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Biology Review Notes
What is Biology?
 Bio = life, -Logy = the study of
 Biology is the study of living things and their surroundings
 Organism = a living thing; anything possessing the characteristics of living things.
 Characteristics of living things:
o All living things grow and develop.
o All living things reproduce.
o All living things are organized.
o All living things adjust to their surroundings (adapt).
o All living things need energy (ATP).
o All living things are made up of cells.
o All living things contain genetic material (DNA).
 Reproduction = organisms making more of their own kind, making offspring.
 Offspring = babies, when organisms reproduce they produce offspring
 Growth = organism gets bigger
 Development = organism changes shape or form. It develops new structures.
 Metamorphosis = type of development where an organism makes a very big change in
shape or form. Ex: tadpole to a frog; caterpillar to a butterfly.
 Environment = organism’s surroundings, both living and nonliving.
 Adaptation = physical change that arises in an organism over time through the
process of evolution.
Adaptations can be physical (webbed feet of ducks to swim) or behavioral (changing
colors to blend in with surroundings)
Animals adapt (thick fur for polar bear to keep warm) but plants also adapt (thorns
for protection from predators, stop photosynthesis when not enough light or water).
Organization:
 All living things are organized in the following way:
o atoms molecules  cell parts  cells  tissues organs  organ system 
organisms
(smallest to largest)
Homeostasis:
 Homeostasis = an organism remaining constant in a changing environment; maintaining
a stable, internal environment
 Every organism tries to regulate how much of each chemical is present in it. They try
to keep the level or the amount constant or the same. TOO much or TOO little is
bad!
o Ex: body temperature = 98.6; too cold or too hot is bad and that is why we
sweat or shiver to maintain that 98.6
Scientific Method:
 Independent variable = the part of the experiment that is changed or manipulated in
the beginning (I change the IV)
 Dependent variable = the part of the experiment that is different at the end; the
part that is measured at the end. (DV = Data)
 Constants = conditions in an experiment that are the same for every group.
 Control = the group that is kept under normal conditions or that is not being tested.
 Hypothesis = prediction. Testable sentence. Usually in If….Then format.
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Experiment = procedure done to test a hypothesis.
Quantitative data = data that can be counted or measured, numbers
Qualitative data = data gathered by observing qualities, descriptive
Ecology:
Organism, population, community, ecosystem
 Biotic factors: living parts of the environment
 Abiotic factors: nonliving parts of the environment
 Symbiosis: two organisms living together
 Mutualism: relationship where both species benefit
 Parasitism: relationship where one species benefits, the other is harmed
 Commensalism: relationship where one species benefits, the other is unaffected
 Producer autotroph makes own food using sun’s energy
 Herbivore: eats only plants, primary consumers
 Carnivore: eats only animals, secondary consumers
 Omnivore: eats both plants and animals
 Decomposer recycles nutrients from dead organisms
Food chain simple linear path showing energy transfer; arrow points to the eater
Food web network of food chains, like energy pyramid have producers at bottom
Energy pyramid larger at base (need more producers to support all consumers in
ecosystem), fewer energy and organisms at top, toxins accumulate as move up pyramid
Cycles:
Water: evaporation and transpiration, condensation, precipitation, runoff
Nitrogen: nitrogen fixing bacteria on roots  plants  animals  decomposers,
needed for proteins and nucleic acids
Carbon: plants  animals  decomposers, fossil fuel burning adding CO2 to
atmosphere leading to greenhouse effect
Biomes:
Tundra: cold, dry, permafrost, animals migrate, low and small vegetation (plants)
Taiga: cold, evergreen trees, animals migrate and have thick fur
Decidious Forest: moderate temp and precipitation, trees lose leaves in fall
Desert: usually hot, dry, animals active at night (nocturnal), plants store water in stems
Rainforest: hot, wet, lots of vegetation and most biodiverse
Grassland: grasses dominate, average temp and precipitation
Aquatic: marine (saltwater), freshwater, estuary (fresh and salt water mix= brackish)
Animal Behavior:
Anything an animal does in response to a stimulus
 Innate: born knowing how to do (breathing, swallowing)
Taxis: animals moving toward stimulus (ex. Moths move to porch lights)
Instinct: performed perfectly without learning (ex. Duck retrieving egg)
Reflex: simple automatic response (ex. Blinking)
Migration: seasonal movement
Hibernation: dormancy during cold
Estivation: dormancy during extreme heat
Fight or flight: stressful situations
 Learned: behavior that changes through practice or experience
Habituation: decreased sensitivity to repeated stimulus (ex. Horses afraid of
car noise but learn to avoid it)
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Imprinting: very young animals form social attachment to mothers
Conditioning: training responses for one stimulus to be associated with
another (ex. Ringing bell and dogs come running for food)
Trial and error: repeat desired behavior that receives reward (ride bike)
Social Behavior: interactions among organisms of same species, usually innate and
provide advantages for survival of species rather than individual
Courtship: mating rituals to attract partner
Communication: using pheromones (ex. Ants leave trail for others to follow)
Biomolecules- molecules that help to make up cell parts, cells, and living things.
Organic Molecules - any molecule that contains some carbon (c). ALL of the biomolecules
are organic.
The FOUR biomolecules:
 Carbohydrates
o Composed of C, H, and O
o Examples include pasta, bread, and many vegetables
o Store and release quick energy
o Structural support in plants
o Monosaccharides, disaccharides, polysaccharides (ex. Cellulose, starch, glycogen)
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Lipids
o Composed of C, H, and O
o Building block (subunit) is glycerol and 3 fatty acids
o Examples include fats, oils, waxes, and steroids
o Long-term energy storage, insulation, protective coatings
o Major part of the cell membrane
o Made in the smooth ER
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Proteins
o Composed of C, H, O, and N
o Building block (subunit) are amino acids, held together by peptide bonds
o Helps with muscle contraction
o Transports oxygen in blood
o Examples include tuna, meat
o Carries out (speeds up) chemical reactions (enzymes)
(enzyme and substrate have lock and key fit at active
site, enzymes can be used over and over because
unchanged by reaction, high temperature and extreme pH
can denature enzyme so it can no longer function)
o Made in ribosomes and rough ER
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Nucleic Acids
o Composed of C, H, O, N, and P
o Building block (subunit) is a nucleotide: sugar, phosphate, nitrogen base
o Examples include DNA and RNA
o Stores genetic information in cells in the form of a code
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Biochemistry
 pH scale
o Scale that determines how acidic (H+) or basic (OH-) a substance is
 Acid: pH of 1-7
 Base: pH of 7-14
 Neutral: pH of 7
Buffers: help reduce sharp sudden changes in pH in living things by acting as weak
acid or base as needed
 Properties of Water
o Expands when freezes: Causes ice to float, forms soil by cracking rocks, lakes do
not freeze solid
o Resists temperature change: keeps organisms’ environments stable, oceans keep
earth warm enough for life
o High heat of vaporization: high energy needed to evaporate; helps body cool
through sweating
o Capillary action: can creep up thin tubes for movement and transport
o High surface tension: molecules stick together
 Osmosis/Diffusion: movement of water (particles) in and out of a cell
o Hypotonic: higher concentration of water OUTSIDE the cell; cell will swell
o Hypertonic: higher concentration of water INSIDE the cell; cell will shrink
Other methods of transport:
Passive transport: no energy, high to low concentration, ex. Osmosis and diffusion
Facilitated diffusion: passive transport with help of transport proteins
Active transport: uses energy, low to high concentration, ex. Pinocytosis (cell
drinking) and phagocytosis (cell eating)
Cells
Important cell scientists:
1. Hooke: Looked at cork (dead cells), came up with term “cell.”
2. Leeuwenhoek: Invented the microscope. First to look at living cells.
3. Schleiden: studied plant cells.
4. Schwann: studied animal cells (schwann sounds like swan).
5. virchow: first to see cells divide under the microscope.; therefore concluded that
cells only come from other cells
The Cell Theory: (based on discoveries made by Schleiden and Schwann)
1. all living things are made of cells. (this is why viruses are NOT living)
2. all cells come from pre-existing cells.
3. cells are the basic unit of organization of life.
Prokaryotic
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cells:
primitive, small, NO organelles or nucleus, circular DNA is in the cytoplasm
first cells on earth were prokaryotic
bacteria are this type of cell
Archaebacteria and Eubacteria = two prokaryotic kingdoms
Eukaryotic Cells:
 Advanced cells, larger than prokaryotic cells, linear DNA in nucleus
(chromatin), has organelles
 Plants, animals, fungi, and protists are made of this kind of cell.
Endosymbiont Theory:
 Big cell ate little cell and kept it around to do work. Little cell became an
organelle.
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Evidence for theory:
 Mitochondria: most scientists believe that they were once aerobic
bacteria.
 Chloroplast: most scientists believe that they were once cyanobacteria
or blue green algae.
Cell Parts:
cell membrane: semi-permeable membrane surrounding all cells; allows materials to enter and
leave the cell, made of lipid bilayer and proteins and cholesterol
cell wall: additional boundary of plant cells providing structural support, made of cellulose
cytoplasm: clear, gel-like fluid inside of a cell, where important chemical reactions take
place
ribosomes: where proteins are made in the cell
ER: folded system of membranes for transport of materials through a cell
Smooth: no ribosomes, makes lipids
Rough: has ribosomes, makes proteins
golgi apparatus: flattened stack of membranes for packaging and sorting proteins
vacuole: storage of food and water
lysosome: digests food and old cell parts
mitochondria: produces ATP (energy) for the cell; powerhouse
chloroplast:: transforms sunlight into glucose (food) in plant cells
nucleus: stores DNA, control center or brain of the cell
nucleolus: region within the nucleus that produces ribosomes
cytoskeleton: internal support system; made of microfilaments and microtubules
unicellular: organism made of one cell
multicellular: organism made of more than 1 cell
centriole: used for cell division in animal cells
flagella: long projections used for movement by cells
cilia: short, hair-like structures used for movement by cells
Plant Cells:
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Plant cells have chloroplasts and cell walls; animal cell
do NOT
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Plant cell do NOT have centrioles
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Vacuoles in plant cells are HUGE for storage
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Plant cells are usually rectangular or square in shape due to cell
walls
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Plant cells cannot pinch in to divide. Instead they must construct
a cell plate to divide the two new cells.
Animal Cell:
 Animal cells have centrioles, plants do
NOT
 Animals cells do NOT have cell walls or
chloroplasts
 Use centrioles for cell division
(mitosis/meiosis)
Biomolecules and Cells:
 Cell membranes are made of phospholipids, which are a type of lipid.
 Cell walls are made of cellulose, a polysaccharide, which is a carbohydrate.
 Cytoskeleton, centrioles, and ribosomes are made up of structural proteins.
 Proteins are made in the ribosomes and rough er.
 Lipids are made in the smooth er.
 DNA, which is a nucleic acid, is stored in the nucleus.
 RNA, which is a nucleic acid, is a copy of DNA, which carries the genetic code
from the nucleus to the ribosome during protein synthesis.
Cell Differentation:
 This is the process where cells in multicellular organisms become specialized or
different. These cells differentiate into cells that do very different jobs. All cells
of individual organism have same DNA but different genes are turned off/ on in
different cells for different functions.
Cell Energy:
 Photosynthesis:
o Happens in plants in chloroplast, two parts to chloroplast: stroma and
thylakoid (grana)
o Chorophyll in plants catches sunlight energy and uses this energy to make
glucose sugar
o Plants need carbon dioxide and water to do photosynthesis
o 6 CO2 + 6 H2O + sunlight → C6H12O6 +6O2
o 2 steps: light reactions use water and light to make oxygen, occurs in
thylakoid
Dark reactions (Calvin cycle) use carbon dioxide to make glucose,
occurs in stroma
o Desert plants adapt to dry conditions: CAM plants open stomata at night
when transpiration rates are slower or close them completely when no water(
become idle= no photosynthesis) ex. cactus. C4 plants photosynthesize rapidly
when hot and dry so stomata open not as long during the day to conserve
water
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Cell Respiration:
o ALL living things do respiration! Even plants, when they have no light!
o happens in mitochondria. Breaks down glucose sugar to make energy or ATP.
o Mitochondria need oxygen and glucose to do respiration
o C6H12O6 + 6O2 → 6CO2 + 6H2O + 36 ATP
o First step is always glycolysis which makes 2 ATP, happens in cytoplasm
o Second step depends on presence of oxygen
If oxygen present: Krebs cycle and electron transport chain make 34 ATP,
water, and CO2
If no oxygen: anaerobic respiration (Fermentation) occurs and makes lactic
acid in muscles and carbon dioxide and alcohol by yeast, also makes 2 ATP but
not enough to Sustain life
Reproduction: asexual (one parent makes identical offspring) or sexual (two parents make
offspring with traits of both parents= hybrid)
Mitosis: asexual reproduction of body cells
Interphase—Mitosis—Cytokinesis (IPMAT)
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Interphase: normal part of cell, DNA and organelles are copied/replicated
Prophase: DNA is wound up into chromosomes, centrioles move to opposite sides of
the cell, nuclear membrane disappears, spindle fiber form.
Metaphase: chromosomes line up at the middle, spindle fibers attach to centrioles.
Anaphase: chromosomes pulled to opposite ends/sides of the cell
Telophase: chromosomes in opposite sides, nucleus reforms, cell splits
Centrioles: only in animal cells, spindle fibers come from these.
Chromosomes: made of DNA, carry genes, neatly packaged, 2 sister chromatids held
together by centromere
Chromatin: DNA unpackaged or unwound, how DNA exists during interphase
Spindle Fibers: pieces of cytoskeleton that attach to chromosomes and pull them to
opposite sides of the cell in mitosis.
Centromeres: dot that holds copies of chromosomes together. Spindle fibers attach
to these.
Mitosis: cell division in body cells
Cytokinesis: when the cytoplasm divides, cell actually splits
Plant cells: can’t pinch due to cell wall, they form cell plate. They also do not have
centrioles.
Cells can NOT be huge/large because:
o Surface area to volume ratio, not enough doors to support in and out traffic
o Only one copy of DNA to share, like building a skyscraper with 1 set of blue
prints
o Diffusion is too slow, oxygen cannot get to the middle of the cell
 Cells divide for growth, reproduction, development, to replace dead or dying
cells, and to repair injuries
 Cancer results when cells divide uncontrollably and can be due to genetic and
environmental factors (smoke, sun’s radiation)
 Stem cells: capable of becoming any cell type, can be used to treat injury and
disease, controversial and ethical issues arise when used from embryonic tissue
Meiosis: (division of sex cells)
Meiosis is the cell division that is done to make gametes
Gametes are the sperm, egg, or pollen
Gametes only have 1 copy of each gene and 1 copy of each chromosome
When gametes are combined they make a zygote (a 1 celled embryo)
Zygotes have 2 copies of each gene and chromosome. They get 1 gene from mom and one
from dad.
 Haploid Cell: a cell with 1 copy of each gene or chromosome
 Diploid Cell: a cell with 2 copies of each gene or chromosome
 Tetraploid cell: a cell with 4 copies of each gene or chromosome, usually in plants
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X chromosome= female chromosome, Y chromosome = male chromosome
XX = female organism, XY = male organism
Humans have 23 pairs of chromosomes in each cell. This means that they have 46
chromosomes total in each cell.
Genetics:
 The father of genetics is Gregor Medel; monk and scientist
 Mendel’s 1 law:
o 2 genes for every trait
o 1 gene from mom and 1 gene from dad
o dominant beats recessive
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Genotype: letter or genes you have for a trait (ex: TT, Tt, tt)
Phenotype: how genes make you look (ex: normal height or
dwarf)
Homozygous: has 2 sets of the same genes for a trait (TT
or
tt)
Heterozygous: has 2 different genes for a trait (Tt)
Also known as a carrier
Alleles: different forms of the gene (ex: T or t)
Blood types: example of codominance and multiple alleles,
4types (A, B, AB, and o) O is universal donor
Dominance patterns: complete (red and white flowers make red flowers), incomplete (red
and white flowers make pink flowers), codominance (red and white flowers make red and
white striped flowers), multiple alleles (many alleles determine
trait ex. Mouse fur color), polygenic traits (many genes
determine trait ex. Human skin color)
Karyotype: examined for sex and chromosomal abnormalities
Sex-linked Traits: gene on X chromosome, show it as exponent
o Female has 2 and male has 1
Monohybrid Cross: punnett square looking at 1 trait at a time
Dihybrid Cross: punnett square looking at 2 genes at a time
Dominant: big letters, beats recessive
Recessive: small letters, weaker than dominant, can be masked
Pedigree Rules:
o Circle is girl, square is boy
o Shaded in means two little letters (dd)
o Not shaded, at least 1 big letter (D_), figure out second letter by looking at
parents and kids
DNA
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DNA stands for Deoxyribonucleic Acid
The structure of DNA was discovered by Watson and Crick; they won the Nobel
Prize. (Rosalind Franklin= xray picture showing the double helix)
DNA is in the shape of a double helix, which is a twisted ladder
In eukaryotic cells, DNA is stored in the nucleus as chromosomes or chromatin
Chromosomes are made up of DNA. Genes are made up of DNA. DNA carries
the genetic code.
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In the DNA molecule, the building blocks are nucleotides. Each nucleotide is
made up of deoxyribose, phosphoric acid, and a nitrogen base. A nucleotide looks
like:
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When the building blocks are put together, the deoxyribose and the phosphoric acid
make up the 2 outer backbones of the molecule:
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The nitrogen bases (A,T,C,G) pair up in the middle. Adenine pairs with thymine and
cytosine pairs with guanine. (AT…CG)
Each chromosome carries many genes. Each gene tells the cell how to make a protein
or a piece of a protein.
Proteins are made at the ribosomes, but the DNA never leaves the nucleus so that it
can stay protected.
DNA replication is where DNA copies itself. It is semiconservative, meaning that
each new copy is half old and half new.
Messenger RNA, also known as mRNA, is a copy of the gene that carries the code to
the ribosomes.
The process where the mRNA is made in the nucleus is called transcription.
Messenger RNA looks like half of a DNA molecule. It uses ribose instead of
deoxyribose. It uses Uracil (U) instead of T.
Every 3 nitrogen bases or letters on a mRNA or DNA molecule is called a codon.
Every codon codes for one amino acid.
Transfer RNA, also known as tRNA, carries amino acids to the ribosomes and has
anticodon.
Amino acids are the building blocks of proteins. Amino acids are joined together by
peptide bonds.
The process where the mRNA code is read to tell what amino acids are needed to
make a protein is called translation. It is called translation because there is a switch
from mRNA language to protein language.
The genes or DNA that a person has makes up the person’s genotype.
The protein that is made from the DNA code give the person the phenotype that the
person has.
Mutations: mistakes in DNA sequence, can be good, bad, or neutral, ex. Inversion
(part of chromosome flips), deletion (piece missing), insertion (addition of
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chromosome part), translocation (part of chromosome attaches to another different
chromosome)
DNA technology: transgenic organism (inserting genes from one organism into
another) ex. Human insulin gene inserted into bacterial plasmid, DNA fingerprinting
used to identify individuals or relationships (ex. father) by examining DNA segments,
small pieces travel further and faster than large ones as move towards positive end of
gel electrophoresis, cloning: making genetically identical copies, gene therapy:
replacing faulty genes with working copies to treat disease
Evolution:
 Biogenesis: life from other life
 Abiogenesis (spontaneous generation): life from nonliving matter
 Evidence of evolution:
fossil record: radioactive dating to age fossils, relative dating oldest at
bottom
biochemistry: (DNA, protein sequences)
comparative anatomy: homologous structures show common ancestor,
analogous structures show similar function, vestigial structures no longer used
today
embryology: development suggests common ancestor if similar pattern
 Natural selection: Darwin’s theory, genetic variation (mutation) provides material for
natural selection, organisms overproduce offspring leading to competition where
those best adapted to environment survive and reproduce
 Adaptations: selected by the environment, not always most advanced feature but
best trait for that environment, ex. Insect populations today becoming resistant to
pesticides, ex. Diseases becoming resistant to antibiotics, in both cases the genes for
resistance were already present in some members of population and insecticides and
antibiotics act as selecting agents
 Speciation: making new species, geographic isolation (physical barrier ex mountains
separate populations), reproductive isolation (can’t make babies anymore), new
species = when 2 populations can no longer reproduce with each other
Classification:
 6 Kingdoms:
1. Archaebacteria: lives in extreme environment, extremophile bacteria, like high
salt, acid, temperatures; prokaryotic cells
2. Eubacteria: normal bacteria, strep throat, E. coli; prokaryotic cells
3. Protista: usually unicellular or microscopic, eukaryotic cells; algae (plant like),
protozoa (animal-like), slime molds (fungus like)
4. Fungi: molds, fungus, athletes foot, mushrooms, decomposer, or parasite
5. Plants: green, chloroplasts, photosynthesis, producer, eukaryotic cells,
multicellular, tissues and organs
6. Animals: move, need oxygen, multicellular, eukaryotic cells, tissues and organ
systems
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7 part name: kingdom, phylum, class, order, family, genus, species
o king phillip came over for good spaghetti
Scientific Name: Genus species
Binomial Nomenclature: every animal has a 2 part name: genus species
Linnaeus is the father of taxonomy
Taxonomy: classification of organisms into groups by similarities in structure, DNA,
protein, behavior, or development
Remember in a dichotomas key ALWAYS start at number 1
Also look over body systems notes (circulatory, digestive, skeletal, muscle, respiratory, and
immune).