Microbiology MCQs with Answer and Explnation | Chapter 14

Answer: IgE

Anaphylaxis is a type I hypersensitivity reaction that is mediated by immunoglobulin E (IgE) antibodies. When a person with IgE antibodies to a particular allergen is exposed to that allergen, their IgE antibodies bind to the allergen and trigger the release of histamine and other inflammatory mediators from mast cells and basophils. These mediators lead to the symptoms of anaphylaxis, which can be severe and even life-threatening.

The other options are incorrect:

• IgA: is an antibody that is found in saliva, tears, and breast milk. It plays a role in mucosal immunity, which is the immune system’s defense against pathogens that enter the body through the mucous membranes.
• IgD: is an antibody that is found on the surface of B cells. It is involved in B cell activation and differentiation.
• IgM: is an antibody that is produced early in the immune response. It is not as specific as IgG or IgE, but it is more effective at neutralizing toxins.
• IgG: is the most abundant antibody in the blood. It is involved in protecting the body against bacteria, viruses, and other pathogens. It is also the antibody that is responsible for long-term immunity.

Answer: Both Increased CD8 + T cells & CD4 +/CD8 + ratio greater than 21

Patients suffering from AIDS (Acquired Immunodeficiency Syndrome) typically exhibit immune abnormalities, and the correct options are “Both b & d”:

• Increased CD8 + T cells (b): Individuals with AIDS often show an increase in CD8 + T cells, which are cytotoxic T cells. This is a characteristic feature of HIV infection.
• CD4 +/CD8 + ratio greater than 21 (d): The normal CD4 +/CD8 + ratio is approximately 2:1. In AIDS patients, this ratio is often reversed, with CD8 + T cells outnumbering CD4 + T cells, leading to a ratio greater than 21.

The other options are incorrect:

• Decreased CD4 + T cells: AIDS is characterized by a significant decrease in CD4 + T cells, which are helper T cells. This decrease in CD4 + T cells compromises the immune system.
• Hypergammaglobulinemia: Hypergammaglobulinemia refers to elevated levels of immunoglobulins (antibodies) in the blood. In AIDS, there is a decline in the production of specific antibodies, leading to immunodeficiency.

Answer: IgE

Among the listed immunoglobulins, IgE is the one that does not efficiently activate complement. IgM and IgG, in particular, are known for their complement-activating abilities.

The other options are incorrect:

• IgM: IgM is a potent activator of the complement system. It can efficiently activate the classical pathway of complement.
• IgG: IgG, especially IgG1, IgG2, and IgG3 subclasses, can activate the complement system through the classical pathway.
• IgA: IgA, while not as efficient as IgM and IgG, can activate complement to some extent, especially through the alternative pathway. IgA, however, is more involved in mucosal immunity.

Answer: Casoni test

The Casoni test is an intradermal skin test used to diagnose hydatid disease, a parasitic infection caused by the larvae of the dog tapeworm Echinococcus granulosus. The test involves injecting a small amount of hydatid cyst fluid or antigen into the skin of the forearm. If the person is infected with hydatid disease, they will develop a local reaction at the injection site within 24-48 hours. This reaction appears as a red, itchy bump with a central white or yellow area.

The other options are incorrect:

• Schick test: The Schick test is a skin test used to diagnose susceptibility to diphtheria. It is not used to diagnose hydatid disease.
• Dick test: The Dick test is a skin test used to diagnose susceptibility to scarlet fever. It is not used to diagnose hydatid disease.
• Freis test: The Freis test is a skin test used to diagnose lymphogranuloma venereum, a sexually transmitted infection. It is not used to diagnose hydatid disease.

Answer: IgE

The Prausnitz-Küstner reaction is a skin test that is used to detect the presence of IgE antibodies in the blood. It is performed by injecting a small amount of serum from a person who is suspected of having IgE antibodies into the skin of a non-allergic individual. If the person who donated the serum has IgE antibodies to a particular allergen, and the non-allergic individual is exposed to that allergen, they will develop a wheal (raised, red bump) at the injection site.

The other options are incorrect:

• IgA is an antibody that is found in saliva, tears, and breast milk. It plays a role in mucosal immunity, which is the immune system’s defense against pathogens that enter the body through the mucous membranes.
• IgG is the most abundant antibody in the blood. It is responsible for long-term immunity to infections and is also important for protecting the body against bacteria, viruses, and other pathogens.
• IgD is an antibody that is found on the surface of B cells. It is involved in B cell activation and differentiation.

Answer: IgE

Elevated levels of IgE (immunoglobulin E) are associated with allergic reactions and conditions such as asthma. IgE is involved in immediate hypersensitivity reactions and plays a crucial role in allergic responses. In individuals with asthma, there is often an increased production of IgE antibodies, which contribute to the hypersensitivity reactions leading to asthma symptoms.

The other options are incorrect:

• IgA: IgA is more associated with mucosal immunity and is not typically elevated in the context of asthma.
• IgM: IgM is involved in the primary immune response and is not specifically associated with asthma.
• IgD: IgD is primarily found on the surface of B cells and has a role in B cell activation but is not typically elevated in asthma.

Answer: Single diffusion in two dimension

Single diffusion in two dimensions, also known as radial immunodiffusion (RID), is a technique used for the quantitative estimation of immunoglobulins. It is a simple and sensitive method that can be used to measure the concentration of a specific immunoglobulin in a serum sample.
In RID, a sample containing the immunoglobulin to be measured is placed in a well in a gel containing the corresponding antibody. The immunoglobulin molecules diffuse through the gel, forming a ring-shaped precipitate around the well. The diameter of the precipitate is proportional to the concentration of the immunoglobulin in the sample.

The other options are incorrect:

• Single diffusion in one dimension is a less sensitive method than RID and is not as commonly used.
• Double diffusion in one dimension is a more complex method than RID and is not as widely used.
• Double diffusion in two dimension is a method that is used to identify proteins, not to measure their concentration.

Answer: All of these

Cell-mediated immunity (CMI) can be identified by various methods, and the options provided cover different aspects of testing CMI.

• Sheep red blood cell (SRBC) rosette formation: This assay involves the ability of lymphocytes to form rosettes with SRBCs. It is used to assess certain aspects of cell-mediated immune function.
• Microphage inhibiting factor: This refers to substances, including cytokines, produced by immune cells that can inhibit the activity of macrophages, a key component of cell-mediated immunity.
• Skin test for delayed hypersensitivity: The skin test, such as the Mantoux test for tuberculosis, is a common method to assess delayed-type hypersensitivity reactions, which are indicative of cell-mediated immunity.

Answer: All of these

All of the provided options are examples of autoimmune diseases:

• Acquired Hemolytic Anemia: In acquired hemolytic anemia, the immune system mistakenly attacks and destroys red blood cells, leading to a reduction in the number of functional red blood cells.
• Rheumatoid Arthritis: Rheumatoid arthritis is an autoimmune disorder where the immune system attacks the joints, leading to inflammation, pain, and joint damage.
• Hashimoto’s Disease: Hashimoto’s disease is an autoimmune condition in which the immune system targets and damages the thyroid gland, leading to hypothyroidism.

Answer: Prepared from tubercle bacilli

Purified Protein Derivative (PPD) is a purified extract of Mycobacterium tuberculosis, the bacterium that causes tuberculosis. It is used in the tuberculin test, a skin test that is used to check for infection with M. tuberculosis. PPD is prepared by dissolving the bacteria in a solution and then filtering out the cells. The filtrate is then concentrated and purified. The purified PPD is then sterilized and freeze-dried.

The other options are incorrect:

• PPD is not inferior to old tuberculin: Old tuberculin (OT) is a cruder preparation of PPD that is no longer used in clinical practice. OT is less specific than PPD and is more likely to cause false-positive reactions.
• PPD does not consist of filtrate of glycerol broth: PPD is a purified extract of M. tuberculosis, not a filtrate of glycerol broth.

Answer: All of these

All of the provided options are examples of inactive (inactivated or killed) viral vaccines:

• Influenza (Flu) Vaccine: Inactivated influenza vaccines are commonly used to protect against seasonal influenza. They contain killed influenza viruses.
• Rabies Vaccine: Rabies vaccines are typically inactivated vaccines made from rabies virus grown in cell cultures. They are used to prevent rabies in humans and animals.
• Russian Spring-Summer Encephalitis Vaccine: Vaccines for Russian spring-summer encephalitis, caused by a flavivirus, are typically inactivated vaccines.

Answer: Influenza virus

Antigenic variation refers to the ability of viruses to alter their surface antigens, making it difficult for the immune system to recognize and mount an effective response. Among the options provided, the influenza virus is known for extensive antigenic variation.
Influenza Virus: Influenza viruses are known for frequent antigenic changes, leading to the need for seasonal flu vaccine updates. This variation is attributed to point mutations (antigenic drift) and occasionally major genetic reassortment (antigenic shift).

The other options are incorrect:

• Smallpox Virus: Smallpox has been eradicated, and the virus did not exhibit the same degree of antigenic variation as some other viruses.
• Measles Virus: The measles virus is relatively stable, and natural infection or vaccination provides long-lasting immunity.
• Herpes Virus: Herpesviruses, including herpes simplex viruses and varicella-zoster virus, can establish latent infections, but their surface antigens do not undergo the same rapid changes as seen in influenza.

Answer: Clostridium botulinum

Clostridium botulinum is a bacterium that produces a toxin called botulinum toxin, which is one of the most poisonous substances known. Botulinum toxin can cause a serious form of food poisoning called botulism. Botulism can cause paralysis and even death if not treated promptly.

The other options are incorrect:

• Clostridium tetani is a bacterium that produces a toxin called tetanus toxin, which causes tetanus. Tetanus is a serious disease that causes muscle stiffness and spasms.
• Clostridium welchii is a bacterium that can cause a type of food poisoning called Clostridium perfringens food poisoning. This type of food poisoning typically causes diarrhea, abdominal cramps, and nausea.
• Diphtheria is a bacterial infection that causes inflammation of the throat and airways. Diphtheria can be a serious illness, but it can be prevented with vaccination.

Answer: Measles

Koplik’s spots are small, white spots with a bluish-white center that appear on the buccal mucosa (the lining of the cheek) in the early stages of measles. They are a pathognomonic sign of measles, meaning that they are unique to this disease and no other.

The other options are incorrect:

• HIV is a virus that causes AIDS. It does not cause Koplik’s spots.
• Mumps is a virus that causes swelling of the salivary glands. It does not cause Koplik’s spots.
• Rubella is a virus that causes a mild rash and other symptoms. It does not cause Koplik’s spots.

Answer: 5’-HMC

5′-hydroxymethylcytosine (5′-HMC) is a modified form of cytosine that is found in DNA. It is more resistant to deamination by the enzyme APOBEC3G, which is a host cell defense mechanism that can destroy viral DNA. This is because the hydroxyl group on the 5′-carbon of HMC makes it more difficult for APOBEC3G to bind to the DNA.

The other options are incorrect:

• 5′-hydroxymethyladenine (5′-HMA) is another modified form of DNA base that is not as resistant to deamination as 5′-HMC.
• 5′-chloromethylcytosine (5′-CHM) is a less common modified form of DNA base that is not as well-studied as 5′-HMC.
• 5′-methylcytosine (5′-MHC) is a modified form of DNA base that is also resistant to deamination by APOBEC3G, but it is not as effective as 5′-HMC.

Answer: Whooping cough, tetanus and Diphtheria

The triple toxoid vaccine, also known as DTaP or DTP, is a combination vaccine that protects against three serious infectious diseases: diphtheria, tetanus, and pertussis (whooping cough). It is one of the most important vaccines for children, and it is typically given as a series of four shots starting at two months of age.

The other options are incorrect:

• Diphtheria, tetanus and rabies: Rabies is not included in the triple toxoid vaccine. There is a separate vaccine for rabies.
• Tetanus, whooping cough, Tuberculosis: Tuberculosis is not included in the triple toxoid vaccine. There is a separate vaccine for tuberculosis.
• Whooping cough, cancer and T.B.: Neither cancer nor tuberculosis is included in the triple toxoid vaccine.

Answer: They have mitochondria

Chloramphenicol is an antibiotic that primarily targets bacterial protein synthesis by binding to the 50S subunit of bacterial ribosomes. Eukaryotic cells, including human cells, have mitochondria, which are believed to have evolved from free-living bacteria. Mitochondria also contain 70S ribosomes, similar to bacterial ribosomes.

The other options are incorrect:

• They have 30 S ribosomes (Incorrect): Eukaryotic cells have 40S and 60S ribosomal subunits, making up the 80S ribosomes, rather than the 30S subunit found in bacterial ribosomes.
• They have 70 S ribosomes (Incorrect): This statement is actually true for eukaryotic cells; they have 80S ribosomes, not 70S. However, the crucial point is that the presence of mitochondria with 70S-like ribosomes makes them susceptible to the effects of chloramphenicol.

Answer: Retrovirus

Acquired immunodeficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV), a type of retrovirus. Retroviruses are a group of viruses that replicate their genetic material through an RNA intermediate using reverse transcriptase. This means that they convert their RNA genome into DNA, which can then be integrated into the host cell’s genome.

The other options are incorrect:

• Prions are not viruses. They are infectious proteins that cause a group of diseases called transmissible spongiform encephalopathies (TSEs), such as Creutzfeldt-Jakob disease (CJD) and mad cow disease.
• Rhabdoviruses are a group of viruses that includes rabies virus. They are not known to cause AIDS.
• Retroprison is not a type of virus.

Answer: Secondary metabolite

Penicillin is a secondary metabolite. Secondary metabolites are organic compounds that are not essential for the growth and development of the organism producing them, but they often play crucial roles in interactions with the environment, including defense mechanisms. Penicillin is produced by the fungus Penicillium and is known for its antibacterial properties.

The other options are incorrect:

• Primary metabolite (Incorrect): Primary metabolites are essential for the basic growth and development of an organism. Examples include carbohydrates, amino acids, and nucleic acids.
• Tertiary metabolite (Incorrect): The term “tertiary metabolite” is not commonly used in biological contexts. The distinction is typically made between primary and secondary metabolites.

Answer: Delayed

The rejection of an organ transplant, such as a kidney transplant, is an example of delayed hypersensitivity. In delayed hypersensitivity reactions, there is a delayed onset of the immune response, typically occurring 24 to 72 hours after exposure to the antigen. In the case of organ transplantation, the recipient’s immune system recognizes the transplanted organ as foreign and mounts a delayed immune response, leading to organ rejection.

The other options are incorrect:

• Immediate (Incorrect): Immediate hypersensitivity, also known as type I hypersensitivity, involves an immediate and severe allergic response, such as in allergies and anaphylaxis.
• Allergy (Incorrect): While allergic reactions can involve hypersensitivity, the term “allergy” is often associated with type I immediate hypersensitivity reactions. Organ transplant rejection is more specifically an example of delayed hypersensitivity.

Answer: Food borne

Listeriosis is primarily a foodborne disease. It is caused by the bacterium Listeria monocytogenes, which can be found in contaminated food, particularly unpasteurized dairy products, raw vegetables, and ready-to-eat meats. The consumption of contaminated food is a common route of transmission for listeriosis.

The other options are incorrect:

• Water borne (Incorrect): Listeriosis is not typically associated with waterborne transmission. It is more commonly linked to the consumption of contaminated food.
• Milk borne (Incorrect): Listeriosis can be associated with the consumption of unpasteurized dairy products, but the term “milk borne” is not commonly used to describe this disease.
• Air borne (Incorrect): Listeriosis is not transmitted through the air. The primary mode of transmission is through the ingestion of contaminated food.

Answer: Pyogenic

Pus-forming forms are called “pyogenic.” The term “pyogenic” is derived from the Greek words “pyon” (meaning pus) and “genes” (meaning producing). Pyogenic bacteria are capable of causing the formation of pus, which is a collection of dead white blood cells, bacteria, and tissue debris. These bacteria are often associated with infections that result in the production of pus.

The other options are incorrect:

• Pyoderm: “Pyoderm” is a term used to describe skin diseases characterized by the formation of pus.
• Pyrogen: “Pyrogen” refers to substances, such as bacteria or their products, that can induce fever.

Answer: Alkaline phosphate

In ELISA (Enzyme-Linked Immunosorbent Assay) technique, antibodies are often labeled with enzymes to detect the presence of specific antigens. Alkaline phosphatase is one of the commonly used enzymes for this purpose. The enzyme-labeled antibodies react with the target antigen, and the enzyme’s activity is later measured using a substrate that produces a detectable signal, such as a color change.

The other options are incorrect:

• Acridine orange (Incorrect): Acridine orange is a fluorescent dye used for staining nucleic acids, but it is not typically used as a label in ELISA.
• Neutral red (Incorrect): Neutral red is a dye commonly used for cell viability assays but is not used as a label in ELISA.
• Bromothymol blue (Incorrect): Bromothymol blue is a pH indicator and is not used as a label in ELISA.

Answer: Agammaglobulinemia

Agammaglobulinemia is a genetic disorder characterized by the absence or extremely low levels of immunoglobulins (antibodies), which are proteins that protect the body from infection. People with agammaglobulinemia are very susceptible to infections, and they may experience recurrent or severe infections, especially of the respiratory tract and gastrointestinal tract.

The other options are incorrect:

• Apitosis is a type of programmed cell death that occurs in response to various stimuli, such as stress or infection. It is not a genetic disorder.
• Gammaglobulinemia is a general term for a decrease in the level of gamma globulins, which are a type of protein that includes immunoglobulins. Agammaglobulinemia is a specific type of gammaglobulinemia that is characterized by a complete or almost complete absence of gamma globulins.
• Sickle-cell anemia is a genetic disorder that affects the shape of red blood cells, causing them to become sickle-shaped. Sickle-shaped red blood cells are less flexible and more likely to clog blood vessels, leading to pain, fatigue, and other complications.

Answer: Genetic counseling

Genetic counseling involves the assessment and communication of information about the risk of genetic disorders within a family. It provides individuals and families with information about the genetic aspects of various conditions, the probability of occurrence or recurrence, and the available options for managing or preventing genetic disorders.

The other options are incorrect:

• Genetic Engineering (Incorrect): Genetic engineering refers to the manipulation of genes or genetic material to produce desired traits or outcomes. It is not focused on analyzing the risk for genetic defects in a family.
• Genetic drift (Incorrect): Genetic drift is a mechanism of evolution that involves random changes in the frequency of alleles within a population. It is not related to the analysis of genetic defects in a family.
• Genetic equilibrium (Incorrect): Genetic equilibrium refers to a stable state in a population where the allele frequencies remain constant over generations. It is a concept in population genetics and is not associated with the analysis of genetic defects in a family.

Answer: Both Proteins and Glyco proteins

Viral antigens are proteins that are found on the surface of viruses. They are responsible for triggering an immune response in the host. Viral antigens can be either proteins or glycoproteins. Glycoproteins are proteins that are attached to carbohydrates.

The other options are incorrect:

• Lipoproteins are not typically found on the surface of viruses. They are a type of molecule that is made up of lipids and proteins.

Answer: End point determination assay

The most suitable assay method for antibiotics is often the end-point determination assay. In this method, the endpoint, such as the inhibition of bacterial growth, is measured. The minimal inhibitory concentration (MIC) is a common endpoint used in antibiotic assays. MIC is the lowest concentration of an antibiotic that inhibits the visible growth of bacteria.

The other options are incorrect:

• Enzymatic assay (Incorrect): Enzymatic assays are typically used to measure the activity of enzymes and are not the primary method for assaying antibiotics.
• Turbidometric assay (Incorrect): Turbidometric assays measure the cloudiness or turbidity of a solution, often related to bacterial growth. While it can be used in antibiotic assays, it’s not as specific as endpoint determination for MIC.
• Metabolic assay (Incorrect): Metabolic assays can be used to assess the overall metabolic activity of cells, but they may not specifically measure the inhibitory effect of antibiotics on bacterial growth, which is a more direct measure for antibiotics.

Answer: AIDS

ELISA (Enzyme-Linked Immunosorbent Assay) is commonly used for the identification of HIV (Human Immunodeficiency Virus), which is the virus associated with AIDS (Acquired Immunodeficiency Syndrome). ELISA detects the presence of antibodies or antigens in a sample, and in the case of HIV testing, it is used to detect antibodies against HIV.

The other options are incorrect:

• Jaundice: ELISA is not typically used for the identification of jaundice. Jaundice is often diagnosed based on clinical symptoms and blood tests measuring bilirubin levels.
• Cancer: While ELISA can be used in cancer research, it is not a standard method for the identification of cancer in clinical diagnostics. Cancer is usually diagnosed through various methods such as imaging, biopsies, and specific tumor markers.
• Diabetes: ELISA is not a primary method for diagnosing diabetes. Diabetes is commonly diagnosed through blood tests measuring blood glucose levels or other specific markers associated with diabetes.

Answer: Bacitracin

Based on the provided options, the bacteriostatic chemotherapeutic agent that stands out is Bacitracin. Bacitracin is not generally considered a bacteriostatic agent; it is primarily classified as a bactericidal agent. Bactericidal agents actively kill bacteria, while bacteriostatic agents inhibit their growth.

The other options are incorrect:

• Chloramphenicol: A broad-spectrum bacteriostatic antibiotic that inhibits bacterial protein synthesis.
• Novobiocin: A bacteriostatic antibiotic that interferes with bacterial DNA replication.
• Tetracycline: A broad-spectrum bacteriostatic antibiotic that inhibits bacterial protein synthesis.

Answer: Protozoa

Kinetosomes, also known as basal bodies or kinetoplasts, are observed in protozoa. These structures are associated with flagella or cilia and play a role in the organization and function of these motile cellular extensions. Protozoa are unicellular eukaryotic organisms, and many of them use flagella or cilia for movement.

The other options are incorrect:

• Algae are a group of photosynthetic eukaryotes that can be found in both freshwater and saltwater. They do not have flagella or cilia, so they do not have kinetosomes.
• Fungi are a group of eukaryotic organisms that are typically found in soil, on plants, or in decaying organic matter. They do not have flagella or cilia, so they do not have kinetosomes.
• Viruses are non-cellular particles that contain genetic material. They do not have flagella or cilia, so they do not have kinetosomes

Answer: Penicillin

The β-lactam ring is a characteristic structural feature found in penicillin and other β-lactam antibiotics. This ring is crucial for the antibacterial activity of these drugs. Penicillins, cephalosporins, carbapenems, and monobactams all contain the β-lactam ring.

The other options are incorrect:

• Erythromycin: Erythromycin belongs to the macrolide class of antibiotics and does not contain a β-lactam ring.
• Tetracyclins: Tetracyclines are a class of antibiotics that do not have a β-lactam ring. They inhibit bacterial protein synthesis.
• Chloramphenicol: Chloramphenicol is an antibiotic that works by inhibiting bacterial protein synthesis. It does not contain a β-lactam ring.

Answer: Vancomycin

Vancomycin is an antibiotic that is produced by the bacterium Streptomyces orientalis. It is effective against a variety of Gram-positive bacteria and is often used in the treatment of infections caused by methicillin-resistant Staphylococcus aureus (MRSA).

The other options are incorrect:

• Streptomycin: Streptomycin is an antibiotic produced by Streptomyces griseus, not Streptomyces orientalis.
• Penicillin: Penicillin is produced by various species of the fungus Penicillium, not by Streptomyces orientalis.
• Both Streptomycin and Penicillin: While Streptomycin and Penicillin are important antibiotics, neither of them is produced by Streptomyces orientalis.

Answer: Nystatin

Nystatin is an antifungal medication used to treat infections caused by Candida species. It is particularly effective against oral and vaginal candidiasis. Nystatin works by binding to sterols in the fungal cell membrane, disrupting the membrane and leading to the death of the fungus.

The other options are incorrect:

• Griseofulvin: Griseofulvin is an antifungal used primarily to treat dermatophyte infections such as ringworm. It is not the drug of choice for candidiasis.
• Amphoterein B: Amphotericin B is a broad-spectrum antifungal, but it is more commonly used for systemic fungal infections rather than localized candidiasis.
• Gentian Violet: Gentian violet is an antifungal dye that has been used in the past, but it is not the preferred treatment for candidiasis.

Answer: Food poisioning by streptococcus bacteria

Botulism is a type of food poisoning caused by the bacterium Clostridium botulinum. This bacterium produces a potent neurotoxin known as botulinum toxin, which can cause serious illness when ingested. The toxin affects the nervous system, leading to symptoms such as muscle weakness, paralysis, and potentially fatal respiratory failure.

The other options are incorrect:

• Food adulteration: Food adulteration refers to the addition of inferior, harmful, or unnecessary substances to food, but it is not the specific cause of botulism.
• Chemical contamination of food: While chemical contamination can lead to foodborne illnesses, botulism is specifically caused by a bacterial toxin, not a chemical.
• Food processing: Food processing involves various methods to prepare and preserve food, and it is not the cause of botulism. Botulism is related to the growth of Clostridium botulinum bacteria in certain conditions, especially in improperly processed or stored foods.

Answer: Streptomyces venezuelae

Chloramphenicol is an antibiotic that was originally isolated from the bacterium Streptomyces venezuelae. It is a broad-spectrum antibiotic used to treat various bacterial infections. Streptomyces species are well-known producers of many antibiotics, and different species may produce different antibiotics.

The other options are incorrect:

Streptomyces griseus: While Streptomyces griseus is another species of bacteria within the Streptomyces genus, it is not the source of chloramphenicol.
Streptomyces pyrogenes: Streptomyces pyogenes is not a known source of chloramphenicol. The correct source is Streptomyces venezuelae.

Answer: Streptomyces griseus

Streptomycin is an antibiotic that is obtained from the bacterium Streptomyces griseus. It was the first aminoglycoside antibiotic discovered and was the first effective treatment for tuberculosis.

The other options are incorrect:

• Streptococcus species: Streptococcus species are not the source of streptomycin. It is produced by the bacterium Streptomyces griseus.
• Staphylococcus aureus: Staphylococcus aureus is not the source of streptomycin. The correct source is Streptomyces griseus.

Answer: All of these

Small bodies of water, such as ponds, lakes, and streams, are often susceptible to contamination from various sources, including agricultural runoff, sewage, and industrial waste. To ensure that this water is safe for drinking, swimming, and other recreational activities, it must undergo a series of treatment processes.

• Disinfection is the first step in treating small bodies of water. It involves killing or inactivating microorganisms that can cause disease. Common disinfection methods include chlorination, ozonation, and ultraviolet (UV) radiation.
• Filtration is the next step in treating small bodies of water. It involves removing suspended solids, such as dirt, sand, and leaves, from the water. This helps to improve the clarity and aesthetic appearance of the water and also removes potential sources of contamination.
• Purification is the final step in treating small bodies of water. It involves removing dissolved impurities, such as chemicals, metals, and organic matter, from the water. This helps to improve the overall quality of the water and make it safe for human consumption.

Answer: Alkaligenes viscolactis

Surface ropiness is often caused by bacteria, and one of the common culprits is Alkaligenes viscolactis. This bacterium is known for its ability to produce a slimy or ropiness effect on the surface of certain liquid media, especially milk.

The other options are incorrect:

• Streptococcus: While some Streptococcus species may contribute to spoilage and defects in fermented products, surface ropiness is more commonly associated with Alkaligenes viscolactis.
• Both Alkaligenes viscolactis and Streptococcus: Surface ropiness is primarily attributed to Alkaligenes viscolactis, and the presence of Streptococcus may not be a common cause.

Answer: Multiplication of bacteria and toxins in blood

Septicaemia refers to a severe infection in which there is the presence and multiplication of bacteria and their toxins in the bloodstream. It is a systemic infection that can lead to a cascade of events, including a widespread inflammatory response and the release of toxins into the bloodstream.

The other options are incorrect:

• Bacteria in blood: This option is partially correct as septicaemia involves the presence of bacteria in the blood, but it is not limited to the mere presence; it also includes their multiplication and associated toxins.
• Toxin in bloo: While toxins are involved in septicaemia, it is not just the presence of toxins but the overall process of bacterial multiplication and toxin release.
• Pus in blood: Septicaemia is not associated with the presence of pus in the blood. Pus is a collection of dead cells, bacteria, and tissue debris and is usually found at the site of infection. In septicaemia, the focus is on the systemic spread of bacteria and toxins.

Answer: Alpha interferon

Kaposi’s sarcoma, a type of cancer often associated with AIDS (Acquired Immunodeficiency Syndrome), may respond to treatment with alpha interferon. Alpha interferon is a type of cytokine that plays a role in the immune system’s response to infections and cancer. It can be used in the treatment of certain cancers, including Kaposi’s sarcoma, by modulating the immune response and inhibiting the growth of cancer cells.

The other options are incorrect:

• Interleukin – 2 infusion: Interleukin-2 (IL-2) is another cytokine that stimulates the immune system. While it has been used in some cancer treatments, it is not typically a primary treatment for Kaposi’s sarcoma.
• Azathioprine: Azathioprine is an immunosuppressive medication that is not commonly used for the treatment of Kaposi’s sarcoma. It is more often used in conditions where immune suppression is desired, such as in certain autoimmune disorders or to prevent rejection in organ transplant recipients.

Answer: DNA gyrase

Ciprofloxacin is a fluoroquinolone antibiotic that acts by inhibiting the bacterial enzyme DNA gyrase. DNA gyrase is responsible for the supercoiling of DNA, and its inhibition interferes with bacterial DNA replication and transcription. This ultimately leads to the inhibition of bacterial growth and is an effective mechanism for treating bacterial infections.

The other options are incorrect:

• Cell wall synthesis: Antibiotics such as penicillins and cephalosporins target bacterial cell wall synthesis, but ciprofloxacin does not.
• RNA synthesis: Rifampin is an antibiotic that primarily inhibits bacterial RNA synthesis, but ciprofloxacin acts on DNA gyrase, not RNA synthesis.
• Folate synthesis: Antibiotics like trimethoprim-sulfamethoxazole (co-trimoxazole) target bacterial folate synthesis, but ciprofloxacin does not act on this pathway.

Answer: Spirochaete

Lyme disease is caused by the spirochete bacterium Borrelia burgdorferi. The bacterium is transmitted to humans through the bite of infected black-legged ticks (deer ticks) and western black-legged ticks.

The other options are incorrect:

• Bacteria: Lyme disease is indeed caused by bacteria, specifically the spirochete Borrelia burgdorferi.
• Fungi: Fungi are eukaryotic organisms that typically reproduce by spores. They do not cause Lyme disease.
• Virus: Viruses are small particles of genetic material that can infect cells and replicate inside them. They do not cause Lyme disease.

Answer: Staph. aureus

Toxic shock syndrome (TSS) is caused by the bacterium Staphylococcus aureus. The condition is associated with the production of toxic shock syndrome toxin-1 (TSST-1), which is released by certain strains of Staphylococcus aureus.

The other options are incorrect:

Staph. albus: Toxic shock syndrome is primarily associated with Staphylococcus aureus, not Staphylococcus albus.
Strep. viridans: Toxic shock syndrome is not caused by Streptococcus viridans.

Answer: P. falciparum

Blackwater fever is a severe complication of malaria, and it is associated with infection by Plasmodium falciparum. It is characterized by the destruction of red blood cells, leading to the release of hemoglobin into the bloodstream and subsequent dark or black urine.

The other options are incorrect:

• P. vivax: P. vivax is one of the parasites that cause malaria but is not specifically associated with blackwater fever.
• P. ovale: P. ovale is another species of Plasmodium that causes malaria, but it is not typically associated with blackwater fever.

Answer: M. tuberculosis

The Mantoux test is a skin test that is used to check for TB infection. It is also known as the purified protein derivative (PPD) skin test. The test involves injecting a small amount of PPD, which is a protein derived from M. tuberculosis, under the skin of the forearm. If the person has been infected with TB, the skin will swell up and form a bump at the injection site. The size of the bump is then measured to determine the result of the test.

The other options are incorrect:

• Cynaobacteria are a group of photosynthetic bacteria that are found in a variety of habitats, including water, soil, and rocks. They are not known to cause TB.
• Clostridia are a group of bacteria that are found in soil and the intestines of animals. Some species of Clostridia can cause tetanus, botulism, and other diseases. They are not known to cause TB.

Answer: All of these

Bactracin, penicillin, and cyclosporine are all antibiotics that act on the cell wall. The cell wall is a rigid structure that surrounds bacterial cells and helps them to maintain their shape and protect them from damage. Antibiotics that act on the cell wall can disrupt the synthesis of the cell wall or weaken the existing cell wall, making it easier for the bacteria to break open and die.

Bactracin is an antibiotic that is produced by Bacillus subtilis. It is a broad-spectrum antibiotic, meaning that it is effective against a wide range of Gram-positive bacteria. Bactracin is typically used to treat skin infections.
Penicillin is an antibiotic that is derived from the fungus Penicillium notatum. It is a narrow-spectrum antibiotic, meaning that it is effective against a limited range of Gram-positive bacteria. Penicillin is one of the most widely used antibiotics in the world.
Cyclosporine is an immunosuppressant medication that is used to prevent organ rejection in transplant patients. It also has some antibacterial activity and is sometimes used to treat skin infections.

Answer: Aspergillus sps

Aflatoxin is produced by certain species of fungi, primarily Aspergillus flavus and Aspergillus parasiticus. These fungi can contaminate crops such as peanuts, corn, and other nuts, leading to the production of aflatoxins. Aflatoxins are potent carcinogenic and toxic compounds.

The other options are incorrect:

• Penicillium sps: While Penicillium species are known for producing antibiotics such as penicillin, they are not associated with aflatoxin production.
• Alternaria sps: Alternaria species are not known for producing aflatoxins. They are more commonly associated with producing mycotoxins such as alternariol, which can contaminate certain crops.

Answer: Fleming

Penicillin was discovered by Sir Alexander Fleming in 1928. Fleming, a Scottish bacteriologist, observed the antibiotic properties of the mold Penicillium notatum, leading to the discovery of the first widely used antibiotic, penicillin.

The other options are incorrect:

• Pasteur: Louis Pasteur was a French chemist and microbiologist known for his contributions to the fields of microbiology and vaccination. However, he was not the discoverer of penicillin.
• Koch: Robert Koch was a German physician and microbiologist known for his work on identifying the causative agents of diseases. He was not involved in the discovery of penicillin.

Answer: both Synergism and Antaginism

• Synergism: When antibiotics used in combination enhance each other’s effectiveness, it is called synergism. In synergism, the combined effect is greater than the sum of their individual effects.
• Antagonism: Antagonism occurs when the combined effect of antibiotics is less than the effect of either antibiotic alone. In some cases, one antibiotic may interfere with the activity of another, leading to reduced efficacy.

Answer: Epinephrine

Epinephrine (Adrenaline): It is the drug of choice for the treatment of anaphylactic shock. Epinephrine acts quickly to reverse the symptoms of anaphylaxis. It constricts blood vessels to increase blood pressure and relaxes the muscles in the airways, making breathing easier.

The other options are incorrect:

• Histamine: Histamine is released during allergic reactions, including anaphylaxis, but it is not a drug used for the treatment of anaphylactic shock.
• Corticosteroid: Corticosteroids may be used in the treatment of anaphylaxis, but they act more slowly than epinephrine. Epinephrine is the first-line treatment for immediate relief of symptoms.