so it cannot be identified using the Kauffmann-White scheme.

Answer: Shiga

Kiyoshi Shiga was a Japanese bacteriologist who is best known for his discovery of the Shigella bacteria, which causes shigellosis. Shiga isolated Shigella from the stool of patients with dysentery during a severe outbreak in Japan in 1897. He also described the clinical features of shigellosis and the pathological changes that it causes in the intestine.

Shiga’s work on Shigella was groundbreaking, and it helped to pave the way for the development of effective treatments for shigellosis. He is also credited with being one of the first scientists to identify a bacterium as the cause of a human disease.

The other options are incorrect:

• Schmitz is the name of the genus that includes the Shigella bacteria. However, Schmitz was not a bacteriologist, and he did not isolate Shigella.
• Sonnei is the name of one of the four species of Shigella bacteria. However, Sonnei was also not a bacteriologist, and he did not isolate Shigella.
• Robert Koch was a German bacteriologist who is considered to be the father of bacteriology. He discovered the causative agents of several human diseases, including tuberculosis, anthrax, and cholera. However, he did not isolate Shigella.

Answer: All of the above

• Blood culture: Blood culture is the most sensitive and specific test for enteric fever. It involves collecting a sample of blood and incubating it in a special broth to see if any bacteria grow. If Salmonella typhi or Salmonella paratyphi grow in the broth, it is a positive blood culture, which confirms the diagnosis of enteric fever.
• Urine and stool culture: Urine and stool cultures can also be used to diagnose enteric fever, but they are less sensitive than blood culture. Urine and stool cultures involve collecting a sample of urine or stool and incubating it in a special broth to see if any bacteria grow. If Salmonella typhi or Salmonella paratyphi grow in the broth, it is a positive urine or stool culture, which can be used to support the diagnosis of enteric fever.
• Widal test: The Widal test is a serological test that detects antibodies to Salmonella typhi in the blood. It is a simple and inexpensive test, but it is not very specific, meaning that it can give false positive results. The Widal test is often used as a screening test for enteric fever, but it should be confirmed with blood culture or other tests.

Answer: Salmonella typhosa

Wilson and Blair medium is a selective and differential medium that is used to isolate Salmonella typhi from stool and other clinical specimens. The medium contains bismuth sulfite and brilliant green, which inhibit the growth of other bacteria while allowing Salmonella typhi to grow. Salmonella typhi produces hydrogen sulfide, which reacts with the bismuth sulfite to produce a black precipitate around the colonies. This makes Salmonella typhi colonies easy to identify on the medium.

Wilson and Blair medium is a very effective medium for isolating Salmonella typhi, and it is widely used in clinical microbiology laboratories.

The other options are not correct:

• Staphylococci are Gram-positive bacteria, and Wilson and Blair medium is a selective medium for Gram-negative bacteria.
• Vibrio cholerae are Gram-negative bacteria, but they are not inhibited by the bismuth sulfite and brilliant green in Wilson and Blair medium.
• Shigella shigae are Gram-negative bacteria, but they do not produce hydrogen sulfide, so they will not form black colonies on Wilson and Blair medium.

Answer: Halophiles

Halophiles are microorganisms that can thrive in environments with high salt concentrations. They are often found in saline environments such as oceans, salt lakes, and salt marshes. Halophiles have adapted to these environments by developing a variety of mechanisms for maintaining their osmotic balance and protecting themselves from the toxic effects of salt.

Osmophiles are microorganisms that can tolerate high osmotic pressure. They are found in a variety of environments, including saline environments, but they are not limited to saline environments. Osmophiles are different from halophiles in that they do not require salt to grow.

Answer: 7 to 12

Alkaliphiles are microorganisms that can grow at high pH values, typically between 7 and 12. They are often found in alkaline environments such as soda lakes, hot springs, and soils with high pH. Alkaliphiles are a diverse group of microorganisms that includes bacteria, archaea, and fungi.

The other options are incorrect:

• 1 to 6 is the pH range for acidophiles, which are microorganisms that can grow at low pH values.
• 6 to 9 is the pH range for neutrophiles, which are microorganisms that can grow at neutral pH values.
• 1 to 11 is the pH range for alkalithermophiles, which are alkaliphiles that can grow at high temperatures.

Answer: Gas pack system

A gas pack system is a laboratory method of cultivating anaerobic microorganisms by creating an oxygen-free environment. This is done by placing the culture in a sealed container with a gas pack containing oxygen-absorbing chemicals. The gas pack system is one of the most common and reliable methods for cultivating anaerobic microorganisms.

The other options are incorrect:

• Brewer jar system: A Brewer jar system is a laboratory method of cultivating anaerobic microorganisms by using a reducing agent such as pyrogallic acid to remove oxygen from the culture. However, Brewer jar systems can be less reliable than gas pack systems.
• Pyrogallic acid over the cotton: Placing pyrogallic acid over the cotton in a culture tube can create a partial anaerobic environment. However, this method is not as reliable as gas pack systems or Brewer jar systems.

Answer: Thermoduric

Thermoduric bacteria are bacteria that can survive pasteurization temperatures (although they do not grow at these temperatures). They are often found in raw milk and other dairy products. Thermoduric bacteria can cause spoilage of food and can also be a source of foodborne illness.

The other options are incorrect:

• Thermophiles are bacteria that grow best at high temperatures.
• Extreme thermophiles are bacteria that grow best at extreme temperatures (above 55 degrees Celsius).
• Facultative thermophiles are bacteria that can grow at a wide range of temperatures, including high temperatures.

Answer:

Actinomycete spores are effectively killed at a temperature of 65°C maintained for a duration of 30 minutes. This heat treatment is commonly employed to ensure the inactivation of actinomycetes in various laboratory and industrial processes.

Answer: All of the above

• Potato dextrose agar (PDA) is a general-purpose culture medium for fungi. It is made with potato extract, dextrose, and agar. PDA is a good medium for growing a wide variety of fungi, including yeasts, molds, and dermatophytes.
• Sabouraud’s agar is another general-purpose culture medium for fungi. It is similar to PDA, but it has a lower pH and contains peptone, which is a source of nitrogen. Sabouraud’s agar is often used to isolate dermatophytes, which are fungi that cause skin infections.
• Czapekdox agar is a synthetic culture medium for fungi. It contains a variety of minerals and nutrients, but it does not contain any complex carbon sources such as glucose or peptone. Czapekdox agar is often used to study the physiology and metabolism of fungi.

In addition to these general-purpose culture media, there are also a number of specialized culture media that are used for specific types of fungi. For example, yeast extract-peptone-dextrose (YPD) agar is commonly used to grow yeasts, while malt extract agar is often used to grow molds.

Answer: Dilution

The streak plate method is a microbiological technique used to isolate pure cultures of bacteria from a mixed population. It is based on the principle of dilution, which means that the inoculum is spread out over the surface of the agar plate in such a way that the number of bacteria per unit area decreases with each streak. This is done by streaking the inoculum across the plate in a series of overlapping zig-zag patterns.

By the time the final streak is made, the inoculum is so diluted that there are only a few individual bacterial cells remaining on the surface of the plate. These cells will then grow into individual colonies, which can be isolated and further studied.

The other options are not correct:

• Separation: The streak plate method is used to separate individual bacterial colonies from a mixed population.
• Streaking: Streaking is the process of spreading the inoculum across the surface of the agar plate.
• Isolation: The streak plate method is used to isolate pure cultures of bacteria from a mixed population.

Answer: Respiration inhibits

When a bacterial cell and mitochondria are treated with cyanide and carbon monoxide, respiration inhibits. This is because cyanide and carbon monoxide bind to the cytochrome oxidase complex, which is part of the electron transport chain. This blocks the flow of electrons, which is necessary for respiration. Photosynthesis and protein synthesis are not affected by cyanide and carbon monoxide. So the answer is respiration inhibits.

Answer: TMV

TMV was the first virus to be discovered, in 1892 by Dmitri Ivanovsky, a Russian botanist. He observed that a sap from infected tobacco plants could still cause disease in healthy plants even after being filtered through a porcelain filter that was small enough to block bacteria. This led him to conclude that the causative agent of the disease was a filterable agent smaller than bacteria, which he later named a virus.

The other options are incorrect:

• Hepatitis B virus was first identified in the 1960s.
• Cauliflower mosaic virus was first identified in the 1950s.
• None of these is correct. TMV was the first virus to be discovered.

Answer: Hypotonic solution

A hypotonic solution has a lower concentration of solutes than the cytoplasm of the cell. When a cell is placed in a hypotonic solution, water will move into the cell by osmosis. This will cause the cell to swell and become flaccid.

The other options are incorrect:

• An isotonic solution has the same concentration of solutes as the cytoplasm of the cell. When a cell is placed in an isotonic solution, there will be no net movement of water into or out of the cell, and the cell will remain the same size.
• A hypertonic solution has a higher concentration of solutes than the cytoplasm of the cell. When a cell is placed in a hypertonic solution, water will move out of the cell by osmosis. This will cause the cell to shrink and become plasmolyzed.
• A normal solution is a solution that has a concentration of solutes that is considered to be normal for a particular type of cell. The term “normal solution” is not commonly used in biology, and it is not synonymous with the term “isotonic solution”.

Answer: Ammonifiaction bacteria

The proteinaceous compounds are converted to ammonia by ammonification bacteria.

Ammonification is a biological process that breaks down organic nitrogen-containing compounds, such as proteins, into ammonia (NH3). This process is carried out by a group of microorganisms called ammonifying bacteria, which are found in soil, water, and the digestive tracts of animals.

The other options are incorrect:

• Putrefactive bacteria are responsible for the decomposition of complex organic matter, such as dead plants and animals.
• Nitrifying bacteria convert ammonia into nitrite (NO2-) and nitrate (NO3-).
• Denitrifying bacteria convert nitrate back into nitrogen gas (N2).

Answer: Cyclins and Cd ks

The cell cycle is regulated by a complex interplay of proteins, including cyclins, cyclin-dependent kinases (Cdks), and checkpoints. These proteins work together to ensure that the cell cycle progresses in an orderly and controlled manner.

• Cyclins are a family of proteins that bind to and activate Cdks. The level of cyclins in the cell varies throughout the cell cycle, and this variation is responsible for the activation of Cdks at specific stages of the cell cycle.
• Cdks are a family of protein kinases that phosphorylate other proteins. Phosphorylation is a chemical modification that can change the activity of a protein. The phosphorylation of specific proteins by Cdks is essential for the progression of the cell cycle.
• Checkpoints are surveillance mechanisms that monitor the progress of the cell cycle and ensure that certain events have occurred before the cell proceeds to the next stage. Checkpoints can halt the cell cycle if they detect any errors or damage.

Answer: Communicable

A communicable disease is an illness that can be spread from one person to another through various means, including direct contact with an infected person, exposure to contaminated body fluids or surfaces, or through the bite of an infected insect or animal.

The other terms you mentioned have related meanings:

• An epidemic is a widespread outbreak of an infectious disease in a community or region.
• A pandemic is a global outbreak of an infectious disease that affects a large number of people across multiple countries or continents.
• Comma is a punctuation mark used to separate words, phrases, or clauses in a sentence. It is not related to the concept of infectious diseases.

Answer: Glycosis

Glycolysis is a metabolic pathway that occurs in all living cells, including aerobic organisms. It is the first step in cellular respiration, and it breaks down glucose into pyruvate, releasing energy in the form of ATP.

The other options are incorrect:

• EMP (Embden-Meyerhof-Parnas pathway) is another name for glycolysis.
• KDPG (ketodiphosphoglycerate) is an intermediate in the glycolysis pathway.

Answer: Genotype

A cell’s genotype is the complete set of genetic information that it carries. This information is stored in the cell’s DNA, which is located in the chromosomes. The genotype of a cell determines its phenotype, which is the physical appearance and characteristics of the cell.

The other options are incorrect:

• A cell’s phenotype is the physical appearance and characteristics of the cell.
• A cell’s cryptotype is the hidden genetic information that a cell carries.
• A cell’s histotype is the type of cell tissue that it belongs to.

Answer: Person to person

The primary mode of transmission of poliovirus is through the person-to-person route, specifically through the fecal-oral route. This means that the virus is spread when an infected person’s feces comes into contact with the mouth of an uninfected person. This can happen through direct contact, such as when an infected person does not wash their hands properly after using the toilet, or through indirect contact, such as when an infected person contaminates food or water with their feces.

The other options are incorrect:

• Flies can transmit poliovirus, but they are not the primary mode of transmission.
• Milk can transmit poliovirus if it is contaminated with the virus from an infected cow or goat. However, this is a rare mode of transmission.
• Food and water can transmit poliovirus if they are contaminated with the virus from an infected person. However, this is also a rare mode of transmission.

Answer: Cytochromes

Cytochromes are a family of proteins that contain heme, an iron-containing porphyrin group. Heme is the prosthetic group that allows cytochromes to carry electrons. Cytochromes are involved in a variety of redox reactions, including the electron transport chain, which is a key part of cellular respiration.

The other options are incorrect:

• NAD (nicotinamide adenine dinucleotide) is a coenzyme that is involved in many redox reactions, but it is not a protein.
• ATPase is an enzyme that breaks down ATP to ADP and inorganic phosphate. ATPase is not involved in the electron transport chain.
• Hydrolases are a class of enzymes that catalyze hydrolysis reactions, which are the breakdown of molecules by water. Hydrolases are not involved in the electron transport chain.

Answer: colchicine

Colchicine is a natural chemical produced by the autumn crocus (Crocus autumnalis). It is a potent inhibitor of microtubule polymerization, meaning that it prevents the assembly of microtubules, which are the structural components of spindle fibers. Without spindle fibers, chromosomes cannot be properly aligned and segregated during cell division, leading to cell death or genetic abnormalities.

Colchicine is a widely used drug in medicine, particularly for the treatment of gout and certain types of cancer. It is also used in research to study the cell cycle and cell division.

The other options are incorrect:

• ATP is a molecule that provides energy for many cellular processes, including cell division. ATP does not directly affect the formation of spindle fibers.
• Hydrazine is a chemical that can damage DNA. Hydrazine does not directly affect the formation of spindle fibers.

Answer: Missence mutation

A missense mutation is a type of point mutation that results in the substitution of one amino acid for another in the protein sequence. This can have a variety of effects on the protein, depending on the specific amino acids involved. In some cases, the mutation may have no effect on the protein’s function. In other cases, the mutation may have a significant impact on the protein’s function, leading to disease or other problems.

The other options are incorrect:

• A point mutation is a general term for any mutation that affects a single nucleotide in the DNA sequence. Missense mutations are a type of point mutation.
• A silent mutation is a type of point mutation that does not result in a change in the amino acid sequence of the protein. Silent mutations are typically harmless.

Answer: Mn+2

Manganese (Mn+2) is a trace element that is essential for the growth and survival of many bacteria. It is involved in a variety of metabolic processes, including:

DNA synthesis: Mn+2 is required for the activity of certain enzymes involved in DNA replication and repair.

Respiration: Mn+2 is a cofactor for several enzymes involved in the electron transport chain, which is a key part of cellular respiration.

Nitrogen fixation: Mn+2 is required for the activity of nitrogenase, an enzyme that converts nitrogen gas (N2) into ammonia (NH3), which can then be used for amino acid synthesis.

Antioxidant defense: Mn+2 helps to protect cells from damage caused by free radicals.

The other options are incorrect:

• Mg+2 is a major element that is required for many cellular functions, including protein synthesis and DNA synthesis.
• Na+ is an essential electrolyte that helps to maintain the osmotic balance of cells.
• Ca+2 is a major element that is required for bone formation and muscle contraction.

Answer: Growth Factors

Vitamins are essential organic compounds that bacteria cannot synthesize on their own and must obtain from their environment. They play crucial roles in various metabolic processes, including energy production, cell division, and DNA synthesis. Without adequate vitamins, bacteria cannot grow and reproduce properly.

The other options are incorrect:

• Sources of energy: Bacteria primarily obtain energy from organic compounds such as carbohydrates, lipids, and proteins. They do not require vitamins as a direct source of energy.
• Sources of carbon: Bacteria can utilize various carbon sources for their growth, including carbon dioxide, organic acids, and methane. Vitamins do not provide carbon directly.
• Sources of electron donors: Bacteria use electron donors, such as hydrogen, to carry out redox reactions and generate energy. Vitamins are not directly involved in electron transfer processes.

Answer: Claveceps

Ergot disease is caused by a fungus of the genus Claviceps, specifically Claviceps purpurea. This fungus infects the ovaries of cereal grains, such as rye and barley, and produces a dark, hard sclerotium in place of the grain. The sclerotium contains ergot alkaloids, which are toxic to humans and animals.

The other options are incorrect:

• Puccinia is a genus of fungi that cause rust diseases in plants. Rust diseases are not caused by Claviceps purpurea.
• Rhizopus is a genus of fungi that are commonly found in soil and decaying organic matter. Rhizopus species do not cause ergot disease.
• Penicillium is a genus of fungi that includes the common mold Penicillium roqueforti, which is used to make blue cheese. Penicillium species do not cause ergot disease.

Answer: P.falsiparum

Cerebral malaria is caused by the parasite Plasmodium falciparum. This is the most severe form of malaria, and it is responsible for the majority of malaria-related deaths.

The other options are incorrect:

• Plasmodium vivax is the most common species of malaria parasite, but it is not typically associated with cerebral malaria.
• P. ovale is a rare species of malaria parasite that is not typically associated with severe illness.
• P. malariae is a chronic species of malaria parasite that is not typically associated with severe illness.

Answer: Person to person

The primary mode of transmission of poliomyelitis is through the fecal-oral route, which is a type of person-to-person transmission. This means that the virus is spread when an infected person’s feces comes into contact with the mouth of an uninfected person. This can happen through direct contact, such as when an infected person does not wash their hands properly after using the toilet, or through indirect contact, such as when an infected person contaminates food or water with their feces.

The other options are incorrect:

• While the oral route (ingesting contaminated food or water) can also spread poliovirus, it is not as common as the fecal-oral route.
• Blood is not a common route of transmission for poliovirus.
• Milk is not a common route of transmission for poliovirus, although it was a concern in the past when raw milk was more widely consumed.

Answer: Cell wall

The most significant virulent factor in pneumococcus is its capsule. The capsule is a polysaccharide layer that surrounds the bacterial cell. It is composed of multiple repeating units of a single type of sugar. The capsule helps the pneumococcus to evade the immune system by preventing phagocytosis, which is the process by which macrophages engulf and destroy bacteria.

The other options are incorrect:

• The cell wall of the pneumococcus is composed of peptidoglycan, a polymer of sugar and amino acids. The cell wall provides structural support for the bacterial cell and protects it from osmotic stress.
• Mesosomes are invaginations of the inner membrane of bacterial cells. They are involved in a variety of cellular processes, including cell division and DNA replication.
• Endotoxins are lipopolysaccharides that are found in the outer membrane of Gram-negative bacteria. They are released when the bacterium lyse, or breaks open. Endotoxins can cause fever, shock, and death.

Answer: Aquaspirillum Magnetotacticum

The correct answer is Aquaspirillum magnetotacticum. This is a type of bacteria that is able to move in response to the Earth’s magnetic field. Aquaspirillum magnetotacticum has tiny crystals of magnetite, a magnetic mineral, embedded in its cells. The magnetite crystals align with the Earth’s magnetic field, and this allows the bacteria to swim in a specific direction.

The other options are incorrect:

• Spirochetes are a type of bacteria that is characterized by their spiral shape. They are not known to be able to move in response to magnetic fields.
• Treponema is a genus of bacteria that includes the causative agent of syphilis. Treponema species are not known to be able to move in response to magnetic fields.