MCAT BIOLOGY COMPLETE STUDY
GUIDE WITH PRACTICE QUESTIONS AND
VERIFIED ANSWERS| GRADED A+ |
GUARANTEED SUCCESS
Updated 2026 Questions and Answers | 100% Verified
Exam Prep and Comprehensive Rationales Included
,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.
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 large amount of tension, adding rigidity to the cell structure. They help
anchor other organelles!
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 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 purple
What color is it? thick later of peptidoglycan (aa + sugar)
Is there a thick or think cell wall (peptidoglycan)? It aids a pathogen by providing protection from a host organism's immune system.
What does the cell membrane contain? 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.
GUIDE WITH PRACTICE QUESTIONS AND
VERIFIED ANSWERS| GRADED A+ |
GUARANTEED SUCCESS
Updated 2026 Questions and Answers | 100% Verified
Exam Prep and Comprehensive Rationales Included
,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.
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 large amount of tension, adding rigidity to the cell structure. They help
anchor other organelles!
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 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 purple
What color is it? thick later of peptidoglycan (aa + sugar)
Is there a thick or think cell wall (peptidoglycan)? It aids a pathogen by providing protection from a host organism's immune system.
What does the cell membrane contain? 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.
