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4/14/2016 1 AP Bio Exam Review “Greatest Hits” AP Bio Exam Review: Evolution Darwin’s Theory of Natural Selection: 1. Populations produce more offspring than can possibly survive. 2. Individuals in a population vary extensively from each other, mostly due to inheritance. 3. Struggle to survive: individuals whose inherited characteristics best fit to environment leave more offspring than less fit. 4. Unequal ability of individuals to survive and reproduce leads to gradual change in pop, with favorable characteristics accumulating over generations. Populations evolve, not individuals. Fitness is determined by the environment. In summary : Natural Selection = differential success in reproduction Product of natural selection = adaptations of populations to environment Evidence for Evolution 1. Biogeography Geographic distribution of a species Geographic, reproductive isolation 2. Fossil Record transitional forms 3. Comparative Anatomy 1. Homologous structures 2. Vestigial structures 4. Embryonic Development 5. Molecular Biology DNA, proteins Hardy-Weinberg Theorem: Frequencies of alleles & genotypes in a population’s gene pool remain constant from generation to generation unless acted upon by agents other than sexual recombination (gene shuffling in meiosis) Equilibrium = allele and genotype frequencies remain constant

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Page 1: AP Bio Exam Review “Greatest Hits” · 2018. 10. 2. · “Greatest Hits” AP Bio Exam Review: Evolution Darwin’s Theory of Natural Selection: 1. Populations produce more offspring

4/14/2016

1

AP Bio Exam Review “Greatest Hits” AP Bio Exam Review:

Evolution

Darwin’s Theory of Natural Selection:

1. Populations produce more offspring than can possibly survive.

2. Individuals in a population vary extensively from each other, mostly due to inheritance.

3. Struggle to survive: individuals whose inherited characteristics best fit to environment leave more offspring than less fit.

4. Unequal ability of individuals to survive and reproduce leads to gradual change in pop, with favorable characteristics accumulating over generations.

• Populations evolve, not individuals.

• Fitness is determined by the environment.

In summary:

Natural Selection = differential success in reproduction

Product of natural selection = adaptations of populations to environment

Evidence for Evolution

1. Biogeography – Geographic distribution of a species

– Geographic, reproductive isolation

2. Fossil Record – transitional forms

3. Comparative Anatomy 1. Homologous structures

2. Vestigial structures

4. Embryonic Development

5. Molecular Biology – DNA, proteins

Hardy-Weinberg Theorem:

• Frequencies of alleles & genotypes in a population’s gene pool remain constant from generation to generation unless acted upon by agents other than sexual recombination (gene shuffling in meiosis)

• Equilibrium = allele and genotype frequencies remain constant

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Hardy-Weinberg Equilibrium

Allele Frequencies:

• Gene with 2 alleles : p, q

p = frequency of allele “A” in a population

q = frequency of allele “a” in a population

p + q = 1

Genotype Frequencies: • 3 genotypes (AA, Aa, aa)

p2 = AA 2pq = Aa q2 = aa

p2 + 2pq + q2 = 1

Conditions for Hardy-Weinberg Equilibrium:

1. Extremely large population size (no genetic drift).

2. No gene flow (isolation from other populations).

3. No mutations.

4. Random mating (no sexual selection).

5. No natural selection.

Genetic drift: a change in a population’s allele frequencies due to chance

A. Bottleneck Effect – genetic drift due to drastic reduction in population size

» Certain alleles may be over/under represented

B. Founder effect – few individuals become isolated from larger population certain alleles over/under represented

Directional Selection: eg. beak sizes of birds during wet/dry seasons in Galapagos

Diversifying Selection: eg. small beaks for small seeds; large beaks for large seeds

Stabilizing Selection: eg. average human birth weight

Biological Species Concept

• Species = population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring

– Reproductively compatible

• Reproductive isolation = barriers that prevent members of 2 species from producing viable, fertile hybrids

Prezygotic barriers impede mating or hinder fertilization if mating does occur

Postzygotic barriers prevent a hybrid zygote from

developing into a viable, fertile adult

REDUCED HYBRID

VIABILITY

REDUCED HYBRID

FERTILITY HYBRID BREAKDOWN

HABITAT ISOLATION TEMPORAL ISOLATION BEHAVIORAL ISOLATION MECHANICAL ISOLATION GAMETIC ISOLATION

Reduced

hybrid

viability

Fertilization Viable,

fertile

offspring

Reduced

hybrid

fertility

Hybrid

breakdown

Mating

attempt

Gametic

isolation

Fertilization

Mechanical

isolation

Behavioral

isolation

Temporal

isolation

Habitat

isolation

Individuals of

different species

Types of Reproductive Barriers

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Convergent Evolution

• Independent development of similar features between 2 unrelated species • Similar environments • Analogous structures • Eg. wings on bees & wings on birds

• Cladogram: diagram of evolutionary relationship of organisms

– Shared characteristics due to common ancestry

– Uses parsimony – simplest explanation, fewest DNA base changes for tree (“keep it simple”)

Cladistics : a form of systematics

LE

25-

11b

Turtle Leopard

Hair

Amniotic egg

Four walking legs

Hinged jaws

Vertebral column

Salamander

Tuna

Lamprey

Lancelet (outgroup)

Cladogram

AP Bio Exam Review: Biochemistry & Cells

1. Polarity of H2O

• O- will bond with H+ on a different molecule of H2O = hydrogen bond

• H2O can form up to 4 bonds

H2O Property Chemical

Explanation Examples of

Benefits to Life

Cohesion •polar •H-bond •like-like

↑gravity plants, trees transpiration

Adhesion •H-bond •unlike-unlike

plants xylem bloodveins

Surface Tension •diff. in stretch •break surface •H-bond

bugswater

Specific Heat •Absorbs & retains E •H-bond

oceanmoderates temps protect marine life (under ice)

Evaporation •liquidgas •KE

Cooling Homeostasis

Universal Substance •Polarityionic •H-bond

Good dissolver solvent

Acids and Bases

Acid: adds H+ (protons); pH<7

Bases: removes protons, adds OH-; pH>7

Buffers = substances which minimize changes in concentration of H+ and OH- in a solution (weak acids and bases)

• Buffers keep blood at pH ~7.4

• Good buffer = bicarbonate

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Functional Groups

Functional Group Molecular Formula Names & Characteristics Draw an Example

Hydroxyl -OH Alcohols Ethanol

Carbonyl >CO Ketones (inside skeleton)

Aldehydes (at end) Acetone Propanol

Carboxyl -COOH Carboxylic acids (organic

acids) Acetic acid

Amino -NH2 Amines Glycine

Sulfhydryl -SH Thiols Ethanethiol

Phosphate -OPO32- / -OPO3H2 Organic phosphates Glycerol phosphate

Dehydration Synthesis (Condensation Reaction)

Hydrolysis

Make polymers Breakdown polymers

Monomers Polymers Polymers Monomers

A + B AB AB A + B

+ H2O + + H2O +

I. Carbohydrates

• Fuel and building

• Sugars are the smallest carbs Provide fuel and carbon

• monosaccharide disaccharide polysaccharide

• Monosaccharides: simple sugars (ie. glucose)

• Polysaccharides: Storage (plants-starch, animals-glycogen)

Structure (plant-cellulose, arthropod-chitin)

Differ in position &

orientation of glycosidic

linkage

II. Lipids

A.Fats: store large amounts of energy

– saturated, unsaturated, polyunsaturated

B.Steroids: cholesterol and hormones

C.Phospholipids: cell membrane

– hydrophilic head, hydrophobic tail

– creates bilayer between cell and external environment

Hydrophilic head

Hydrophobic tail

amino acids polypeptides protein • Protein structure and function are sensitive to

chemical and physical conditions

• Unfolds or denatures if pH and temperature are not optimal

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IV. Nucleic Acids

Nucleic Acids = Information

Monomer: nucleotide

DNA RNA

•Double helix •Thymine •Carries genetic code •Longer/larger •Sugar = deoxyribose

•Single strand •Uracil •Messenger (copies), translator •tRNA, rRNA, mRNA, RNAi •Work to make protein •Sugar = ribose

AP Bio Exam Review: Cells and Membranes

Prokaryote Vs. Eukaryote • No nucleus

• DNA in a nucleoid

• Cytosol

• No organelles other than ribosomes

• Small size

• Primitive

• i.e. bacteria

• Has nucleus and nuclear membrane

• Cytosol

• Has organelles with specialized structure and function

• Much larger in size

• More complex

• i.e. plant/animal cell

• Cells must remain small to maintain a large surface area to volume ratio

• Large S.A. allows increased rates of chemical exchange between cell and environment

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Animal cells have intercellular junctions:

• Tight junction = prevent leakage

• Desomosome = anchor cells together

• Gap junction = allow passage of material

Cell Membrane 6 types of membrane proteins

hypotonic / isotonic / hypertonic

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Exocytosis and Endocytosis transport large molecules

3 Types of Endocytosis: • Phagocytosis (“cell eating” - solids)

• Pinocytosis (“cell drinking” - fluids)

• Receptor-mediated endocytosis

• Very specific • Substances bind to

receptors on cell surface

AP Bio Exam Review: Cell Energy

(Respiration & Photosynthesis)

Substrate Specificity of Enzymes

• The reactant that an enzyme acts on is called the enzyme’s substrate

• The enzyme binds to its substrate, forming an enzyme-substrate complex

• The active site is the region on the enzyme where the substrate binds

Allosteric Regulation

• a protein’s function at one site is affected by binding of a regulatory molecule at another site

• Allosteric regulation may either inhibit or stimulate an enzyme’s activity

Feedback Inhibition

• In feedback inhibition, the end product of a metabolic pathway shuts down the pathway

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Cellular Respiration Mitochondrion Structure

Citric Acid Cycle (matrix)

ETC (inner membrane)

Glycolysis

Fermentation

• Occurs in plants and animals

• Occurs in cytosol

• Keep glycolysis going by regenerating NAD+

• No oxygen needed

• Creates alcohol [+ CO2] or lactic acid

Respiration

• Release E from breakdown of food with O2

• Occurs in mitochondria

• O2 required (final electron acceptor)

• Produces CO2, H2O and up to 38 ATP (NADH, FADH2)

O2 present Without O2 Various sources of fuel

• Carbohydrates, fats and proteins can ALL be used as fuel for cellular respiration

• Monomers enter glycolysis or citric acid cycle at different points

Leaf cross section Vein

Mesophyll

Stomata CO2 O2

Mesophyll cell Chloroplast

5 µm

Outer membrane

Intermembrane space

Inner membrane

Thylakoid space

Thylakoid

Granum Stroma

1 µm

Sites of Photosynthesis

• mesophyll: chloroplasts mainly found in these cells of leaf

• stomata: pores in leaf (CO2 enter/O2 exits)

• chlorophyll: green pigment in thylakoid membranes of chloroplasts

Photosynthesis = Light Reactions + Calvin Cycle

“photo” “synthesis”

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Light Reactions

Both respiration and photosynthesis use chemiosmosis to generate ATP

Calvin Cycle = produce 3C sugar (G3P)

Photorespiration: low carbon-fixation when stomata closed in hot, dry climate

C3 C4 CAM C fixation & Calvin

together C fixation & Calvin in

different cells C fixation & Calvin at

different TIMES

Rubisco (normally fixes CO2)

PEP carboxylase fixes CO2

Organic acid

Mesophyll cells Mesophyll: fix CO2

Bundle Sheath: Calvin Cycle

Night: fix CO2 in 4C acids

Day: Calvin Cycle

Ex. rice, wheat, soybeans

Ex. sugarcane, grass Ex. cacti, pineapple,

succulent

AP Bio Exam Review: Genetics

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2nd division of

meiosis separates

sister chromatids

1st division of

meiosis separates

homologous pairs

Double division of meiosis

DNA replication

Meiosis 1

Meiosis 2

Mitosis vs. Meiosis

Trading pieces of DNA

• Crossing over – during Prophase 1, sister

chromatids intertwine

• homologous pairs swap pieces of chromosome – DNA breaks & re-attaches

tetrad

synapsis

prophase 1

What did Mendel’s findings mean?

• Traits come in alternative versions – purple vs. white flower color

– alleles • different alleles vary in the sequence of nucleotides

at the specific locus of a gene – some difference in sequence of A, T, C, G

purple-flower allele &

white-flower allele are two DNA

variations at flower-color locus

different versions of gene at

same location on homologous

chromosomes

What did Mendel’s findings mean?

• Some traits mask others

– purple & white flower colors are separate traits that do not blend

• purple x white ≠ light purple

• purple masked white

– dominant allele

• functional protein

– recessive allele

homologous

chromosomes

I’ll speak for both of us!

wild type

allele producing

functional protein

mutant

allele producing

malfunctioning

protein

Genotype vs. phenotype

• Difference between how an organism “looks” & its genetics – phenotype

• description of an organism’s trait

• the “physical”

– genotype • description of an organism’s genetic makeup

F1

P X

purple white

all purple

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Mendel’s 1st law of heredity

• Law of segregation

– during meiosis, alleles segregate

• homologous chromosomes separate

– each allele for a trait is packaged into a separate gamete

PP

P

P

pp

p

p

Pp

P

p

Mendel’s 2nd law of heredity • Law of independent assortment

– different loci (genes) separate into gametes independently • non-homologous chromosomes align independently

• classes of gametes produced in equal amounts

– YR = Yr = yR = yr

• only true for genes on separate chromosomes or on same chromosome but so far apart that crossing over happens frequently

round

wrinkled

yellow

green

: 1 1 : 1 : 1

Yr Yr yR yR YR YR yr yr

YyRr

Incomplete dominance

true-breeding red flowers

true-breeding white flowers

X P

100%

100% pink flowers

F1 generation (hybrids)

self-pollinate

��25% white

F2 generation

25% red 1:2:1

50% pink

Co-dominance

• 2 alleles affect the phenotype equally & separately

– not blended phenotype

– human ABO blood groups

– 3 alleles

• IA, IB, i

• IA & IB alleles are co-dominant – glycoprotein antigens on RBC

– IAIB = both antigens are produced

• i allele recessive to both

Polygenic inheritance

• Some phenotypes determined by additive effects of 2 or more genes on a single character

– phenotypes on a continuum

– human traits

• skin color

• height

• weight

• intelligence

• behaviors

Genes on sex chromosomes

• Y chromosome

– few genes other than SRY

• sex-determining region

• master regulator for maleness

• turns on genes for production of male hormones

– many effects = pleiotropy!

• X chromosome

– other genes/traits beyond sex determination

• mutations: – hemophilia

– Duchenne muscular dystrophy

– color-blindness

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Hemophilia

Hh x HH XHY XHXh

XHXh

XH

Xh

XHY

Y

XH

sex-linked recessive

XH Y male / sperm

XH

Xh

fem

ale

/ e

gg

s

XHXH

XHXh

XHY

XhY

XHXH XHY

XHXh XhY

carrier disease

Chromosomal abnormalities

• Incorrect number of chromosomes

– nondisjunction

• chromosomes don’t separate properly during meiosis

– breakage of chromosomes

• deletion

• duplication

• inversion

• translocation

Gene Mapping

If two genes are on the same chromosomes…

70

Now cross (AB ab) F1 progeny with (ab ab) tester to look for recombination on these chromosomes. Suppose you Get…… AB ab 583 parental

ab ab 597 parental

Ab ab 134 recombinant aB ab 134 recombinant total= 1448 268 recombinants /1448 progeny = 0.185 recombinants/progeny= 8.5% recombinants= 18.5 mu

Starting with pure breeding lines, Cross Parent 1(AA BB) with Parent 2(aa bb) Parental gametes in the F1 have to be AB and ab

Mapping the distance between two genes

AP Bio Exam Review: Molecular Biology

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Structure of DNA

Nitrogenous Bases

– Adenine (A)

– Guanine (G)

– Thymine (T)

– Cytosine (C)

• Pairing:

– purine + pyrimidine

– A = T

– G Ξ C

purine

pyrimidine

DNA Comparison

Prokaryotic DNA

• Double-stranded

• Circular

• One chromosome

• In cytoplasm

• No histones

• Supercoiled DNA

Eukaryotic DNA

• Double-stranded

• Linear

• Usually 1+ chromosomes

• In nucleus

• DNA wrapped around histones

(proteins)

• Forms chromatin

Flow of Genetic

Information in

Prokaryotes vs.

Eukaryotes

The Genetic Code

mRNA (5’ 3’) complementary to template

mRNA triplets (codons) code for amino acids in polypeptide chain

For each gene, one DNA strand is the template strand

Transcription Transcription unit: stretch of DNA that codes for a

polypeptide or RNA (eg. tRNA, rRNA)

RNA polymerase:

– Separates DNA strands and transcribes mRNA

– mRNA elongates in 5’ 3’ direction

– Uracil (U) replaces thymine (T) when pairing to

adenine (A)

– Attaches to promoter (start of gene) and stops at

terminator (end of gene)

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RNA Splicing

• Pre-mRNA has introns (noncoding sequences) and exons (codes for amino acids)

• Splicing = introns cut out, exons joined together

Translation

Most current definition for a gene: A region of DNA whose final product is either a polypeptide or an RNA molecule

A Summary of Protein Synthesis

Bacterial control of gene expression

Operon: cluster of related genes with on/off switch

Three Parts:

1. Promoter – where RNA polymerase attaches

2. Operator – “on/off”, controls access of RNA poly

3. Genes – code for related enzymes in a pathway

Repressible Operon (ON OFF)

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Eukaryotic gene expression

regulated at different stages

Gene Cloning

PCR (Polymerase Chain

Reaction): amplify (copy)

piece of DNA without use

of cells

Gel Electrophoresis: used to separate DNA molecules on

basis of size and charge using an electrical current (DNA

+ pole)

RFLPs – Disease Diagnosis

AP Bio Exam Review: Animal and Plant Systems

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Negative Feedback

• “More gets you less.”

• Return changing conditions back to set point

• Examples: – Temperature

– Blood glucose levels

– Blood pH

Plants: response to water limitations

Positive Feedback

• “More gets you more.”

• Response moves variable further away from set point

• Stimulus amplifies a response

• Examples: – Lactation in mammals

– Onset of labor in childbirth

Plants: ripening of fruit

Second Messengers • small, nonprotein molecules/ions that can relay

signal inside cell

– Eg. cyclic AMP (cAMP), calcium ions (Ca2+), inositol triphosphate (IP3)

Neuron = dendrite + cell body + axon

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Conduction of an action

potential

Cell communication: neurotransmitter released at synapses Axon (presynaptic cell) Dendrite (postsynaptic cell)

Types of Immunity

Innate Immunity Adaptive Immunity

• Non-specific

• All plants & animals

• Pathogen-specific

• Only in vertebrates

• Involves B and T cells

Adaptive Response Lymphocytes (WBCs): produced by stem cells in bone marrow

T cells: mature in thymus

helper T, cytotoxic T

B cells: stay and mature in bone marrow

plasma cells antibodies

Antigen: substance that elicits lymphocyte response

Antibody (immunoglobulin – Ig): protein made by B cell that binds to antigens

Humoral Immune Response

(antibodies)

Cell-Mediated Immune

Response

(T Cells)

Antigen-presenting

cell

Helper T cell

B cell Cytotoxic T cell

Plasma cell

Infected cell

Antibodies

Identify and

destroy

tag for

destruction

pathogen

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Immunological Memory Primary immune response: 1st exposure to antigen

Memory cells:

Secondary immune response: repeat exposure faster, greater response AP Bio Exam Review

Ecology Unit

Ecology: the scientific study of the interactions between organisms and the environment

• The ecological study of species involves biotic and abiotic influences.

– Biotic = living (organisms)

– Abiotic = nonliving (temp, water, salinity, sunlight, soil)

Heirarchy

• Organisms

• Population: group of individuals of same species living in a particular geographic area

• Community: all the organisms of all the species that inhabit a particular area

• Ecosystem: all the abiotic factors + community of species in a certain area

• Biosphere: global ecosystem

Clumped. For many animals, such as these wolves, living in groups increases the effectiveness of hunting, spreads the work of protecting and caring for young, and helps exclude other individuals from their territory.

Uniform. Birds nesting on small islands, such as these king penguins on South Georgia Island in the South Atlantic Ocean, often exhibit uniform spacing, maintained by aggressive interactions between neighbors.

Random. Dandelions grow from windblown seeds that land at random and later germinate.

Patterns of Dispersal:

1. Clumped – most common; near required resource

2. Uniform – usually antagonistic interactions

3. Random – not common in nature

Survivorship Curves:

• Type I curve: low death rate early in life (humans)

• Type II curve: constant death rate over lifespan (squirrels)

• Type III curve: high death rate early in life (oysters)

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• Zero population growth: B = D

• Exponential population growth: ideal conditions, population grows rapidly

Number of generations

Po

pu

lati

on

siz

e (

N)

2,000

= 1.0N

1,000

1,500

500

0 15 10 5 0

dN dt

= 0.5N dN dt

• Unlimited resources are rare

• Logistic model: incorporates carrying capacity (K)

– K = maximum stable population which can be sustained by environment

• dN/dt = rmax((K-N)/K)

• S-shaped curve

• K-selection: pop. close to carrying capacity

• r-selection: maximize reproductive success

K-selection r-selection

Live around K Exponential growth

High prenatal care Little or no care

Low birth numbers High birth numbers

Good survival of young Poor survival of young

Density-dependent Density independent

ie. Humans ie. cockroaches

Factors that limit population growth:

• Density-Dependent factors: population matters

– i.e. Predation, disease, competition, territoriality, waste accumulation

• Density-Independent factors: population not a factor

– i.e. Natural disasters: fire, flood, weather

Microorganisms and other

detritivores

Tertiary consumers

Secondary consumers

Detritus Primary consumers

Sun

Primary producers

Heat

Key

Chemical cycling

Energy flow

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Primary Production

• Total primary production is known as gross

primary production (GPP).

– This is the amount of light energy that is

converted into chemical energy.

• The net primary production (NPP) is equal to

gross primary production minus the energy used

by the primary producers for respiration (R):

– NPP = GPP – R

• NPP = storage of chemical energy available to

consumers in an ecosystem 1,000,000 J of sunlight

10,000 J

1,000 J

100 J

10 J Tertiary

consumers

Secondary

consumers

Primary

consumers

Primary

producers

10% transfer of

energy from one

level to next

Matter Cycles in Ecosystem

• Biogeochemical cycles: nutrient cycles that contain both biotic and abiotic components

• organic inorganic parts of an ecosystem

• Nutrient Cycles: water, carbon, nitrogen, phosphprus