MBIO 3401 EXAM 1 ZHANG QUESTIONS
WITH VERIFIED SOLUTIONS GRADED A+
PASSED 2025
FACULATIVE
Microorganisms:
are life forms too small to be seen with the human eyes
What is the criteria to be a microorgansim?
- Can grow and reproduce in nature
- Active metabolism
- Responsive to stimuli
- Diameter < 0.2 Millimeter or 200 micrometer
who was the first to observe single- celled microbes?
Antonie van Leeuwenhoek
Where do microbes come from?
They have parents or they spontaneously generate from inanimate materials.
Louis Pasteur
- Discovered the alcoholic fermentation was a biological process
- disproved theory of spontaneous generation
- Developed vaccines for anthrax, fowl cholera, and rabies
Robert Kock
- demonstrated the link between micrboes and infectious diseases
- identified causative agents of anthrax, tuberculosis, and cholera
What are microbes?
bacteria, archaea, eukaryotic microbes, and viruses
Bright Field Microscopy:
Pros:
- simple
- affordable
Cons:
- need staining
- hard for small/ colorless cells
,dark field microscopy
Pros:
-Highly sensitive for small cells/ structures
Cons:
- poor resolution
- prone to artifacts
Phase contrast and Diffrential interference microscopy:
Pros:
- Visualize live cells w/o staining, some internal stucture
Cons:
- Hard for small cells
Fluorescence confocal microscopy
Pros:
- Very high resolution
- 3D
- Vibrant colors
- Live Cells
Cons:
- Exspensive
Transmission electron microscopes (TEM):
- For internal stuctures
- Electron cryotomography: to obtain three-dimensional images
Scanning electron microscopes:
- For surface/ External structures
passive transport:
Follows concentration gradient ( energy- independent)
Active transport:
accumulate solutes against concentration gradient (energy- dependent)
What are the three classes of transport systems?
- Simple transport
- ABC transporter
- Group translocation
Cell wall
- need to withstand osmotic/ turgor pressure to prevent cell lysis
- Maintains cell shape and rigidity
,Bacterial Capsules and Slime formation:
- assist in attachment to surfaces
- role in development and maintenance of biofilms
- Contribute to infectivity
- Prevent dehydration/desiccation
Cell inclusions:
- inclusions function as energy reserves, carbon or phosphorus reservoirs, and/or have special functions
- Enclose bu thin protein membrane
- Reduces osmotic stress
The bacterial endospore:
Survuval structures to endure unfavorable growth conditions
Osmotaxis:
Response to ionic strength
Hydrotaxis
response to water
Aerotaxis
repsonse to oxygen
Phototaxis
response to light
Mycoplasma:
- A group of bacteria that have no cell wall, only membrane
- Small cell size
slow growth
difficult to culture
- Resistance to cell wall inhibitors
Which structure is involved in the genetic exchange (conjugation) between cells?
pilus
All bacterial cells must have cell walls containing peptidoglycan.
true
How do cells generate energy?
Chemotroph and phototroph
How do cells use energy to sustain life?
, Degradation Catabolic Exergonic Energy yielding Synthesis Anabolic Energy dependent Endergonic
Chemoorganotrophs
obtain energy and reducing power from organics
Chemolithotrophs
obtain energy and reducing power from inorganics
Heterotrophs
obtain carbon from organics
Autotrophs
(primary producers) obtain carbon from CO2
Enzymes:
- Catalysts lower activation energy, increasing reaction rate
- typically proteins (some RNAs)
- highly specific as a result of structure
oxygenic
(e.g., cyanobacteria, algae, plants), forming O2 as a waste product
anoxygenic
many bacteria
Macronutrients
- Nutrients required in large amounts
- C, O, N, H, P, S, K, Na, Ca, Mg, Cl, Fe
Micronutrients
- Nutrients required in minute amounts
- Trace metals and growth factors
Defined media:
exact chemical composition known
What is a microbe? How small does an organism have to be to be considered a microbe?
A microbe is a living organism that requires a microscope to be seen. Microbe diameter must be less
than 0.15 mm.
True or false: Some microbes can consist of a single cell.
WITH VERIFIED SOLUTIONS GRADED A+
PASSED 2025
FACULATIVE
Microorganisms:
are life forms too small to be seen with the human eyes
What is the criteria to be a microorgansim?
- Can grow and reproduce in nature
- Active metabolism
- Responsive to stimuli
- Diameter < 0.2 Millimeter or 200 micrometer
who was the first to observe single- celled microbes?
Antonie van Leeuwenhoek
Where do microbes come from?
They have parents or they spontaneously generate from inanimate materials.
Louis Pasteur
- Discovered the alcoholic fermentation was a biological process
- disproved theory of spontaneous generation
- Developed vaccines for anthrax, fowl cholera, and rabies
Robert Kock
- demonstrated the link between micrboes and infectious diseases
- identified causative agents of anthrax, tuberculosis, and cholera
What are microbes?
bacteria, archaea, eukaryotic microbes, and viruses
Bright Field Microscopy:
Pros:
- simple
- affordable
Cons:
- need staining
- hard for small/ colorless cells
,dark field microscopy
Pros:
-Highly sensitive for small cells/ structures
Cons:
- poor resolution
- prone to artifacts
Phase contrast and Diffrential interference microscopy:
Pros:
- Visualize live cells w/o staining, some internal stucture
Cons:
- Hard for small cells
Fluorescence confocal microscopy
Pros:
- Very high resolution
- 3D
- Vibrant colors
- Live Cells
Cons:
- Exspensive
Transmission electron microscopes (TEM):
- For internal stuctures
- Electron cryotomography: to obtain three-dimensional images
Scanning electron microscopes:
- For surface/ External structures
passive transport:
Follows concentration gradient ( energy- independent)
Active transport:
accumulate solutes against concentration gradient (energy- dependent)
What are the three classes of transport systems?
- Simple transport
- ABC transporter
- Group translocation
Cell wall
- need to withstand osmotic/ turgor pressure to prevent cell lysis
- Maintains cell shape and rigidity
,Bacterial Capsules and Slime formation:
- assist in attachment to surfaces
- role in development and maintenance of biofilms
- Contribute to infectivity
- Prevent dehydration/desiccation
Cell inclusions:
- inclusions function as energy reserves, carbon or phosphorus reservoirs, and/or have special functions
- Enclose bu thin protein membrane
- Reduces osmotic stress
The bacterial endospore:
Survuval structures to endure unfavorable growth conditions
Osmotaxis:
Response to ionic strength
Hydrotaxis
response to water
Aerotaxis
repsonse to oxygen
Phototaxis
response to light
Mycoplasma:
- A group of bacteria that have no cell wall, only membrane
- Small cell size
slow growth
difficult to culture
- Resistance to cell wall inhibitors
Which structure is involved in the genetic exchange (conjugation) between cells?
pilus
All bacterial cells must have cell walls containing peptidoglycan.
true
How do cells generate energy?
Chemotroph and phototroph
How do cells use energy to sustain life?
, Degradation Catabolic Exergonic Energy yielding Synthesis Anabolic Energy dependent Endergonic
Chemoorganotrophs
obtain energy and reducing power from organics
Chemolithotrophs
obtain energy and reducing power from inorganics
Heterotrophs
obtain carbon from organics
Autotrophs
(primary producers) obtain carbon from CO2
Enzymes:
- Catalysts lower activation energy, increasing reaction rate
- typically proteins (some RNAs)
- highly specific as a result of structure
oxygenic
(e.g., cyanobacteria, algae, plants), forming O2 as a waste product
anoxygenic
many bacteria
Macronutrients
- Nutrients required in large amounts
- C, O, N, H, P, S, K, Na, Ca, Mg, Cl, Fe
Micronutrients
- Nutrients required in minute amounts
- Trace metals and growth factors
Defined media:
exact chemical composition known
What is a microbe? How small does an organism have to be to be considered a microbe?
A microbe is a living organism that requires a microscope to be seen. Microbe diameter must be less
than 0.15 mm.
True or false: Some microbes can consist of a single cell.
