Chpt 24 Health And Diseases(I) Flashcards
- What is the difference between pathogenicity and virulence?
Answer:Pathogenicity is the ability of a microorganism to cause disease in a host. Virulence refers to the degree or severity of the disease caused by the microorganism.Explanation:Pathogenicity is a qualitative trait that determines whether an organism can cause disease while virulence is a quantitative measure indicating how severe or harmful the disease is. For example both Escherichia coli and Salmonella are pathogenic but Salmonella may have greater virulence causing more severe symptoms.
- Describe the structure of a typical virus.
Answer:A typical virus consists of:1. Nucleic acid core: Contains either DNA or RNA which encodes the viral genes.2. Capsid: A protein shell that protects the genetic material.3. Envelope (in some viruses): A lipid layer derived from the host cell membrane often with embedded glycoproteins for host recognition.4. Spikes (if present): Glycoproteins on the envelope that aid in attachment to host cells.Explanation:Viruses are acellular meaning they lack the cellular structures of living organisms. The nucleic acid carries the genetic instructions for replication while the capsid provides protection. Enveloped viruses like influenza have an outer lipid layer while non-enveloped viruses like adenoviruses do not.
- Outline the steps involved in the lytic cycle of viral replication.
Answer:1. Attachment: The virus binds to specific receptors on the host cell surface.2. Penetration: The viral genetic material enters the host cell.3. Biosynthesis: The host’s machinery is used to produce viral proteins and replicate viral DNA/RNA.4. Assembly: Newly synthesized viral components are assembled into complete viruses.5. Lysis: The host cell bursts (lyses) releasing new viruses to infect other cells.
- Explain the structural differences between Gram-positive and Gram-negative bacteria.
Answer:Gram-positive bacteria: Thick peptidoglycan layer. No outer membrane. Contains teichoic acids. Stains purple in a Gram stain.Gram-negative bacteria: Thin peptidoglycan layer. Has an outer membrane containinglipopolysaccharides (LPS). Stains pink/red in a Gram stain.Explanation:The structural differences between Gram-positive and Gram-negative bacteria are significant because they influence their susceptibility to antibiotics. For instance the outer membrane in Gram-negative bacteria makes them more resistant to certain antibiotics while the thick peptidoglycan layer in Gram-positive bacteria is a target for drugs like penicillin.
- What are the main types of fungal pathogens and what are their characteristics?
Answer:The main types of fungal pathogens include:1. Yeasts: Unicellular fungi e.g. Candida albicans.2. Molds: Multicellular fungi with hyphae e.g. Aspergillus.3. Dimorphic fungi: Exist as yeasts or molds depending on environmental conditions e.g. Histoplasma capsulatum.Characteristics:Yeasts reproduce asexually by budding. Molds form spores (conidia or sporangia) for reproduction. Dimorphic fungi switch forms to adapt to environmental changes often becoming yeasts in host tissues.Explanation:Fungal pathogens cause mycoses ranging from superficial infections (e.g. athlete’s foot) to systemic infections (e.g. histoplasmosis). Their classification aids in diagnosis and treatment selection.
- Which of the following is a fungal toxin that can cause serious liver damage?a) Aflatoxin b) Botulinum toxin c) Tetanospasmin d) Cholera toxin
Answer: a) AflatoxinExplanation: Aflatoxin is a toxin produced by certain species of the fungus Aspergillus and is known to cause serious liver damage if ingested repeatedly [1].
- The term “prokaryote” comes from the Greek words “pro” meaning “before” and “karyon” meaning:a) Cell b) Nucleus c) Life d) Membrane
Answer: b) NucleusExplanation: Prokaryotes are organisms that lack a true nucleus and other membrane-bound organelles hence “before nucleus” [2].
- Which of the following is NOT a component of a virion?a) Nucleic acid b) Ribosome c) Capsidd)Envelope
Answer: b) RibosomeExplanation: A virion or a complete virus particle consists of a nucleic acid core (DNA or RNA) surrounded by a protein coat called a capsid. Some viruses also have an outer envelope derived from the host cell membrane. Ribosomes
- The process by which a virus attaches to a host cell is called:a) Penetration b) Uncoating c) Replication d) Adsorption
Answer: d) AdsorptionExplanation: Adsorption is the first step in viral infection where the virus attaches to specific receptors on the host cell surface [3].
- An integrated virus in a bacterial genome is called:a) Provirus b) Prophage c) Lysogen d) Virion
Answer: b) ProphageExplanation: When a virus integrates its genome into a bacterial genome the integrated viral DNA is called a prophage [3].
- Which of the following is a sign or symptom of mumps?a) Fever with headache b) Painful swelling of the parotid gland c) Nasal and bronchial irritation d) Loss of weight and appetite
Answer: b) Painful swelling of the parotid glandExplanation: Mumps is characterized by painful swelling of the parotid glands which are salivary glands located near the ears [4].
- What is the mode of transmission for Hepatitis B?a) Droplet infection b) Blood infection c) Contaminated food d) Contact with lesion
Answer: b) Blood infectionExplanation: Hepatitis B is primarily transmitted through contact with infected blood or other body fluids [4].
- Which of the following bacteria is responsible for typhoid fever?a) Vibrio cholera b) Salmonella Typhi c) Mycobacterium tuberculosis d) Clostridium tetani
Answer: b) Salmonella TyphiExplanation: Typhoid fever is caused by the bacterium Salmonella Typhi [2].
- What shape is Clostridium tetani?a) Comma shaped b) Rod shaped c) Spherical shaped d) Spiral shaped
Answer: b) Rod shapedExplanation: Clostridium tetani the bacteria responsible for tetanus is rod-shaped [2].
- A dimorphic fungi can change from the yeast form to the ______ form in response to environmental factors.a) Mold b) Hyphae c) Mycelium d) Spore
Answer: a) MoldExplanation: Dimorphic fungi can exist in two forms: yeast and mold. They change from one form to another depending on environmental factors like temperature and nutrients [5].
- Which of the following is a quantitative measurement of the ability to cause a disease in a host?a) Pathogenicity b) Virulence c) Infectivity d) Toxicity
Answer: b) VirulenceExplanation: Virulence describes the degree of pathogenicity. It refers to the severity of the disease a pathogen can cause [1].
- Which of the following is an example of a disease caused by a viral pathogen?a) Tetanus b) Tuberculosis c) Typhoid fever d) Mumps
Answer: d) MumpsExplanation: Mumps is caused by a virus called the Mumps Virus. The other options are bacterial diseases [2].
- Which of the following is a characteristic of Gram-positive bacteria?a) Thin peptidoglycan layer b) Presence of teichoic acid c) Outer membrane with lipopolysaccharides d) All of the above
Answer: b) Presence of teichoic acidExplanation: Gram-positive bacteria have a thick peptidoglycan layer in their cell walls and contain teichoic acid [3].
- A mycelium is a:a) Type of yeast cell b) Mass of hyphae c) Spore-producing structure d) Unicellular fungal form
Answer: b) Mass of hyphaeExplanation: A mycelium is a network of branching thread-like hyphae that make up the body of a multicellular fungus [3].
- Which of the following is an example of an exotoxin?a) Lipopolysaccharide (LPS) b) Teichoic acid c) Tetanospasmin d) Peptidoglycan
Answer: c) TetanospasminExplanation: Exotoxins are actively secreted by some bacteria and have a wide range of effects including inhibition of certain biochemical pathways in the host. Tetanospasmin is a well-known exotoxin produced by Clostridium tetani [4].
Which of the following is NOT true about health?
a) It means different things to different people [5]
b) It meant the same thing to different people.
c) A Pathologist sees it as correct cellular make-up. [5]
d) A Psychiatrist means it as well-adjusted and balanced personality. [5]
“Answer: b) It meant the same thing to different people Explanation: Health is a concept with diverse interpretations. [5]”
Which of the following is the World Health Organisation’s (WHO) definition of health in 1948?
a) A state of complete physical mental and social well-being and not merely the absence of disease and infirmity. [5]
b) Ability to maintain homeostasis. [5]
c) The ability to change or cope with the environment. [5]
d) The tendency of the body to seek and maintain a condition of balance or equilibrium within its internal environment. [5]
“Answer: a) A state of complete physical
Which of the following is NOT a revised definition of health by WHO?
a) The achievement to which an individual or group is able to realize aspirations. [5]
b) The satisfaction of needs. [5]
c) To change or cope with the environment. [5]
d) To maintain homeostasis. [5]
“Answer: c) To change or cope with the environment. Explanation: While coping with the environment is related to health it’s not the central point of WHO’s revised definition.”
[5] Disease can be said to begin when one begins to: a) Fall ill b) Criticize or without ease c) Have an abnormal condition d) Have a disorder of a structure or function that affects part or all of an organism
Answer and ExplanationAnswer: b) Criticize or without easeExplanation: Disease begins when one experiences discomfort or criticism suggesting a departure from a state of ease.
What does the Greek word “Pathos” mean? a) Study b) Disease c) Suffering d) Agent
Answer and ExplanationAnswer: c) SufferingExplanation: The root word “Pathos” in “Pathology” comes from the Greek meaning “suffering” indicating the study of disease is related to understanding suffering
Which of the following is NOT a biological agent that causes disease? a) Pathogen b) Bacteria c) Virus d) Stone
Answer and ExplanationAnswer: d) StoneExplanation: Stones are not biological agents; they are inanimate objects. Pathogens bacteria and viruses are biological entities capable of causing diseases.
Pathogens are microbes that: a) Always cause disease b) Are capable of causing disease c) Are not capable of causing disease d) Cause only mild diseases
Answer and ExplanationAnswer: b) Are capable of causing diseaseExplanation: Pathogens are those microbes with the ability to cause disease when they infect a host not all microbes are pathogenic
Pathogenesis is the: a) Study of disease b) Formation of disease c) Process by which an infection leads to disease d) Severity of a disease
Answer and Explanation
Answer: c) Process by which an infection leads to diseaseExplanation: Pathogenesis delves into the mechanisms through which an infection develops into a disease within a host.
