©SIRJOEL EXAM SOLUTIONS 2024/2025
ALL RIGHTS RESERVED.
MBI 111 Exam 1 Study Guide.
Colonization - Answers✔an attachment to and replication in/on a host
Infection - Answers✔a colonization of the body leading to damage
Disease - Answers✔any deviation from health
-not all disease is due to infection
-infection does not always cause disease
Symptoms - Answers✔subjective evidence of disease (pain, headache)
Signs - Answers✔objective evidence of disease (rash, fever)
Why do microbes cause disease? - Answers✔-Pathogens evolved to cause human disease
-Disease symptoms develop equilibrium does not develop between the pathogen and host
-Humans are accidental hosts of microorganisms that normally occupy a different niche
Symbiosis - Answers✔a situation in which 2 populations of organisms interact in a close and
sustained association
-benefits: food, protection, support, other life-sustaining factors
1|Page
, ©SIRJOEL EXAM SOLUTIONS 2024/2025
ALL RIGHTS RESERVED.
Synergism - Answers✔two populations that live together and accomplish what neither could
alone
ex: lichens=fungus and algae; mitochondria and chloroplasts in animal and plant cells
Mutualism - Answers✔benefits BOTH organisms
ex: nitrogen-fixing bacteria living in plant root nodules
Commensalism - Answers✔one population benefits, the other neither benefits nor is harmed;
microorganisms that inhabit our inner and outer surfaces without harming us; benefit to host
may be unrecognized
Antagonism (parasitism) - Answers✔the relationship is beneficial to one organism, HARMFUL to
the other
ex: pathogens (microorganisms that cause human disease are typical pathogens/parasites)
Normal microbiota (normal flora) - Answers✔microorganisms that infect WITHOUT causing
disease
ex: mutualism or commensalism
Pathogenicity - Answers✔the ability to enter host tissues and cause disease
Virulence - Answers✔the DEGREE of pathogenicity of a particular parasite
ex: highly virulent= cholera, typhoid, Ebola
less virulent= common cold viruses NOT cause disease
2|Page
ALL RIGHTS RESERVED.
MBI 111 Exam 1 Study Guide.
Colonization - Answers✔an attachment to and replication in/on a host
Infection - Answers✔a colonization of the body leading to damage
Disease - Answers✔any deviation from health
-not all disease is due to infection
-infection does not always cause disease
Symptoms - Answers✔subjective evidence of disease (pain, headache)
Signs - Answers✔objective evidence of disease (rash, fever)
Why do microbes cause disease? - Answers✔-Pathogens evolved to cause human disease
-Disease symptoms develop equilibrium does not develop between the pathogen and host
-Humans are accidental hosts of microorganisms that normally occupy a different niche
Symbiosis - Answers✔a situation in which 2 populations of organisms interact in a close and
sustained association
-benefits: food, protection, support, other life-sustaining factors
1|Page
, ©SIRJOEL EXAM SOLUTIONS 2024/2025
ALL RIGHTS RESERVED.
Synergism - Answers✔two populations that live together and accomplish what neither could
alone
ex: lichens=fungus and algae; mitochondria and chloroplasts in animal and plant cells
Mutualism - Answers✔benefits BOTH organisms
ex: nitrogen-fixing bacteria living in plant root nodules
Commensalism - Answers✔one population benefits, the other neither benefits nor is harmed;
microorganisms that inhabit our inner and outer surfaces without harming us; benefit to host
may be unrecognized
Antagonism (parasitism) - Answers✔the relationship is beneficial to one organism, HARMFUL to
the other
ex: pathogens (microorganisms that cause human disease are typical pathogens/parasites)
Normal microbiota (normal flora) - Answers✔microorganisms that infect WITHOUT causing
disease
ex: mutualism or commensalism
Pathogenicity - Answers✔the ability to enter host tissues and cause disease
Virulence - Answers✔the DEGREE of pathogenicity of a particular parasite
ex: highly virulent= cholera, typhoid, Ebola
less virulent= common cold viruses NOT cause disease
2|Page
