MCAT Biology Study Questions
These are questions I came up with when I was studying for the MCAT.
On this page :
Also, see MCAT Physiology Study
MCAT is a registered trademark
of the Association of American Medical Colleges, which is not affiliated with
this web site.
- In eukaryotes, where do the following take place : glycolysis, Krebs
cycle, electron transport, beta-oxidation of fatty acids, fatty acid
synthesis, gluconeogenesis, phospholipid production, transcription,
- What is the original substrate of glycolysis? How many ATP are
invested originally? What is the net return in ATP?
- What is the main product of glycolysis? How many are produced?
How many carbon atoms does this molecule have?
- What is the structural difference between pyruvate and lactate?
- What determines whether pyruvate will enter the TCA cycle or be converted
- What is NADH commonly used for? What is NADPH commonly used for?
What are the differences between the two?
- What does the Krebs cycle do? What are some synonyms for this cycle?
What molecule does Acetyl CoA combine with to form citrate?
- What is the difference between succinic acid and succinate?
- How many carbons does citrate have? How many does oxalacetate have?
What happens to the carbons?
- What is a decarboxylation reaction? When does it occur? What
does it produce? Does the reverse ever happen in the human body?
If so, when? If not, why not?
- What is the backbone of trigylcerides? How many carbons does it
- In humans, can acetyl-CoA be converted into glucose via gluconeogenesis?
If not, why not? If so, how?
- What are enzymes made of? What are ribozymes made of?
- What do enzymes do? How do they do this? Do they change the
equilibrium constant of a reaction? Do they affect the activation
- Can the same enzyme catalyze both forward and reverse reactions?
- What are substrates? Are enzymes specific for substrates?
- What are 'Standard Physiological Conditions' (concentrations,
- What formula does one use in calculating the standard biological free
energy change from the standard potential?
- What is the difference between competitive inhibition, non-competitive
inhibition, and uncompetitive inhibition?
- What type of inhibition experiences saturation kinetics?
- What does allosteric mean?
- What is feedback inhibition?
- What are the components of a nucleotide? A nucleoside? Which
- What type of nucleic acid are the following used to build : ATP, GTP, CTP,
- What type of nucleic acid are the following used to build : dATP, dGTP,
- Which sugar is used in RNA? in DNA?
- How are members of a nucleotide sugar ring numbered? What about the
- What is the difference between phosphate and phosphorus?
- If ATP loses a pyrophosphate, what are the products?
- If ATP loses an inorganic phosphate, what are the products?
- What is the difference between the DNA replication and transcription in
eukaryotes? When in the cell cycle does each occur?
- What occurs during the S phase of the cell cycle?
- What is meant by "semi-conservative replication"?
- What is a cofactor? What is a coenzyme? What are prosthetic
- What is the common name for Vitamin B1? Vitamin B12? Vitamin
- Pantothenate is the vitamin precursor for what coenzyme?
- What are transcription factors?
- What is the TATA box?
- How are primary RNA transcripts modified before leaving the eukaryotic
nucleus? (three main modifications)
- What is the difference between a calorie and a nutritional calorie?
- What do tRNAs do? What eukaryotic structure is responsible for rRNAs?
- On what molecules are anticodons located?
- Are prokaryotic and eukaryotic ribosomes the same?
- What is a stop codon? What is the code?
- In what direction are new strands of DNA or RNA created? In what
direction on the template are these new strands created?
- What are Okazaki fragments? Are they associated with the leading or
- What is DNA helicase? What does it do? What does DNA gyrase
do? What does DNA ligase do?
- What are three three types of RNA polymerases in eukaryotes? What
type of RNA do each transcribe?
- What is the difference between DNA and RNA? What type of parasite
might one find double stranded RNA?
- What is the difference between dATP and ATP? What about the
difference between AMP, ADP, and ATP?
- What type of DNA error correction is done during DNA replication?
What enzyme is responsible for this?
- What is GTP?
- What is substrate phosphorylation? What is oxidative phosphorylation?
- What is a synthase? What is a synthetase?
- What is a phosphorylase? kinase? phosphatase?
- What is the difference between inorganic phosphate and pyrophosphate?
In what type of reaction is pyrophosphate released?
- What is the difference in the molecular structures of uracil and thymine?
- How does methylation affect transcription?
- What is a point mutation? What is a transversion mutation?
What is a transition mutation?
- Adenine binds with what other nitrogenous base? What type of bonds
- What is a purine? How many rings does it have? What is a
pyrimidine? How many rings does it have?
- The number of cytosine in a set of double stranded DNA is equal to the
number of what other base?
- What is complementary DNA? How does it differ from regular DNA?
What is reverse transcriptase?
- Which of the two sets of base pairs are more likely to separate : G&C or
- What type of nitrogenous base is guanine? cytosine? adenine?
- What is the difference between pyrimidine and pyridine?
- What are frame shift mutations? What are nonsense mutations?
- What are deletions? inversions? translocations?
- cAMP is produced by what enzyme? What trigger this enzyme?
What does cAMP concentration affect? What breaks down cAMP? What
is the biochemical effect of caffeine?
- What is a trimeric G-protein? What activates it? What
- What can cause neighboring pyrimidines to dimerize? What can repair
- What is the G0 phase? In what other phase is it located?
- What does coenzyme A do?
- In what stage of metabolism is carbon dioxide produced?
- In what stage of metabolism is oxygen consumed? What happens to the
- What is irreversible inhibition?
- What is an agonist? An antagonist?
- What ultimately happens to the amino nitrogens in amino acids?
- Why are a number of the amino acids considered "essential"? What
does it mean to be "non-essential"?
- What is a codon? Is the code for translation ambiguous? Is the
code for translation degenerate?
- What is the role of the rough endoplasmic reticulum in translation in
eukaryotes? What is the role of the Golgi apparatus?
- What is the difference between glycogen and glucose? Where in the
body is glycogen found?
- What types of biomolecules can the brain utilize for energy? What
are ketone bodies? Who is most likely to produce ketone bodies?
- Where does oxidative phosphorylation occur? Across what is the
proton gradient established?
- What is an ATPase? Where are these commonly found?
- Which produces the most energy/gram in metabolic processes : fats, sugars,
- What type of biomolecules are the main lipid component of the cell
- Which part of the cell membrane is non-polar? How does membrane
cholesterol affect passage through the membrane?
- What is anabolism? What is catabolism?
- Where does photosynthesis occur in eukaryotes? In prokaryotes?
- Do plant cells have mitochondria? Do red blood cells have
mitochondria? Do brain cells have mitochondria?
- Does an spontaneous reaction have a positive or negative change in Gibbs
free energy? What about potential?
- What is a zymogen? How are they activated?
- What happens to ethanol in the liver?
- What does the cytochrome P450 enzyme system do?
- What is the difference between the terms HISTIDINE, HISTAMINE, and HISTONE?
- How might a change in pH cause protein to settle out of solution?
- What is the difference between adenine and adenosine?
- What is the difference between thymine, thymidine, and thiamin?
- What are restriction enzymes? How are these used in recombinant DNA?
- What are "inborn errors of metabolism"? What is phenylketonuria?
- What is a lipid bilayer? What is between layers?
- What is active transport? What is passive transport? To which
group does facilitated diffusion belong to?
- What is the difference between primary and secondary active transport?
- What types of molecules can freely diffuse through the lipid membrane?
What types must be "carried" through?
- How do lipid soluble hormones behave differently than water soluble
- What is the significance of the phosphate group in phospholipids in cell
- What is an integral protein?
- What type of biomolecule(s) are receptors?
- How does cholesterol in the membrane affect its fluidity?
- What do ribosomes do? Of what types of biomolecules are ribosomes
- What is the term for the nuclear structure that produces ribosomes?
- Do bacterial cells have ribosomes? Mitochondria?
- How many membranes do mitochondria have? What is the inner
compartment of mitochondria called?
- Where in mitochondria is the high proton gradient established during the
electron transport chain? To where do the protons diffuse?
- What does the Golgi apparatus do? What does the cis side face?
What does the trans side face?
- What is a vacuole? What is a lysosome? What is a peroxisome?
- What does endocytosis mean? What does transcytosis mean?
- What is pinocytosis? What is phagocytosis? What are some
examples of phagocytes?
- How do viruses enter cells? How does glucose enter cells? How
do ions enter cells?
- What is the difference between the rough ER and the smooth ER? Which
is associated with lipid production? Which is associated with
- How many membranes does the ER have? how many do mitochondria have?
- What triggers a ligand-gated ion channel? a voltage-gated ion
- What are inclusions?
- How many membranes does the nucleus have?
- Is an organism with more than one nucleus per cell more likely to be a
fungus or a bacterium?
- What is the cytoskeleton? What are microfilaments? What are
microtubules? What are intermediate filaments? Which are the
- What is the sarcolemma? In what type of cell is this found?
- What does the concentration of potassium inside a cell usually compare
with outside of a cell? sodium? chloride? anionic proteins?
- What is meant by resting membrane potential?
- What is the sodium-potassium pump? What is the ratio of ions
transported? What does it use as a fuel? Is this responsible for
the repolarization of a cell in the short term?
- What is the difference between apoptosis and necrosis?
- Do animals have cell walls? Do plants? Do fungi? Do
- What is the difference between the Protista and the Sandinistas?
Which would you rather have living in your GI tract? Does Nicaragua have
anything to do with the MCAT?
- What is antiport? What is symport?
- What are the main types of tissues?
- In epithelia, what is the luminal side? What is the basolateral
- What is the basal lamina? What is meant by basement membrane?
Is this acellular?
- What is a tight junction? What is a gap junction? What is a
desmosome? What is a hemidesmosome?
- What does hypertonic mean? How is this often used differently than
- What is the difference between cellulose and celluloid?
- What is chitin? What type of organism is chitin often found?
How is chitin pronounced? (not that useful for MCAT)
- What is dynein? What is kinesin? What is tubulin?
- In what part of cell division are microtubule used? actin filaments?
- What is the order of the stages in mitosis?
- What is the difference between the terms CHROMOSOME, CHROMATID, and
- What is the difference between the terms NUCLEUS, NUCLEOSOME, NUCLEOID,
- What are nucleosomes made of?
- What is chromatin made of?
- What is the difference between centromeres and telomeres? What is
the significance of telomeres?
- What does the kinetochore do? To what does it attach?
- What are spindles? What are asters? How are centrioles used in
- When during mitosis does the nuclear membrane break down? Why does
this occur? When does it reform?
- What is interphase? At what interphase stage is DNA replicated?
- What interphase stage represents "growth arrest"? What causes a cell
to stop growing? Why is this important? What role might this play
- What is usually being referred to by the term "9+2"?
- Where is the vast majority of ATP produced in animal cells?
- What is the structure of a bipolar neuron? What about the other two
main types? Where are they usually found?
- What are glial cells? Where are they found?
- What is the extracellular matrix?
- What is hydroxyapatite? What minerals is it composed of? Where
is this substance found?
- What are adipocytes?
- What is meant by areolar connective tissue?
- What type of tissue is blood?
- Where are transitional epithelia cells found?
- What type of tissue(s) are glands?
- What is meant by mucous membranes?
- Can non-neuron cells have action potentials?
- Do blood cells have ribosomes? Do bacteria cells have ribosomes?
- What is keratin? Where is it found?
- Does a neuron have more DNA than an epithelial cell? Does an
epithelial cell have more DNA than a red blood cell? Does a red blood
cell have more DNA than a white blood cell?
- What is the difference between paracrine and autocrine?
- What is the difference between apocrine and eccrine sweat glands?
Which one causes body odor?
- What is chemotaxis?
- What is a second messenger? What is a first messenger? What is
a phosphorylation cascade?
- What type of protein usually activates adenylate cyclase?
- What is the difference between hypertrophy and hyperplasia?
- What type of cytoskeleton component is used in animal cell cytokinesis? In
the separation of chromosomes in mitosis?
- What are two important functions of actin?
- How might the cell cytoskeleton function in cell movement?
- How are microtubules used to transport cargo in a cell? What serves
as a motor? What significance is the polarity of microtubules?
- What is an axoneme?
- What are centrioles? Where are they found? What is the
microtubule organizing center?
- What is the main type of cell in the human body that lacks organelles?
What are the implications of this? What is the average lifespan of this
- What are the main places, macroscopically, that one finds cilia/flagella
- What are oncogenes? How do they contribute to cancer?
- What is the nuclear envelope? What are the nuclear pores?
- What is meant by fluid mosaic model? What types of molecules make up
the cell membrane?
- What is membrane potential? What establishes this potential?
What is an electrochemical gradient? On what two factors is it dependent
- What is the bacterial cell wall made out of?
- What are the structural differences between Gram positive bacteria and
Gram negative bacteria? What colors are they in the Gram stain?
- Do prokaryotes have a nucleus? Do they have mitochondria? Do
they have ribosomes? Do they have organelles? Do they have
- What shape are cocci? What shape are bacilli?
- Do bacteria undergo mitosis? If so, when? If not, why not?
- What differences between prokaryotes and eukaryotes do antibiotics
- In a healthy individual, do bacteria normally reside on the skin? In
the large intestines? In the mouth? In the stomach? In the
kidneys? In the abdominal cavity? In the pleural cavity? In
the blood? In the nose? In CSF?
- What other types of relationships between bacteria and host (besides
parasitic)? How do certain non-pathogenic bacteria in the GI system help
prevent an infection? What types of nutritional services are provided by
- About how big is the average bacterium, in micrometers? About how
big are mitochondria (in eukaryotes)?
- What are obligate anaerobes? What do aero-tolerant bacteria
have that obligate anaerobes do not?
- What are obligate intracellular bacteria? What are facultative
- How many chromosomes does a typical prokaryote have? What do
bacterial chromosomes look like? Are they double stranded or single
- What are the three mechanisms of genetic material transfer among
- What is a plasmid? How are plasmids exchanged? What types of
genes are commonly found on plasmids?
- What is the difference between bacterial capsules and bacterial cell
walls? How many lipid membranes do Gram positive bacteria have?
How many in Gram negative bacteria?
- E. coli is commonly found in what part of the body? What do E. coli
look like in a Gram stain?
- What is a "vegetative state"? What is a bacterial spore?
- What, generally speaking, is a virulence factor?
- What are exotoxins? What are endotoxins? What is another name
for the common endotoxin? What type of bacteria (Gram stain) have
endotoxin? When are each of these types of toxins usually released?
- What is a culture? What is a tissue culture? What is agar?
Of what use is sheep blood agar?
- Which bacteria employ photosynthesis? Do they have chloroplasts?
Do they have mitochondria?
- Do bacteria have hemoglobin? Myoglobin? Why or why not?
- What are archaebacteria? What are eubacteria? Are eubacteria
eukaryotes or prokaryotes?
- What is designated by the term MONERA?
- What is catalase? Do all bacteria have catalase? What
does catalase protect against?
- What is an operon?
- At how many sites on a bacterial chromosome does replication begin?
- How is prokaryotic DNA polymerase different than eukaryotic DNA
polymerase? Do prokaryotic DNA polymerases use Roman numerals or Greek
letters to set them apart?
- How is prokaryotic RNA polymerase different than eukaryotic RNA
polymerase? How many different types of prokaryotic RNA polymerases are
- Do bacteria produce mRNA? tRNA? rRNA? Do they have an
exon splicing system? Do they perform post-transcriptional modification
- What is the difference between the terms nucleoid, nucleus, and nucleolus?
- Do bacterial cells have nuclear pores?
- Are all prokaryotes unicellular organisms? Are all unicellular
- Can bacteria be infected by viruses? If so, what type? If not,
- What are reactive oxygen species? What molecules serve as examples
- Does bacterial RNA use thymine or uracil?
- Do bacteria use ATP? If so, how do they get ATP? If not, what
do they use?
- Can bacteria produce proteins? Can they replicate on their own
without a host?
- Is strep throat caused by bacteria? Is the common cold?
malaria? the flu? anthrax? syphilis? a yeast infection? tetanus?
toxic shock syndrome? cyanide poisoning? cholera?
- Is it possible to get sick from bacteria without being infected?
- What is the difference between cloning and PCR? What is so special
(useful) about the bacteria called "Taq"?
- What is the difference between a bacterial cell wall and a plant cell
- Who has a bigger cell wall: bacterial cells or animal cells?
- Can bacteria live inside eukaryotic cells? If so, how do they get in
there? If not, why not?
- Can bacteria live underwater? Do they have lungs? Do they have
- Do bacterial proteins use the same amino acids as humans? Do all
organisms use approximately the same code for translating RNA into DNA?
- Of what significance is f-Methionine in bacterial translation? What
is the corresponding eukaryotic amino acid?
- What are pyrogens? Who produces them?
- What is toxic-shock-syndrome-toxin? How does it affect blood
- What are the similarities between mitochondria and prokaryotes? If
mitochondria were derived from prokaryotes, where did the outer mitochondrial
membrane come from?
- Is a bacteriophage a prokaryote? What is the general structure of a
- What is transduction? What serves as the DNA carrier?
- Can bacteria exhibit motility? If not, why not? If so, by what
- What is binary fission? How is it different than analogous
- How would bacterial growth best be described (in terms of entire
- What makes bacteria very genetically adaptable?
- What is the difference between autosomal and sex-linked?
- How many chromosomes does the human cells have? What is the haploid
- How do chromosomes determine the sex of an individual? Is an
individual with two X chromosomes and one Y chromosome male or female?
How about an individual with a single X chromosome?
- The vast majority of sex-linked genes are found on what chromosome?
- What is the difference between HOMOZYGOUS, HETEROZYGOUS, and HEMIZYGOUS?
- How are X-linked recessive traits passed? Can a father pass it to a
son? Can a mother pass it to a son? Can a father pass it to a
daughter? Must a father pass it to a daughter? Can a mother pass
it to a daughter?
- What is usually meant by "carrier"? Do these people show the trait?
- Which gender is more likely to show the traits of a sex-linked recessive
genetic disease? Why?
- If a person inherits and exhibits an autosomal dominant disease (not due
to a recent mutation), must at least one of the parents show the disease?
- Are mutations in germ cells passed on to the next generation? Are
mutations in somatic genes passed on to the next generation?
- What is meant by euploidy? What is aneuploidy? What is meant
- Which human cells are haploid? How are they created?
- What is the difference between mitosis and meiosis? What are the
products of each?
- What is trisomy? What is monosomy? Which three trisomies can a
human have and survive past birth?
- What is Turner's syndrome? What is Klinefelter's syndrome? How
many chromosomes does a person with Turner's syndrome have? How many
chromosomes with Klinefelter's syndrome?
- What is nondisjunction? Where and when does it often happen?
- What two events contribute to genetic recombination?
- During what specific phase of meiosis does crossing-over occur?
- What are dihybrids? An organism that is homozygous dominant for two
traits that mates with someone that is homozygous recessive for both traits
will produce what type of offspring?
- What is a test-cross?
- What is codominance? What is incomplete dominance? What is
meant by "leakage"?
- What is PCR? What is required to use it? How is it used
clinically? Where do the heat-stable enzymes come from?
- What is the difference between phenotype and genotype?
- What are sister chromatids? When are they not equivalent?
- What are homologous chromosomes? When are they paired?
- What is a recombination frequency? How is it calculated? How
can it be used to determine the relative locations of genes on a chromosome?
What is the highest possible value? What is a centimorgan?
- What is meant by the term "linkage"? What are crossovers? What
- What are transposons?
- Does the DNA differ significantly for different types of cells in an
organism? What about mRNA?
- How is mitochondrial DNA inherited primarily?
- What is the difference between a gamete and a zygote?
- What is genetic epistasis?
- What is penetrance? What is expressivity?
- What condition is necessary for the law of independent assortment to apply
to two genes?
- What is an allele? What is a gene? What is meant by locus?
- When (in the cell cycle) does nuclear DNA replication occur? (answer
is NOT mitosis)
- When (in the cell cycle) do chromosomes condense?
- What is polymorphism? Can multiple (>2) alleles exist?
- What is a gene pool?
- What can cause mutations? Can mutations "just happen"? Can
mutations be beneficial? Can mutations be harmful?
- What is a reverse mutation?
- What is the significance of an error replicating DNA versus an error
transcribing DNA? Which will have a greater effect?
- What is meant by "parental generation"? What is F1? What is
- On a pedigree, how are males represented? How are females
represented? How are children represented?
- What is the formula for Hardy-Weinberg equilibrium? What do the
- What are the conditions required for Hardy-Weinberg equilibrium?
- What is the difference between GENETIC DRIFT and GENE FLOW?
- What is meant by "selection pressures"? Are they responsible for
- What is meant by evolutionary "fittest"?
- What is the founder effect? What is a bottle-neck?
- What is speciation? What is the definition of a species? Can
two different species mate and produce fertile offspring?
- What is parthenogenesis?
- What is referred to by CHORDATE? What are the common characteristics
of a chordate?
- What is the significance of a dorsal nerve cord?
- What are the different classes of vertebrates?
- What is a kingdom? What kingdom are humans in?
- What is a phylum? What phylum are humans in? What subphylum
are humans in?
- What is a genus? What is the plural for genus? Is the genus
- What is a species? Is the species name capitalized?
- What is meant by "homologous structures"? What is meant by
- What is the difference between a bat and a bird?
- What is the difference between a shark and a whale?
- What is divergent evolution? What is convergent evolution?
- What is meant by "bilateral symmetry"? What is meant by "axial
- Can behavior be encoded genetically?
- What are circadian rhythms?
- What is nitrogen fixation? What organisms are chiefly responsible
- What is meant by symbiosis? What is parasitism? What is
- What are fungal spores? Are they diploid or haploid? Is this
usually part of asexual or sexual reproduction?
- Do fungi live most of their lives in a haploid or diploid state?
When do they switch?
- What is a unicellular fungus commonly called?
- Do fungi have cell walls? Do they have a nucleus? Do they have
multiple chromosomes? Are they photosynthetic?
- How is evolutionary success measured in relation to a population?
- What is an ecological niche?
- What is meant by "Ontogeny recapitulates phylogeny?" What do each of
these terms mean? Is this an accepted belief?
- What is inbreeding? What is outbreeding? Which offspring has a
greater chance of expressing recessive traits?
- What is meant by the term "instar"?
- What is meant by the following terms : larva, pupa, molting?