BIOLOGY IS CONTAGIOUS
116 THINGS YOU NEED TO
KNOW TO PASS THE MCAS
BIOLOGY EXAM
Living things are mostly made of
the elements C,H,O,N,P, and S
Organic compounds contain carbon
Four important macromolecules are
carbohydrates, lipids, proteins,
and nucleic acids
Polymers are long chains of monomers
The monomer of a protein is an amino
acids
The monomer of a nucleic acid is a
nucleotide
A nucleotide consists of a sugar, a phosphate group, and a nitrogenous
base
The function of a carbohydrate is to provide a cell with
energy
Lipids store energy and are a
component of cell membranes and are
used to produce hormones
Proteins have a variety of functions in the cell and make
up muscles, hair, and nails
Nucleic acids store genetic information
for cells
Enzymes are proteins that speed
up chemical reactions (also
known as catalysts)
In a chemical reaction, reactants combine/change to
form products
Substrates fit into the active site of an enzyme like a “lock
in a key”
A substrate is a reactant in an
enzyme-catalyzed reaction
Enzymes work by lowering the
activation energy of a chemical reaction
Two things that affect enzyme function are
temperature and the pH(acid/base) of
a solution
Organelles are the parts of a cell
Prokaryotes do not have a nucleus; eukaryotes do
Plant cells contain cell walls, large vacuoles, and chloroplasts
Animal cells lack a cell well, never have
chloroplasts, and contain centrioles
DNA is found within the nucleus in a eukaryotic cell
Mitochondria produce energy (ATP) for cells
Chloroplasts are green and capture sunlight energy to
make sugar (glucose) for cells
The endoplasmic reticulum and the Golgi bodies work together to modify and ship proteins
Ribosomes are the site of protein
synthesis
The cytoskeleton gives the cell shape
and structure
The cell wall of a plant is made of a
carbohydrate (cellulose) and gives
plant their rigid shape
Cell membranes are found in all cells and
are made of a semi-permeable
lipid bilayer
Pump and channel proteins are also found in the cell
membrane
Active transport uses energy (ATP) to move molecules
from low concentration
to high conc.
Active transport requires protein
pumps
Facilitated diffusion uses protein
channels to move molecules from high
conc. to low conc.
Diffusion moves small molecules
through a membrane from high conc. to low
conc.
Osmosis is the diffusion of water
molecules through a semi-permeable
membrane
Photosynthesis: 6H2O +6CO2 + light C6H12O6 +6O2
(occurs in chloroplast)
Cellular Respiration: C6H12O6 +6O2 6H2O +6CO2 + ATP
(occurs in mitochondria)
Energy in a molecule of ATP is stored in the bonds between phosphate
groups
The stages of cell division (mitosis)
are prophase, metaphase,
anaphase, and telophase
Cytokinesis causes a cell to divide in two. Animal cells pinch,
plant cells assemble membrane and wall
Gametes (sperm/egg) are
made through a two rounds of reductive
division called meiosis
After mitosis, there is an equal number of chromosomes in each cell (diploid)
After meiosis, there is half the normal
amount of chromosomes in
each cell (haploid)
Fertilization is when sperm cells and egg cells join together
Crossing over in meiosis helps
increase genetic variation in offspring
DNA stores protein instruction in a
sequence of nitrogenous bases
called a gene
The sugar-phosphate
backbone gives the DNA molecule
structure
DNA is a double stranded molecule with a deoxyribose
sugar
A pairs with T and U ; G pairs with C
RNA is a single stranded molecule with a ribose sugar
RNA contains U instead of T
Three types of RNA: messenger,
ribosomal, and transfer
Replication is when DNA makes an
exact copy of itself
Transcription is when a gene is
copied onto mRNA
Translation is when the mRNA transcript
is used to make a polypeptide (protein)
Mutations can alter a DNA sequence, sometimes (not
always) causing a change in the
protein
The phenotype is what an organism
physically looks like
The genotype is what copies of a
gene an organism has
Alleles are different versions of a gene
Dominant alleles mask recessive
alleles
A heterozygous individual has two different alleles
A homozygous individual has two of
the same alleles
Blended phenotypes (red + white = pink) show that the alleles
are incompletely dominant
Mixed phenotypes (orange + blue = orange and blue) show codominant
alleles
Polygenic traits are controlled by more than one gene and
show a normal (bell) distribution
Evolution is change over long periods of
time
Natural selection states that the best adapted individuals will survive and pass
on their genes
Evidence for evolution is shown
in fossils, DNA sequences,
embryology, and homology
Genetic variation among organism
comes from crossing over and mutations
Speciation occurs when gene pools
become separated over long periods of
time
Organisms are classified by the
kingdom, phylum, class, order, family,
genus, species system
All organisms are descended with changes from an ancient, common
ancestor
Polygenic distribution curves
can undergo stabilizing,
disruptive, or directional selection
The three domains are eukarya, archea,
and bacteria
The six kingdoms are archeabacteria,
eubacteria, animalia, plantae,
fungi, protista
Evolutionary relationships are
based on DNA sequences NOT
physical appearance
The deeper in a rock layer a fossil is
found, the older that fossil is.
Population size is affected by birth
rates, death rates, and migration rates.
Limiting factors dictate the size of a
population
Carrying capacity is the maximum
number of individuals an ecosystem can
support
Ecological organization:
species – population – community –
ecosystem – biome - biosphere
Producers are autotrophs – they
make their own food
Consumers are heterotrophs – they
eat their food
A food web shows all of the feeding relationships in a
particular ecosystem
Energy arrows always flow from
the producers to the consumers
Only 10% of the available energy is transferred to the next trophic level
Herbivores are primary consumers
The main source of energy for living things is the sun
Carbon enters the biosphere through
photosynthesis
Carbon is returned to the atmosphere
by breathing (respiration) and the
burning of fossil fuels
Bacteria fix nitrogen gas into a form usable by living
organisms (nitrogen fixation)
Parasitic relationships involve
one organism benefiting and the
other organism suffering
Mutual relationships show a benefit for both organisms
Commensalism shows a benefit for one organism, and
no effect for the other
Homeostasis works via feedback loops
and maintains a constant internal
environment
Carbohydrates, fat, and protein are all
important sources of energy and nutrition
The stomach and mouth digest (break
down) food into smaller molecules
using enzymes
Nutrients are absorbed into the blood by the small
intestines
The kidneys filter waste materials out
of the blood
Blood is a suspension of red blood cells, white
blood cells, plasma, and platelets
Red blood cells carry oxygen, white
blood cells fight infection, and
platelets clot blood
The heart pumps blood throughout
the body
Veins carry blood to the heart (low oxygen) and
arteries carry blood to the body (high
oxygen)
Lungs contain tiny sacs called alveoli
Oxygen diffuses into the blood and carbon dioxide
diffuses out of the blood at the alveoli
Air enters the lungs via the trachea
(windpipe)
The bolus (mashed food and saliva)
enters the stomach via the esophagus
The nervous system allows the body to communicate and
coordinate functions
Neurons consist of a long axon, several
short dendrites, and a cell body
The endocrine system sends
chemical signals (hormones)
throughout the body
Muscles allow the body to move
There are three types of muscle: skeletal, smooth,
and cardiac
Red blood cells are made in bones
Bones provide structure and a site for mineral storage
Viruses are made of a protein coat and genetic material
(DNA/RNA). They are not alive!
Nerve use electrical impulses and
chemical (neurotransmitters)
to communicate