Honors Biology Notes
Science – A system of answering
questions about the universe around us
by proposing hypotheses (possible
answers) and conducting experiments to
test our hypotheses. If our data
contradicts a hypothesis we can say the
hypothesis has been proven falseHowever, if our data supports our
hypothesis we NEVER say the hypothesis
has been proven true. Instead, we say
the hypothesis is supported by the data.
Further testing is needed and eventually
the hypothesis may become a theory-
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In Science you can NEVER prove a
hypothesis is true, you can only prove
them false.
Theory – a general hypothesis which has
been supported by many experiments
over time (it is continually supported by
the data) and is solidly accepted as the
answer.
Science Vocabulary –
1) Law – a phenomenon which is
repeatedly and consistently
observed- does not attempt an
explanation
2) Variables- factors which may (or
may not) affect the question we ask
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3) Independent Variable (manipulated
variable)- the variable which the
experimenter controls – always
labeled on the X-axis on a graph- If
the research is not experimental,
the independent variable is the
variable which changes by itself –
ex- if you were examining how
rabbits behave during daylight
versus at night, then time would be
the independent variable
4) Dependent variable (responding
variable)- always labeled on the Yaxis - a variable that depends on or
responds to the independent
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5)
6)
7)
8)
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variable-ex how the rabbits behave
depends on what time of day it is
Control – a duplicate experiment
where various variables are kept
constant-except the one being
tested
Quantitative data – data that you
measure – numerical data –ex mass,
length – collecting data on foot
length in our class is quantitative
data
Qualitative data – data that is
descriptive- ex – color, texture
Observation – what the
experimenter actually witnessesObservations are recorded as data
9) Inference – the logical conclusions
drawn from (based on) the
observations/data
10) Causation – variable A causes
variable B to change
11) Correlation – Variable A and
variable B both change together,
but A does NOT CAUSE B to change
The students from a local elementary
school had their feet measured and the
students were given a standardized
math and reading test. It was found that
students with bigger feet had higher test
scores. Conclusion – Individuals with
bigger feet are smarter. How is this
inference flawed?
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Biology- The study of Life
Organism – Any single living thing
Properties of Life1) Reproduction- organisms must be
able to reproduce or the species will
go extinct
2) Growth – All living things grow –
3) Use of Energy – Energy is required
by organisms for growth and for
many other activities and chemical
reactions occurring within
organisms.
4) Response to environmental
stimulus – all organisms respond to
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their environment- ex – you touch a
hot stove, what happens?
5) Homeostasis – all organisms
attempt to maintain a stable
internal environment (within the
organism) ex – our body temp 37C
6) All organisms have an
organizational structure of at least
one cell – cells are the basic building
blocks/units of life
7) All organisms have genes made of
DNA which allow them to evolve
and adapt to the environment
Levels of Biological Organization:
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1) Cell- The cell is the smallest unit of
life-some organisms are only made
of one cell
2) Tissue – A group of cells which work
together for a common function
3) Organ – A group of tissues which
work together for a common
function
4) Organ System – several organs
working together for a common
function
5) Organism – a single individual
6) Population – all the organisms of a
specific type living in one area
7) Community – all the different types
of populations living in one area
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8) Ecosystem – the community plus
abiotic (non-living) factors
9) Biome - Global – Area on Earth
where all of a specific ecosystem is
found
10) Biosphere – entire region of Earth
where all life is found- six miles
above and six miles below sea level
Properties of water which are essential
for life –
Polarity – water (H2O) is a polar
molecule-this means the oxygen pulls
harder on electrons (which are
negatively charged) so the oxygen side
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of each water molecule gets a slight
negative charge- the side with hydrogen
gets a slight positive chargeHydrogen Bond-two different water
molecules are attracted to each other as
the positive end of one forms a weak
bond with the negative end of the otherThis bond is called a hydrogen bond (fig
1 on board)
Electronegativity – How hard an atom
pulls on electrons
Cohesion – Two of the same type of
molecule bond together as a result of
hydrogen bonds
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Adhesion-two different types of
molecules bond together as a result of
hydrogen bondsCapillarity: As a result of cohesion +
adhesion, plants draw water up the stem
because the water molecules are
attached to each other by hydrogen
bonds – a straw works the same
way.(video)
Surface Tension – Hydrogen bonding at
the surface of water – some insects can
“skate” across the surface (pg. 161), and
Belly flops hurt! Cohesion at surface.
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Water is less dense as a solid - As H20
begins to freeze (0 degrees C) the
hydrogen bonds push the H20 molecules
slightly apart (pg. 162 Zebra)– The result
is that ice is less dense than liquid water
– so ice floats – otherwise, living things
in the water would freeze to death – The
layer of ice also keeps the liquid water
below it warmer.
Specific Heat: The amount of heat
needed to raise the temperature of 1
gram of a substance by 1⁰ C. Water has a
high specific heat (1 calorie) so it can
absorb a lot of heat and not go up in
temperature – Therefore water helps
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regulate air temperature along coastal
regions by absorbing a lot of heat. Also,
our body temperature doesn’t shoot up
on a hot day.
Water is a versatile solvent- Water
dissolves many polar and ionic
substances by surrounding charged
atoms within a hydration shell –this is
caused by the water’s polar charges
pH scale – a measure of acidity – the
more H+ ions (a hydrogen atom that is
missing its electron) a solution has, the
greater its acidity – pH goes from 0 – 14
(0 is very acidic and 14 is very basic)
(pg.165)
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Pure water has a pH of 7 which is neutral
– human blood has a ph 7.4-7.8.
Organic Macromolecules There are four
types of organic (containing carbon)
macromolecules:
a) Carbohydrates
b) Lipids
c) Proteins
d) Nucleic acids
-all living things are constructed from
these molecules – most
macromolecules are formed by a
process called polymerization – small
molecules (monomers) are joined
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together to form macromolecules
(polymers)
1) Carbohydrates (pg 168)– Used
mainly for energy and structuremonomers for carbohydrates are
monosaccharides
a) Monosaccharides – main energy
source for metabolic activitiesex -glucose
b) Disaccharides - (two
monosaccharides bonded
together) ex – sucrose which is
table sugar
c) Polysaccharides – three or more
monosaccharides bonded
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together-Types of
Polysaccharides:
Starch – long chains of glucose -plants
store excess carbohydrates as starch-ex
– potatoes – energy storage in plants
Glycogen – animals store excess
carbohydrates as glycogen around their
liver and muscle cells-short term energy
storage in animals
Cellulose – non-digestible-the cell walls
of plants are made of cellulose- cellulose
is a structural carbohydrate – pg. 168
Chitin – the cell walls of fungi are made
of chitin – also, the exoskeleton of
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arthropods are made of chitin – chitin is
a structural carbohydrate
2) Lipids (lipids are NOT polymers) – (pg
169) Lipids are mostly made of just
carbon and hydrogen-they are nonpolar
and do not mix with water. Molecules
which do not mix with water are called
hydrophobic. Examples include:
A) Triglycerides – these are fats – They
serve as a long term energy storage
molecules (also used for insulation ex.
whale blubber) - things like butter, lard,
and cooking oils are triglycerides.
Triglycerides are built from a glycerol
molecule and three long “fatty acid tails”
of carbon and hydrogen (any molecule
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made of just hydrogen and carbon is
called a hydrocarbon). If the covalent
bonds in these tails are all single bonds
(one pair of shared electrons) then the
Triglyceride is called a saturated fat and
is a solid at room temperature -If there
are double bonds ( two pairs of shared
electrons) within the “tails” then they
are called unsaturated fats and are
liquids at room temperature. This is
caused by the bending of the “tails” and
the creation of space between them.
(draw fig 1)
B) Steroids – include molecules such as
cholesterol (part of cell membrane) and
hormones - important in chemical
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messages throughout the body-consist
of four rings of carbon
3) Proteins – Proteins are polymers- the
monomers of proteins are amino acidsThe structure of an amino acid is
important to know (pg 170)
Draw an amino acid:
Amino acids are linked to each other by
a covalent bond called a peptide bond.
Proteins make up over 50% of your dry
body mass. Your hair, muscles, skin, and
nails are all made of different types of
proteins. Proteins have many functions
within organisms such as:
- transport (hemoglobin carries oxygen)
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-Speeding up chemical reactions
(enzymes are proteins which speed up
chemical reactions)
-Immune response (antibodies are made
of protein)
4) Nucleic Acids – These macromolecules
are polymers consisting of monomers
called nucleotides-(pg 171) A nucleotide
has three parts:
a) sugar – either ribose (RNA) or
deoxyribose (DNA)
b) a (nitrogen-containing) base
c) a phosphate group
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There are two types of nucleic acids:
DNA (deoxyribonucleic acid) – stores
genetic information
RNA (ribonucleic acid) – transmits
genetic information from the DNA to the
rest of the cell
Enzymes
Reactants – The starting substances in a
chemical reaction. Shown on the left
side of the arrow in a chemical equation.
Products – The substances formed
during the reaction. Shown on the right
side of the arrow.
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Activation Energy (pg. 158)– The energy
required for reactants to form into
products-the energy that is required to
get a reaction started
Exergonic/exothermic reactions – (pg.
158 top) the products have less energy
than the reactants. Energy is released
during the reaction. Ex-digestion
Endergonic reactions - (pg. 158 bottom)
the products have more energy than the
reactants. Energy is absorbed during the
reaction. ex-polymerization
Catalyst (pg. 159) – A substance which
speeds up a chemical reaction by
lowering the activation energy. The
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catalyst itself is not part of the chemical
reaction and is not used up. The catalyst
does not increase the amount of
product, it just affects how fast it is
produced.
Enzymes – Biological Catalysts made of
protein. Enzymes are used in many
chemical reactions within the body such
as digestion.
Substrates (pg. 160)– The reactants that
bind to the enzyme.
Active site – (pg. 160)- The specific
location where a substrate binds on an
enzyme. The substrate fits into the
active site like two puzzle pieces (shapes
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match). Each particular type of enzyme
only works on one particular substrate.
Induced Fit – Once the substrate fits
into the active site, the active site
tightens around the substrate. The
bonds within the substrate are twisted
and stressed which lowers the activation
energy.
Effects of Temperature and pH on
enzyme activity – (pg. 164 bottom) Each
enzyme works at an optimal pH and
temperature. For example, pepsin in
your stomach works best at a pH of 2. If
the pH or temperature strays too far
from the optimal level, the enzyme stops
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working. The protein unravels
(denatures)
Cellular Structure and Function
A cell is the basic structural and
functional unit of all living things.
In 1665, Hooke first saw cells in a piece
of cork using a primitive microscope.
Soon after, Leeuwenhoek saw living cells
moving around.
Cell Theory
a) All living things are composed of
one or more cells
b) Cells are the basic units of structure
and organization of all living things
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c) Cells arise only from previously
existing cells, with cells passing
copies of their genetic material to
their daughter cells.
Cellular Transport
All cells have a plasma membrane
(same as a cell membrane) (pg. 188)
which is a membrane that controls
what materials enter and exit the cell.
The plasma membrane is composed of:
a) Phospholipid bi-layer – each
phospholipid has a polar phosphate
(hydrophilic) head which faces
outwards/inwards where there is
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water. The hydrophobic lipid tails
face toward the interior of the
membrane – Responsible for the
structure of the cell membrane.
Draw fig 1
b) Proteins - help transport certain
materials across the membrane
c) Cholesterol – (animal cell
membranes only) Acts as a buffer
that helps keep the membrane from
getting too stiff or too fluid.
d) Carbohydrates-help cells recognize
each other.
A key property of the plasma (cell)
membrane is selective permeability by
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which a membrane allows some
substances to pass through while
keeping others out. Small AND
uncharged molecules (ex. CO2 and O2)
can go through the membrane while
large molecules or substances with a
charge (ex. Sucrose, H2O and Ca2+ ions)
need help getting through.
In a solution, a substance called a solute
is dissolved in a solvent. Water is the
solvent in a cell and its environment.
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Passive Transport – the transport of
solutes across a membrane without the
use of energy.
a) Diffusion (copy fig 1) – the
movement of particles from an
area where there are many
particles (high concentration) to
an area where there are fewer
particles (low concentration). We
say the particles are moving down
a concentration gradient (when
there are more solutes on one
side of a membrane than the
other). Diffusion does not require
energy, it happens naturally (like
water going down a waterfall). If
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there are equal amounts of
particles on both sides of a
membrane, we say the particles
have reached equilibrium and the
particles go back and forth at
equal rates.
b) Facilitated Diffusion (fig. 2)– Also
requires no energy and happens
naturally. The particles also go
from areas of high concentration
to areas of low concentration. The
ONLY DIFFERENCE between
diffusion and facilitated diffusion
is that in facilitated diffusion the
particle needs the help of a
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protein channel/carrier to move
through the membrane.
Osmosis – The diffusion of water across
a selectively permeable membrane.
Water always moves across a membrane
toward the area of HIGHER solute
concentration.
a) Cells in a hypotonic solutionmore solutes are in the cellwater moves into the cell and
the cell swells (it may even
pop). (draw fig. 1) Plant cells
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want to be in a hypotonic
solution since it keeps them
from wilting.
b) Cells in a hypertonic solution –
more solutes are outside the
cell- water moves out of the
cell and the cell shrivels. (draw
fig. 2)
c) Cells in an isotonic solution –
the same amount of solutes
inside and outside the cellwater moves in and out of the
cell at the same rate
(equilibrium) and the cell
remains the same size/shape.
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This is the normal state for an
animal cell.(draw fig. 3)
Some cellular processes require energy.
The energy usually comes from the
molecule ATP (adenosine tri-phosphate).
(pg. 221)The three phosphate groups are
negatively charged and repel each other.
As the third phosphate breaks off the
molecule, energy is released and the
molecule becomes ADP (adenosine diphosphate).
Active Transport (Draw fig 4) – The
movement of substances across a
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plasma membrane against (up) the
concentration gradient-Active transport
REQUIRES ENERGY and a protein carrier!
The energy comes from ATP. When the
third phosphate breaks off the ATP it
attaches to the protein carrier and
changes its shape. This pumps the
substance across the membrane against
the concentration gradient.
Bulk Transport Involves large
substances moving in and out of cells.
Bulk transport requires the input of
energy (ATP). The cell membrane
envelops and surrounds the substance
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and brings it into the cell. (pg. 207)
There are two types of bulk transport:
1. Endocytosis – Large materials enter
the cell –
a) Phagocytosis – large solid
materials enter the cell. ex- a
white blood cell engulfs a
bacteria cell
b) Pinocytosis – liquid material
enters the cell
2. Exocytosis – large waste products
and substances such as hormones
exit the cell. Works like endocytosis
in reverse
Origin of Cells – (extra-credit on test)
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Roughly 4 billion years ago-no one
knows exactly how it happened-the
most popular hypothesis follows:
1) Organic molecules (ex. amino acids)
formed in water and got washed
onto shore
2) These molecules became
concentrated on land and joined
together to form macromolecules
(ex-proteins)
3) The macromolecules were washed
into the ocean where they
surrounded water droplets and
formed protocells (ex.
microspheres)
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4) These protocells took in RNA which
allowed them to evolve and pass on
characteristics.
Types of Cells and Organelles
Organelles – specialized structures
within cells that carry out specific
functions
Eukaryote cell – cells which contain a
nucleus and other organelles that are
bound by membranes- All multi-cellular
organisms are made of eukaryote cells
(ex – animals, plants). Some unicellular
organisms are also eukaryotes exprotists, yeast
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Nucleus – a central organelle that
contains the cell’s genetic material in the
form of DNA
Prokaryote cell – cells without a nucleus
or other membrane-bound organellesorganisms with prokaryote cells are all
unicellular and they are considered the
most primitive types of organisms ex –
bacteria
pg. 199 (Zebra Book) SKIP FIVE LINES
BETWEEN ENTRIES
Pg. 192 has pictures of Plant, Animal,
Prokaryote cells
Add the following to the list
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Cell Wall – made of long fibers of
cellulose (plants) or Chitin (Fungi)-
Centrioles -
Chloroplast- (pg.222) contain many disk
shaped structures called thylakoidsbetween the thylakoids is a semi-fluid
region called stroma – They have their
own DNA separate from the nuclear
DNA
Cilia – move the cell by rowing in unison
like the oars of Viking ship
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Cytoskeleton – made of long, thin
protein fibers that form a framework
and help provide an anchor for
organelles. Also has a function in cell
division and cell movement.
Endoplasmic Reticulum (E.R.) – made of
a phospholipid bi-layer just like the cell
membrane – ER has two areas: A)Rough
E.R. has ribosomes attached and is an
area of protein manufacturing, B)
Smooth E.R. has no ribosomes attached
and is where certain lipids are made-also
detox function.
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Flagella – Long, projections which move
the cell by a whip-like motion
Golgi Apparatus – modifies, packages
and sorts products (ex. proteins) made in
the endoplasmic reticulum – made of a
phospholipid bi-layer just like the cell
membrane.
Lysosome – Also digest food particles,
bacteria, and viruses that have entered
the cell through endocytosis
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Mitochondria – Most ATP is produced in
the mitochondria (cellular respiration)Glucose and other sources of chemical
energy are broken down to make ATPmitochondria have their own DNA
separate from the nuclear DNA
Nucleus – surrounded by a nuclear
membrane (phospholipid bi-layer) –
contains chromatin (DNA and associated
proteins) Also contains a region called
the nucleolus which is where ribosomes
are built - the nucleus is the control
center for the cell.
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Plasma membrane – ALL cells have a
plasma membrane
Ribosomes – made of protein and RNAorganelles which put together amino
acid chains (proteins are built) – ALL cells
contain ribosomes
Vacuole – Plant cells have a huge central
vacuole which stores proteins, ions, and
wastes
Cytoplasm – the region between the
nucleus and the plasma membrane
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Cytosol – the fluid which fills the cell
Eukaryote cells :
a)
b)
c)
d)
Protists
Fungi
Plants
Animals
Prokaryote cells:
a)Bacteria
b)Archaea
How did organelles evolve:
1) Endosymbiotic hypothesis –
a) Explains origin of mitochondria
and chloroplasts
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b) A large prokaryote cell engulfed
(endocytosis) smaller prokaryote
cells but did not digest them
c) Evidence – mitochondria and
chloroplasts have their own DNA
and replicate independently
from the cell they’re inside of.
2) Infolding Hypothesis:
a) Explains origin of the
Endoplasmic reticulum and the
Golgi apparatus
b) The cell membrane folded-in on
itself and created these
organelles
c) Evidence – the membrane
structure of these organelles is
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exactly the same as the cell
membrane
Types of Microscopes:
1) Light Microscope – positive – you
can view living things – negative –
limited in magnification
2) Electron Microscope- positive-much
greater magnification-negativeobjects must be dead
a) Transmission type –views the
interior of objects
b) Scanning type – views the
surface of objects
Photosynthesis and Cellular Respiration
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Autotroph (producers) – An organism
that can make its own food. Most
autotrophs use photosynthesis to make
their food. Ex – plants are autotrophs
Heterotroph (consumers) – An organism
that must obtain its food from the
environment by either absorbing it (ex –
fungi) or by eating (ex- animals)
Metabolism – all the chemical reactions
in a cell
Anabolic reactions – use energy
(endergonic) to build large molecules
from smaller molecules
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Catabolic reactions – release energy
(exergonic) when breaking down large
molecules into smaller molecules
Photosynthesis – the anabolic reaction
where light energy from the sun is
converted into chemical energy (light
energy is used to build glucose) for use
by the cell.
The equation for photosynthesis:
6CO2 + 6H2O + light energy ---> C6H12O6 + 6O2
Cellular Respiration – The catabolic
reaction where the chemical energy
stored in the glucose is released in the
form of ATP which is used to energize all
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sorts of cellular processes. The equation
for cellular respiration:
C6H12O6 + 6O2 --->6CO2 + 6H2O + Energy (ATP)
When the third phosphate breaks off the
ATP, the energy released is used for
cellular work (this process of ATP
providing energy is called energy
coupling) such as:
a) Active transport
b) Building large molecules such as
amino acid chains (anabolic
reactions)
c) Movement (ex – muscle fibers
sliding against each other as the
muscle flexes).
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Photosynthesis occurs in the chloroplastFig. 1 on board – Draw it.
There are two stages of photosynthesis:
A) Light Dependent Reactions (LDR) –
occur in the thylakoids- Light
absorbing molecules called
pigments are located in the
thylakoid – chlorophyll is the main
pigment-light energy and H2O are
used to make ATP and a molecule
called NADPH (electron carriers). O2
is released into the atmosphere as a
by-product
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B) Calvin Cycle – Occurs in the stromaThe ATP and NADPH produced in
the light dependent reactions and
CO2 from the atmosphere are used
to make Glucose (C6H12O6). The ATP
provides energy to make the
glucose and the NADPH provides
electrons that were energized by
the sun light. The carbon in the
glucose comes from the CO2
Cellular Respiration has two parts:
A) Glycolysis (fig 1)– occurs in the
cytoplasm (the fluid filled area
between the nucleus of the cell
and the cell membrane) –
Glycolysis is an anaerobic
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process ( anaerobic means: does
NOT require oxygen) – In
glycolysis, one molecule of
glucose is broken down into two
molecules of pyruvate- Two ATP
and two NADH (electron
carriers) are produced.
B) Aerobic Respiration (fig 2)–
Occurs in the mitochondria – It’s
an aerobic process (it requires
oxygen) – There are two parts in
aerobic respiration:
a. Krebs cycle (Citric Acid
Cycle) occurs in the matrix of
the mitochondria – completely
breaks down pyruvate (made
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in glycolysis) – 2 ATP, CO2 and
NADH (electron carriers) are
produced
b. Electron transport chain –
All the NADH produced in the
Krebs cycle and glycolysis
deliver their electrons to the
electron transport chain(made
of proteins) – the electrons go
down the chain and release
energy to produce a lot of ATP
(about 34 ATP) Oxygen grabs
the electrons at the end of the
chain and water is formed.
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Fermentation (anaerobic respiration)After glycolysis, if oxygen is present
the pyruvate will go into the
mitochondria for aerobic respiration,
however if there is not enough oxygen
(or oxygen is absent) the pyruvate will
stay in the cytoplasm and go through
Fermentation (also called anaerobic
respiration)
Fermentation is an anaerobic process
where molecules (specifically NAD+)
necessary for glycolysis are
regenerated. The main purpose of
fermentation is to keep glycolysis
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going (so ATP can be made). There are
two types of fermentation:
A) Lactic Acid fermentation- Enzymes
convert the pyruvate made during
glycolysis into lactic acid. Muscle
cells switch to lactic acid
fermentation if they are not
getting enough oxygen during
periods of strenuous exercise. The
build-up of lactic acid causes the
muscles to feel sore. Bacteria that
produce food products such as
cheese and yogurt also use lactic
acid fermentation.
B) Alcohol fermentation – occurs in
yeast cells and some bacteria – the
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pyruvate made during glycolysis is
converted into alcohol and CO2 is a
by-product. That is why beer is
carbonated.
Lose Electrons Oxidized
Gain Electrons Reduced
LEO the lion says “GER!”
The Cell Cycle
Cells grow until they reach their size
limit, then they either stop growing or
divide. Cell division is how organisms
grow larger and how we heal. Some
cells stop dividing (ex. nerve cells), some
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cells occasionally divide (ex. liver cells)
and some cells are continually dividing
(ex. skin cells)
Cell size limitations – As a cell grows, the
ratio of surface area to volume gets
smaller. This means that there is less
surface area for important molecules
(e.g. nutrients/reactants and wastes) to
pass through. If a cell gets too big it
won’t be able to supply itself with, or get
rid of, these molecules. By staying small,
cells can more easily transport important
molecules across their membranes.
The cell cycle – cells reproduce by a cycle
of growing and dividing called the cell
cycle-Each time the cell goes through
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one complete cycle it becomes two cellsThere are three main phases of the cell
cycle:
1) Interphase (G1,S,G2)- 21-22 hours
2) Mitosis (prophase, metaphase,
anaphase, telophase)
3) Cytokinesis
Mitosis and Cytokinesis together
are called the M-phase (lasts 1
hour)
fig.3 pg 246 (draw it)
Interphase (21 hours) – is split into
three stages:
A) G1 – The cell grows larger and
performs normal cell functions
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B) S – Same as G1 but also the DNA in
the nucleus replicates
C) G2 – Same as G1 and the cell
prepares to divide.
Chromatin – During all of interphase,
the DNA is in a relaxed, unraveled form
called chromatin. The proteins which
the DNA is wrapped around are also
part of the chromatin.
Cell division is divided into two stages
Mitosis – The stage of the cell cycle
where the nucleus divides into two
nuclei
Mitosis is split into four stages:
A) Prophase
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B) Metaphase
C) Anaphase
D) Telophase
Cytokinesis is the 2nd stage
A) Prophase –
a) The chromatin coils up into
thick, rope-like chromosomes
b) The nuclear membrane dissolves
c) Spindle apparatus (fibers) forms
– The Spindle apparatus is part
of the cytoskeleton and helps
move chromosomes around
during mitosis
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At this point each chromosome is
shaped like an “X”. Each half of the X is
called a sister chromatid and represents
one copy of the DNA that was replicated
during S phase. The two halves are
attached at a region called the
centromere. Draw fig 1
B) Metaphasea) the spindle apparatus lines up the
chromosomes along the metaphase
plate (an imaginary line along the center
of the cell)-The spindle fibers are
attached to the centromere regionC) Anaphase –
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a) The spindle fibers separate sister
chromatids and pull them to opposite
sides of the cell- once the sister
chromatids are separated, they are
called chromosomes D) Telophasea) Nuclear membrane/envelope start
reappearing
b) Cell elongates
c) Chromosomes start unraveling
back into chromatin form
Cytokinesis
The cell actually splits into two cells. If it
is an animal cell, a cleavage furrow
forms which pinches the original cell into
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two cells. If it is a plant cell, a cell plate
forms from the Golgi apparatus which
divides the original cell into two cells.
The end result of mitosis and cytokinesis
are two daughter cells which are both
genetically identical to the original
parent cell. This process is how
organisms grow and heal. For
unicellular, eukaryote organisms, this is
also how they reproduce.
Meiosis
Chromosomes come in pairs called
Homologous pairs – A human has 23
homologous pairs of chromosomes for a
63
total of 46 – cells with chromosomes in
pairs are called diploidSomatic cells – all the cells in an
organism except for sex cells (sperm and
egg).
Gametes are sex cells (sperm and egg).
They are haploid - chromosomes not in
pairs -they only have one from each pairso they have half the number of
chromosomes-in a human there would
be 23 chromosomes in a gamete
Meiosis – The process where a single
diploid parent cell (located in the testes
64
or ovaries) is split into four haploid
gametes fig 5 pg. 273
Gametes must be haploid since when
they come together during fertilization
they produce a diploid zygote (an egg
that has been fertilized)
Differences between meiosis and
mitosis:
1) Meiosis only occurs in cells of the
testes and ovaries and produces
sperm and eggMitosis occurs in many types of
cells throughout the body
65
2) Meiosis makes 4 haploid gametes
which are NOT identical to the
parent cell or to each other –
Mitosis makes 2 diploid daughter
cells that are identical to each other
and to the parent cell
3) Meiosis involves two cell divisions
(meiosis I and meiosis II) –
Mitosis only involves one cell
division- draw pic 1
4) Meiosis – During Prophase I
chromatin condenses into
chromosomes and chromosomes
group in homologous pairs
(tetrads). This process is called
synapsis. Crossing over occurs
66
between inner chromatids which
exchanges genetic information
(DNA) between chromosomes.
Creates new genetic combinations.
Mitosis – Chromosomes do not
group together as tetrads.
Draw pic#2
5) Meiosis – During metaphase I the
chromosomes line up along the
metaphase plate in homologous
pairs –
Mitosis – During metaphase the
chromosomes line up along the
metaphase plate as individual
chromosomes- draw pic#3
67
6) Meiosis – During anaphase I the
homologous pairs separate BUT the
sister chromatids stay togetherSister chromatids don’t separate
until the second cell division
(anaphase II)
Mitosis – During anaphase the
sister chromatids separate- draw
pic#4
Law of Segregation – Each chromosome
pair separates during meiosis (anaphase
I ) and the offspring has a 50% chance of
getting either. Draw pic #1
Law of Independent Assortment – the
alignment of homologous pairs during
metaphase I determines the
68
chromosome combinations that will be
present in the gametes-the alignment is
totally random (draw pic#2)
The total number of chromosome
combinations in the gametes is 2n (n =
the number of chromosome pairs) exhumans 223 = 8,388,608 chromosome
combinations (provides a lot of
variation!) PLUS variation from crossing
over.
Molecular Genetics
Structure of DNA – (Deoxyribonucleic
Acid) – is composed of a series of
nucleotides arranged in a twisted ladder
(double helix) shape. (pg. 332 fig 9)
69
There are three parts in a DNA
nucleotide:
1) Sugar (deoxyribose)
2) Phosphate group
3) Nitrogenous base
The nucleotides are attached and make
a ladder shape (pg. 329 fig 4, pg 331 fig
8)
There are 4 nitrogenous bases in DNA
(pg. 329 fig 4)
70
Purines
Pyrimidines
1) Adenine
2) Guanine
3) Thymine
4) Cytosine
The sides of the ladder are made of
sugar and phosphate groups – the steps
of the ladder are made of paired bases
which are hydrogen bonded to each
otherBase Pairing Rules
Adenine always pairs with Thymine
A-T, T-A
Guanine always pairs with Cytosine
G-C, C-G
DNA Replication – DNA replication
occurs in the “S” phase of interphaseDNA replication takes place in the cell
nucleus.
71
DNA Replication is the process where
DNA makes an identical copy of itself. –
The DNA ladder “unzips” itself and free
nucleotides attach to the exposed edges.
The enzyme which builds the new edges
is called DNA polymerase (pg. 334 fig 11)
- Replication is semi-conservative – this
means each new DNA molecule includes
one edge from the old DNA molecule
and one new edge. (pg. 333 fig. 10)
RNA – Ribonucleic acid – differences
between RNA and DNA:
1) There are many types of RNA and
each type has a different shape
72
2) RNA has the base Uracil (U) instead
of Thymine (T). Instead of Thymine,
Uracil bonds with Adenine in RNA
U-A, A-U
3) The nucleotides of RNA have ribose
as a sugar instead of deoxyribose
Protein Synthesis:
a) Transcription – the process where
RNA is copied from DNA – the enzyme
RNA polymerase builds the RNA.
Transcription occurs in the nucleus- The
DNA bubbles and free RNA nucleotides
attach to one edge of the DNA and form
long “strings” of RNA which then are set
loose and leave the nucleus (fig.13 pg
337)
73
b) Translation – The process where
proteins (amino acid chains/polypeptide
chains) are assembled from the mRNA –
translation occurs at ribosomes within
the cytoplasm
There are three types of RNA involved in
Translation (pg 336 table 2):
1) mRNA (messenger RNA) – takes the
genetic message out of the nucleus
and into the cytoplasm – every
three bases of mRNA is called a
codon – the three bases of a codon
determine which amino acid will be
74
attached next as the protein is
built.(pg. 338 fig 14)
2) tRNA (transfer RNA) – brings the
correct amino acid over to the
ribosome (the site where the
protein is being built) There are
three bases on the tRNA called an
anti-codon- the bases of the anticodon pair up with the bases of the
codon (A-U,G-C) and that ensures
the correct amino acid will be
brought over.
3) rRNA ( ribosomal RNA) is a main
part of ribosomes- ribosomes are
made of rRNA and protein – the
codon (mRNA) and the anti75
codon(tRNA) match up within the
ribosome-The mRNA moves
through the ribosome (like a label
maker)- as it moves, new tRNA
molecules enter the ribosome
(bringing their amino acid) and
empty tRNA molecules leave the
ribosome (pg. 339 fig 15).The amino
acids bond together at the
ribosome.
The codon/amino acid code is 99.9999%
universal. Virtually all living things share
the same code.
Genetic Mistakes 76
Mistakes in chromosome numbers:
A) aneuploidy – during anaphase of
meiosis a pair of chromosomes
doesn’t separate
(nondisjunction)and a gamete gets
two copies instead of one-if that
gamete gets fertilized the zygote
will have three copies of the
chromosome. (ex- trisomy 21 – has
three copies of the 21st
chromosome - Down Syndrome)
draw fig 1
B) polyploidy – same thing as above
but it happens to all the
chromosome pairs so instead of a
77
diploid zygote, you get a triploid
zygote. Draw fig 2
Mutations: random changes in the
sequence of nucleotides in DNAmutations can occur naturally by errors
during DNA replication, mitosis and
meiosis or specific agents can interact
with DNA and cause mutations- These
agents are called mutagens (ex. of
physical mutagens are x-rays and UV
light; ex. of chemical mutagens are
saccharine and tobacco)
There are two types of mutations:
1) chromosomal mutations
2) point mutations
78
Chromosomal mutations:
A) deletion – a piece of a chromosome
breaks off and is lost (draw fig 1)
B) duplication – a piece of a
chromosome breaks off and
attaches to its homologous partner
(draw fig 2)
C) translocation- a piece of a
chromosome breaks off and
attaches to a non-homologous
chromosome (draw fig 3)
D) Inversion- a piece of a chromosome
breaks off and re-attaches in
reverse (draw fig 4)
Point Mutations-Unlike chromosomal
mutations which affect entire pieces of
79
chromosomes, point mutations affect a
single nucleotide within a single gene.
They are how new alleles are created:
A) Substitution – A change in a single
nucleotide where one base is
substituted for another base- An
example is the sickle cell mutation
(draw fig 5)
B) Frameshift mutation – the deletion
or addition of nucleotides that
disrupt the reading of codons and
changes the protein dramatically by
adding the wrong amino acids
THE FAT CAT ATE THE RAT becomes:
THF ATC ATA TET HER AT
80
RNA Processing
Introns – sections of DNA/RNA
which are transcribed, but then get
cut out of the RNA strand before
the mRNA leaves the nucleusIntrons are not expressed as
proteins – after the introns are cut
out, the remaining mRNA (called
exons) is spliced together and
leaves the nucleus
Exons – sections of DNA which are
transcribed into mRNA and do exit the
nucleus for translation into protein
Exons/introns only apply to eukaryote
cells (draw fig 1)
81
DNA Fingerprinting (Gel
Electrophoresis)– a technique which
allows DNA from different samples to be
matched1) A special enzyme called a restriction
enzyme is used to chop the DNA
samples into fragments- the cuts
occur at specific nucleotide
sequences
2) The chopped fragments from each
sample are put in wells at the end
of a gel plate-DNA is negatively
charged and so the fragments move
from the negative end of the gel
(where the wells are) to the positive
end- the smaller fragments move
82
faster and go further- the fragments
form bands
3) The bands are compared and can be
matched together.
Cancer- Certain gene products (proteins)
control whether a cell divides or not.
Mutations that occur in genes which
control the cell cycle can cause cells to
divide uncontrollably. Cancer is
uncontrolled cell growth and division.
Mendelian Genetics
Gene – a section of a chromosome that
codes for a protein
Allele – the specific form of a gene
83
Genotype – a listing of the alleles ex –
BB,Bb,bb
Dominant allele – The allele which
expressed when two different alleles are
present -symbolized with an uppercase
letter – ex. B
Recessive allele – the allele which is
masked/hidden when two different
alleles are present – symbolized with a
lowercase letter- ex. b
Homozygous Genotype – Alleles are
identical (Homozygous Dominant- ex.
BB)
(Homozygous Recessive- ex. bb)
84
Heterozygous Genotype – two different
alleles -ex Bb (sometimes called a
hybrid)
Phenotype – Physical
appearance/expression of the genotype
Incomplete Dominance – Heterozygous
genotype will display a blending of the
homozygous phenotypes.
(Pg. 272 fig 11-11)
Ex. – In the flowers called snapdragons
R – red flower so RR is a red flower
phenotype
W – white flower so WW is a white
flower phenotype
85
The heterozygous (RW) codes for pink
flower phenotype
Co-Dominance – The heterozygous
genotype displays both homozygous
phenotypes fully.
Ex – Sickle Cell Anemia –
SS–Normal shaped blood cells-Draw fig 1
ss – Sickle shaped blood cells-Draw fig 2
But Ss has both shapes of blood cells
fully expressed-Draw fig 3
If you are heterozygous (Ss) you gain a
partial immunity to malaria (the
deadliest disease ever!) and you don’t
have the full effects of sickle cell anemia.
86
This explains why the sickle cell allele (s)
is common among people originating
from areas with a lot of malaria such as
Africa.
Polygenic Trait – a single trait affected
by multiple genes. Ex – skin color- Draw
fig. 4
Pleiotropy – multiple traits affected by a
single gene. Ex – Sickle cell disease
causes heart problems, paralysis, pain in
the joints. Draw fig. 5
Punnett squares – Show probabilities of
certain parents producing offspring of
different genotypes and phenotypes.
87
Multiple Alleles – Although each
individual has two alleles for a given
gene, there may be more than two
alleles in the entire population.
Ex – Blood types- There are 3 alleles for
blood type in the human species:
I A, I B , i
IA and IB are co-dominant to each other
and they are both dominant to i.
Your blood type determines which
carbohydrates are on the membrane of
your blood cells
88
1) If your genotype is IAIA or IAi then
you have type A blood – draw fig.6you can receive A blood or O blood
2) If your genotype is IBIB or IBi then
you have type B blood – draw fig.7you can receive B blood or O blood
3) If your genotype is IAIB then you
have type AB blood – draw fig. 8You can receive any type of blood
4) If your genotype is ii then you have
type O blood – draw fig.9-You can
only receive O blood but you can
donate to anyone
Pedigree – a chart that shows how a trait
and the genes that control it are
89
inherited through multiple generations
of a family. Squares are males, circles
are females, colored shapes express the
trait in their phenotype. You can
determine whether a trait is dominant or
recessive by examining the pedigree.
You can also figure out many genotypes
of the family members. Draw fig. 10 (ex.
1 & 2)
Carrier - An individual who has a
recessive allele (usually for something
bad like a disease) which is masked by
the normal dominant allele. In other
words, they are heterozygous and have a
normal phenotype. Ex- Cc C – normal, ccystic fibrosis
90
Test Cross – If you have a dominant
phenotype, you can figure out if the
genotype is homozygous dominant or
heterozygous by crossing the organism
with a homozygous recessive
phenotype. If all offspring are dominant
phenotype then the parent is
homozygous dominant/ if the offspring
are 50% recessive phenotype then the
parent is heterozygous. Draw fig. 11
Sex Linked Genes- All of your
homologous pairs are of equal length
and have the same genes in the same
locations except for the 23rd pair (the sex
chromosomes) If you are a male, your
91
sex chromosomes do not match. You
have an X chromosome and Y
chromosome (females have two X
chromosomes). The Y chromosome is
very small and doesn’t have many genes.
Certain genes are only carried on the X
chromosome. These are called sex
linked genes.
Punnett Squares for sex linked traits:
1) Write out the sex chromosomes for
the parents
2) The actual alleles are drawn as
superscripts
3) The Y chromosome gets NO allele
Draw fig. 12
92
Dealing with two genes at once - the
following applies to multiple genes
which are independent (on different
chromosome pairs) from one another. If
two or more genes are on the same
chromosome pair none of the following
applies :
1) Draw a punnett square for each
gene
2) Multiply the probabilities (use
fractions) for each outcome
together to get the total probability
Draw fig.13
93
Evolution – a change in allele frequency
within a gene pool over time.
Gene pool – the total number of alleles
in a population- draw fig 1
Lamarck- 1809 – the first real hypothesis
concerning evolution – Inheritance of
Acquired Characteristics (IAC) – An
individual passes on traits which it has
acquired over its lifetime – ex- an
antelope stretches its neck during its
lifetime, it has offspring with slightly
longer necks – eventually (after many
generations a giraffe evolves).
94
But IAC is wrong since traits must be
genetic to be passed on.
Four forces of Evolution
1)
2)
3)
4)
Genetic Drift
Mutation
Migration (gene flow)
Natural Selection
1) Genetic drift - random fluctuations
in allele frequencies – the smaller
the population size, the more
powerful genetic drift. Very
powerful in very small populations
and very weak in very large
populations. Draw fig 2
95
Types of Genetic Drift
A) Bottleneck – random disaster,
decimates a population - by
chance, the survivors have a disrepresentative allele frequencythey will start a new population
with new allele frequencies- draw
fig 3
2) Mutation (ex. inversion,
translocation, frameshift) – New
alleles are actually created by
mutations-mutations are the
ultimate source of genetic variation3) Migration – (gene flow)- alleles
enter (immigration) or exit
96
(emigration) a population thus
changing the allele frequency.
4) Natural Selection – Darwin 1859Evolutionary (Darwinian) Fitness- An
individual’s reproductive success relative
to other individuals in the population –
the more genes you pass on, (i.e. the
more offspring you have) the higher
your fitness
Darwin’s Observations:
a) For any species, population sizes
would increase exponentially if
all individuals that are born
reproduced successfully.
97
b) However, populations tend to
remain stable
c) Resources are limited
Inference – there is a struggle
for survival and competition for
limited resources-only a fraction
of offspring survive to reproduce
Observation:
a) There is variation among
individuals in a population;
no two individuals are exactly
alike
Inference: Certain variations
give individuals advantages in
98
survival and reproduction. If
these variations are heritable,
they will be passed on to the
offspring and increase in
frequency in future
generations since those who
have them have a higher
fitness.
In Natural Selection, who
lives/dies/reproduces is tied to
phenotype and NOT random like
Genetic Drift.
Types of Natural Selection:
99
A) Directional Selection – selection
for an extreme phenotype –
example is the peppered motha) up until the 1800’s birch trees in
Northern England were white and
the lighter colored moths were well
camouflaged on the trees-
b)Industrial revolution occurred
in the 1800’s and the trees
turned black with soot from
smoke released by factories –
Now the darker moths were at
an advantage and the population
turned dark – (there was
100
directional selection for dark
coloration) –
c) in the 1900s laws were passed
which cleaned up the
environment and the trees
turned white again-within a few
generations the moth population
also became lighter. Draw fig 1
B) Stabilizing Selection – Selection
for an intermediate phenotype –
ex. Human babies born with
below average or above average
birth weight have a lower survival
101
rate so human birth weight varies
little. Draw fig 2
C) Disruptive selection – Selection
which splits a population into two
phenotypes– Selection works
against the average phenotype
and favors the two extremes ex.
Populations of Northern Water
snakes which live on mainland
shores inhabit grasslands and
have splotched brown scales but
populations which live on rocky
island shores have gray scales.
Each population is adapted to its
local environment-A snake with
an intermediate phenotype
102
would not be camouflaged
against either background. Draw
fig 3.
Evolution Vocabulary
1) Adaptation – A trait shaped by
natural selection- it increases your
fitness
2) Cryptic coloration – Camouflage
coloration which allows individuals
to remain hidden
3) Aposematic coloration – warning
coloration on a poisonous or
venomous species – ex. coral snake
4) Batesian mimicry – a harmless
animal evolves to mimic a
poisonous or venomous one – ex.
103
scarlet kingsnake mimics a coral
snake
5) Homologous traits – traits which
have evolved from a common
ancestor but now have different
functions- ex. Whale flipper, Bat
wing, and Monkey hand all evolved
from a primitive mammal limb, but
now have different functions
6) Convergent evolution – two
unrelated organisms evolve to look
alike as a result of living in the same
type of environment. Ex – Dolphins
(mammals) have evolved to look
like Sharks (fish)
104
7) Niche – the specific role an
organism occupies within its
environment.
8) Analogous traits – traits which have
evolved the same function, but
have evolved independently and do
not share a common ancestor-they
are the result of convergent
evolution –ex. dolphin flipper and
shark fin
9) Vestigial traits – traits which no
longer serve a purpose and tend to
be reduced – ex-whale hip bone
105
10) Co-evolution – two different
species which closely interact and
evolve in a specific context with
each other – ex. hummingbirds and
certain flowers.
11) Adaptive radiation – a single
species enters a new area and
evolves into different species as all
vacant niches in the ecosystem are
filled. Ex – marsupials in Australia
12) Species- An interbreeding
population of organisms that
produce fertile offspring and are
reproductively isolated from other
populations in nature.
106
13) Speciation – When a single species
evolves into two or more species
overtime, or a species evolves into a
different species
Types of speciation –
a) Allopatric speciation – a physical
barrier divides a population and two
new species form as they adapt to
their local environmentb) Sympatric speciation – No physical
barrier is involved – Perhaps there
is disruptive selection from
predator or some sort of behavioral
change where certain individuals
only mate with certain others in the
population. Ex – dark colored snails
107
only mate with other dark colored
snails and light colored snails only
mate with light colored snails
Pace of EvolutionA) Gradualism – species continually
and slowly evolve and split off from
other lineages-draw fig 1
B) Punctuated Equilibrium – Long
periods of no phenotypic change
are interrupted by quick splits of
different lineages-draw fig 2
Hardy-Weinberg – A formula to figure
out allele and genotype frequencies in
populations. Assumptions: No forces of
108
Evolution are affecting the trait. (this is
rare)(must have large populations)
q2= frequency of the homozygous
recessive genotype (aa)
q = frequency of the recessive allele (a)
p = frequency of the dominant allele (A)
p2 = frequency of the homozygous
dominant genotype (AA)
2pq = frequency of the heterozygous
genotype (Aa)
p+q=1, p2+2pq+q2 =1
Diversity/Classification
109
Taxonomy – the field of biology that
identifies and classifies organisms
(based on how closely related they
are).
Domains are the largest taxonomic
level. All living things are grouped into
one of three Domains:
1) Archaea-includes certain
prokaryotes which live in extreme
environments such as very hot or
very salty water
2) Bacteria-includes most
prokaryotes
3) Eukarya-includes all organisms
with eukaryote cells
110
Each Domain is further broken down
into Kingdoms:
1) Archaea is broken down into the
one kingdom called Archaebacteria
2) Bacteria is broken down into the
one kingdom called Eubacteria
3) Eukarya is broken into four
kingdoms:
a) Fungi – eukaryotic heterotrophs
with cell walls made of chitin – mostly
multicellular
b) Plantae – Multicellular eukaryotic
autotrophs with cell walls made of
cellulose
111
c) Animalia – Multicellular eukaryotic
heterotrophs with no cell walls
d) Protista – Eukaryotic organisms that
don’t fit into any of the above three
kingdoms
Taxonomic levels:
1) Kingdoms split into Phyla (plural for
phylum)
2) Phylum are split into classes
3) Class is split into orders
4) Order is split into families
5) Family is split into Genera (plural for
genus)
6) Genus is split into species
7) Species
112
The smallest taxonomic level is: Species
Example:
Domain Eukarya – pine tree, mushroom,
rabbit, ant, jellyfish, lion, wolf, domestic
cat, cobra, tiger, Haley Nesto
Kingdom animalia – rabbit, ant, cobra,
lion, domestic cat, jellyfish, tiger, wolf,
Haley Nesto
Phylum chordata – rabbit, cobra, lion,
domestic cat, tiger, wolf, Haley Nesto
Class mammalia – rabbit, lion, domestic
cat, tiger, wolf, Haley Nesto
Order carnivora – lion, domestic cat,
tiger, wolf
113
Family felidae – lion, domestic cat, tiger
Genus Panthera – lion, tiger
Species leo - lion
The further down the list two organisms
are together, the more closely related
they are.
Binomial nomenclature – a system of
naming organisms by their genus and
species.
How to write a scientific name:
1) Write both the genus and the
species name
114
2) Capitalize the first letter of the
genus
3) Underline both words (or italicize)
Ex – Ophiophagus hannah is a ????
We write scientific names to avoid
confusion. There are many common
names for the same organism (excottonmouth, water moccasin), but each
organism only has one scientific name.
VOCABULARY 1) Cladogram – an evolutionary “tree”
which splits organisms into
taxonomic groups based on shared
derived traits. Once a trait evolves,
115
everything from that point on shares
the trait. Draw fig 1
2) Dichotomous Key – a tool used to
identify organisms based on
phenotype and a series of choices.
3) Invertebrates – animals without a
backbone
4) Chordate – organisms within the
phylum chordata. They have four
characteristics:
a) Notochord – thin rod of cartilage
which provides support
b) Dorsal nerve cord
c) Gill slits – at least at some point in
development
116
d) Post anal tail – at least at some
point in development
5) Vertebrate – a chordate whose
notochord is replaced by a backbone
(spine)
ECOLOGY – The study of how
organisms interact with each other
and their environment
1) Organism – a single living
individual – ex- a lion
2) Population – all of the same type
of organism living in a specific
area –ex- all the lions in an area
117
3) Community – all the different
populations living in a specific
area –ex- all the lions plus all the
zebras, all the hyenas, all the
acacia trees, all the grass, all the
bacteria, etc.
4) Ecosystem – the community plus
abiotic (nonliving) factors – exthe above community plus the
sunlight, water, oxygen, rocks,
etc.
5) Biome – all of a specific
ecosystem across the Earth – exsavanna
6) Biosphere – the region on Earth
where all life naturally exists – six
118
miles above sea level and six
miles below sea level
Producer – an autotroph – makes
its own food – ex- plants
Consumer – a heterotroph – gets
nutrients from the environment –
ex – fungi, animals
a) Primary consumer –
consumer which eats the
autotroph – an herbivore –
ex – caterpillar eats leaves
b) Secondary consumer – eats
the primary consumer – exbird eats the caterpillar
119
c) Tertiary consumer – eats
the secondary consumer-exfox eats the bird
An organism can play the role of more
than one level –ex- grizzly bear eats
berries (role of primary consumer) and
deer (role of secondary consumer)
Decomposer – detritivore – feed on
waste and dead organic matter from all
levels (ex-fungi,vultures)
Each level of the food chain is called a
trophic level.
Autotrophs make up the first trophic
level. They get their energy from the
120
sun. Heterotrophs make up the
remaining levels and each level gets its
energy from the trophic level below it.
Food chain – a simple model that shows
how energy flows through an ecosystem
draw fig 1.
Food web – a model representing many
connected food chains within an
ecosystem. Draw fig. 2
Pyramid of Energy – Each level
represents the amount of energy that is
available to that trophic level. With each
step up there is an energy loss of 90%.
The energy is consumed by cellular
121
processes or lost as heat- ENERGY IS
NOT RECYCLED-WE CONSTANTLY NEED
“NEW” ENERGY FROM THE SUN. draw fig
3. –
Biomass also works like a pyramid-the
mass of each trophic level decreases by
90% as you go up the pyramid
Matter is anything which has mass and
takes up space. Unlike energy, matter is
recycled through an ecosystem
Water Cycle – water is stored in lakes,
oceans, and aquifers (underground
lakes)-the water evaporates into the
atmosphere in the form of water vapor –
122
the water condenses around dust
particles which forms clouds – water
falls from the sky as precipitation (rain,
snow, sleet) and the water goes back
into lakes, oceans and aquifers-a small
amount of water (10%) enters the
atmosphere from the surfaces of plants
(transpiration)Carbon Cycle – carbon is stored in the
ecosystem in the following ways:
1) CO2 (carbon dioxide) in the
atmosphere,
2) Fossil fuels (coal, oil),
3) Organic material such as cellulose and
wood
123
-Plants use carbon dioxide in
photosynthesis, animals consume plants
or other animals- plants and animals
release carbon dioxide through cellular
respiration and decomposition-also
carbon dioxide is released when organic
material (such as wood and fossil fuels)
is burned.
Ecological succession – when one
community replaces another as a result
of changing biotic and abiotic factorsthere are two types of succession:
a) primary succession-occurs when a
community is established where
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there was no previous life – ex - a
new volcanic island that rises from
the sea – certain (pioneer) species
can live on the bare rock (such as
lichens) and when they die, a poor
soil is established-other species (ex
– grasses) can then live in the poor
soil and when they die, the soil
becomes better quality-eventually
many organisms can live on the
island
b) secondary succession –
establishment of a community
where there is already soil present –
ex- a fire destroys a forest but seeds
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still live deep within the soil- new
life appears very quickly-
Population Ecology
A population’s growth rate (r) is
determined by the following equation:
r= (births-deaths)/N
N is the current population size
Biotic potential – the maximum growth
rate of a population under ideal
conditions (with unlimited resources and
no growth restrictions).
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Carrying capacity – the maximum
number of individuals of a population
that can be sustained by a particular
habitat- this prevents a population from
reaching its biotic potential- carrying
capacity is determined by two types of
limiting factors :
a) Density-dependent factors – as the
population grows these factors
become more intense- (ex – food,
space, disease)
b) Density-independent factors –
these factors occur independently
of how big the population is (ex –
natural disasters such as fires,
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volcanic eruptions and extremes of
climate such as deep freezes)
Populations which have not hit their
carrying capacity have an exponential
growth curve draw fig 1
Populations which have hit their carrying
capacity have a logistic growth curve
draw fig 2.
Herbivore – Only eats producers
Symbiosis- a term applied to two species
that live together in close contact. There
are three types of symbioses:
a) Mutualism – a relationship where
both species benefit. Ex – Acacia
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trees provide food and housing for
ants. In exchange resident ants kill
any insects or fungi found on the
tree.
b) Commensalism – one species
benefits and the other is
unaffected- ex. birds build nests in
tree branches which provide safetythe tree is not affected
c) Parasitism – one species benefits
and the other is harmed – ex.
tapeworms live in the digestive
tract of animals, stealing nutrients
from their hosts.
Aquatic ecosystems – Different types of
organisms exist within aquatic
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ecosystems due to chemistry (pH,
oxygen levels, carbon dioxide levels,
nitrogen levels, phosphorous levels, and
salinity), geography, light, depth, and/or
temperature – examples:
a) The Great Salt Lake is so salty that
fish can’t live in it. However, Brine
shrimp can tolerate the salinity.
b) Fresh water fish rarely drink and
urinate often. This is because they
are in hypotonic solution and
constantly absorb water. Salt water
fish constantly drink and rarely
urinate because they are in a
hypertonic solution and constantly
lose water
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c) Higher altitude lakes tend to be
nutrient poor and have fewer
species than lower altitude, nutrient
rich lakes.
d) Plants can only grow in depths that
sunlight can penetrate (around
200m). Phytoplankton in the ocean
are found only up to this depth.
Human Impact on the Biosphere1) Global climate change – the burning
of fossil fuels (oil/coal) increases
CO2 in the atmosphere – Increases
in CO2 cause more heat to be
trapped in the Earth’s atmosphereAs a result, global temperatures are
rising (Greenhouse effect)- Warmer
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temperatures could raise sea levels
(by melting more ice) and decrease
agricultural output (by affecting
weather patterns)
2) Ozone depletion- the ozone (O3)
layer in the atmosphere protects
the Earth against dangerous
ultraviolet rays – the use of
chloroflorocarbons (CFCs) in aerosol
sprays and refrigerants has broken
down and thinned out the ozone
layer (especially at the poles) and
allowed more UV radiation to hit
the Earth
3) Acid rain – the burning of fossil fuels
release SO2 and NO2 into the
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atmosphere – these interact with
water vapor and create sulfuric acid
and nitric acid – when it rains, these
acids kill plants and animals in lakes,
rivers and land
4) Deforestation – Clear cutting of
forests causes erosion, flooding and
changes in weather patterns- the
destruction of Rain Forests and
other habitats are causing the
extinction of plants and animals in
greater numbers than the planet
has ever previously experienced–
This loss of biodiversity may
prevent us from discovering new
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sources of medicine, foods, or
industrial products
A) Sustainable resources – if used
properly they can be replaced- ex .
only cutting down certain trees and
allowing the other trees to grow
and replace the ones cut down
B) Non-sustainable resource – once
you use it, it’s gone – ex. oil and
coal
Circulatory system (cont.)
Blood Pressure - normal blood pressure
is 120/80 - The first number is called the
systolic pressure and it is the pressure in
the arteries when the ventricles
contract-the second number is the
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diastolic pressure and it is the pressure
in the arteries when the ventricles relax-
Two diseases of the circulatory system
a) High blood pressure (hypertension)
– people with high blood pressure
are more likely to develop heart
problems because the heart is
forced to work harder-they are also
more likely to develop
strokes/aneurysms
b) atherosclerosis- a condition in
which fatty deposits called plaque
build up on the inner walls of the
arteries – these deposits can block
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coronary arteries which bring
oxygen and nutrients to the heart
itself – heart tissue will then start to
die- this is called a heart attack – if
there is a blockage in one of the
arteries leading to the brain, it’s
called a stroke
Factors which affect blood flowa) Genetics – there is a genetic
component to conditions such as
high blood pressure and
atherosclerosisb) Fatty diets and smoking – smoking
and eating fatty foods are big
factors in atherosclerosis and high
blood pressure- fatty/high
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cholesterol diets make it more likely
that plaque will build up in arteries
– being overweight stresses your
heart and forces it to pump harder–
c) Exercise and healthy diets help keep
your heart healthy. Cardiovascular
exercise increases your heart rate
which exercises your heart muscle
Immune system1) First line of defense – nonspecific –
a) skin – oily and acidic barrier
against invaders
b) Mucous membranes – protects
inner surfaces such as mouth and
lungs – lungs have cilia which sweep
invaders out
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2) Second line of defense –
nonspecifica) phagocytes – white blood cells
which engulf pathogens (disease
causing organisms) by phagocytosis.
b) Inflammatory response
c) Interferon
3) Third line of defense – specific –
known as the Immune Response:
a) Humoral Response-B cells
(mature in bone marrow)produce
specific antibodies (little protein
markers) which target specific
antigens (any foreign cell, virus,
molecule, poison) Once the antigen
is marked, phagocytes will destroy
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the antigen. One kind of B cell
called a memory B cell stores all
antibodies and if the person is
exposed again to the antigen, there
is already a small “army” of
antibodies in reserve.
b) Cell Mediated Response- T cells
(mature in Thymus)- destroy the
body’s own cells which have
become cancerous or have become
infected by some pathogen.
Vaccine – an inactive form of virus is
put into the body – B cells make
antibodies and memory B cells store
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the antibodies- if the dangerous
form of the virus invades, the
antibodies are already there to
mark it
Everything listed above is called
active immunity
When antibodies from other people
or animals are injected into
somebody for temporary relief, it’s
called passive immunity ex – if you
are bitten by a venomous snake,
the doctor might inject you with
antivenin which has antibodies
(made in horses) that mark the
venom’s enzymes.
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Brain parts and sex organs
Plant Taxonomy
1) Bryophytes – (mosses) – no
stems – no vascular tissue
2) Pterophytes – (ferns) – seedless,
vascular – Vascular tissue:
a) Xylem tissue carries
water/minerals up the stem
from roots to leaves – wood
is made of xylem tissue –
xylem tissue is dead
b) Phloem tissue – carries
products of photosynthesis
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from leaves to other parts of
the plant
Seed Plants
Seed – a plant embryo that is
surrounded by a food supply
(endosperm) and encased in a
protective covering
3) Gymnosperms – (conifers) – no
flowers
4) Angiosperms – flowering and
fruiting plants – almost all plants
are angiosperms
Flower - the sex organ of an
angiosperm
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Fruit - As angiosperm seeds
mature, the ovary walls thicken
to form a fruit that encases the
developing seeds
Parts of flower (worksheet):
Plant Anatomy and PhysiologyStomata – small openings on the
surface of leaves – allow CO2 to
enter and H2O and O2 to exit the
plant – Guard cells control the
openings to prevent excess water
loss through the stomata.
1) Water and mineral transport in
plants:
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a) Root pressure pushes the water
(just a little) up from the roots
b) Capillary action (cohesion and
adhesion) – keeps the water
column together as it moves up
the plant stem/trunk
c) Transpiration – low pressure is
formed at the leaves as water
molecules evaporate out of the
stomata – this low pressure pulls
the water column up the stem
and water (with dissolved
minerals) gets to all parts of the
plant (draw fig. 1)(video).
2) Double Fertilization in flowering
plants (video)144
Pollen grain has two cells
a) Tube cell
b) Generative cell
A) Pollen grain lands on stigma (this is
called Pollination)– The tube cell digs a
tube through style into ovary –
B) Meanwhile Generative cell splits into
two sperm cells which go down the tube
C) One sperm fertilizes the egg (within
the ovule) in the ovary and makes a
zygote – the other sperm fertilizes
another cell (with two polar nuclei)
inside the ovule and makes a triploid
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tissue called endosperm – endosperm is
the food source for the early embryo
(draw fig 2)
Plant Anatomy – three basic parts:
1) Root – anchor plant and bring in
water and minerals from soilanatomy of root (worksheet)
a) Zone of Cell Division – where new
cells are actually produced (in the
apical meristem) – the root cap
protects the dividing cells as they
are pushed farther into the ground-
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b) Zone of Elongation – Cells get
longer (stretch out) – this pushes
the root farther into the ground
c) Zone of Maturation/differentiation
– Cells differentiate into different
types of tissues (ex- phloem/xylem)
2) Stem – transport substances
between roots and leaves-hold
leaves up to sunlight 3) Leaf – see worksheet
Plant tissue:
a) Vascular tissue– xylem, phloem
b) Dermal tissue – outer covering of
plant (ex - epidermis)– root hair
cells are made of dermal tissue and
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provide a large amount of surface
area for water absorption
c) Ground tissue – between dermal
and vascular layers – examples
include mesophyll tissue
(parenchyma) in leaves which have
a lot of chloroplasts and is the main
site for photosynthesis
d) Meristematic tissue – tissue which
has not yet differentiated into any
of the above types-consists of new
cells
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