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STEPS OF SCIENTIFIC METHOD
1. Design an experiment.
2. Ask a ques on.
3. Create a hypothesis.
4. Se ng up a controlled experiment.
5. Record and analyze data.
6. Draw a conclusion.
Sources of Experimental Error
Measurements without well defined values.
No measurements at all
Mul ple independent variables
No controlled variable
Scien fic problem is not clearly defined
METRIC UNITS Measurement Unit
Temperature Celsius
Volume Liter
Mass Gram
Distance Meter
Scien fic Theories that have been changed/ modified over me.
Alchemy
Geocentricity
Spontaneous Genera on
Bio 1
Chesapeake Public Schools Biology SOL Review Created by Tiffany Byrum and Sherry Carmony from Grassfield High School
Bio 2
Covalent‐sharing of electrons (a)
Polarity‐ unequal distribu on of electrons (b)
O2‐ nega ve charge
H+ ‐ posi ve charge
Cohesion‐ a rac on of similar molecules
Adhesion‐ a rac on of different molecules
Water is universal sol‐vent
Main components of living cells;
No one Can Help Our Pupils Study
Nitrogen,Carbon,Hydrogen,
Oxygen,Phosphorus,Sulfur
Water is essential for life on Earth. Water absorbs heat when it evapo-rates, allowing organisms to release excess heat. The solid form of water, ice, floats, preventing lakes and oceans from freezing solid. Water molecules are both cohesive and adhesive due to the nature of hydrogen bonding .
The ATP/ADP cycle. ATP (adenosine TRI‐
phosphate) is synthesized by adding a
single phosphate group to ADP. When
ATP is cleaved in a chemical reac on, the
energy is released and made available to
cells to do work.
Fat/Lipid Cell membrane,
insula on, back up
energy
3 fa y acids & 1
glycerol
Protein Catalysts, chemical
messengers
Amino acids
Nucleic Acid Gene c informa on,
protein syntheses
5 Carbon sugar,
phosphate and
nitrogen base
Carbohydrates Food energy 6 Carbons, 12
Hydrogens, and
6 Oxygens
Macromolecule Func on Structure
The pH Scale
TheBuffers are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH to help in maintain homeostasis
Acids Bases
0 14
Neutral 7 (Water)
6Carbon Dioxide + 6 Water yields Glucose & 6 Oxygen (Photosynthesis)
Scientific Investigation
Graphing
Independent variable on the X Y axis and dependent variable on the Y axis X
Independent Variable
The variable that is changed or manipulated.
Dependent Vari-able
The variable that is changed as a result of the ma-nipulated variable.
Constant
The variable that remains the same in each and every trials.
Control An experiment without variables.
Quantative Data recorded as a numerical value.
Qualatative Data recorded which has a descriptive value.( language)
Hypothesis is a proposed scien fic explana on for a set of observa ons.
Theory A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted.
Law A statement that describes invariable relation-ships among phenomena under a specified set of conditions
Inference An interpretation based on prior knowledge
Prediction A rigorous (often quantitative) statement about what will happen under specific conditions.
Complete the Ques ons
1. If the high power objec ve on a
microscope is 40X and the ocular is
10X, what is the total magnifica on
of high power? ________
2. Aurora is working on a project.
“Does sour lo on affect the speed
of hair growth?” Her family is will‐
ing to volunteer for the experiment.
Describe how she should perform
the experiment and iden fy the
control group, independent and
dependent variables.
3. Label the parts of the microscope 1‐10
clockwise. ______________________
4. What is this piece off equipment used to
separate pieces by density? _____________
Proper es of Water:
High specific heat, Surface tension, Polarity, Heat
of vaporiza on, Ice less dense than water, Capil‐
lary ac on
*Substances added to H20 can low‐
er or raise the pH.
* pH and temperature can change
the structure of proteins and alter
their func on.* (B)
Organic compounds have C and H, I
inorganic does not have C and H.
Enzymes (proteins) are catalysts
Cell Theory –scien sts developing this theory were Schwann, Schleiden, and Virchow.
All living things are composed of one or more cells by the process of cellular reproduction.
Cells are the basic units of structure and function in living things. Because many of these structures act as if they are specialized organs, these structures are known as organelles, literally “little organs.”
New cells are produced from existing cells.
Bio 3
Fluid Mosaic Model‐Plasma Membrane‐Cell Membrane
Homeostasis: Is the ability or tendency of an organism or cell to maintain internal equilibrium
by adjus ng its physiological processes.
Metabolism is the chemical processes occurring within a living cell or organism that are
necessary for the maintenance of life. In metabolism some substances are broken down to
yield energy for vital processes while other substances, necessary for life, are synthesized
Diffusion is the movement of molecules from an area of greater concentra on to an area of
lesser concentra on. E.g. Exchange of gases in the lungs or body ssues.
Osmosis (ocean =H2O) is the diffusion of water through a semi‐permeable membrane from
an area of low solute to an area of high solute concentra on.
Facilitated diffusion is the passive transport of molecules down a concentra on gradient. It is
simply diffusion that involves a protein to make diffusion happen more easily across a cell
membrane.
Ac ve transport is the moving of substances across the cell membrane using the cell's ener‐
gy. Molecules are moved against a concentra on gradient, i.e. they move from an area of
lesser concentra on to an area of greater concentra on. This is done by carrier molecules
which gets its energy from ATP.
Cell Discovery Key Events: *Robert Hooke: coined the word cell, cork *Antonie van Leeuwenhoek- animalcules/microorganisms”
Bio 3
Organelle
Funcon W
ithin Cell
Job Sim
ilarity
Cell W
all
Supports and protects;rigid;strong
Plasm
a (Cell) M
embrane
Selecvely perm
eable; allows materials to
enter and leave
Nucleu
s Controls cell acvi
es
Cytoplasm
Jelly‐like substance; h
olds organelles in place;
contains dissolved
substances
Chloroplast
Contains chlorophyll; m
akes food from light
during photosynthesis; glucose
Mitochondria
Power house; makes energy (ATP); breaks
down food
Vacuole
Fluid filled sac; stores water, food, chem
icals
Chromosomes (DNA)
Works with ribosomes in
protein synthesis
Ribosomes
Site of protein synthesis
Nuclear Mem
brane
Controls m
ovement in or out of nucleu
s
Cen
trioles
Separates chromosomes during cell division
Endoplasm
ic Re
culum
Transports chemicals between cells and within
cells; Intracellular highway
Golgi Bodies
Modifies chem
icals to m
ake them
funconal;
sorts, packages, secretes chemicals in and out
of cell
Lysosome
Breaks down waste m
aterials
How is a cell related to a school? Use the informa on provided in the
chart below to decide which job may be most similar to the organelle.
Archaebacte‐
ria
Eubacteria
Pro
sta
Plantae
Anim
alia
Fungi
Cell W
all
Archae(no pep
‐doglycan) Eu
Pep
doglycan)
Present in
some; Varie‐
ty of types
Cellulose,
Polysaccha‐
rides
None
Chin
Gen
ec
Recom‐
bina
on
Conjuga
on,
Binary fission,
Spore for‐
ma
on
Ferliza
on
and M
eiosis
Ferliza
on
and M
eiosis
Ferliza‐
on and
Meiosis
Ferliza
on
and M
eiosis
Nutri‐
on
Autotroph
Autotroph
and Hetero‐
trooph
Autotroph
Hetero‐
troph
(ingeson)
Heterotroph
(absorp
on)
Mobility
Flagella,
glides or
nonmobile
Cilia, Flagel‐
la, A
moe‐
boids, Con‐
trac
les
None (m
ost
form
s)
Cilia, Fla‐
gella,
Contraciles
Mobile and
Nonmobile
Number
of Cells
Unicellular
Uni and
mulcellular
Mul (all
form
s)
Mul
Yeast (uni)
The rest are
mul
Nervous
System
None
Some can
conduct
smuli
Some can
conduct s
muli
Complex
(excep
on:
sponges
have none)
None
BIio
4
KING
DOM
COMP
ARIS
ON
The surface area to volume ratio of an object decreases when its size increases.
Thus small size facilitates the exchange of material into and out of the cell.
Hypotonic: The RBC expands due to lower concentra on of solute than in the cell.
Hypertonic: The RBC shrivels due to a higher concentra on of solute than in the cell.
Isotonic: The RBC and solu on are equal.
Complete the Ques ons.
1. If a jelly (coelenterate) was put in fresh water, what would happen to it? Why? _____________________
2. Why is energy needed for ac ve transport? _______________ What type of energy?
Bio 4
Lister, Joseph (1860s)
Chemical inhibi on of infec on:
Connected and applied Pasteur's work to develop and popularize the chemical inhibi on of infec on during surgery.
Ly c and Lysogenic Life cycle of a virus
Hershey and Chase used radioac ve markers to show that
the T4 bacteriophage injected DNA into the host cell in order
to reproduce.
Complete the kingdom list accurately.
Prokaryotes: Lack a nucleus 2. Eukaryotes: True Nucleus 3. 4. 5. 6.
Bio 5
Cell growth occurs during the G1, S, and G2 phases (also known as inter‐
phase). Mitosis occurs during the M phase and cytokinesis completes the
process of cell division.
Meiosis Mitosis
Crossing Over Yes No
Centromeres Split Anaphase II Anaphase
Occurs in Animalia, Plantae, Fungi All organisms
Daughter Cells Produced 4 Haploids 2 Diploids
Creates Sex Cells Only: Sperm or Egg
Everything other than sex cells
Reproduc on Type Sexual Asexual
Number of Divisions 2 1
Pairing of
Homologues
Yes No
Chromosome Number Reduced by Half Remains the Same
Complete the Ques ons.
1. How many chromosomes
does Mike have total?
_______
2. If Mike has 23 chromo‐
somes in each sperm cell,
how many are in his liver
cells?_________
3. What is another name for
sex cells? ______
Meiosis and Mitosis Compari‐
Germ Theory of Disease:
Antoni van Leewenhoek first to see bacteria.
Robert Koch's Postulates are a sequence of experimental
steps directly rela ng a specific microbe to a specific disease
Louis Pasteur and Koch credited with Germ Theory
Microorganisms enter body a number of ways
Natural immunity is an inherited resistance to infec on.
Cell Specializa on is finalized
by differen a on. External
s muli trigger variety; once
differen ated, these cells are
usually terminal and nondivid‐ing.
Differen ated cells use
specificProteins of their type.For
example, red blood cells pro‐
duce hemoglobin to transport
oxygen. Differen ated cells
Endosymbio c theory‐ eukaryo c cells
formed from a symbiosis among several
different prokaryo c organisms.
DNA molecule “unzips” and the two strands unwind; via helicase.
unwound strands of DNA serve as templates for new DNA.
DNA polymerase joins individual nucleo des to produce a new strand.
Chargaff’s rules of base pairing
Kingdoms
Hershey and Chase showed DNA passed gene c info.
Rosalind Franklin made cri cal contribu ons to the un‐
derstanding of the DNA becoming famous for the work
with the X‐ray diffrac on images of DNA.
Watson and Crick used the images to formulate the
structure of DNA and confirm the helical structure of
DNA with a model in 1953.
Bio 5
Steps to protein produc on:
DNA unzips and RNA molecule is produced.
Transcrip on‐DNA strand serves as template by RNA polymerase to synthesize a mRNA from nucleus to cytoplasm.
mRNA goes through splicing. The coding mRNA sequence is 3 nucleo des (codon).
rRNA is ribosomal when mRNA binds to the ribosome.
Transla on‐amino acids linked to tRNA sequen ally bind to the appropriate codon in mRNA forming complementary base pairs.
Amino acids are added one by one translated into polypep des or proteins.
One specific amino acid can correspond to more than one codon; therefore, the gene c code is said to be degenerate.
Gene c varia on results in phenotyp‐
ic varia on when the order of nucleo‐
des in the DNA sequence results in a
different order of amino acids. The
differences in amino acid sequence
Influence the shape, and func on of
the enzyme.
Independent assortment: Gene c
varia on can also be produced by the
recombina on of chromosomes that
occurs during sexual reproduc on.
Impact of DNA Technologies:
Improved Medicines
Improved Livestock
Improved Crops
Preven on of Gene c Diseases
Lowering the cost of medica on
Treatment for pre‐exis ng condi‐
ons
Ethical dilemmas
Bio 5
Gene cs:
Inheritable traits are responsible for characteris cs
Phenotype (physical makeup) is based on Genotype (gene c makeup)
True‐breeding individuals are homozygous or both alleles are the same
Hybrid individuals are heterozygous or the alleles are different
Law of Dominance states that when different alleles for a characteris c are inher‐ited (heterozygous), the trait of only one (the dominant one) will be expressed.
Law of Segrega on states that each gene c trait is produced by a pair of alleles which separate (segregate) during reproduc on
Law of Independent Assortment states that each factor (gene) is distributed (assorted) randomly and independently in the forma on of gametes
Mul ple alleles (3 or more) may determine a trait such as in ABO Blood type
Punne square:
A diagram used to predict the outcome of an original or parent (P) cross to determine the probability of offspring (F1) having a par cular genotype. It summarizes all possi‐ble combina ons for each gene crossed. The ra o of the phenotypes is 3:1, typical for a monohybrid cross. The ra o of the phenotypes is 3:1, typical for a monohybrid cross. The genotype is 100% of the offspring will be Bb. Crossing the F1 genera on will result in recessive alleles appearing (F2 gen‐era on).
Bb
Bb
DNA sequence, complementary RNA strand...
Turner’s
4. What is nondisjunc on? _____________
5. What does it cause? _________________
A
Muta
ons
Mul gene cs, muta ons, and environmental factors
may contribute to disorders. Whirling is a fic ous
disorder! Disorders may be recessive, dominant,
sexlinked or nonsexinked.
Ped
igree Chart
Dihybrid Crosses are more complicated crosses looking at two or more genes. The Punne square sort genes independent of each other. Dihybrid crosses between two heterozygous pea plants. R represents the dominant allele for shape (round), while r represents the recessive allele (wrinkled). Y represents the dominant allele for yel‐low (color), while y represents the Green recessive allele. Each allele for shape and Color genes are independent; therefore, four types of gametes with all possible combina ons are produced. The ra o is 9:3:3:1.
Alleles A & B for blood are dominant,
while O is recessive
Chromosomal altera ons are involved in the following human disorders:
Down syndrome, Klinefelters
syndrome (illus A), XYY syn‐
drome Trisomy X, Monosomy
X
Bio 6 Bio 6
Organisms with structural similari es proves animals all have a common
ancestor.
Comparison of developmental stages
Biochemical similari es and differences among organisms
Homologous: traits of organisms are due to sharing a com‐
mon ancestor; Created the same way; same use (Whale
and human)
Analogous: Evolved separately; Created differently but
serve same purpose (bu erfly and bird)
Evolu onary change and evolu on‐
ary rela onships are represented in
“family trees,” how these trees are
constructed, and how this knowledge
affects biological classifica on. Time‐
line of evolu onary history and infor‐
ma on can show some specific
events in the history of life: human
evolu on and the origin of life.
1 3 4
Each lineage has ancestors that are unique to that
lineage and ancestors that are shared with other
lineages—common ancestors.
Carolus Linneus is credited with Binomial
Nomenclature: La n 2 part genus and
species formal naming system. For exam‐
ple, humans belong to the genus Homo and
within that genus to the species Homo
sapiens.
King Phillip Came Over For Ginger Snaps is
a mnemonic for the classifica on system
Kingdom, Phylum, Class, Order, Family,
Genus, Species. Kingdom is the largest and
most diverse while species the specific.
2
Molecular comparisons of
different groups normally
show degrees and pa erns of
rela onship consistent with
that revealed by other kinds
of comparisons (anatomy,
fossils, embryology, cytology,
and other various examples.)
Cladis cs is helpful for show‐
ing common ancestry and
sequence of evolu on be‐
tween taxa.
The fossil
record shows the history of the modern‐
day horse Equus. The earliest fossils in this
lineage is _____5________, which was
the size of a dog, with cusped low‐crowned
molars, four toes on each front foot, three
on each hind foot ( adapta ons for forest
living). When forests were replaced by
grasslands, the best adapted had grinding
teeth, speed an increase in size, and de‐
crease in toes. Living organisms resemble
most recent fossils in the line of descent.
The similari es allow us to trace a line of
ancestry through me.
Fossils:
The fossil record is the history of life
documented by remains from the
past. Fossils consist of skeletons,
shells, seeds, insects trapped in am‐
ber, dung, DNA and other chemicals,
imprints of leaves, and tracks of
organisms that lived in the distant
past. Most fossils are at least 10,000
years old.
Analogy of bat & bird wings
Bat wings and bird wings are analogous as flight structures: their structure and func on have evolved by
different routes from a flightless rep lian ancestor. Note for example that a good por on of the flight surface
in bats consists of a membrane stretched between the extended digits (chiropatagium), whereas the digits of
the bird are rela vely small and do not support the flight surface.
Note also that bat and birds wings are homologous as forelimbs.
Bio 7
Bio 7
How we know this!
Rela ve Da ng: The rock layers on the bo om are deemed older than the ones de‐posited above (Superposi on).
Absolute Da ng: Relies on the decay of radio‐ac ve elements (ie, carbon). Very old rocks are dated by volcanic material. Sedimentary rocks less than 50,000 years old can be dated using radioac ve carbon.
Geologists have assembled a geological me scale based on numerical (absolute) da ng of rocks from around the world.
Molecular clocks allow scien sts to use the amount of gene c divergence between organ‐isms to extrapolate backwards to es mate dates.
___________________
_________________: Two species evolve in response to each other over me.
Darwin concluded: Individuals be er adapted to the environment competed be er than the others,
survive longer and reproduce more Reproducers passed on more successful characteris cs to the next genera on. Survival of the fi est, struggle for existence and natural selec on.
Types of Natural Selection - selection and change in allele frequency 1. Disrup ve Selec on Disrup ve selec on favors individuals at both ex‐tremes of varia on: selec on is against the middle of the curve. This causes a break of the varia ons, caus‐ing two or more changes or dis nct phenotypes. (African swallowtail bu erfly) 2. Stabilizing Selec on Occurs when the environment (includes natural selec on) doesn't change or cause change, there‐fore, when the environment doesn't change there is no pressure for a well‐adapted species to change. Fossils suggest that many species remain unchanged for long periods of geological me. (Coelocanth) 3. Direc onal Selec on This occurs when environment changes in a par cular way crea ng selec ve pressure for species to change in response to the environment. *Peppered Moth *An bio c Resistance: An bio cs kill bacteria, but occasionally a chance mutant appears that is resistant to that an bio c. Environments where the an bio c is o en present, the mutant has a selec ve advantage since the normal bacteria are killed leaving the mutant cell free to reproduce and colonize, leaving the environment without compe on. Some farmers feed an bio cs to ani‐mals to prevent infec on, crea ng a perfect environment for resistant bacteria to thrive. The best answer is to stop using the an bio cs so the resistant strain has no selec ve advantage, and may die off. *DDT was a widely used insec cide. A er a few years of extensive use, DDT lost its effec veness on insects. Re‐sistance to DDT is a gene c trait that the presence of DDT in the environment made into a favorable trait. Only those insects resistant to DDT survived, leading over me to popula ons largely resistant to DDT.
Geographical Isolation
1. Interbreeding population of one species (divergence/adaptive radiation). 2. Population becomes divided by a physical barrier as water, mountains. This can happen when some of the population migrates or is dispersed or when the geography changes cata-strophically (e.g. earthquakes, volcanoes, floods) or gradually (erosion, continental drift). 3. If the two environments (abiotic or biotic) are different, the two populations will experi-ence different selection pressures and will evolve separately. Even if the environments are similar, the populations may change by random genetic drift, especially if the population is small.
4. If two populations meet again, they are so different that they can no longer interbreed. They are therefore reproductively isolated and are two distinct species. They may both be different from the original species, if it still exists elsewhere.
Gene flow:
Gene flow is any movement of genes from one population to another and is an important source of
genetic variation.
Increases variation within a population by introducing new alleles produced in another population
Continuous tends to decrease the diversity among populations, causing gene pools to become similar.
Reduction or restriction between populations is necessary for the development of new species.
The frequency of alleles can change from generation to generation as a result of chance in a small gene
pool (genetic drift).
Genetic drift is changes in allele frequencies of a gene pool due to chance or random events. It can occur
in large or small populations. Genetic drift causes gene pools of two isolated populations to become different as some alleles are lost and others are stable.
Genetic drift occurs when founders (or colonizers) establish a new population, or after interbreeding.
The founder effect is genetic drift in which rare alleles, or combinations of alleles, occur in higher fre‐quency in a population isolated from the general population. Founding individuals contain a fraction of the total genetic diversity of original gene pool. The alleles carried by founders is determined by chance.
All gene c varia on in a popula on is generated by muta on. Muta on is any heritable change in DNA. Muta‐
ons can be changes of a single nucleo de base or may involve changes in chromosome number. Whether a
muta on is good, neutral, or harmful depends on how it affects survival and reproduc ve success.
New species usually develop due to:
Geographical isola on (allopatric specia on) Reproduc ve isola on (sympatric specia on)
____________of the Galapagos finches from ancestral coloniz‐
ers from the South American mainland. (Adap ve Radia on)
Galapagos tortoises, note the difference in the height
of the shell and necks between the le and right .
______________ evolu on: Unrelated organisms independently
evolve similari es when adap ng to similar environments
Pa erns of Evolu on
Gradualism (le ): The evolu on of new species by slow steady accumula on of small gene c changes over long periods of me. Punctuated equilibrium (right): Proposes organisms go through long stable periods interrupted by brief periods of more rapid change‐introducing new species. Gould’s idea is controversial to Darwin’s tradi onal evolu onary view of gradual and con nuous change.
Sex can introduce new gene combina ons into a popula on. This gene c
shuffling is another important source of gene c varia on.
Natural or Ar ficial Selec on
Gene (Nucleo de sequence) muta ons or Chromosomal muta ons (inversions and transloca ons)
Crossing over during meiosis
Random segrega ons and combina on of gametes during fer liza on.
Hardy‐Weinberg’s Laws
Fossil Record: Represents Earth’s History
MYA
Life on
Earth
Life on Earth
Use the terms below to fill in the blanks.
Ex nc on, Coevolu on, Convergent, Divergence
Bio 8
Abio c factors,: Includes all non‐living things like light, air, wa‐ter, temperature, minerals, soil and clima c aspects.
Bio c factors,: Includes all living organisms like plants, animals and microbes working directly or indirectly to influence the lives of each other.
These are the interac ons between the organisms of the same species. Significant
intraspecific bio c factor examples are as follows:
1. Compe on among animals of the same species for food, shelter and mate.
2. Compe on among plants of the same species for light, water and space.
3. Interac on among the animals of social organiza ons such as flocks, herds.
These are the interac ons between the organisms belonging to two or more differ‐
ent species. Significant interspecific bio c factor examples are as follows :
1. Predator and prey rela onships.
2. Different rela onships like parasi sm, commensalism, and mutualism.
3. Mutual rela onships between plants and animals for food, pollina on and dispersal of fruits and seeds.
Bio 8
Popula on growth occurs when available resources exceed the
number of individuals able to exploit them. Reproduc on is rapid,
and death rates are low, producing a net increase in the popula‐
on size.
Factors Influencing Popula on Growth: Provided resources are
available, popula ons have the poten al to expand at an exponen‐
al rate, since reproduc on is generally a duplica ng process. Two
most basic factors that affect the rate of popula on growth are the
birth rate, and the death rate. .
Carrying capacity is the point
where popula on size levels
off.
Limi ng factor or resource is a
factor that controls a process,
such as organism growth or
species popula on, size, or
distribu on.
When two interac ng species, for example predator and prey, evolve together, they can influ‐ence the evolu on of the other. This is referred to as coevolu on. Some mes coevolu on re‐sults in two species that influence (both posi vely or nega vely) from each other, in a rela on‐ship referred to as symbiosis. The various types of symbiosis include:
parasi sm ‐ one species (parasite) benefits more than the other species (host)
commensalism ‐ one species benefits while a second species is neither helped nor injured
mutualism ‐ both species benefit from the interac on
Match the type of symbiosis with one of the 3 pictures below.
1. _____________
Whale fin and
barnacles
2. ________________ 3. _____________
Clownfish and
Sea anem
one
Lamprey & Fish
Nutrient Cycles
Carbon atoms con nually move
through living organisms, the
oceans, the atmosphere, and the
crust of the planet. This movement
is known as the carbon cycle.
The water cycle describes the con‐
nuous movement of water on,
above and below the surface of the
Earth through physical processes of
evapora on, transpira on, conden‐
sa on, precipita on, infiltra on,
runoff, and subsurface flow.
There are 5 steps of nitrogen cycle that
help in fixing atmospheric nitrogen:
Nitrogen Fixa on (N2 to NO3‐ or NH4)
Nitrifica on (NH3 to NO3‐)
Assimila on (here the NH3 and NO3‐
are incorporated into the biological
ssues)
Ammonifica on (organic nitrogen com‐
pounds to NH3)
Denitrifica on (NO3‐ to N2)
An organism’s role within an ecosystem depends on how it obtains its food. Plants
and animals obtain their food in very different ways, so they have very different
roles in an ecosystem. The way in which an organism obtains food also affects its
interac ons with other organisms in the ecosystem.
Producers are organisms that are able to make their own food using abio c ele‐
ments
Consumer: an organism that eats other living things for energy:
herbivore: an organism that eats plants only
carnivore: an organism that eats other animals only
scavenger: an organism that eats already dead animals
omnivore: an organism that eats both plants and animals
detrivore: an organism that feeds on decaying plant and animal ma er
decomposer: an organism that consumes and breaks down dead organisms or
The hierarchy represented in this figure is one of nutri onal
dependency. Organisms on each level are dependent upon
organisms below for nutrients essen al to growth and metab‐
olism. The obvious excep on is the bo om level of decom‐
posers, which take nutri on from organic ma er le behind
by organisms on the several levels above.
Recall that cell respira on “burns” food to release its energy, producing ATP. ATP is then used to fuel life processes. Although a lot of energy may be taken in at any level, the energy that ends up being stored there – food available to the next level — is far less. Scien sts have calculated that an average of 90% of the energy entering each step of the food chain is “lost” this way .
Bio 8
Bio 8
Pyramid of Numbers‐based on the
number of individual organisms at
each trophic level.
In aqua c ecosystems and herbaceous commu‐
ni es, autotrophs are present in large numbers
per unit area. They support a lesser number of
herbivores, which inturn support fewer carni‐
vores.
Pyramid of Biomass shows that ener-gy can never be destroyed and neither can it be created. Energy can only be transferred from one form to another. The pyramid symbolizes the animals eat plants, then the herbivores, then those feeding on other animals...the circle of life. The last step is the decomposers. The energy is transferred through the chain and converted in the biomass.
A food chain shows how each living thing gets its food. Some animals eat
plants and some animals eat other animals. For example, a simple food
chain links the trees & shrubs, the giraffes (that eat trees & shrubs), and
the lions (that eat the giraffes). Each link in this chain is food for the next
link. A food chain always starts with plant life and ends with an animal.
Food Webs‐A food web describes the feeding rela onships in an ecosys‐
tem that form a network of complex interac ons. A food web links all the
food chains in an ecosystem together. The arrows in the web face to‐
wards the energy.
Organisms –Ecosystems and Adapta ons:
Chesapeake Bay
Salinity and pH influenced by rain and des
Seasonal fluctua ons influence temperature
Light fluctuates daily, is weather and seasonally dependent
Erosion (natural or human destruc on) reduces light penetra on
Areas of the Bay have fluctua ng oxygen levels
Summer is usually the most stressful me due to human impact
Pyramid of numbers/biomass/energy reflect a decrease in organ
isms with each increasing level of the food chain
Carbon dioxide is found in dissolved in water.
Carbon is transferred up the food chain and returned as waste
products
In marine systems, nitrogen is a limi ng factor
Phosphate is a limi ng factor affected by nutrient runoff in fresh
water systems (fer lizer and cleaning products)
Density Independent Factors:
Storms: Hurricanes such as Agnes (1972), Isabella (2003)
River flooding following localized thunder storms
Unseasonable temperature fluctua ons & drought
Human ac vi es: Dams, clear cu ng forests, pollu on: spills or runoff
Density Dependent Factors:
Compe on: interac on of organisms for resources such as food and habitat.
Preda on: predators tend to eat the prey organism encountered most o en Toad‐
fish eats fish, crabs, and/or oysters (Chesapeake blue crabs notorious)
Chesapeake Bay Invasive Species: Nutria, Asia c clam, Zebra mussel, Rapa Whelk,
Phragmites (plant), Purple Loosestrife. No natural predators disrupts the ecosys‐
tem.
Parasi sm: increased organism numbers makes transmission easier
Disease: spreads more readily in densely populated groups
Biome: Complex of terrestrial communi es that cover a
large area and is characterized by certain soil and climate
condi ons and par cular assemblages of plants and animals.
Bio 8 Bio 8
5. Write the le ers of the ponds in order from the youngest, to
the oldest. ________________________________________
Lakefront: grass may invade a build‐up of sand. Humus formed
by the grass‐ gives root to oaks and pines and lesser vegeta on,
which displaces the grass forming altered humus. That soil
eventually nourishes maple and beech trees, which crowds out
the pines and oaks and forms a climax community.
Other than trees, successive communi es shelter many other
life forms, with the greatest diversity popula ng the climax
community.
Chesapeake Bay and Human Ac vi es:
In the1600’s, the Chesapeake Bay was the healthiest. The watershed was
mainly comprised of forested buffers, wetlands, and resources lands that
absorbed and filtered nutrients.
Development stripped the watershed of certain buffers, and today pollu‐
on flows undiluted into waterways. Farms, factories, ci es, and suburbs
have replaced much of these natural filters and impaired water quality so
severely that the Chesapeake Bay is on the Environmental Protec on
Agency's "dirty waters'' list.
Nutrients—primarily nitrogen and phosphorus—are essen al for the
growth of all living organisms in the Chesapeake Bay. However, excessive
nitrogen and phosphorus degrade the Bay's water quality.
Nitrogen pollu on is the most serious pollu on problem for the Bay be‐
cause it causes algal blooms that consume oxygen. The blooms lower
dissolved oxygen levels so severely that fish and shellfish die and it blocks
the sun keeping grasses from growing.
Outbreaks of poisoning due to various toxins accumulated by shellfish and
fish such as the recent Pfiesteria outbreaks in Chesapeake Bay have oc‐
curred several mes in the past few years.
Atlan c oyster used to cover extensive regions, but overharves ng of
oysters during the last century has now eliminated commercial oyster
reefs. The organic ma er falls to the bo om and is consumed by benthic
microbes, leading to low oxygen condi ons.
The Chesapeake Bay Program is a regional partnership that has directed
the restora on of the since 1983.
U.S. Environmental Protec on Agency has developed a Bay‐wide
"pollu on diet" that outlines the maximum amount of nitrogen, phospho‐
rus, and sediment pollu on each state in the watershed can contribute to
the Bay if we are to be successful in ge ng it off the "dirty waters" list.
Farmers have made the Conserva on Reserve Enhancement Program
(CREP) one of Virginia's most ac ve water quality efforts. Financial incen‐
ves are offered to farmers who voluntarily restore wetlands and shrub/
forest buffers.
4. Explain the succession of the forest 1‐5. __________________
Succession: gradual long term changes in altered ecosystems Succession is a slow ecosystem force which is most easily recog‐nized a er a destruc ve force has devastated an environment. Primary succession: rock ‐> lichen ‐> moss ‐> grass ‐> shrub ‐> trees ‐> oak hickory forest Slow process because of soil forma on and species introduc on Secondary succession: re‐establishment of life following a disrupt‐ ive force. grass ‐> shrub ‐> trees ‐> oak hickory forest
Quicker process because ingredients for life are in place and previ‐
ous species are nearby and ready to re‐invade.
Climax Communi es have reached the stable stage. When well
defined, the climax community is called a biome. Examples are
tundra, grassland, desert, and the deciduous, coniferous, and trop‐
ical rain forests.
Posi ve Human Impact:
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