STARR Biology EOC
What to Expect
A total of 54 questions:
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Cell Structure and Function: 11 questions
Genetics: 11 questions
Evolution and Classification: 10 questions
Biological Processes and Systems: 11
questions
• Ecology: 11 questions
Cell Structure and Function
• Prokaryotes vs eukaryotes
– Both have nucleic acids (DNA and or RNA)
– Both have ribosomes
– Both have cellular membranes and or cell walls
– Eukaryotes have membrane-bound organelles,
prokaryotes do not
– Prokaryotes are unicellular, eukaryotes can either
be unicellular or multicellular
– Prokaryotes are more primative/simpler than
eukaryotes
Eukaryotic Cell
Prokaryotic Cell
Organelles and their functions:
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•
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Mitochondria: energy and cellular respiration
Ribosomes: protein synthesis (make proteins)
Nucleus: control center, contains chromatin (genetic material)
Endoplasmic reticulum: packaging and sorting proteins
Golgi apparatus: transports proteins
Protein: building blocks of organisms, produced by ribosomes
Cell (plasma) Membrane: barrier that separates inner and
outer cell, maintains homeostasis
Lysosomes: digestion, waste disposal and recycling
Nucleolus: makes ribosomes
Vacuole: storage
Chloroplast: site for photosynthesis in plants
Cellular Processes
• ATP (Chemical that stores energy)
• Cellular Respiration:
• Two types: Aerobic (with oxygen) and Anaerobic (without oxygen)
• Equation for cellular resp. : C6H12O6 + 6O2 --- 6CO2 + 6H2O
•Glycolysis (glucose splitting) first step of respiration that does not require oxygen,
only 2 ATP molecules are produced
• Kreb’s Cycle and Electron Transport Chain: breakdown of pyruvic acid, takes
place in the mitochondria, can only happen in the presence of oxygen, makes 36
ATP molecules
• Photosynthesis:
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•
•
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Carbon dioxide and water are taken in by plants
Plants absorb light energy and convert it to a usable form.
Energy is used to “fix” carbon dioxide into sugar molecules
Sugar is converted to starch and stored for use by the plant, and by animals
when they eat plants.
• Occurs in the chloroplast of a plant cell
• Equation: 6CO2 + 6H2O --- C6H12O6 + 6O2
chloroplast
Membrane Transport:
• Selectively permeable plasma membrane
Structure ensures …
Essential molecules enter
Metabolic intermediates remain
Waste products exit
• Ways to move across a membrane:
• Passive transport does not require an input of energy – down or with
gradient
• Passive diffusion - Diffusion of a solute through a membrane without
transport protein
• Facilitated diffusion - Diffusion of a solute through a membrane with the
aid of a transport protein
• Active transport requires energy – up or against gradient
• Endocytosis vs. Exocytosis
• Endo: brings substances into the cell; Exo: sends substances
out of the cell
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ATP
ADP + Pi
(a) Diffusion—
passive transport
b) Facilitated diffusion— (c) Active transport
passive transport
(
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Osmosis:
• Movement of water across a selectively permeable
membrane
• Three types of solutions:
• Hypotonic: there are less dissolved
substances such as sugar or salt in the
solution than in the cell; water will move
into the cell causing it to swell
• Isotonic: there is an equal amount of
dissolved substances such as sugar or salt
in the solution and in the cell; water will
move in and out of the cell at the same
rate keeping the cell the same size
• Hypertonic: there are more dissolved
substances such as sugar or salt in the
solution than in the cell; water will move
out of the cell causing it to shrink
• Macromolecules:
• Also known as biomolecules, often found in chains called polymers:
• Carbohydrate: biomolecule composed of carbon, hydrogen, and oxygen with a ratio
of about two hydrogen atoms and one oxygen atom for every carbon atom.
• Proteins: made up of polymers of amino acids (carbon, hydrogen, oxygen, nitrogen
and sometimes sulfer)
• Enzymes are important proteins found in living things. An enzyme is a protein
that changes the rate of a chemical reaction.
• Lipids: fats, oils and waxes, made up of carbon, hydrogen and a small amount of
oxygen
• Nucleic acids : DNA and RNA, made up of nucleotides (sugar, phosphate and
nitrogenous base)
Nucleotide
Water is Polar
•
A polar molecule is a molecule with an unequal distribution of charge; that
is, each molecule has a positive end and a negative end.
•
Water is an example of a polar molecule.
•
Water can dissolve many ionic compounds, such as salt, and many
other polar molecules, such as sugar.
•
Water molecules also attract other water molecules.
• Water resists changes in temperature.
Therefore, water requires more heat to
increase its temperature than do most
other common liquids.
•
Water is one of the few substances that
expands when it freezes. Ice is less
dense than liquid water so it floats as it
forms in a body of water
Acids and bases
The pH is a measure of how acidic or basic a
solution is.
A scale with values ranging from 0 to 14 is used to measure pH.
More acidic
Neutral
More basic
Substances with a pH below 7 are acidic. An acid is any substance
that forms hydrogen ions (H+) in water.
Substances with a pH above 7 are basic. A base is any substance
that forms hydroxide ions (OH-) in water.
Genetics
• DNA carries the instructions for making proteins
– DNA vs RNA:
• DNA is double stranded while RNA is single stranded
• DNA contains the sugar deoxyribose while RNA has ribose
• DNA has the bases Adenine, Thymine, Guanine and
Cytosine while RNA has Adenine, Uracil, Guanine and
Cytosine
– DNA and RNA are nucleic acids made up of:
• Nucleotides: phosphate group, sugar, nitrogenous base
DNA
RNA
Protein Synthesis (making proteins):
Nucleus
– Transcription: occurs in the
nucleus when messenger RNA
(mRNA) makes a copy of the
DNA
– Translation: occurs at a
ribosome where mRNA lines up
as transfer RNA (tRNA) delivers
the appropriate amino acids to
the mRNA sequence
Ribosome
Genetics: The study of heredity, how
traits are passed from parent to
offspring
The study of heredity started
with the work of Gregor Mendel and his
pea plant garden
Mendel was an Austrian Monk that lived
in the mid 1800’s
Trait - any characteristic that can be passed from parent to
offspring
Heredity - passing of traits from parent to offspring
Genetics - study of heredity
Monohybrid cross - cross involving a single trait
e.g. flower color
Dihybrid cross - cross involving two traits
e.g. flower color & plant height
Punnett Square
Used to help solve
genetics problems
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Alleles – alternate or two different forms of a gene (dominant
& recessive)
Dominant - stronger of two genes expressed in the hybrid;
represented by a capital letter (R)
Recessive - gene that shows up less often in a cross;
represented by a lowercase letter (r)
Genotype - gene combination for a trait (e.g. RR, Rr, rr)
Phenotype - the physical feature resulting from a genotype
(e.g. red, white)
 Homozygous genotype - gene combination involving 2 dominant or 2
recessive genes (e.g. RR: homozygous dominant or rr: homozygous
recessive); also called pure
 Heterozygous genotype - gene combination of one dominant & one
recessive allele (e.g. Rr); also called hybrid
Mendel’s Laws
20
Law of Dominance
In a cross of parents that are
pure for contrasting traits, only
one form of the trait will appear in
the next generation.
All the offspring will be
heterozygous and express only the
dominant trait.
RR x rr yields all Rr (round seeds)
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Law of Dominance
22
Law of Segregation
• During the formation of gametes (eggs or
sperm), the two alleles responsible for a
trait separate from each other.
• Alleles for a trait are then "recombined"
at fertilization, producing the genotype for
the traits of the offspring.
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Applying the Law of Segregation
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Law of Independent Assortment
• Alleles for different traits are
distributed to sex cells (& offspring)
independently of one another.
• This law can be illustrated using
dihybrid crosses.
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Let’s Solve Together
• In guinea pigs, the allele for short
hair (S) is dominant to long hair (s),
and the allele for black hair (B) is
dominant over the allele for brown
hair (b). What is the probable
offspring phenotype ratio for a cross
involving two parents that are
heterozygotes for both traits?
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Dihybrid Cross
• Short hair = dominant = SS or Ss Long
Hair = recessive = ss
Black coat =
dominant = BB or Bb Brown coat =
recessive = bb
• SsBb x SsBb (gametes done by the FOIL
method)
–SB, Sb, sB, sb and SB, Sb, sB, sb
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SsBb x SsBb
SB
Sb
sB
sb
SB
SSBB SSBb SsBB SsBb
Sb
SSBb SSbb SsBb
Ssbb
sB
SsBB SsBb
ssBB
ssBb
sb
SsBb
ssBb
ssbb
Ssbb
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The Cell Cycle:
• Mitosis
• Meiosis
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Cell cycle
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G1 – first gap
S – synthesis of DNA
Interphase
G2 – second gap
M – mitosis and cytokinesis
• G0 – substitute for G1 for cells postponing
division or never dividing again
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S
G1
Two daughter cells form, each
containing 6 chromosomes.
Interphase
M
G2
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Meiosis
Sexual reproduction requires a fertilization
event in which two haploid gametes unite
to create a diploid cell called a zygote
 Meiosis is the process by which haploid
cells are produced from a cell that was
originally diploid

34
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G1 phase prior to meiosis
A diploid cell
Homologous pair
of chromosomes
prior to
chromosomal
replication
Meiosis I
Diploid cell
with replicated
and condensed
chromosomes
Sister chromatids
Haploid cells
with pairs
of sister
chromatids
Meiosis II
4 haploid cells with individual chromosomes
35
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Meiosis I
(a) Prophase I
(b) Prometaphase I
Spindle Centrosome
forming
(d) Anaphase I
(e) Telophase I and cytokinesis
Metaphase
plate
Bivalent
Sister
chromatids
(c) Metaphase I
Bivalent
Cleavage furrow
Meiosis II
(f) Prophase II
(g) Prometaphase II
(h) Metaphase II
(i) Anaphase II
36
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(d) Anaphase I
(e) Telophase I and cytokinesis
Cleavage furrow
(i) Anaphase II
(j) Telophase II and cytokinesis
Four haploid cells
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Meiosis vs. Mitosis

Mitosis produces two diploid daughter
cells that are genetically identical
6

chromosomes in 3 homologous pairs
Meiosis produces four haploid daughter
cells
 Each
daughter has a random mix of 3
chromosomes
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Evolution and Classification:
Evolution and Classification:
Theory of Evolution:
Gradual change in a species through
adaptations over time.
Natural Selection
Mechanism for change in a population; occurs when organisms
with favorable variations survive, reproduce, and pass their
variations to the next generation.
HMS Beagle Voyage 1835
Darwin studied
the changes in the
beaks of Finches
Darwin’s key ideas:
• A. REPRODUCTION: Organisms produce more
offspring than can survive
• B. VARIATION:Variety in traits exist
• C. SURVIVAL OF THE FIT: Some traits allow
survival & are passed on
• D. Over time certain variations make up most
of a population & they may be different from
their ancestors
Evolution Evidence:
1. Adaptations
2. Fossils
3. Comparative anatomy
4. Comparative embryology
5. Comparative Biochemistry
6. Plate Tectonics
Comparative Anatomy Structures:
Analogous:
1. Different ancestors
2. “analogy”=like
3. Different underlying
structures
4. Same Function
5. Similar Environments
Homologous:
1. Same ancestor
2. “homo”=same
3. Same underlying
structures
4. Different
Functions
5. Different
Environments
Analogous Structures
• Different underlying structures (different
ancestors)
• Same function, similar environments
Bird Wing
Fly wing
Homologous Structures:
Same underlying structures, different functions,
different environments & common ancestor
Vestigial Structures- structures in a present-day organism
that no longer serve its natural purpose, but was probably
useful to an ancestor, provides evidence for evolution
4. Comparative embryology:
Similar embryo development in closely related species
Camouflage-enables a species to blend with their
surroundings to avoid detection by predators
Mimicry-enables one species to resemble another
species; may provide protection from predators or other
advantages
Taxonomy
• Hierarchical system involving successive levels
• Each group at any level is called a taxon
• Domain
– Highest level
– All of life belongs to one of 3 domains
– Bacteria, Archaea, and Eukarya
51
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Taxonomic
group
Gray wolf
found in
Number of
species
Domain
Eukarya
Supergroup
Opisthokonta
>1 million
Kingdom
Animalia
>1 million
Phylum
Chordata
~50,000
Class
Mammalia
Order
Carnivora
Family
Canidae
Genus
Canis
7
Species
lupus
1
~ 4– 10 million
~5,000
~270
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Binomial nomenclature
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•
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Genus name and species epithet
Genus name always capitalized
Species epithet never capitalized
Both names either italicized or underlined
Rules for naming established and regulated by
international associations
• Example: Homo sapiens
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Phylogenetic trees
• Phylogeny – evolutionary history of a species
or group of species
• To propose a phylogeny, biologists use the
tools of systematics
• Trees are usually based on morphological or
genetic data
• Diagram that describes phylogeny
• A hypothesis of evolutionary relationships
among various species
54
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Present
F
I
G
J
Millions of years ago (mya)
Time
B
5
H
E
C
D
B
10
A
55
K
Cladograms:
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Notochord
Vertebrae
Hinged jaw
Tetrapod
Mammary
glands
Lancelet
Lamprey
Salmon
Lizard
Rabbit
Yes
No
No
No
No
Yes
Yes
No
No
No
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
(a) Characteristics among species
Lancelet
Lamprey
Salmon
Lizard
Rabbit
Mammary
glands
Tetrapod
Hinged jaw
Vertebrae
Notochord
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(b) Cladogram based on morphological traits
Ecology:
• Ecology is the study of interactions that take place between
organisms and their environment.
• All the living organisms that inhabit an environment are called
biotic factors.
• The nonliving parts of an organism’s environment are the
abiotic factors. Examples of abiotic factors include air currents,
temperature, moisture, light, and soil.
• Ecosystem: Populations of plants and animals that interact
with each other in a given area and with the abiotic
components of that area.
• A niche is the role or position a species has in its
environment—how it meets its specific needs for food and
shelter, how and where it survives, and where it reproduces in
its environment.
Symbiosis
• Symbiosis: means “living together”; there are 3 types of
symbiotic relationships
• Parasitism: the host is harmed and the parasite benefits (ex: human and
a tapeworm)
Host
Parasite
-
+
• Commensalism: one organism is not harmed nor benefited and the
other organism benefits (ex: tree and a bird)
Organism Unaffected
0
Organism Benefited
+
• Mutualism: both organisms benefit (ex: termite and paramecium)
Organism Benefited
+
Organism Benefited
+
Food Chains
•
Food Chain: represents the flow of energy in an ecosystem; the arrows represent
the direction of energy flow and are called trophic levels, there are usually 3-4
trophic levels in a food chain, but no more than 5 levels
Grass
Insect
Bird
Hawk
(plant)
(herbivore)
(carnivore)
(carnivore)
•
Producer: organisms that undergo photosynthesis (grass); these are also called
autotrophs
•
Consumer: organisms that must eat producers/consumers; these are also called
Heterotrophs
•
Primary consumer: these organisms eat the producers (insect)
•
Secondary consumer: these organisms eat the primary consumers (bird)
•
Tertiary consumer: these organisms eat the secondary consumers (hawk)
Pyramids
There must always be more prey than predators because the predators can
not use all the energy that is consumed from the prey. The lower an
organism is on the food chain, the higher the numbers of these organisms.
The more organisms there are at a trophic level, the more mass the group
of organisms has.
Energy Pyramid
Fox
0.1%
Birds
1%
Grasshoppers
10%
Grasses
100%
Number Pyramid
Biomass Pyramid
Fox
1 kg
Birds
10 kg
Grasshoppers
100 kg
Grasses
1000 kg