ANSWER KEY - 1
edu.parkerreno.net
Comprehensive
Biology Study Guide
Answer Key: Semester II, 2012-2013
Pages 3-10 contain content. Cover and page 2 contain a table of
contents and copyright information and do not need to be printed.
This guide provides a lot of information, but may be missing information
and is not a replacement for reviewing your notes.
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ANSWER KEY - 2
Table of Contents
Genetics ...................................................................................................................................................... 3
Punnett Squares .................................................................................................................................... 3
Protein Synthesis .................................................................................................................................. 4
Biotechnology ............................................................................................................................................ 5
Classification.............................................................................................................................................. 6
Evolution ..................................................................................................................................................... 6
Carbohydrates ........................................................................................................................................... 7
Respiration ................................................................................................................................................. 8
Photosynthesis .......................................................................................................................................... 8
The Cycles .................................................................................................................................................. 9
Water Cycle ............................................................................................................................................ 9
Carbon Cycle ......................................................................................................................................... 9
Nitrogen Cycle....................................................................................................................................... 9
Ecology, Populations, and Human Impact .......................................................................................... 9
Populations........................................................................................................................................... 10
Human Impact ..................................................................................................................................... 10
Feedback Loops ............................................................................................................................... 10
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ANSWER KEY - 3
Genetics
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Genetics is the study of gene structure/ action AND the patterns of trait inheritance
from parent to offspring
In 1860 Gregor Mendel discovered genetic principles in pea plants
o Studied thousands of crosses and their offspring
Trait Dominance:
o Some traits are dominant (it will mask the other trait, preventing its
expression)
o The recessive gene is not visible for this generation
Segregation
o For every trait, an organism has 2 genes, one from each parent
o Independent assortment: distribution of traits are random
Traits are written using letters, capitals represent the dominant trait and lowercase
represents the recessive trait. The capital is always written first
o Homozygous – the individual contains one allele for a trait
 TT = homozygous dominant
 tt = homozygous recessive
o Heterozygous – contains different alleles for a trait (Tt)
o Genotypes tell you the genetic makeup (genes) of the organism
o Phenotypes are the organism’s appearance
 Controlled by the genotype, TT -> tall, Tt -> tall, tt -> short
Punnett Squares
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Used to predict genotypic and phenotypic results of crosses
Mono- and dihybrid crosses
Complete the monohybrid cross, highlight homozygotes then underline which genotypes
will express the short phenotype.
T
t
T
TT
Tt
t
Tt
tt
See GENETICS – DIHYBRID CROSSES notes for dihybrid practice
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ANSWER KEY - 4
Protein Synthesis
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DNA Replication
o CGATATCGCC
o GCTATAGCGG
 Tip to remember: use existing knowledge to match the bases, e.g. AT&T or
CGI
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Polypeptides
o Composition: Amino acids
o Function: Enzymes (proteins) do the ‘nitty-gritty’ jobs of every living cell
Three differences between DNA and RNA
o RNA is single stranded
o RNA uses uracil instead of thymine
o RNA contains ribose sugar; DNA contains deoxyribose sugar
The three types of RNA:
o Type: name, function
o mRNA: messenger, copies [transcribes] instructions from DNA and carries to
RNA
o tRNA: transfer¸ carries amino acids to the ribosome [does not carry
transcribed RNA]
o rRNA: ribosomal, composes the ribosome
What is the Central Dogma?
o The one-way information flow of DNA -> RNA -> Proteins
o Uses replication, transcription (DNA to RNA), and translation (RNA to protein)
o Replication vs Transcription
 Replication creates two [one copy], complete, semi-conservative
stands of DNA
 Transcription targets specific genes and creates mRNA, can create
many copies
o Replication: occurs within the nucleus, DNA remains in nucleus
o Transcription: occurs within nucleus, resulting mRNA leaves nucleus
 Advantage: protects DNA from harm
 Process: RNA polymerase unzips DNA and creates mRNA by pairing
DNA with free floating nucleotides. Uracil replaces thymine in this
stage.
o Translation: occurs in cytoplasm at a ribosome, results in amino-acid chain
(protein)
 Process: mRNA is brought to a ribosome (rRNA), where tRNA’s anticodons (codons are on the mRNA strand) match up and create the
amino-acid strand.
Codons and Amino Acids
o How many amino acids? 20
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ANSWER KEY - 5
Codons:
 Codons are on the mRNA strand
 Anti-codons (complementary to codons) are on the tRNA
 Multiple codons can code for the same amino-acid
 One start codon (AUG), three stop codons (UAA, UAG, UGA)
 Stop codons do not produce an amino acid
Mutations
o A change in the DNA when a base is incorrectly copied (usually in replication)
OR as a result of DNA damage because of environment damage.
o If a mutation occurs in a sex cell it can be passed to offspring; if a mutation
occurs in a body cell it will not be passed to offspring
o Types of Mutations:
 Silent mutations: the result is the same amino acid as before
 Missense: one amino acid is changed and likely affects protein
function
 Nonsense: causes coding to terminate early, protein will not function.
Practicing the Process:
o Start with the DNA strand:
o TAC TAG GGC CCA CGA ATT
o
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o
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Transcribe to mRNA [group into codons]:
AUG AUC CCG GGU GCU UAA
o Find matching anti-codons (tRNA):
o UAC UAG GGC CCA CGA AUU
 A common mistake is to use these to find the amino acids! Don’t, instead use
the codons on the mRNA.
o
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Translate to amino acids (see codon chart) [USE THE mRNA]:
Met Ile Pro Gly Ale STOP
Biotechnology
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Gel electrophoresis
o Separates macromolecules based on their rate of movement under the influence
of an electric current
o Mixture of nucleic acids are placed in wells, the gel is then placed in a aqueous
solution containing a buffer to complete the circuit
o Charge is applied and molecules move based on size and charge – the rate of
movement is inversely proportional to size (larger molecules move slower)
o The higher the voltage, the faster the molecules travel
o DNA and RNA are negatively charged and move towards the positive electrode
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ANSWER KEY - 6
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Pipette procedure
1. Select amount of liquid to be used DO NOT GO BEYOND THE RANGE OF
THE PIPETTE
2.
3.
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5.
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Attach a new tip to the pipette
Depress plunger to first stop
Insert into liquid and slowly release plunger
Remove from liquid and insert into desired destination
Depress plunger fully
REMOVE PIPETTE FROM LIQUID then release plunger
Dispose of pipette tip
Classification
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Taxonomy
o Kingdom > Phylum > Class > Order > Family > Genus > Species
o Kids Playing Catch On Freeways Get Smashed
o Bionomial nomenclature: Genus then species (e.g. Homo sapiens)
Species are able to interbreed and produce viable offspring
Prokaryotes
o Eubacteria – harmful to you (e.g. e. coli, staph, MRCA)
o Archeabacteria – live in extreme environments, can be helpful to you
Eukaryotes
o Protists – Generally unicellular and found in water (e.g. algae, phytoplankton)
o Fungi – Decomposers, eat dead organic matter (e.g. mushrooms, mold, yeast)
o Plants – Photosynthetic
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Non-vascular = no tubes (e.g. moss, liverworts)
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Vascular = tubes
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Seedless – use spores (e.g. ferns)
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Gymnosperms – “naked seed” (e.g. pine, fir, spruce, cedar)
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Angiosperms – “closed seed” (i.e. flowering plants: fruits and nuts)
o Animals – Reproduce sexually
Evolution
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“The changes in various genes of a species over time”
Evolution refers to populations not individuals and changes are passed on to the
next generation
1809: Lamarck’s [Incorrect] Theory of Evolution
o Individuals’ characteristics can change over time
o If muscles are used, they grow stronger and these are passed to the next
generation
1858: Darwin and Wallace propose evolution is caused by natural selection
o Characteristics that allow for survival are passed on (e.g. food shortages
cause giraffes with long necks to survive and breed)
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ANSWER KEY - 7
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Basics Tenets of Evolution
o Populations produce more offspring than the environment can support
o Overpopulation leads to competition and survival of the fittest (natural
selection)
o Variation in individuals is controlled by their genes and therefore inheritable
 Better adapted individuals pass on their characteristics and species
gradually change over generations
Speciation
o When groups of a species adapt to different environments, they eventually
become new species and cannot interbreed
Evidence of Evolution
o Fossils show intermediate stages of evolution
o Vestigial Structures: present in an organism but reduced in size or useless
o Homologous Structures: similar structures in different organisms showing
they share a common ancestor (bat wings have similar structures to other
mammals’ hand/ fins/ feet)
o Embryonic development: similarities of embryos at different stages of
development, but not in the adult stage of the species
o Shared or similar genetic code
Endosymbiosis
o One organism lies within the body of another and both benefit
 An example of mutualism
o The theory proposes certain organelles (such as mitochondria and
chloroplasts) came from free-living protobacteria/ prokaryotes
o Evidence:
 Mitochondria and chloroplasts replicate via binary fission
 They have a membrane only shared by bacteria
 They have their own set of DNA outside of the nucleus
 They are the same size as their prokaryotic counterparts
 Start with the same amino acid as bacteria (unlike eukaryotic proteins)
Carbohydrates
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Sugars ending with the suffix –ose
Produced by photosynthesis
Contain Carbon, Hydrogen, and Oxygen
Monosaccharides (simple sugars)
o C6H12O6 – Glucose, Fructose, Galactose
o Animals get their energy from these
Disaccharides (two)
o Formed via dehydration synthesis of two monsaccharides
Polysaccharides (many sugars/ complex carbohydrates)
o Chains of monosaccharides formed via dehydration synthesis
o Used for energy storage (starch) and support/ composition
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ANSWER KEY - 8
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o Broken into monosaccharides via hydrolysis (cut with water)
Storage Carbs: Starch (amylase) in plants, Glycogen in animals
Structural Carbs: Cellulose in plants, chitin in animals
Respiration
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C6H12O6 (glucose) + 6 Oxygen  6 Water + 6 CO2 (carbon dioxide) + ATP
o Opposite of photosynthesis
 Everything does it, takes place in the mitochondria
1. Glycolysis: glucose broken down into two pyruvic acid molecules, some ATP
2. Citric Acid Cycle (Krebs Cycle): pyruvic acid  CO2, some more ATP
3. Electron Transport Chain (ETC): Hydrogen released, forms water with oxygen
o Lots of ATP produced
 Anaerobic (without oxygen) vs aerobic (with oxygen)
o Anaerobic respiration (fermentation) occurs only in oxygen deprived
environments
o Byproduct is alcohol and doesn’t produce as much ATP
Photosynthesis
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Energy (ATP) + 6 Water + 6 CO2 (carbon dioxide)  C6H12O6 (glucose) + 6 Oxygen
o Opposite of respiration (woah cycles…)
o Done by autotrophs (producers)
Takes place in various parts of the chloroplast
o Thylakoid: light is captured, ATP is made to start process
 Chlorophyll: captures the sunlight
o Stroma: glucose produced
Stoma/ Stomata: used to capture/ release gasses such as CO2, H2O, O2
o
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ANSWER KEY - 9
The Cycles
Water Cycle
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Evaporation: liquid to vapor in atmosphere
Condensation: vapor to liquid
Precipitation: water falling from sky (rain)
Transpiration: water vapor from plants to atmosphere
o More humidity  less transpiration
o Higher temperature  more transpiration
o More wind  more transpiration
o To combat these factors, the stomata can open to release more water or
close to conserve it
Carbon Cycle
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All organisms return CO2 to the atmosphere via respiration
Plants acquire CO2 through stomata and cycle it via photosynthesis
Decomposition recycles carbon to the soil and atmosphere
Combustion also creates CO2
Nitrogen Cycle
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N2 makes up 79% of our atmosphere but most organisms cannot obtain nitrogen
through the atmosphere
o Needed by plants and animals to create proteins and DNA
Animals acquire nitrogen by eating plants
o Plants get nitrogen from nitrogen fixing/ nitrifying bacteria in the soil
o Bacteria creates usable NO3
Denitrifying bacteria return N2 to the atmosphere via anaerobic respiration
Ecology, Populations, and Human Impact
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Ecology, “the study of where one lives”
Levels of organization
o Atom  Molecule  Cell  Tissue  Organ  System  Organism 
Population  Community  Ecosystem  Biosphere
o The Biosphere is the thin layer of earth and its atmosphere that supports life
An ecosystem is a community (many species that live together) and their habitat
o Physical boundaries aren’t obvious, no ecosystem is completely isolated
Abiotic factor: NEVER living, biotic: living or was once living.
Habitat: where a population lives
Community: all the interacting organisms in an area
Predation
Parasitism
Commensalism
Mutualism
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One organism eats the other
One organism benefits, the other loses but lives
One organism benefits, the other gains or loses nothing
Both organisms benefit each other
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ANSWER KEY - 10
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The food chain shows the of energy through food consumption
All energy originates from the sun (producers & photosynthesis)
Pyramids
o Energy: uses calories (cal) or joules (j)
o Biomass: uses kilograms, pounds, grams, etc
o Number: uses number of organisms
Autotrophs create their own food, heterotrophs eat other organisms for food
Producers make food (photosynthesizers) and are eaten by primary consumers
o Primary consumers are eaten by secondary consumers, and so on.
Populations
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Exponential (J curve, infinite expansion) vs logistic (s curve, limited expansion)
growth
Population density: amount of organisms divided per an area (e.g. 2 sloths per m2)
Human population growth is exponential
o We haven’t reached carrying capacity because of advances in medicine,
agriculture, and sanitation.
Human Impact
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The greenhouse effect (how the Earth stays warm)
o Heat either escapes or is absorbed by greenhouse gases and reflected back
o Greenhouse gases are CO2 (carbon dioxide), H2O (water), CH4 (methane), and
N2O (nitrous oxide)
o Natural effect, but too much can have negative consequences
Global warming: the human increase of the greenhouse effect
o As more CO2 is trapped, temperatures increase
o Higher temperatures, increased drought and extreme weather, rising sea
levels caused by melting ice
Albedo is how reflective a surface is, given in fraction or percent.
o 0% = non-reflective, black. 100% = reflective, white.
Renewable resources cannot be used up by humans or are replenished quicker than
they are used (e.g. water, trees, sunlight, wind)
o Non-renewable resources are used quicker than they are created
Feedback Loops
 Positive feedback loops
o A creates/ increases B, which in turn creates more of A
o Causes a constant increase or decrease of something
o Example: Global warming melts ice, which increases temperatures and melts
more ice
 Negative feedback loops
o A creates/ increases B, which lowers or eliminates A
o Usually promotes stability, for example sweating to lower body temperature
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