MCAT BIOLOGY EXAM QUESTIONS NEWEST 2025 ACTUAL EXAM COMPLETE 300 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!
Cell•Theory - Four Tenets:
1. All living things are composed of cells
2. The cell is the basic functional unit of life
•
3. Cells arise only from preexisting cells
4. Cells carry genetic information in the form of DNA
• )(*&^
Eukaryotic Cells - Contain a true nucleus enclosed in a membrane.
%$#@!
Prokaryotic Cells - Do not contain a nucleus.
Organelles - Suspended in semifluid cytosol. In eukaryotic cells they are membrane bound,
allowing for compartmentalization of functions. The membranes are made of a phospholipid
bilayer, surfaces are hydrophilic, they interact with the environment.
Cytosol - Allows for diffusion of molecules throughout the cell.
Nucleus - Genetic material is encoded in DNA, organized in chromosomes. This DNA provides all
the genetic material needed for replication of the cell. It is surrounded by the nuclear
membrane or envelope, which forms a double membrane. Nuclear pores allow for selective
exchange of material between cytoplasm and the nucleus.
Genetic Material of the Nucleus - DNA contains coding regions called genes. Linear DNA is
wound around organizing proteins known as histones, and further wound into chromosomes.
Nuclear Membrane - Contains nuclear pores that allow for selective 2-way exchange of material
between the cytoplasm and the nucleolus
Nucleolus - -Subsection of the nucleus
-Where ribosomal RNA is synthesized
-The darker spot that is 25% of the nucleus
Mitochondria - Power plant of the cell. Two layers, inner and outer membrane. The outer
membrane is a barrier between the cytosol and the inner environment of the mitochondria.
The inner membrane, made up of infoldings called cristae, contains the molecules and enzymes
necessary for the electron transport chain. The intermembrane space separates them, creating
a matrix between them.
The pumping of protons from the matrix to the intermembrane space creates a proton-motive
force that generates ATP via protons flowing through and turning ATP synthase (oxidative
phosphorylation). The mitochondria is semiautonomous, meaning they replicate independently
of the the nucleus via binary fission.
They can kill the cell via release of enzymes that aid in apoptosis.
Lysosomes - Membrane-bound structures containing hydrolytic enzymes that are capable of
breaking down many different substrates, including those ingested by endocytosis and cellular
waste products.
,MCAT BIOLOGY EXAM QUESTIONS NEWEST 2025 ACTUAL EXAM COMPLETE 300 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!
The•enzymes are sequestered to protect the cell, releasing these enzymes causes autolysis,
resulting in apoptosis...in this case, the released enzymes directly lead to cell degradation.
•
Rough Endoplasmic Reticulum (RER) - Interconnected membranes that are actually contiguous
with the nuclear envelope. It is folding into complex structures with a central lumen. The Rough
ER is• studded with ribosomes that permit translation of proteins destined for secretion into the
lumen. )(*&^
%$#@!
Golgi Apparatus - Stacked membrane-bound sacs that are transferred from the ER via vesicles.
The Golgi modifies the products via addition of various groups. It modifies cellular products
thought the introduction of signal sequences, which help direct the delivery of product to a
specific cellular location. Can also send to lysosomes for degredation
Exocytosis - Used in secretion, when the secretory vesicle merges with the cell membrane and
its contents.
Peroxisomes - Contain hydrogen peroxide. It breaks down long chain fatty acids via beta
oxidation. They help in the synthesis of phospholipids.
Cytoskeleton - Provides structure to the cell and helps it to maintain its shape. It also provides a
conduit for transport of material around the cell.
Microfilaments - Solid polymerized rods of actin organized into bundles and networks that are
resistant to compression and fracture. They assist in cytokinesis and cleavage furrow. Present in
muscle
Actin - Subunit of microfilaments, used with ATP to generate force for movement by interacting
with myosin for muscle contraction.
Microtubules - Hollow polymers of tubulin proteins that provide a primary pathway along which
motor proteins like kinesin and dynein carry vesicles. Makes cilia and flagella. Also makes
centrioles
Cilia - Projections of the cell that are primarily involved in movement of materials along the
surface of a cell. They are made of microtubules and an example is respiratory cilia.
Flagella - Structures involved in the movement of the cell itself, such as the movement of sperm
cells through the reproductive tract.
9 + 2 Structure - Used in flagella and cilia. Nine pairs of microtubules, with two in the center.
Centrioles - Found in a region of the cell called the centrosome. They are the organization
centers for microtubules and are structured as nine triplets of microtubules with a hollow
center. They migrate to opposite poles of the dividing cell and organize the mitotic spindle.
They attach via kinetochores to the chromosomes.
Intermediate Filaments - Include keratin (hair, nails, skin) and desmin. They are involved in cell-
cell adhesion, or maintenance of the overall integrity of the cytoskeleton. They can withstand a
,MCAT BIOLOGY EXAM QUESTIONS NEWEST 2025 ACTUAL EXAM COMPLETE 300 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!
• amount of tension, adding rigidity to the cell structure. They help anchor other organelles!
large
Epithelial Tissue and Basement Membrane - Cover the body and lines its cavities. Involved in
•
protection, absorption, secretion, and sensation. They are tightly joined to each other and to an
underlying layer of connective tissue known as the basement membrane.
• )(*&^
Simple Epithelia - One layer of cells
%$#@!
Stratified Epithelia - Multiple layers of cells
Pseudostratified Epithelia - Appear to have multiple layers due to difference in cell height, but
are really one layer.
Cuboidal, Columnar, and Squamous Cells - Cuboidal: cube-shaped
Columnar: Long and thin
Squamous: flat, scale-like
Connective Tissue - Supports the body and provides framework for the epithelial cells to carry
out their functions. Main contributors to the stroma, or support structure. Examples are bone,
cartilage, tendons, ligaments, adipose tissue, and blood. They help to form the extracellular
matrix.
Nucleoid Region - Where prokaryotes keep their genetic material - organized into a single
circular DNA molecule, which is stored here
Archaea - Single-celled organisms that contain genes and several metabolic pathways that are
more similar to eukaryotes. There are extremophiles, found mostly in harsh environments.
They mostly use alternative sources of energy, such as photosynthetic, or chemosynthetic.
Bacteria - Contain a cell membrane and cytoplasm, and some have flagella or fimbriae. They
work with humans as mutualistic symbiotes, for example with the human gut producing
Vitamin K and biotin. Pathogens or parasites will provide no advantage to the host, and cause
disease.
Cocci - Spherical bacteria.
Bacilli - Rod-shaped bacteria.
Spirilli - Spiral-shaped bacteria.
Obligate Aerobes - Bacteria that require oxygen for metabolism.
Anaerobes - Bacteria that use either fermentation or some other form of cellular metabolism
that does not require oxygen.
Obligate Anaerobes - Cannot survive in an oxygen-containing environment.
Facultative Anaerobes - Toggle between metabolic processes. Can do aerobic and anaerobic
, MCAT BIOLOGY EXAM QUESTIONS NEWEST 2025 ACTUAL EXAM COMPLETE 300 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!
•
respiration.
Aerotolerant Anaerobes - Unable to use oxygen for metabolism but are not harmed by its
•
presence
Prokaryotic
• Cell Structure - Major difference is that there is a lack of a nucleus and membrane-
bound organelles. They do have ribosomes. They are single celled. )(*&^
%$#@!
Cell Wall - Outer barrier of the cell. Provides structure and controls the movement of solutes
into and out of the bacterium. This maintains concentration gradients relative to the
environment. Two types: gram positive and gram negative.
Gram Positive Bacteria
What color is it?
Is there a thick or think cell wall (peptidoglycan)?
What does the cell membrane contain? - purple
thick later of peptidoglycan (aa + sugar)
It aids a pathogen by providing protection from a host organism's immune system.
It also contains lipoteichoic acid
Cell Membrane - Next layer of the prokaryotic cell. It is composed of phospholipids.
Envelope - The cell wall and cell membrane together.
Bacterial Flagella - Used for propulsion. Triggered via chemotaxis which is the movement to or
from a chemical stimuli. Made of a filament, hollow structure of flagellin anchored by a basal
body, and a hook, which connects the filament and the basal body to increase torque.
Plasmids - Small circular structures of DNA acquired from external sources. They carry DNA that
is not necessary for survival of the prokaryote, but may confer an advantage such as antibiotic
resistance.
Prokaryotic vs Eukaryotic ribosome - Prokaryotes have a 30 S and 50 S ribosome
Euk have 40 and 60s ribosome
Generation of ATP (in bacteria) - Done via the cell membrane where ETC lies.
Gram Negative Bacteria
What color is it?
Is there a thick or think cell wall (peptidoglycan)?
What does the cell membrane contain? - Appears pink
Thin cell wall
phospholipids and lipopolysaccharides (elicit a stronger immune response)
Binary Fission - Simple form of asexual reproduction in prokaryotes. Chromosome attaches to
the cell wall and replicates while the cell continues to grow in size.
Genetic Recombination - Plasmids will carry genes that impart some benefit on the bacteria or
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!
Cell•Theory - Four Tenets:
1. All living things are composed of cells
2. The cell is the basic functional unit of life
•
3. Cells arise only from preexisting cells
4. Cells carry genetic information in the form of DNA
• )(*&^
Eukaryotic Cells - Contain a true nucleus enclosed in a membrane.
%$#@!
Prokaryotic Cells - Do not contain a nucleus.
Organelles - Suspended in semifluid cytosol. In eukaryotic cells they are membrane bound,
allowing for compartmentalization of functions. The membranes are made of a phospholipid
bilayer, surfaces are hydrophilic, they interact with the environment.
Cytosol - Allows for diffusion of molecules throughout the cell.
Nucleus - Genetic material is encoded in DNA, organized in chromosomes. This DNA provides all
the genetic material needed for replication of the cell. It is surrounded by the nuclear
membrane or envelope, which forms a double membrane. Nuclear pores allow for selective
exchange of material between cytoplasm and the nucleus.
Genetic Material of the Nucleus - DNA contains coding regions called genes. Linear DNA is
wound around organizing proteins known as histones, and further wound into chromosomes.
Nuclear Membrane - Contains nuclear pores that allow for selective 2-way exchange of material
between the cytoplasm and the nucleolus
Nucleolus - -Subsection of the nucleus
-Where ribosomal RNA is synthesized
-The darker spot that is 25% of the nucleus
Mitochondria - Power plant of the cell. Two layers, inner and outer membrane. The outer
membrane is a barrier between the cytosol and the inner environment of the mitochondria.
The inner membrane, made up of infoldings called cristae, contains the molecules and enzymes
necessary for the electron transport chain. The intermembrane space separates them, creating
a matrix between them.
The pumping of protons from the matrix to the intermembrane space creates a proton-motive
force that generates ATP via protons flowing through and turning ATP synthase (oxidative
phosphorylation). The mitochondria is semiautonomous, meaning they replicate independently
of the the nucleus via binary fission.
They can kill the cell via release of enzymes that aid in apoptosis.
Lysosomes - Membrane-bound structures containing hydrolytic enzymes that are capable of
breaking down many different substrates, including those ingested by endocytosis and cellular
waste products.
,MCAT BIOLOGY EXAM QUESTIONS NEWEST 2025 ACTUAL EXAM COMPLETE 300 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!
The•enzymes are sequestered to protect the cell, releasing these enzymes causes autolysis,
resulting in apoptosis...in this case, the released enzymes directly lead to cell degradation.
•
Rough Endoplasmic Reticulum (RER) - Interconnected membranes that are actually contiguous
with the nuclear envelope. It is folding into complex structures with a central lumen. The Rough
ER is• studded with ribosomes that permit translation of proteins destined for secretion into the
lumen. )(*&^
%$#@!
Golgi Apparatus - Stacked membrane-bound sacs that are transferred from the ER via vesicles.
The Golgi modifies the products via addition of various groups. It modifies cellular products
thought the introduction of signal sequences, which help direct the delivery of product to a
specific cellular location. Can also send to lysosomes for degredation
Exocytosis - Used in secretion, when the secretory vesicle merges with the cell membrane and
its contents.
Peroxisomes - Contain hydrogen peroxide. It breaks down long chain fatty acids via beta
oxidation. They help in the synthesis of phospholipids.
Cytoskeleton - Provides structure to the cell and helps it to maintain its shape. It also provides a
conduit for transport of material around the cell.
Microfilaments - Solid polymerized rods of actin organized into bundles and networks that are
resistant to compression and fracture. They assist in cytokinesis and cleavage furrow. Present in
muscle
Actin - Subunit of microfilaments, used with ATP to generate force for movement by interacting
with myosin for muscle contraction.
Microtubules - Hollow polymers of tubulin proteins that provide a primary pathway along which
motor proteins like kinesin and dynein carry vesicles. Makes cilia and flagella. Also makes
centrioles
Cilia - Projections of the cell that are primarily involved in movement of materials along the
surface of a cell. They are made of microtubules and an example is respiratory cilia.
Flagella - Structures involved in the movement of the cell itself, such as the movement of sperm
cells through the reproductive tract.
9 + 2 Structure - Used in flagella and cilia. Nine pairs of microtubules, with two in the center.
Centrioles - Found in a region of the cell called the centrosome. They are the organization
centers for microtubules and are structured as nine triplets of microtubules with a hollow
center. They migrate to opposite poles of the dividing cell and organize the mitotic spindle.
They attach via kinetochores to the chromosomes.
Intermediate Filaments - Include keratin (hair, nails, skin) and desmin. They are involved in cell-
cell adhesion, or maintenance of the overall integrity of the cytoskeleton. They can withstand a
,MCAT BIOLOGY EXAM QUESTIONS NEWEST 2025 ACTUAL EXAM COMPLETE 300 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!
• amount of tension, adding rigidity to the cell structure. They help anchor other organelles!
large
Epithelial Tissue and Basement Membrane - Cover the body and lines its cavities. Involved in
•
protection, absorption, secretion, and sensation. They are tightly joined to each other and to an
underlying layer of connective tissue known as the basement membrane.
• )(*&^
Simple Epithelia - One layer of cells
%$#@!
Stratified Epithelia - Multiple layers of cells
Pseudostratified Epithelia - Appear to have multiple layers due to difference in cell height, but
are really one layer.
Cuboidal, Columnar, and Squamous Cells - Cuboidal: cube-shaped
Columnar: Long and thin
Squamous: flat, scale-like
Connective Tissue - Supports the body and provides framework for the epithelial cells to carry
out their functions. Main contributors to the stroma, or support structure. Examples are bone,
cartilage, tendons, ligaments, adipose tissue, and blood. They help to form the extracellular
matrix.
Nucleoid Region - Where prokaryotes keep their genetic material - organized into a single
circular DNA molecule, which is stored here
Archaea - Single-celled organisms that contain genes and several metabolic pathways that are
more similar to eukaryotes. There are extremophiles, found mostly in harsh environments.
They mostly use alternative sources of energy, such as photosynthetic, or chemosynthetic.
Bacteria - Contain a cell membrane and cytoplasm, and some have flagella or fimbriae. They
work with humans as mutualistic symbiotes, for example with the human gut producing
Vitamin K and biotin. Pathogens or parasites will provide no advantage to the host, and cause
disease.
Cocci - Spherical bacteria.
Bacilli - Rod-shaped bacteria.
Spirilli - Spiral-shaped bacteria.
Obligate Aerobes - Bacteria that require oxygen for metabolism.
Anaerobes - Bacteria that use either fermentation or some other form of cellular metabolism
that does not require oxygen.
Obligate Anaerobes - Cannot survive in an oxygen-containing environment.
Facultative Anaerobes - Toggle between metabolic processes. Can do aerobic and anaerobic
, MCAT BIOLOGY EXAM QUESTIONS NEWEST 2025 ACTUAL EXAM COMPLETE 300 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED A+||BRAND NEW!!
•
respiration.
Aerotolerant Anaerobes - Unable to use oxygen for metabolism but are not harmed by its
•
presence
Prokaryotic
• Cell Structure - Major difference is that there is a lack of a nucleus and membrane-
bound organelles. They do have ribosomes. They are single celled. )(*&^
%$#@!
Cell Wall - Outer barrier of the cell. Provides structure and controls the movement of solutes
into and out of the bacterium. This maintains concentration gradients relative to the
environment. Two types: gram positive and gram negative.
Gram Positive Bacteria
What color is it?
Is there a thick or think cell wall (peptidoglycan)?
What does the cell membrane contain? - purple
thick later of peptidoglycan (aa + sugar)
It aids a pathogen by providing protection from a host organism's immune system.
It also contains lipoteichoic acid
Cell Membrane - Next layer of the prokaryotic cell. It is composed of phospholipids.
Envelope - The cell wall and cell membrane together.
Bacterial Flagella - Used for propulsion. Triggered via chemotaxis which is the movement to or
from a chemical stimuli. Made of a filament, hollow structure of flagellin anchored by a basal
body, and a hook, which connects the filament and the basal body to increase torque.
Plasmids - Small circular structures of DNA acquired from external sources. They carry DNA that
is not necessary for survival of the prokaryote, but may confer an advantage such as antibiotic
resistance.
Prokaryotic vs Eukaryotic ribosome - Prokaryotes have a 30 S and 50 S ribosome
Euk have 40 and 60s ribosome
Generation of ATP (in bacteria) - Done via the cell membrane where ETC lies.
Gram Negative Bacteria
What color is it?
Is there a thick or think cell wall (peptidoglycan)?
What does the cell membrane contain? - Appears pink
Thin cell wall
phospholipids and lipopolysaccharides (elicit a stronger immune response)
Binary Fission - Simple form of asexual reproduction in prokaryotes. Chromosome attaches to
the cell wall and replicates while the cell continues to grow in size.
Genetic Recombination - Plasmids will carry genes that impart some benefit on the bacteria or
