MicroBiology MCQs with Answer and Explnation | Chapter 49

Answer: Ribosomes

Ribosomes are the protein-synthesizing machinery within the cell and are highly conserved across different species. This high level of conservation means that they are less likely to have unique features that can be specifically targeted by the immune system as antigens.

The other options are incorrect:

• Cell wall: The cell wall often contains unique molecules specific to the bacterial strain, making it a good target for antigen development.
• Flagella: Flagella proteins can be variable and can be used to distinguish different bacterial strains, making them potential antigens.
• Capsule: The capsule is a layer of polysaccharides surrounding some bacteria and can contain unique features specific to the strain, making it a potential antigen.

Answer: E.coli

N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) are the building blocks of peptidoglycan, a major component of bacterial cell walls. Therefore, only bacteria, like E.coli, will have structures composed of these molecules.

The other options are incorrect:

• Mycoplasmas: These lack a cell wall altogether, thus no peptidoglycan or NAM/NAG.
• Amoeba: This is a eukaryote and does not have a bacterial cell wall or peptidoglycan.
• Spheroplast: This is a bacterial cell that has lost its outer cell wall due to treatment, leaving only the cytoplasmic membrane and peptidoglycan layer. While it has remnants of peptidoglycan, it isn’t a complete and functional cell wall.

Answer: Lipopolysaccharides

Endotoxin is a potent inflammatory molecule associated with gram-negative bacteria. It’s located in the outer membrane of these bacteria and is primarily composed of lipopolysaccharides (LPS). LPS molecules have a unique structure with a core polysaccharide, an inner oligosaccharide, and an outer O-antigen chain. The O-antigen chain is highly variable and can trigger an immune response, contributing to the endotoxin’s inflammatory effects.

The other options are incorrect:

• Steroids: These are organic molecules found in both eukaryotes and prokaryotes, but they are not associated with the cell wall or endotoxin activity.
• Peptidoglycan: This is a major component of the bacterial cell wall in both gram-positive and gram-negative bacteria. However, it’s not a specific component of endotoxin, which is primarily found in the outer membrane of gram-negative bacteria.
• Polypeptide: This is a general term for a chain of amino acids, which can be found in various cellular components, including proteins. However, it’s not a specific component of endotoxin and doesn’t directly contribute to its structure or function.

Answer: Contains proteins and phospholipids

“Contains proteins and phospholipids.” The prokaryotic cell membrane is primarily composed of a phospholipid bilayer with embedded proteins. This structure forms a barrier that separates the interior of the cell from its external environment and plays a crucial role in various cellular functions.

The other options are incorrect:

• Contains metabolic enzymes: While prokaryotic cells contain metabolic enzymes, these enzymes are primarily found in the cytoplasm and other cellular compartments, not within the cell membrane. The membrane is more focused on maintaining the cell’s structure and regulating transport.
• Is selectively permeable: This is also correct. The prokaryotic cell membrane is selectively permeable, allowing certain substances to pass through while restricting the passage of others to maintain cellular homeostasis.
• Regulates the entry and exit of materials: This statement is accurate. The prokaryotic cell membrane regulates the entry and exit of materials, controlling the passage of substances in and out of the cell to maintain internal balance.

Answer: Enterococcus faecalis

While the other options (Vibrio cholerae, Escherichia coli, and Clostridium perfringens) are all well-established causes of diarrhea, Enterococcus faecalis is not typically recognized as a primary cause. Although it can be found in the gut microbiome and occasionally cause opportunistic infections, it’s not a common culprit for diarrhea in healthy individuals.

The other options are incorrect:

• Vibrio cholerae: This bacterium produces a toxin that disrupts the intestinal fluid balance, leading to profuse watery diarrhea.
• Escherichia coli: Some strains of E. coli, particularly enterotoxigenic (ETEC) and enterohemorrhagic (EHEC) strains, can cause diarrhea through various mechanisms, including toxin production and adherence to intestinal cells.
• Clostridium perfringens: This bacterium produces toxins that damage the intestinal lining, leading to foodborne illness with diarrhea as a common symptom.

Answer: Bacteroides fragilis

While the other options (Proteus mirabilis, Escherichia coli, and Klebsiella pneumoniae) are all common culprits in urinary tract infections (UTIs), Bacteroides fragilis is not typically associated with UTIs. This anaerobic bacterium primarily resides in the human gut and rarely ventures into the urinary tract environment.

The other options are incorrect:

• Proteus mirabilis: This versatile bacterium can ascend the urinary tract and readily colonize, causing UTIs with symptoms like burning urination and pelvic pain.
• Escherichia coli (E. coli): This bacterium, particularly uropathogenic strains, is the most common cause of UTIs, especially in women. It colonizes the urethra and can ascend to the bladder and kidneys, causing infection.
• Klebsiella pneumoniae: Though less common than E. coli, this bacterium can also cause UTIs, particularly in individuals with compromised immune systems or urinary catheters.

Answer: Q-fever

Q-fever is a bacterial infection caused by Coxiella burnetii and is diagnosed primarily through serological tests. These tests detect the presence of antibodies against Coxiella burnetii in the patient’s blood, indicating either a past or current infection.

The other options are incorrect:

• Actinomycosis: This bacterial infection is typically diagnosed by isolating the causative organism (Actinomyces) from a biopsy sample or culture. While serological tests can be used as a supplementary tool, they are not the primary diagnostic method.
• Pulmonary tuberculosis: This Mycobacterium tuberculosis infection is usually diagnosed using chest X-rays and sputum cultures. Serological tests are not considered reliable for diagnosing active tuberculosis due to cross-reactivity with other Mycobacterium species.
• Gonorrhea: This sexually transmitted infection caused by Neisseria gonorrhoeae is primarily diagnosed through nucleic acid amplification tests (NAAT) on genital swabs. Serological tests for gonorrhea are not widely used due to limitations in sensitivity and specificity.

Answer: Streptococcus pyogenes

While the other listed options (Shigella dysenteriae, Clostridium difficile, and Salmonella enteriditis) are all well-established bacterial causes of diarrhea, Streptococcus pyogenes is not typically associated with causing diarrhea. This bacterium is more commonly known for causing infections like strep throat, tonsillitis, and skin infections.

The other options are incorrect:

• Shigella dysenteriae: This bacterium produces toxins that damage the intestinal lining, leading to severe diarrhea with bloody stools (dysentery).
• Clostridium difficile: This bacterium thrives in the gut after antibiotic use, producing toxins that disrupt the microbiome and cause severe diarrhea.
• Salmonella enteriditis: This bacterium contaminates food sources and causes foodborne illness with diarrhea as a prominent symptom.

Answer: Staphylococcus aureus from Staphylococcus epidermidis

The coagulase test is a simple and rapid test used to differentiate between Staphylococcus aureus and other coagulase-negative staphylococcal species, especially Staphylococcus epidermidis. This differentiation is crucial because S. aureus is a significant human pathogen responsible for various infections, while S. epidermidis is typically non-pathogenic or opportunistic.

The other options are incorrect:

• Staphylococcus epidermidis from Neisseria meningitidis: These belong to different bacterial genera and can be easily distinguished by Gram staining. Neisseria meningitidis is gram-negative, while staphylococci are gram-positive.
• Streptococcus pyogenes from Enterococcus faecalis: While both are gram-positive cocci, they can be differentiated by various tests, including hemolysis patterns and antibiotic susceptibility profiles. The coagulase test is not used for this differentiation.
• Streptococcus pyogenes from Staphylococcus aureus: These are easily distinguished by Gram staining and their different colony morphologies. Streptococcus pyogenes is gram-positive and forms chains of cocci, while Staphylococcus aureus is gram-positive and forms clusters of cocci.

Answer: Their cell wall is composed of peptidoglycan

Prokaryotic cells, particularly bacteria, possess a rigid cell wall composed of peptidoglycan, a complex polymer not found in eukaryotic cells. This cell wall provides structural support and protection against osmotic pressure. When placed in hypotonic environments (dilute solutions), water rushes into the cell due to osmosis. The rigid peptidoglycan wall in prokaryotes helps resist this inward pressure, preventing excessive water uptake and cell lysis.

The other options are incorrect:

• They are selectively permeable: All cells, including eukaryotes, have selectively permeable membranes. While selective permeability helps regulate molecule exchange, it doesn’t directly contribute to resistance against osmotic shock.
• They contain osmoregulating porins: Some bacteria have porins that can adjust their size to regulate solute flow, but this ability alone isn’t sufficient to explain their strong resistance to osmotic shock.
• They block water molecules from entering the cell: This statement is incorrect. Prokaryotic membranes are permeable to water, and osmotic pressure arises from water movement.

Answer: Mycoplasma

Mycoplasmas are unique bacteria that lack a cell wall, making them the smallest self-replicating cells known. Interestingly, despite lacking a cell wall, they possess a sterol-containing membrane. This sterol, called mycoplasma cholesterol, plays a crucial role in maintaining membrane stability and function in the absence of a cell wall.

The other options are incorrect:

• Vibrio: Vibrio species have a typical gram-negative bacterial cell wall, composed of peptidoglycan and an outer membrane with lipopolysaccharides. They do not contain sterols in their membranes.
• Escherichia: Escherichia coli, like Vibrio, also has a gram-negative cell wall structure and lacks sterols in its membrane.
• Chlamydia: Chlamydia are obligate intracellular pathogens that lack a cell wall but also do not contain sterols in their membranes. They rely on the host cell membrane for many functions.

Answer: Bdellovibrio

Bdellovibrio is a unique genus of bacteria known for its ability to parasitize and lyse other gram-negative bacteria. Unlike most bacteria that compete for resources, Bdellovibrio attaches to and enters the outer membrane of its prey, replicating within the periplasmic space. It then releases enzymes that break down the host cell wall, causing lysis and release of nutrients that Bdellovibrio utilizes for its own growth and reproduction.

The other options are incorrect:

• Proteus mirabilis: While Proteus mirabilis can compete with other bacteria, it does not specifically target or lyse other gram-negative bacteria.
• Haemophilus influenza: This bacterium is a human pathogen causing respiratory infections and lacks the predatory behavior of Bdellovibrio.
• Pseudomonas putida: This bacterium is known for its metabolic versatility and ability to degrade various organic compounds. It does not exhibit predatory behavior towards other bacteria.

Answer: M13

The phage used for the phage display technique is M13. The M13 bacteriophage is a filamentous phage that is commonly employed in phage display experiments. Phage display is a technique where foreign peptides or proteins are expressed on the surface of the phage, allowing for the selection and identification of specific binding molecules, such as antibodies.

The other options are incorrect:

• T7: T7 phage is commonly used in molecular biology, particularly as a vector for DNA cloning and protein expression. However, it is not the primary phage used in the phage display technique.
• ƛ-phage: Lambda (ƛ)-phage is a bacteriophage that infects Escherichia coli. It is commonly used in genetic research, but it is not the primary phage used in phage display.
• ɸ6: Phi6 (ɸ6) is a double-stranded RNA bacteriophage. While it is used in virology research, it is not the phage typically utilized for phage display experiments.

Answer: cutaneous anthrax

Cutaneous anthrax: This is a skin infection caused by Bacillus anthracis, a bacteria often found in soil and associated with animals like deer. Processing deer hides, including skinning, can expose humans to spores of the bacteria, potentially leading to infection. Symptoms include a painless, black eschar (scar-like lesion) on the skin, which is similar to the description in the case.

The other options are incorrect:

• Tetanus: This is caused by Clostridium tetani, a bacteria found in soil and manure. While it can also be contracted through animal contact, the primary symptom is muscle stiffness and spasms, not an eschar on the skin.
• Listeriosis: This is caused by Listeria monocytogenes, a bacteria found in contaminated food products. It can cause flu-like symptoms, meningitis, and pregnancy complications, but not typically skin lesions.
• Tattoo: Although a tattoo could appear as a dark mark on the skin, it wouldn’t develop as a response to an infection and wouldn’t be described as an eschar.

Answer: gastrointesntinal

Typhoid fever is a bacterial infection caused by Salmonella enterica serotype Typhi, primarily transmitted through contaminated food and water. It manifests with symptoms primarily affecting the gastrointestinal tract, such as abdominal pain, diarrhea or constipation, nausea, vomiting, and fever. In severe cases, it can lead to intestinal perforation and life-threatening complications.

The other options are incorrect:

• Respiratory: Typhoid fever is not primarily a respiratory infection. While respiratory symptoms such as coughing or respiratory distress may occur in severe cases due to complications, they are not characteristic of the disease.
• Urogenital: Typhoid fever does not typically involve the urogenital system. Its primary symptoms are gastrointestinal in nature, as described above.
• Nervous, fever, eyes: While typhoid fever does cause fever as a hallmark symptom, it primarily affects the gastrointestinal system rather than the nervous system or eyes.

Answer: the covering of the spinal cord and brain

Meningitis is an infection that involves inflammation of the meninges, which are the protective coverings of the spinal cord and brain. The meninges consist of three layers: the dura mater, arachnoid mater, and pia mater. Bacterial or viral infections can cause inflammation of these membranes, resulting in the condition known as meningitis.

The other options are incorrect:

• The peripheral nervous system: While the peripheral nervous system can be affected by other conditions, it’s not the primary target of meningitis.
• The spinal cord and brain: Although the inflammation can affect these structures indirectly due to their close proximity to the meninges, the meninges themselves are the primary site of infection.
• The blood brain barrier: The blood-brain barrier is a protective membrane that separates the bloodstream from the brain, not the meninges. It can become compromised during meningitis, but it’s not the primary target of the infection.

Answer: Bacillus thuringiensis

Bacillus thuringiensis (Bt) is a bacterium commonly used as a biopesticide because it produces a protein toxin that specifically targets and kills butterfly caterpillars. This toxin is harmless to humans and other beneficial insects, making it a safe and environmentally friendly option.

The other options are incorrect:

• Trichoderma: This fungus is typically used as a biocontrol agent against fungal diseases in plants, not insect pests.
• Baculovirus: This type of virus specifically targets and kills certain insect pests, but it doesn’t have broad-spectrum activity against butterfly caterpillars like Bt does.
• Glomus: This is a type of mycorrhizal fungus that forms a symbiotic relationship with plant roots, helping them absorb nutrients more efficiently. It doesn’t have any insecticidal properties.

Answer: competitive inhibition of folic acid synthesis

Sulfanilamide is a bacteriostatic antibiotic that works by competitively inhibiting the enzyme dihydrofolate reductase, which is crucial for folic acid synthesis in bacteria. By blocking this step, sulfanilamide prevents bacteria from producing essential folates they need for growth and replication.

The other options are incorrect:

• Affects fungal nucleic acid synthesis: Sulfanilamide primarily targets bacterial folic acid synthesis and doesn’t directly affect fungal nucleic acids.
• Inhibits function of cell membrane: While some antibiotics target the cell membrane, sulfanilamide’s primary mode of action is through folic acid inhibition.
• Inhibits RNA synthesis: RNA synthesis inhibition is the mechanism of action for some antibiotics like rifampicin, but not for sulfanilamide.

Answer: orange juice

While beer, bread, and cheese all undergo fermentation processes involving microorganisms like yeast or bacteria, orange juice is simply squeezed from oranges and doesn’t involve any fermentation step.

The other options are incorrect:

• Beer: Yeast ferments sugars in barley grains to produce alcohol and carbon dioxide, creating the characteristic flavor and fizz of beer.
• Bread: Yeast ferments sugars in the dough, releasing carbon dioxide that causes the dough to rise, resulting in the fluffy texture of bread.
• Cheese: Bacteria convert lactose in milk into lactic acid during fermentation, giving cheese its unique tangy flavor and texture.

Answer: Hippocrates

Hippocrates, a Greek physician born around 460 BC, is widely considered the “father of Western medicine” for his groundbreaking contributions to the field. He established a more rational and systematic approach to medical practice, emphasizing observation, diagnosis, and prognosis over supernatural explanations for illness. He is also credited with founding the Hippocratic School of medicine and contributing to the development of the Hippocratic Oath, a foundation of medical ethics that remains relevant today.

The other options are incorrect:

• Marcus Terentius Varro: This Roman scholar wasn’t specifically focused on medicine but made contributions to various fields, including agriculture and history.
• Thucydides: A prominent historian who documented the Peloponnesian War, not known for advancements in medicine.
• Antonie van Leeuwenhoek: A pioneer in microbiology, known for discovering microorganisms but not specifically credited as the “father of Western medicine.”

Answer: Antonie van Leeuwenhoek

Antonie van Leeuwenhoek, a Dutch cloth merchant from the 17th century, is universally recognized as the first person to observe and document “animalcules,” which we now know as microorganisms, using his self-made single-lens microscopes. His meticulous observations laid the foundation for microbiology and revolutionized our understanding of the invisible world.

The other options are incorrect:

• Ötzi the Iceman: This well-preserved mummy lived around 3300 BC and didn’t have access to microscopes or scientific tools.
• Marcus Terentius Varro: A Roman scholar from the 1st century BC known for his vast knowledge, but his work didn’t involve microscopes or microbiology.
• Robert Koch: A German physician from the 19th century, a renowned microbiologist known for identifying the causative agents of specific diseases like tuberculosis, but he wasn’t the first to observe microorganisms.

Answer: Marcus Terentius Varro

Marcus Terentius Varro, a Roman scholar from the 1st century BC, is credited with theorizing that tiny, disease-causing animals too small to see could exist in swamps. While he lacked the technology to prove his theory, it foreshadowed the later discovery of microbes by Antonie van Leeuwenhoek centuries later.

The other options are incorrect:

• Thucydides: This Greek historian documented the Peloponnesian War but didn’t make significant contributions to medicine or disease theories.
• Hippocrates: The “father of Western medicine” focused on observation and treatment methods and lacked knowledge of microbes.
• Louis Pasteur: A 19th-century French microbiologist known for germ theory and pasteurization, but his contributions came much later than Varro’s proposal.

Answer: mineral

While Linnaeus’s two-kingdom system classified living organisms as either Animalia or Plantae, it did not include a kingdom for minerals. His system focused on biological entities, while minerals are non-living inorganic substances.

The other options are incorrect:

• Animal: This kingdom included multicellular, heterotrophic organisms capable of movement and locomotion.
• Protist: Though not originally included by Linnaeus, later revisions incorporated a kingdom for Protista, encompassing unicellular eukaryotic organisms not classified as Animalia or Plantae.
• Plant: This kingdom comprised multicellular, autotrophic organisms with cell walls capable of photosynthesis.

Answer: Homo sapiens

Binomial nomenclature is a system for naming living organisms using two Latin words: the genus name (always capitalized) and the specific epithet (not capitalized). In this case, “Homo” is the genus and “sapiens” is the specific epithet.

The other options are incorrect:

• Homo Sapiens: The first letter of the specific epithet should be lowercase.
• homo sapiens: The genus name should be capitalized.
• Homo Sapiens: Both the first and last letter of the specific epithet should be lowercase.

Answer: Teichoic acid

Teichoic acids are cell wall components found in gram-positive bacteria. They are known to play a role in the pathogenicity of these bacteria. Teichoic acids can stimulate the immune system and may contribute to the development of septic shock by triggering an exaggerated immune response in the host.

The other options are incorrect:

• Capsular protein: While some capsular proteins can contribute to virulence, they are not directly involved in triggering septic shock.
• Endotoxin: This is a component of the cell wall of gram-negative bacteria, not gram-positive bacteria.
• Peptidoglycan: While peptidoglycan can also trigger an immune response, it is not as potent as teichoic acid in this regard.
• Phospholipid: This is a major component of all cell membranes, including those of bacteria, but it does not play a significant role in septic shock development.

Answer: Inhibition of protein synthesis

Aminoglycosides primarily act by inhibiting protein synthesis in bacteria, specifically by binding to the 30S ribosomal subunit and interfering with the translation process. This disrupts the formation of essential proteins, ultimately leading to bacterial cell death.

The other options are incorrect:

• Disruption of cytoplasmic membrane function: While some aminoglycosides may have secondary effects on the membrane, this is not their primary mode of action.
• Inhibition of bacterial cell wall synthesis: This is the mechanism of action for penicillin and other beta-lactam antibiotics, not aminoglycosides.
• Inhibition of bacterial DNA gyrase: This is the mechanism of action for fluoroquinolone antibiotics, not aminoglycosides.
• Interference with bacterial folic acid metabolism: This is the mechanism of action for sulfonamide antibiotics, not aminoglycosides.

Answer: inhibits cell wall synthesis

Cephalosporins are a class of beta-lactam antibiotics that work by inhibiting bacterial cell wall synthesis. They do this by binding to penicillin-binding proteins (PBPs), which are enzymes essential for the formation of the bacterial cell wall. When PBPs are inhibited, the bacteria cannot build a strong cell wall, leading to their death.

The other options are incorrect:

• affects protzoal metabolism: While some antibiotics target protozoa, cephalosporins are not one of them. They specifically target bacteria.
• affects fungal nucleic acid synthesis: This is the mechanism of action for some antifungal drugs, but not for cephalosporins.
• inhibits RNA synthesis: Some antibiotics, like rifampicin, target RNA synthesis, but cephalosporins do not.

Answer: cell walls with mycolic acid

Cell walls with mycolic acid: This is the key characteristic of acid-fast bacteria. Mycolic acid is a complex waxy lipid that makes their cell walls particularly thick and impermeable, giving them their acid-fast staining properties.

The other options are incorrect:

• Exotoxin production: While some acid-fast bacteria can produce exotoxins, it’s not a defining characteristic of all of them.
• Skin infections that can lead to septicimia: This is more specific to specific types of acid-fast bacteria, like Staphylococcus aureus, not all of them.
• Diseases that come in stages: This description is too vague and not specific to acid-fast bacteria. Many diseases can have stages.

Answer: inflammation

Heat, redness, swelling, and pain are the cardinal signs of inflammation, which is a complex biological response to injury or infection. These characteristics occur due to changes in blood flow, increased permeability of blood vessels, and the accumulation of immune cells at the site of injury or infection.

The other options are incorrect:

• Cell-mediated response: This is a specific type of immune response involving T cells and doesn’t necessarily manifest as heat, redness, swelling, and pain.
• Humoral response: This is another specific type of immune response involving B cells and antibody production, and although it can contribute to inflammation, it doesn’t directly cause the cardinal signs mentioned.
• Complement cascade: This is a series of proteins in the blood that helps with immune function, but it’s not directly responsible for the cardinal signs of inflammation.

Answer: the capsid

The capsid is a protein shell that encloses the viral genome, protecting it from the environment and the host’s immune system. It is a crucial component of viruses, essential for their survival and ability to infect cells.

The other options are incorrect:

• The genome: While the genome is the genetic material of the virus, it doesn’t act as a protective covering. It needs the capsid to shield it from external threats.
• The envelope: Some viruses possess an envelope, a lipid bilayer surrounding the capsid. While it can provide additional protection, it’s not always present and not the primary protective barrier.
• The capsomere: This is a single protein subunit that forms the building blocks of the capsid. Although important for capsid structure, it’s not the entire protective covering itself.

Answer: vaginal yeast infections and thrush of the mouth

These infections occur when Candida overgrows, leading to symptoms such as itching, discharge, and discomfort in the case of vaginal yeast infections, and white patches or lesions in the mouth for thrush.

The other options are incorrect:

• Infections in Canadians: This option is not accurate. Candida infections are not specific to Canadians; they can occur in individuals worldwide. The location or nationality is not a determining factor for Candida infections.

Answer: spread while staying at hospital

HAI stands for Hospital-acquired infection, also known as nosocomial infection. It refers to an infection that a patient or healthcare worker acquires while receiving treatment in a healthcare facility, such as a hospital or clinic. These infections are not present or incubating in the patient at the time of admission.

The other options are incorrect:

• Degree of pathogenicity: This refers to the ability of a microorganism to cause disease, not specifically to infections acquired in hospitals.
• World wide outbreak of disease: While some HAIs can cause outbreaks within hospitals, not all do, and not all widespread outbreaks are considered HAIs.
• Vector of infection: This refers to an organism that carries and transmits an infectious agent from one infected individual to another, which is not the primary mode of transmission for HAIs.

Answer: respiratory

Streptococcal pneumonia refers to a respiratory infection caused by Streptococcus pneumoniae bacteria. It affects the respiratory system, specifically the lungs, and is a common cause of bacterial pneumonia. Symptoms may include difficulty breathing, chest pain, cough, fever, and other respiratory-related issues.

The other options are incorrect:

• Urogenital: While Streptococcus pneumoniae can cause urinary tract infections in some cases, it’s not the primary source of pneumonia.
• Nervous, fever, eyes: Fever is indeed a common symptom of pneumonia, but pneumonia specifically targets the lungs, not the nervous system or eyes as its primary site of infection.
• Gastrointestinal: Some other types of pneumonia can affect the gastrointestinal system, but streptococcal pneumonia typically doesn’t.
• Skin: Streptococcal bacteria can cause skin infections, but not pneumonia.
• Muscles: Pneumonia primarily affects the lungs, not muscles.

Answer: rheumatic fever and glomerulonephritis

Long-term effects of untreated or inadequately treated strep throat can include the development of rheumatic fever and glomerulonephritis. Rheumatic fever is an inflammatory condition that can affect the heart, joints, skin, and nervous system. Glomerulonephritis is inflammation of the kidney’s filtering units (glomeruli). Both conditions can result from an immune system response to the streptococcal infection.

The other options are incorrect:

• Encephalitis: While certain strep infections can rarely cause encephalitis, it’s not a typical long-term consequence of untreated strep throat. Encephalitis usually occurs alongside other neurological symptoms during the acute infection stage, unlike the delayed complications like rheumatic fever and glomerulonephritis.
• Death: Although very rare, death can happen in extreme cases of strep throat complications, primarily due to untreated rheumatic fever impacting the heart. However, it’s not a common long-term effect of strep throat and can be prevented by seeking timely medical attention.

Answer: fungus

Mycelium is the vegetative part of a fungus, consisting of thread-like hyphae that grow and spread in the environment. It plays a crucial role in nutrient acquisition, reproduction, and colonization for fungi.

The other options are incorrect:

• Bacteria: These are single-celled organisms and don’t have a mycelium structure.
• Protozoa: These are also single-celled organisms, often motile, and don’t have a mycelium.
• Algae: These are photosynthetic organisms, often multicellular, and don’t have a mycelium.
• Virus: These are non-cellular entities and don’t have any structures like a mycelium.

Answer: macropapular rash

Hepatitis viruses primarily attack the liver, and symptoms associated with liver dysfunction include jaundice (yellowing of the skin and eyes), dark urine, and light-colored feces. However, a macropapular rash is not a typical symptom of hepatitis. Skin manifestations can occur in some viral infections, but a macropapular rash is not a characteristic feature of hepatitis.

The other options are incorrect:

• Jaundice: Jaundice is a common symptom of hepatitis and results from the accumulation of bilirubin in the blood, leading to yellowing of the skin and eyes.
• Dark urine: Dark urine (dark yellow to brown) can occur in hepatitis due to the presence of bilirubin in the urine, indicating liver dysfunction.
• Light-colored feces: Light-colored or pale stools can be a sign of liver dysfunction in hepatitis, as bilirubin is not properly excreted into the intestines.

Answer: exotoxin production

Exotoxin production: Hemolytic streptococcus bacteria produce several exotoxins, which are proteins released by the bacteria that can damage host cells and tissues. These toxins contribute to various symptoms of streptococcal infections, such as skin rashes, fever, and sore throat.

The other options are incorrect:

• Cell walls with mycolic acid: This is a characteristic of Mycobacterium, not streptococcus. Mycolic acid is a complex lipid found in the cell walls of Mycobacterium species, including those causing tuberculosis and leprosy.
• Skin infections that can lead to septicimia: While hemolytic streptococcus can cause skin infections, it’s not the only bacteria with this ability. Additionally, septicimia is a serious complication that can occur with various infections, not specific to hemolytic streptococcus.
• Diseases that come in stages: This description is too vague and doesn’t apply to all infections caused by hemolytic streptococcus. Some streptococcal infections may have distinct stages, like impetigo, but not all.
• Diarrhea of varying degrees: Diarrhea is not a typical symptom of hemolytic streptococcus infections. It’s more commonly associated with other types of bacteria or viruses that affect the gastrointestinal tract.

Answer: respiratory

Streptococcal pneumonia is a respiratory infection caused by Streptococcus pneumoniae bacteria. It primarily affects the respiratory system, specifically the lungs, leading to symptoms such as cough, difficulty breathing, chest pain, and fever.

The other options are incorrect:

• Urogential: While Streptococcus pneumoniae can cause urinary tract infections in some cases, it’s not the primary source of pneumonia.
• Nervous, fever, eyes: Fever is indeed a common symptom of pneumonia, but pneumonia specifically targets the lungs, not the nervous system or eyes as its primary site of infection.
• Gastrointestinal: Some other types of pneumonia can affect the gastrointestinal system, but streptococcal pneumonia typically doesn’t.

Answer: old folks

The age group at most risk for legionelliosis, caused by the bacterium Legionella, is older adults, particularly those over the age of 50. Older individuals, especially those with weakened immune systems or underlying health conditions, are more susceptible to severe respiratory infections, including Legionnaires’ disease, which is a severe form of legionelliosis.

The other options are incorrect:

• Youngins: Legionelliosis is generally less common and less severe in younger age groups. It is not typically associated with a higher risk in very young children.
• Teenagers: While teenagers can contract legionelliosis, the risk is generally lower compared to older adults. Legionnaires’ disease is more likely to affect individuals with compromised immune systems.
• Adults: The term “adults” is broad and may include individuals of various ages. Legionelliosis tends to be more severe in older adults, especially those with certain risk factors.

Answer: all of the above

While all of the above might seem like the best answer since it encompasses both the fact that it affects a wider age range and is caused by many organisms, it’s not entirely true. While pneumonia can affect both the very young and the elderly, it’s not strictly limited to these age groups. People of all ages can develop pneumonia.

• A disease affecting the very young and the elderly: This statement is partially true, as these age groups are at higher risk due to weaker immune systems, but it excludes other vulnerable populations like people with chronic illnesses or weakened immunity.
• Fluid in the lungs: This is a characteristic symptom of pneumonia, but it doesn’t capture the entire picture of the disease. Pneumonia also involves inflammation and infection.
• Caused by a wide variety of organisms: This is the most accurate statement. Pneumonia can be caused by bacteria, viruses, fungi, and even some parasites.

Answer: worldwide outbreak of disease

Worldwide outbreak of disease: This definition captures the essence of a pandemic. It signifies a disease that has spread across a large geographical area, affecting a significant number of people globally.

The other options are incorrect:

• Disease outbreak: This is a broader term that can encompass any localized or regional increase in cases of a disease, not necessarily reaching the global scale of a pandemic.
• Disease that is easily spread: While transmissibility is a factor, a disease can be highly contagious without being a pandemic if it remains confined to a specific region.
• Vector of infection: This refers to an organism that transmits a disease from one infected individual to another, not the outbreak itself. Vectors can play a role in the spread of diseases that can potentially become pandemics, but they are not the defining characteristic.

Answer: the bacteria is highly resistant to detergents and antibiotics

Highly resistant to detergents and antibiotics: Pseudomonas bacteria, particularly Pseudomonas aeruginosa, have developed various mechanisms of resistance to common antibiotics and disinfectants. This includes producing enzymes that break down antibiotics, mutations in their cell walls that prevent antibiotics from entering, and biofilm formation that shields them from both antibiotics and immune system attacks. These factors make it challenging to find effective treatments, especially for long-term infections.

The other options are incorrect:

• Metabolically versatile: While Pseudomonas can survive in various environments and utilize different energy sources, this doesn’t directly contribute to their resistance to treatment.
• It is found everywhere: While Pseudomonas is widespread in soil, water, and even on human skin, its ubiquity doesn’t necessarily make it harder to treat infections it causes.
• Causes nosocomial infections: While Pseudomonas is a common cause of hospital-acquired infections, this doesn’t explain the difficulty in treatment. Hospital settings can contribute to the spread of resistant strains due to antibiotic overuse, but the bacteria itself is inherently resistant.

Answer: gullian barre syndrome

Guillain-Barré syndrome (GBS): This is a rare but serious autoimmune disorder that can affect the nerves, causing muscle weakness and paralysis. While the exact cause is unknown, Campylobacter jejuni infection is one of the strongest risk factors for developing GBS.

The other options are incorrect:

• Ulcerative peritonitis: This is an inflammation of the inner lining of the abdomen and usually associated with bacterial infections like E. coli, not Campylobacter jejuni.
• Toxic megacolon: This is a life-threatening complication of inflammatory bowel diseases like ulcerative colitis and Crohn’s disease, not typically associated with Campylobacter jejuni infection.

Answer: the maginification of the objective x the magnification of the ocular

The magnification of the objective lens x the magnification of the ocular: This is the standard formula for calculating the total magnification of a compound microscope. The objective lens provides the initial magnification of the object, and the ocular further magnifies that image. Multiplying these two values gives you the overall magnification you see through the microscope.

The other options are incorrect:

• The magnification of the objective lens x the number of eye pieces: While the objective lens magnification is crucial, the number of eyepieces doesn’t influence the total magnification. Most microscopes have a single eyepiece.
• The total of all of the objectives: A microscope typically comes with multiple objectives with different magnification powers, but you only use one at a time to observe the sample. Adding them all wouldn’t represent the actual magnification used.
• The price of the microscope: The price doesn’t determine the magnification; different microscopes with varying price points can have the same total magnification depending on their lenses.

Answer: nervous, fever, eyes

While Hansen’s disease can have skin manifestations, it primarily affects the peripheral nerves, causing nerve damage. This can lead to various symptoms like numbness, tingling, and muscle weakness. Additionally, it can affect the eyes, leading to inflammation and potential blindness, and cause fevers during certain stages of the disease.

The other options are incorrect:

• Respiratory: While some respiratory symptoms like cough can occur in rare cases, it’s not the primary system affected by Hansen’s disease.
• Urogenital: Hansen’s disease doesn’t primarily affect the urogenital system.
• Gastrointestinal: The gastrointestinal system isn’t typically involved in Hansen’s disease.

Answer: the genome

The genome of a virus may be either DNA or RNA but not both. The genome is the genetic material of the virus that carries the instructions for viral replication and other functions. Viruses can have either DNA or RNA as their genetic material, but not both simultaneously.

The other options are incorrect:

• The capsid: The capsid is the protein coat surrounding the viral genome. It does not determine whether the virus has a DNA or RNA genome.
• The envelope: The envelope is a lipid membrane that some viruses acquire from the host cell membrane during the process of budding. It does not dictate whether the viral genome is DNA or RNA.
• The capsomere: The capsomere is a subunit of the capsid, and it also does not determine the nature of the viral genome.

Answer: the cell walls of these organisms are not affected by penicillin

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), has a unique cell wall composition that includes mycolic acids. These mycolic acids provide resistance to the action of antibiotics like penicillin, which primarily target bacterial cell walls. Penicillin is more effective against bacteria with different cell wall structures.

The other options are incorrect:

• Spores: While some Mycobacterium tuberculosis strains can form spores, they are not the primary reason for antibiotic resistance. Even in spore-forming bacteria, antibiotics can still target and kill the active, vegetative form of the bacteria.
• Encystment: While some bacteria can form protective cysts, Mycobacterium tuberculosis doesn’t typically exhibit this behavior. Even if it did, antibiotics like penicillin can often penetrate cysts and reach the bacteria within.
• Gram-negative bacteria: Penicillin is generally less effective against Gram-negative bacteria due to their outer membrane barrier. However, Mycobacterium tuberculosis is Gram-positive, so this characteristic doesn’t explain its resistance to penicillin.

Answer: 30%

Approximately 30% of the global population is estimated to be infected with Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB). It is important to note that not all individuals who are infected with TB develop active disease; many carry the infection in a latent, non-infectious form.

The other options are incorrect:

• 1%: The prevalence of Mycobacterium tuberculosis infection is higher than 1%. The correct estimate is approximately 30%.
• 10%: The prevalence of Mycobacterium tuberculosis infection is higher than 10%. The correct estimate is approximately 30%.
• 20%: The prevalence of Mycobacterium tuberculosis infection is higher than 20%. The correct estimate is approximately 30%.

Answer: asymptomatic people dont realize they have it

Asymptomatic people don’t realize they have it: A significant proportion of people infected with gonorrhea and chlamydia show no symptoms, especially in the early stages. This allows them to unknowingly transmit the infection to others without seeking treatment. This silent spread makes controlling these STIs challenging.

The other options are incorrect:

• People hate condoms: While condom use may not always be optimal, their effectiveness in preventing STIs, including gonorrhea and chlamydia, is well established. Educational campaigns and accessibility can improve condom use.
• It is mainly spread by young irresponsible teenagers: While teenagers might be at higher risk, gonorrhea and chlamydia can affect people of all ages and demographics. Blaming specific groups can create stigma and hinder prevention efforts.
• Highly antibiotic resistant: While antibiotic resistance is a growing concern for some STIs, it’s currently not a major factor for gonorrhea and chlamydia. Early diagnosis and treatment with proper antibiotics remain effective.

Answer: inflammation

 When tissues become inflamed, a complex series of events occur, including the release of chemical mediators like histamine and prostaglandins. These mediators signal blood vessels to dilate, increasing blood flow to the affected area. This dilation of capillaries, including those near the inflammation site, is a characteristic sign of inflammation, aiding in immune cell delivery and facilitating healing.

The other options are incorrect:

• Cell-mediated response: While involved in the immune response, this pathway primarily activates specific immune cells, not directly causing capillary dilation.
• Humoral response: This pathway focuses on antibody production to neutralize pathogens, not directly affecting capillary diameter.
• Complement cascade: This system works alongside other immune components and can increase vascular permeability, but not directly dilate capillaries.