MIC 102 FINAL PAPER 2025/2026 QUESTIONS AND
ANSWERS GRADED A+
✔✔Which group is the most highly-evolved product of evolution? - ✔✔All living species
are equally evolved and share a common ancestor (LUCA)
✔✔Which statement describes evidence in support of the endosymbiosis theory of
organellogenesis for mitochondria and chloroplasts?
Select all options that apply.
Chloroplasts use 80S ribosomes to synthesize protein, just as bacteria do
Mitochondria use similar division machinery as bacteria
Mitochondria have linear genomes, just as most bacteria do
Chloroplasts have a double membrane, while mitochondria do not - ✔✔Mitochondria
use similar division machinery as bacteria
✔✔Which structure is found in the cell envelope of a typical gram-positive bacterium?
Select all options that apply.
Peptidoglycan cell wall (murein)
Teichoic acid
Outer membrane
Phospholipid
Lipopolysaccharide - ✔✔Peptidoglycan cell wall (murein)
Teichoic acid
Phospholipid
✔✔Which structure is found in the cell envelope of a typical gram-negative bacterium?
Select all options that apply.
Phospholipid
Teichoic acid
Peptidoglycan cell wall (murein)
Outer membrane
Lipopolysaccharide - ✔✔Phospholipid
Peptidoglycan cell wall (murein)
Outer membrane
Lipopolysaccharide
✔✔s-layer - ✔✔Proteins that attach to the cell wall of a bacteria and then the capsule
encapsulates everything. In Archaea there is ONLY an s-layer and no cell
wall/peptidoglycan
✔✔capsule - ✔✔polysaccharide and/or polymer of amino acids
,✔✔Lipopolysaccharide (LPS) - ✔✔fatty acid, phosphorylated disaccharide, and
repeating units of sugars
✔✔Phospholipids - ✔✔fatty acid tails connected to glycerophosphate heads via ester
bonds
✔✔peptidoglycan (murein) - ✔✔glycan chains composed of N-acetylglucosamine
alternating with an N-acetylmuramic acid subunits and cross linked with peptide bonds.
✔✔Species that are isolated from the environment and then passaged (cultured) many
times in the laboratory sometimes lose the ability to make structures that are
unnecessary for growth in artificial culture. (Why waste the energy making something
you don't need?)
For example, some Streptococcus species lose their ability to make a thick, slime layer
after extended periods of lab culturing.
How might the loss of its slime layer impact the ability of Streptococcus mutans, a
causative agent of dental cavities, to colonize and persist in its host (us)?
Select all options that apply.
Decreased biofilm formation
Increased risk of phagocytosis (clearance by host immune defenses)
Increased resistance to desiccation (water loss)
Decreased attachment to surfaces - ✔✔Decreased biofilm formation
Increased risk of phagocytosis (clearance by host immune defenses)
Decreased attachment to surfaces
✔✔slime layer - ✔✔Slime layers help cells retain water, slow the diffusion of nutrients
away from the cell, attach to surfaces, avoid being cleared (engulfed) by phagocytic
immune cells or bound by immune molecules, evade viral infections (by blocking access
to the bacterial structures they bind to), and more.
✔✔Which factor needs to be considered when culturing an acidophile?
Select all options that apply.
pH of the media
Gas mixture of the atmosphere
Incubation temperature
Natural habitat of the organism
Elemental composition of the media - ✔✔pH of the media
Gas mixture of the atmosphere
Incubation temperature
Natural habitat of the organism
Elemental composition of the media
, ✔✔True or False: The cell membrane is an important site of energy production. -
✔✔True (The phospholipid bilayer of the cell membrane is impervious to ions, such as
H+ or Na+, which allows the cells to build a transmembrane ion gradient, with the
charged ions trapped outside the cell membrane. The resultant electrochemical gradient
(e.g., proton motive force) is a form of stored energy the cells can use to make ATP,
rotate flagella, transport molecules across the membrane, and more.
Note: Because it is critical to cell function, every cell MUST have an ion motive force of
some kind to survive, even if it doesn't have an electron transport chain (e.g., is strictly
fermentative).
✔✔Consider this chemical reaction: ATP + H2O --> ADP + Pi.
Identify the FALSE statement regarding this reaction.
It is coupled to less energetically-favorable reactions during biosynthesis
It is exergonic (releases energy)
It is irreversible
It involves the cleavage of a high-energy phosphate bond - ✔✔It is irreversible
✔✔Which form of the electron carrier NAD+/NADH contains the least amount of energy
and electrons?
Select the best option of those available.
NAD+ (oxidized form)
NADH and NAD+ have the same amount of energy and electrons (rearranged)
NADH (reduced form) - ✔✔NAD+ (oxidized form) --> NAD+ has 1 less hydrogen (H)
atom and, therefore, 2 fewer electrons than NADH. The molecule with fewer electrons is
the more oxidized form.
Tip: use the mnemonic OIL RIG: oxidation is loss (of electrons), reduction is gain (of
electrons).
✔✔Photosynthetic cyanobacteria (carbon source: atmosphere) - ✔✔photoautotroph aka
photosynthesis
✔✔animal pathogen - ✔✔chemoheterotroph (if the source of energy and reducing
power. is a chemical sources microbes are said to be chemotrophs and microbes that
obtain their carbon from organic compounds are called heterotrophs)
✔✔A species growing under the surface of the rock in a desert (carbon source:
atmosphere; electron source: minerals in the rock) - ✔✔chemoautotroph (if the source
of energy and reducing power. is a chemical sources microbes are said to be
chemotrophs and if they are using inorganic sources of carbon (such as carbon dioxide)
are named autotrophs)
ANSWERS GRADED A+
✔✔Which group is the most highly-evolved product of evolution? - ✔✔All living species
are equally evolved and share a common ancestor (LUCA)
✔✔Which statement describes evidence in support of the endosymbiosis theory of
organellogenesis for mitochondria and chloroplasts?
Select all options that apply.
Chloroplasts use 80S ribosomes to synthesize protein, just as bacteria do
Mitochondria use similar division machinery as bacteria
Mitochondria have linear genomes, just as most bacteria do
Chloroplasts have a double membrane, while mitochondria do not - ✔✔Mitochondria
use similar division machinery as bacteria
✔✔Which structure is found in the cell envelope of a typical gram-positive bacterium?
Select all options that apply.
Peptidoglycan cell wall (murein)
Teichoic acid
Outer membrane
Phospholipid
Lipopolysaccharide - ✔✔Peptidoglycan cell wall (murein)
Teichoic acid
Phospholipid
✔✔Which structure is found in the cell envelope of a typical gram-negative bacterium?
Select all options that apply.
Phospholipid
Teichoic acid
Peptidoglycan cell wall (murein)
Outer membrane
Lipopolysaccharide - ✔✔Phospholipid
Peptidoglycan cell wall (murein)
Outer membrane
Lipopolysaccharide
✔✔s-layer - ✔✔Proteins that attach to the cell wall of a bacteria and then the capsule
encapsulates everything. In Archaea there is ONLY an s-layer and no cell
wall/peptidoglycan
✔✔capsule - ✔✔polysaccharide and/or polymer of amino acids
,✔✔Lipopolysaccharide (LPS) - ✔✔fatty acid, phosphorylated disaccharide, and
repeating units of sugars
✔✔Phospholipids - ✔✔fatty acid tails connected to glycerophosphate heads via ester
bonds
✔✔peptidoglycan (murein) - ✔✔glycan chains composed of N-acetylglucosamine
alternating with an N-acetylmuramic acid subunits and cross linked with peptide bonds.
✔✔Species that are isolated from the environment and then passaged (cultured) many
times in the laboratory sometimes lose the ability to make structures that are
unnecessary for growth in artificial culture. (Why waste the energy making something
you don't need?)
For example, some Streptococcus species lose their ability to make a thick, slime layer
after extended periods of lab culturing.
How might the loss of its slime layer impact the ability of Streptococcus mutans, a
causative agent of dental cavities, to colonize and persist in its host (us)?
Select all options that apply.
Decreased biofilm formation
Increased risk of phagocytosis (clearance by host immune defenses)
Increased resistance to desiccation (water loss)
Decreased attachment to surfaces - ✔✔Decreased biofilm formation
Increased risk of phagocytosis (clearance by host immune defenses)
Decreased attachment to surfaces
✔✔slime layer - ✔✔Slime layers help cells retain water, slow the diffusion of nutrients
away from the cell, attach to surfaces, avoid being cleared (engulfed) by phagocytic
immune cells or bound by immune molecules, evade viral infections (by blocking access
to the bacterial structures they bind to), and more.
✔✔Which factor needs to be considered when culturing an acidophile?
Select all options that apply.
pH of the media
Gas mixture of the atmosphere
Incubation temperature
Natural habitat of the organism
Elemental composition of the media - ✔✔pH of the media
Gas mixture of the atmosphere
Incubation temperature
Natural habitat of the organism
Elemental composition of the media
, ✔✔True or False: The cell membrane is an important site of energy production. -
✔✔True (The phospholipid bilayer of the cell membrane is impervious to ions, such as
H+ or Na+, which allows the cells to build a transmembrane ion gradient, with the
charged ions trapped outside the cell membrane. The resultant electrochemical gradient
(e.g., proton motive force) is a form of stored energy the cells can use to make ATP,
rotate flagella, transport molecules across the membrane, and more.
Note: Because it is critical to cell function, every cell MUST have an ion motive force of
some kind to survive, even if it doesn't have an electron transport chain (e.g., is strictly
fermentative).
✔✔Consider this chemical reaction: ATP + H2O --> ADP + Pi.
Identify the FALSE statement regarding this reaction.
It is coupled to less energetically-favorable reactions during biosynthesis
It is exergonic (releases energy)
It is irreversible
It involves the cleavage of a high-energy phosphate bond - ✔✔It is irreversible
✔✔Which form of the electron carrier NAD+/NADH contains the least amount of energy
and electrons?
Select the best option of those available.
NAD+ (oxidized form)
NADH and NAD+ have the same amount of energy and electrons (rearranged)
NADH (reduced form) - ✔✔NAD+ (oxidized form) --> NAD+ has 1 less hydrogen (H)
atom and, therefore, 2 fewer electrons than NADH. The molecule with fewer electrons is
the more oxidized form.
Tip: use the mnemonic OIL RIG: oxidation is loss (of electrons), reduction is gain (of
electrons).
✔✔Photosynthetic cyanobacteria (carbon source: atmosphere) - ✔✔photoautotroph aka
photosynthesis
✔✔animal pathogen - ✔✔chemoheterotroph (if the source of energy and reducing
power. is a chemical sources microbes are said to be chemotrophs and microbes that
obtain their carbon from organic compounds are called heterotrophs)
✔✔A species growing under the surface of the rock in a desert (carbon source:
atmosphere; electron source: minerals in the rock) - ✔✔chemoautotroph (if the source
of energy and reducing power. is a chemical sources microbes are said to be
chemotrophs and if they are using inorganic sources of carbon (such as carbon dioxide)
are named autotrophs)
