Chpt 24 Health And Diseases(I)

Question 1

1. What is the difference between pathogenicity and virulence?

Answer 1

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.

Question 2

2. Describe the structure of a typical virus.

Answer 2

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.

Question 3

3. Outline the steps involved in the lytic cycle of viral replication.

Answer 3

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.

Question 4

4. Explain the structural differences between Gram-positive and Gram-negative bacteria.

Answer 4

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.

Question 5

5. What are the main types of fungal pathogens and what are their characteristics?

Answer 5

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.

Question 6

1. 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 6

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].

Question 7

2. The term “prokaryote” comes from the Greek words “pro” meaning “before” and “karyon” meaning:a) Cell b) Nucleus c) Life d) Membrane

Answer 7

Answer: b) NucleusExplanation: Prokaryotes are organisms that lack a true nucleus and other membrane-bound organelles hence “before nucleus” [2].

Question 8

3. Which of the following is NOT a component of a virion?a) Nucleic acid b) Ribosome c) Capsidd)Envelope

Answer 8

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

Question 9

4. The process by which a virus attaches to a host cell is called:a) Penetration b) Uncoating c) Replication d) Adsorption

Answer 9

Answer: d) AdsorptionExplanation: Adsorption is the first step in viral infection where the virus attaches to specific receptors on the host cell surface [3].

Question 10

5. An integrated virus in a bacterial genome is called:a) Provirus b) Prophage c) Lysogen d) Virion

Answer 10

Answer: b) ProphageExplanation: When a virus integrates its genome into a bacterial genome the integrated viral DNA is called a prophage [3].

Question 11

6. 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 11

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].

Question 12

7. What is the mode of transmission for Hepatitis B?a) Droplet infection b) Blood infection c) Contaminated food d) Contact with lesion

Answer 12

Answer: b) Blood infectionExplanation: Hepatitis B is primarily transmitted through contact with infected blood or other body fluids [4].

Question 13

8. Which of the following bacteria is responsible for typhoid fever?a) Vibrio cholera b) Salmonella Typhi c) Mycobacterium tuberculosis d) Clostridium tetani

Answer 13

Answer: b) Salmonella TyphiExplanation: Typhoid fever is caused by the bacterium Salmonella Typhi [2].

Question 14

9. What shape is Clostridium tetani?a) Comma shaped b) Rod shaped c) Spherical shaped d) Spiral shaped

Answer 14

Answer: b) Rod shapedExplanation: Clostridium tetani the bacteria responsible for tetanus is rod-shaped [2].

Question 15

10. 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 15

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].

Question 16

11. 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 16

Answer: b) VirulenceExplanation: Virulence describes the degree of pathogenicity. It refers to the severity of the disease a pathogen can cause [1].

Question 17

12. 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 17

Answer: d) MumpsExplanation: Mumps is caused by a virus called the Mumps Virus. The other options are bacterial diseases [2].

Question 18

13. 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 18

Answer: b) Presence of teichoic acidExplanation: Gram-positive bacteria have a thick peptidoglycan layer in their cell walls and contain teichoic acid [3].

Question 19

14. A mycelium is a:a) Type of yeast cell b) Mass of hyphae c) Spore-producing structure d) Unicellular fungal form

Answer 19

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].

Question 20

15. Which of the following is an example of an exotoxin?a) Lipopolysaccharide (LPS) b) Teichoic acid c) Tetanospasmin d) Peptidoglycan

Answer 20

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].

Question 21

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 21

“Answer: b) It meant the same thing to different people Explanation: Health is a concept with diverse interpretations. [5]”

Question 22

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 22

“Answer: a) A state of complete physical

Question 23

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 23

“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.”

Question 24

[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 24

Answer and ExplanationAnswer: b) Criticize or without easeExplanation: Disease begins when one experiences discomfort or criticism suggesting a departure from a state of ease.

Question 25

What does the Greek word “Pathos” mean? a) Study b) Disease c) Suffering d) Agent

Answer 25

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

Question 26

Which of the following is NOT a biological agent that causes disease? a) Pathogen b) Bacteria c) Virus d) Stone

Answer 26

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.

Question 27

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 27

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

Question 28

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 28

Answer and Explanation

Question 29

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.