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AP Biology Review Outline
WHAT DOES THE TEST ACTUALLY TEST?
1. Questions on the AP Exam will require a combination of specific knowledge
from the concept outline as well as its application through the science
practices.
2. In order to answer multiple-choice questions correctly, students will NOT be
required to recall specific illustrative examples. However, an illustrative
example may appear on the exam provided that the question includes
sufficient information to enable students to answer the question.
3. For the free response questions, students will be expected to provide
appropriate scientific evidence and reasoning to support their responses.
Students can draw upon the illustrative examples or any other appropriate,
relevant examples in order to assist in answering the questions.
4. As the emphasis of quantitative questions is on the application of
quantitative skills and mathematical reasoning, students will not be required
to recall specific formulas. A formula list will be provided within the exam
materials.
THE BIG IDEAS
Big Idea #1 – The process of evolution drives the diversity and unity of life.
1.
Natural selection is a major mechanism of evolution
a. Key points: Darwin’s theory, evolutionary fitness measured by
reproductive success, mutation and genetic variation play a key
role as do pressures due to environment, and chance especially in
small populations. Examples:
i. Peppered Moth, pocket mice on lava flows
b. Understand Hardy-Weinberg and the conditions where the
equations can be used.
2.
Phenotypic variation significantly increases or decreases the fitness of
an organism. Examples:
i. DDT resistance in insects
ii. Sickle-cell anemia and heterozygote advantage
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3.
Humans impact variation on other species. Examples:
i. Artificial selection (e.g. dog breeds, livestock etc)
ii. Overuse of antibiotics
4.
Biological evolution is supported by scientific evidence from many
disciplines, including mathematics. Understand:
a. Fossil evidence and relative age
b. Morphological homologies, vestigial structures
c. DNA and protein (e.g. cytochrome C) similarities
d. Phylogenetic Trees and cladograms
5.
Organisms are linked by lines of descent from common ancestry
a. Domains (Archaea, eubacteria, eukarya) all linked by a common
genetic code, metabolic pathways (glycolysis, electron transport)
b. All eukaryotic cells possess the same or similar organelles, all
prokaryotes possess the same or similar structures
c. Evolution of the heart fish through mammals (2,3,4 chambers)
6.
Life continues to evolve
a. Speciation due to divergence and adaptive radiation
i. Reproductive isolation (allopatric, sympatric, prezygotic
and postzygotic isolating) can result in new species
b. Extinction due to human impact on ecosystems
c. Evolution evidence: Antibiotic resistance, directional selection
(peppered moth), recent research on Galapagos finch beaks
7.
The origin of living systems is explained by natural processes
a. Understand how the early inorganic molecules in the primordial
atmosphere and oceans could have formed simple organic
compounds (Miller experiment) which eventually may have led to
complex organic molecules and the first rudimentary cells
b. RNA world hypothesis
c. Evidence that all life came from the “same place” includes a
common genetic code, and molecular building blocks are common
to all life forms (monomers of proteins, carbs, fats, nucleic acids)
Big Idea #2 – Biological systems utilize free energy and molecular building
blocks to grow, to reproduce and to maintain dynamic homeostasis
1.
All living systems require a constant input of free energy
a. Life requires a highly ordered system, order is maintained by a
constant input of free energy to decrease entropy
b. Order is maintained by coupling cellular processes that increase
entropy (exergonic -ΔG such as cellular respiration) with cellular
processes that decrease entropy (endergonic +ΔG such as ATP
synthesis and the Calvin Cycle).
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c. Energy related pathways in biological systems are sequential and
may be entered at multiple points in the pathway
i. Example to know: Cellular respiration and how ATP can be
made from glucose, fats, proteins and where each enters
the cycle (Acetyl Co-A crossroads), and anabolic (building
up) and repair the body from these macromolecules when
not used for ATP
d. Organisms use free energy to maintain organization, grow,
reproduce
i. Organisms use various strategies to regulate body
temperature and metabolism. Example to know: Endo or
ectothermy
ii. Reproduction and rearing of offspring require free energy
beyond that used for maintenance and growth. Example to
know: seasonal reproduction in animals and plants
iii. Smaller the organism the higher the metabolic rate
iv. Changes in free energy can result in changes in population
size
v. Changes in free energy availability can result in disruptions
to an ecosystem. Example to know: Pyramid of energy
2.
Organisms capture and store free energy for use in biological
processes
a. Photosynthetic autotrophs use the sun, chemosynthetic
autotrophs use inorganic compounds
b. Heterotrophs capture free energy present in carbon compounds
produced by other organisms, aerobically and or anaerobically
(fermentation)
c. Energy capturing processes have different electron acceptors
i. NADP+ in photosynthesis
ii. Oxygen in cellular respiration
d. Photosynthesis – understand reaction center boosting of electrons
to higher energy levels, photosystems connected by electron
transport chains, establishment of a proton gradient and the
chemiosmotic production of ATP, how ATP and NADPH power the
production of carbohydrates in the Calvin Cyle
i. The evolution of photosynthesis in prokaryotic organisms
was responsible for the formation of an oxygenated
atmosphere, and eukaryotic photosynthesizers via
endosymbiosis.
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e. Cellular respiration in eukaryotes – Understand how glycolysis
produces pyruvate and makes ATP and reduces NAD+ to NADH
(substrate level phosphorylation-SLP), how SLP occurs in the
Krebs cycle and how coenzymes NADH and FADH2 are involved,
how the electrochemical gradient works to produce ATP in the
cristae of the mitochondria (creation of the proton gradient),
chemiosmosis, oxidative phosphorylation
3.
Organisms must exchange matter with the environment to grow,
reproduce and maintain organization. Know specifically:
a. What elements are needed for each macromolecule
b. Properties of water: Adhesion, cohesion, high specific heat,
universal solvent, high heat of vaporization and high heat capacity
c. Surface area to volume ratio affects a biological system’s ability to
obtain necessary resources or eliminate wastes. Important
examples:
i. Root hairs, reason for cell division
4.
Cell membranes are selectively permeable due to their structure
a. Know the structure of the plasma membrane (fluid mosaic model)
and how and why key molecules enter and/or exit
b. Know cell walls: make up, and function in plants, bacteria and
fungi
5.
Growth and dynamic homeostasis are maintained by the constant
movement of molecules across membranes
a. Passive transport (PT). Know: No energy involved, how PT allows
for waste elimination and nutrient procurement, role of
membrane proteins, tonicity. Examples: osmosis, Na/K pump,
facilitated transport of glucose
b. Active transport (AT). Know the involvement of carrier proteins,
exo and endocytosis, Na/K pump, proton pumps in ETC
6.
Eukaryotic cells maintain internal membranes that partition the cell
into specialized regions
a. Benefits: Surface area increased, minimizes competing reactions.
Examples: Mitochondria, Nuclear envelope/ E.R.
7.
Organisms use feedback mechanisms to maintain their internal
environments and respond to external environmental changes
a. Negative feedback mechanisms maintain dynamic homeostasis.
Example: temp regulation, glucose/glucagon
b. Positive feedback amplifies responses and initiate change.
Examples: Ripening of fruit, progression of uterine contractions
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c. Alteration of feedback mechanisms can result in deleterious
consequences. Example: diabetes mellitus in response to
decreased insulin or desensitization of receptors
8.
Organisms respond to changes in their external environments
through behavioral and physiological mechanisms
a. Examples: Photoperiodism and phototropism in plants, shivering
and sweating in humans
9.
All biological systems from cells and organisms to populations,
communities and ecosystems are affected by complex biotic and
abiotic interactions involving exchange of matter and free energy
a. Cells – know how they are affected by water availability
b. Organisms – know how they are affected by symbiosis (mutualism,
commensalism, parasitism)
c. Stability of populations, communities and ecosystems – know how
they are affected by food chains and food web, density dependent
factors
10.
Homeostatic mechanisms reflect both common ancestry and
divergence due to adaptation in different environments
a. Organisms have various methods for obtaining nutrients and
eliminating wastes: Example to know: Nitrogenous waste
production in various animals (aquatic and terrestrial)
b. Homeostatic control mechanisms in species of microbes, plants
and animals support common ancestry. Example: Circulatory
systems in fish, amphibs and mammals - # of loops
11.
Biological systems are affected by disruptions to their dynamic
homeostasis
a. Disruptions at the molecular and cellular levels affect the health of
the organism
i. dehydration or response to allergens
b. Disruptions to ecosystems impact the dynamic homeostasis or
balance of the ecosystem
i. Example: Human impacts – logging, fertilizers, CO2
12.
Plants and animals have a variety of chemical defenses against
infections that affect dynamic homeostasis
a. Plants, invertebrates and vertebrates have multiple, non-specific
immune responses. Example: inflammation, or other non-specific
defenses
b. Mammals use specific immune responses triggered by natural or
artificial agents that disrupt dynamic homeostasis
i. Know: B and T cell immunity and how it all works, second
exposure results in a more enhanced immune response
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13.
Timing and coordination of specific events are necessary for the
normal development of an organism, and these events are regulated
by a wide variety of mechanisms.
a. Observable cell differentiation results from the expression of
genes for tissue-specific proteins.
b. Induction of transcription factors during development results in
sequential gene expression. Know the following:
i. Homeotic genes are involved in developmental patterns
ii. Embryonic induction in development results in the correct
timing of events
iii. Temperature and the availability of water determine seed
germination in most plants
iv. Genetic mutations can result in abnormal development
v. Genetic transplantation experiments support the link
between gene expression and normal development
vi. Genetic regulation by microRNAs plays an important role in
the development of organisms and the control of cellular
functions.
c. Programmed cell death (apoptosis) plays a role in the normal
development and differentiation
i. Important examples: morphogenesis of fingers and toes,
suppression of immune response leaving memory B and T
cells
14.
Timing and coordination of physiological events are regulated by
multiple mechanisms
a. In plants, physiological events involve interactions between
environmental stimuli and internal molecular signals. Examples:
i. Phototropism
ii. Photoperiodism, flowering of long and short day plants
b. In animals, internal and external signals regulate a variety of
physiological responses that synchronize with environmental
cycles and cues. Examples:
i. Jet lag in humans
ii. Circadian rhythms
c. In fungi, protists and bacteria, internal and external signals
regulate a variety of physiological respoonses that synchronize
with environmental cycles and cues. Example:
i. Quorum sensing in bacteria
15.
Timing and coordination of behavior are regulated by various
mechanisms and are important in natural selection
a. Individuals can act on information and communicate it to others.
i. Innate behaviors are those that are inherited
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ii. Learning occurs through interactions with the environment
and other organisms
b. Responses to information and communication of information are
vital to natural selection. Examples:
i. Photoperiodism
ii. Phototropism
iii. Behaviors in animals are triggered by environmental cues
and are vital to reproduction, natural selection and
survival. Examples:
1. Courtship
2. Hibernation
c. Cooperative behavior within or between populations contributes
to the survival of the populations. Know the following:
i. Niche and resource partitioning
ii. Mutualistic relationships such as (lichens, bacteria in
digestive tracts, mycorrhizae, biology of pollination)
iii. Kin selection
Big Idea #3 – Living systems store, retrieve, transmit and respond to
information essential to life processes.
1.
DNA, and in some cases RNA, is the primary source of heritable information.
Know each of the following:
a.
Non eukaryotic organisms have circular chromosomes, while
eukaryotic organisms have multiple linear chromosomes, with a few
exceptions
b.
Prokaryotes, viruses and eukaryotes contain plasmids, which are selfreplicating
c.
Proof that DNA is the hereditary material is based on historical
experiments. Know specifically the contributions of:
1.
Watson, Crick, Wilkins, Franklin
2.
Avery-MacLeod-McCarty
3.
Hershey-Chase
d.
DNA replication is semi-conservative, bidirectional, uses DNA
polymerase and other enzymes, and the processes of replication differ
with the leading and lagging strands
e.
Know how retroviruses such as HIV work with respect to replication
2.
DNA and RNA have structural similarities and differences that define
function.
a.
Know similarities: nucleotides connected by covalent bonds, 3’ to 5’
ends, nitrogenous bases
b.
Know differences: deoxyribose vs ribose, thymine vs uracil, double
stranded vs single stranded
c.
Know purines: A, G and pyramids: C,T,U and what bonds with what
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d.
e.
3.
Know types of RNA: mRNA, tRNA, rRNA, small RNA’s (used in RNAi)
RNAi: regulates gene expression post-transcription
Genetic information flows from a sequence of nucleotides in a gene to a
sequence of amino acids in a protein.
a.
RNA polymerase reads the DNA molecule in a 3’ to 5’ direction and
synthesizes complementary mRNA molecules that determine the
order of amino acids in a polypeptide
b.
This primary mRNA transcript is then processed:
1.
addition of a poly-A tail
2.
addition of a GTP cap
3.
excision of introns
c.
Translation of the mRNA occurs in the cytoplasm on the ribosome.
Translation involves initiation, elongation and termination and
involves energy (tRNA charging needs energy)
1.
mRNA interacts with rRNA of the ribosome to initiate
translation at the start codon
2.
mRNA is read in triplets called codons
3.
each codon codes for an amino acid except for the 3 stops and
there are amino acids that are coded for by more than one
codon
4.
tRNA carries the amino acid to the correct place on the mRNA
5.
the amino acid is transferred to the growing polypeptide chain
6.
the process continues until a stop codon is reached
7.
the process terminates by release of the newly synthesized
polypeptide
4. Phenotypes are determined through protein activities, especially enzyme
reactions
5. Genetic engineering techniques can manipulate the heritable information of
DNA and, in special cases, RNA
a. Know the following: Electrophoresis, plasmid-based transformation,
restriction enzyme analysis of DNA, PCR
b. Know at least one of the following examples of the use of genetic
engineering: Genetically modified foods, transgenic animals, cloned
animals, human insulin production
II.
In eukaryotes, heritable information is passed to the next generation via
processes that include the cell cycle and mitosis or meiosis plus fertilization
1. The cell cycle is a complex set of stages that is highly regulated with
checkpoints, which determine the ultimate fate of the cell. Know each of
the following:
a. Interphase consists of 3 phases: growth, synthesis of DNA,
preparation for mitosis (G1, S, G2)
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b. The cell cycle is directed by internal controls or checkpoints.
Internal an external signals provide stop-and-go signs at the
checkpoints. Know:
i. Growth factors
ii. Cyclins and cyclin dependent kinases control the cell cycle
iii. Mitosis alternates with interphase in the cell cycle
iv. Cancer results from disruptions in cell cycle control
2. Mitosis passes a complete genome from the parent cell to daughter cells.
Understand each of the following:
a. Mitosis occurs after DNA replication
b. Mitosis followed by cytokinesis produces two identical daughter
cells
c. Mitosis plays a role in growth, repair and asexual reproduction
d. Understand that mitosis is a continuous process with observable
structural features such as replication, alignment, separation.
3. Meiosis, a reduction division, followed by fertilization ensures genetic
diversity in sexually reproducing organisms. Understand the following:
a. Meiosis ensures that each gamete receives one complete haploid
set of chromosomes (1n)
b. During meiosis, homologous chromosomes are paired, with one
homologue originating from the maternal parent and the other
from the paternal parent. Orientation of the chromosome pairs is
random with respect to the cell poles (random
assortment/independent alignment)
c. Separation of homologous chromosomes ensures that each gamete
receives a haploid (1n) set of chromosomes composed of both
maternal and paternal chromosomes
d. During meiosis, crossing over occurs which increases genetic
variability
e. Fertilization involves the fusion of two gametes made by meiosis,
increases genetic variation in populations by providing for new
combinations of genetic information in the zygote, and restores
the diploid number of chromosomes
III.
The chromosomal basis of inheritance provides an understanding of the
pattern of passage (transmission) of genes from parent to offspring
1.
Rules of probability can be applied
2.
Segregation and independent assortment result in genetic variation.
Understand each of the following
a. Segregation and independent assortment can be applied to genes
on different chromosomes
b. Genes that are adjacent and close to each other on the same
chromosome tend to move as a unit (gene linkage) and the
probability that they will segregate together as a unit is a function
of the distance between them
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3.
4.
c. Pattern of inheritance (mono-hybrid, dihybrid, sex-linked and
gene linkage) can be predicted using Punnett squares
Certain human genetic disorders can be attributed to the inheritance
of single gene traits or specific chromosomal changes such as
nondisjunction. Know at least one of the following:
a. Sickle-cell anemia
b. Huntington’s disease
c. X-linked color blindness
d. Trisomy 21/Down syndrome
Many ethical, social and medical issues surround human genetic
disorders. Designer babies is a good example
IV.
The inheritance pattern of many traits cannot be explained by simple
Mendelian genetics.
1. Many traits are the product of multiple genes and/or physiological
processes. This can be determined by comparing observed phenotypic
ratios with predicted phenotypic ratios
2. Some traits are determined by genes on sex-chromosomes. Know at least
one of the following:
a. Sex-lined genes reside on the sex-chromosomes (X in humans)
b. Y in humans and flies is small and carry few genes
c. X-linked recessive traits are always expressed in males
d. Some traits are sex limited: i.e. milk production in female
mammals
3. Some traits result from non-nuclear inheritance. Understand the
following:
a. Chloroplasts and mitochondria are randomly assorted to gametes
and daughter cells, thus traits determined by chloroplast and
mitochondrial DNA do not follow simple Mendelian rules.
b. In mammals, mitochondria DNA is transmitted by the egg and not
by the sperm, as such, mitochondrial-determined traits are
maternally inherited.
V.
Gene regulation results in differential gene expression, leading to cell
specialization.
1. Both DNA regulatory sequences, regulatory genes, and small regulatory
RNAs are involved in gene expression. Understand each of the following:
a. Regulatory stretches of DNA that interact with regulatory proteins
to control transcription. Know at least one of the following:
i. Promoters
ii. Terminators
iii. Enhancers
b. A regulatory gene is a sequence of DNA encoding a regulatory
protein or RNA
2. Both positive and negative control mechanisms regulate gene expression
in bacteria and viruses. Know each of the following:
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a. The expression of specific genes can be turned on by the presence
of an inducer (Lac Operon, inducible operon)
b. The expression of specific genes can be inhibited by the presence
of a repressor (TRP Operon, repressible operon)
c. Inducers and repressors are small molecules that interact with
regulatory proteins and/or regulatory sequences
3. In eukaryotes, gene expression is complex and control involves
regulatory genes, regulatory elements and transcription factors that act
together. Understand each of the following:
a. Transcription factors bind to specific DNA sequences and/or other
regulatory proteins
b. Some of these transcription factors are activators (increase
expression), while others are repressors (decrease expression)
c. The combination of transcription factors binding to the regulatory
regions at any one time determines how much, if any, of the gene
product will be produced
4. Gene regulation accounts for some of the phenotypic difference between
organisms with similar genes
VI.
A variety of intercellular and intracellular signal transmissions mediate gene
expression.
1. Signal transmission within and between cells mediates gene expression.
Know at least one of the following:
a. Levels of cAMP regulate metabolic gene expression in prokaryotes
(lac operon example – CAP activator)
b. Seed germination and gibberellin
c. Ethylene levels cause changes in the production of different
enzymes, allowing fruits to ripen
2. Signal transmission within and between cells mediates cell function.
Know the following:
a. Morphogenes stimulate cell differentiation and development
b. Changes in p53 activity can result in cancer
c. HOX genes and their role in development
VII.
Changes in genotype can result in changes in phenotype
1. DNA mutations can be positive, negative or neutral based on the effect or
the lack of effect the have on the resulting nucleic acid or protein and the
phenotypes that are conferred by the protein. External factors such as
radiation and chemicals can cause mutations. Whether these mutations
are beneficial or not is determined by the environment
2. Errors in mitosis or meiosis can result in changes in phenotype.
Understand each of the following:
a. Results associated with changes in chromosome number
i. New phenotypes, triploidy induced sterility and increased
vigor of other polyploids (4n and beyond)
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ii. Human disorders trisomy 21 and Turner syndrome (XO)
and associated developmental limitations
3. Changes in genotype that affect phenotypes can result in natural
selection. Know at least one of the following:
a. Antibiotic resistance mutations
b. Sickle cell disorder and heterozygote advantage
4. Selection results in evolutionary change.
VIII.
Biological systems have multiple processes that increase genetic variation
1. The imperfect nature of DNA replication and repair increases variation.
2. Transformation, transposition, transduction in prokaryotes increase
variation (horizontal gene transfer)
3. Know what leads to genetic variation in eukaryotes
IX.
Viral replication results in genetic variation, and viral infection can introduce
genetic variation into the hosts
1. Viral replication differs from other reproductive strategies and generates
genetic variation via various mechanisms. Know each of the following:
a. Viruses have highly efficient replicative capabilities that allow for
rapid evolution and acquisition of new phenotypes
b. Know the lytic cycle, Lysogenic cycle, and HIV
c. RNA viruses lack replication error checking mechanisms, and thus
have higher rates of mutation
d. Viruses transmit DNA or RNA when they infect a host cell
X.
Cell communication processes share common features that reflect a shared
evolutionary history.
1. Communication involves transduction of stimulatory or inhibitory signals
from other cells, organisms, or the environment.
2. Correct and appropriate signal transduction processes are generally
under strong selective pressure
3. In single celled organisms, signal transduction pathways influence how
the cell responds to its environment. Know at least one of the following:
a. Quorum sensing by microbes
b. Response to external signals by bacteria that influences cell
movement
4. In multicellular organisms, signal transduction pathways coordinate the
activities within individual cells that support the function of the organism
as a whole. Know at least one of the following:
a. Epinephrine stimulation of glycogen breakdown in mammals
b. Temperature determination of sex in some vertebrate organisms
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XI.
Cells communicate with each other through direct contact with other cells of
from a distance via chemical signaling.
1. Cells communicate by cell-to-cell contact. Know at least one of the
following:
a. How APCs trigger helper-T cells by direct contact
b. How plasmodesmata allow materials to be transported from cell to
cell
2. Cells communicate over short distances by using local regulators that
target cells in the vicinity of the emitting cell. Examples
a. Neurotransmitters
b. Quorum sensing in bacteria
3. Signals released by one cell type can travel long distances to target cells
of another cell type.
a. Endocrine signals are produced by endocrine cells that release
signaling molecules which are specific and can travel long
distances through the blood to reach all parts of the body.
Examples:
i. Insulin
ii. Thyroxine
iii. Estrogen
XII.
Signal transduction pathways link signal reception with cellular response.
1. Signaling begins with the recognition of a chemical messenger, a ligand,
by a receptor protein. Know each of the following:
a. Different receptors recognize different chemical messengers,
which can be peptides or steroids
b. A receptor protein recognizes signal molecules causing the
receptor protein’s shape to change, which initiates transduction of
the signal. Know at least one of the following:
i. G-protein linked receptors
ii. Ligand-gated ion channels
2. Signal transduction is the process by which a signal is converted to a
cellular response. Know each of the following:
a. Signaling cascades relay signals from receptors to cell targets,
often amplifying the incoming signals, with the result of
appropriate responses by the cell.
b. Second messengers are often essential to the function of the
cascade. Know at least one of the following:
i. Ligand-gated ion channels
ii. Second messengers, such as cyclic AMP and calcium ions
c. Many signal transduction pathways include:
i. Protein modifications (such as how methylation alters the
signaling process)
ii. Phosphorylation cascades in which a series of protein
kinases add a phosphate group to the next protein in the
cascade sequence
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XIII.
Changes in signal transduction pathways can alter cellular response
1.
Conditions where the signal transduction pathway is blocked or
defective can be deleterious or preventative. Know at least one of the
following:
a. Diabetes, or a different autoimmune disease
b. Effects of drugs such as antihistimes or birth control pills
XIV.
Individuals can act on information and communicate it to others
1.
Organisms exchange information with each other in response to
internal changes and external cues, which can change behavior. Ex::
a. Fight or flight response
b. Protection of young
c. Predator warnings
2.
Communication occurs through various mechanisms. Understand
each of the following:
a. Living systems have a variety of signal behaviors or cues that
produce changes in the behavior of other organisms and can result
in reproductive success. Examples:
i. Territorial markings
ii. Coloration in flowers to attract specific pollinators
3.
Animals use visual, audible, tactile, electrical and chemical signals to
indicate dominance, find food, establish territory and ensure
reproductive success. Examples:
a. Territorial markings
b. Bird songs
c. Bee dances
d. Coloration
4.
Responses to information and communication of information are vital
to natural selection and evolution. Understand each of the following:
a. Natural selection favors innate and learned behaviors that
increase survival and reproductive fitness. Examples:
i. Courtship and mating behaviors
ii. Parent and offspring interactions
b. Cooperative behavior tends to increase the fitness of the
individual and the survival of the population. (Kin selection)
Examples:
i. Pack behavior in animals
ii. Predator warning
XV.
Animals have nervous systems that detect external and internal signals,
transmit and integrate information, and produce responses.
1. The neuron is the basic structure of the nervous system that reflects
function. Understand each of the following:
a. A typical neuron has a cell body, axon and dendrites. Many axons
have a myelin sheath that acts as an external insulator
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b. The structure of the neuron allows for the detection, generation,
transmission and integration of signal information
c. Schwann cells, which form the myelin sheath (the individual “hot
dogs”), are separated by gaps of unsheathed exon over which the
impulse travels as the signal propagates along the neuron
2. Action potentials propagate impulses along neurons. Understand:
a. Membranes of neurons are polarized by the establishment of
electrical potentials across the membranes
b. In response to a stimulus, Na+ and K+ gated channels sequentially
open and cause the membrane to become polarized at a particular
axon node
c. Na+/K+ pumps, powered by ATP, work to maintain membrane
potential
3. Transmission of impulses across synapses involves chemical messengers
called neurotransmitters resulting in a response that can be stimulatory
or inhibitory. Examples:
a. Acetylcholine
b. Epinephrine
c. Serotonin
4. Different regions of the vertebrate brain have different functions. Ex:
a. Rudimentary workings of the eye
b. Rudimentary workings of the ear
c. Functions of the Cerebrum (forebrain), brain stem (midbrain) and
cerebellum (hindbrain)
Big Idea #4 – Biological systems interact, and these systems and their
interactions possess complex properties.
I.
The subcomponents of biological molecules and their sequence determine
the properties of that molecule.
1. Structure and function of polymers are derived from the way their
monomers are assembled. Understand each of the following:
a. Biological information is encoded in sequences of nucleotide
monomers. DNA and RNA differ in function and their slight
structural differences account for the differing functions.
b. In proteins, the primary structure of the amino acids determines
the overall shape of the protein which also involves secondary,
tertiary and quaternary structure and, thus, its function. The Rgroup if an amino acid can be categorized by chemical properties
(hydrophobic, hydrophilic and ionic) and the interactions of these
R groups determine structure and function of that region of the
protein.
c. In general, lipids are non-polar; however phospholipids exhibit
structural properties, with polar regions that interact with other
polar molecules such as water, and with non-polar regions where
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differences in saturation determine the structure and function of
lipids
d. Carbohydrates are composed of sugar monomers whose
structures and bonding with each other by dehydration synthesis
determine the properties and functions of the molecules. Know
specifically cellulose vs starch.
2. Directionality influences structure and function of the polymer.
Understand each of the following:
a. Nucleic acids have 3’ and 5’ carbons of the sugar in the nucleotide
that determines the direction of replication (leading and lagging
strands) and transcription from 5’ to 3’ of the new strand.
b. Proteins have an amino (NH2) end and a carboxyl (COOH) end and
the linear sequence of amino acids are connected by the formation
of peptide bonds by dehydration synthesis between the amino and
carboxyl ends of adjacent molecules.
c. The nature of the bonding of the carbohydrate subunits
determines their relative orientation in the carbohydrate which
determines the structure of the polysaccharide.
II.
The structure and function of subcellular components and their interactions,
provide essential cellular processes.
1. Ribosomes are small structures consisting of two interacting parts: rRNA
and protein. These serve as sites for protein synthesis.
2. ER can be smooth or rough. Know each of the following:
a. RER functions to compartmentalize the cell, serves as mechanical
support, provides site-specific protein synthesis with ribosomes
attached and plays a role in intracellular transport.
b. SER makes lipids, both add surface area for reactions
3. The Golgi is a membrane-bound structure that consists of a series of
flattened membrane sacs (cisternae). Understand the following:
a. The functions of the Golgi include the synthesis and packing of
materials for transport in vesicles and the production of
lysosomes.
4. Mitochondria specialize in energy capture and transformation of energy
to other forms. Understand each of the following:
a. Mitochondria have a double membrane that allows
compartmentalization and is important to function.
b. The outer membrane is smooth but the inner membrane (cristae)
is folded to increase surface area for cellular respiration
c. Cristae contain enzymes important to ATP production (ATPsynthase for example)
5. Lysosomes are membrane-enclosed sacs that contain hydrolytic enzymes,
which are important for intracellular digestion, the recycling of the cell’s
organic materials and programmed cell death (apoptosis).
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6. A vacuole is a membrane-bound sac that plays roles in intracellular
digestion and the release of cellular waste products. In plants a large
vacuole stores pigments, stores defense poisons and aids in cell growth.
The large vacuole allows for a large surface area to volume ratio.
7. Chloroplasts are specialized organelles found in algae and higher plants
that capture energy through photosynthesis. Know each of the following:
a. The structure and function relationship in the chloroplast allows
cells to capture the energy available in sunlight and convert it to
chemical bond energy via photosynthesis
b. Chloroplasts contain chlorophylls which are responsible for the
green color of a plant are the key light-trapping molecules in
photosynthesis. There are several types of chlorophyll but the
main form is chlorophyll a.
III.
Interactions between external stimuli and regulated gene expression result
in specialization of cells, tissues and organs
1. Differentiation in development is due to external and internal cues that
trigger gene regulation by proteins that bind to DNA.
2. Structural and functional divergence of cells in development is due to
expression of genes specific to a particular tissue or organ type.
3. Environmental stimuli can affect gene expression in a mature cell.
IV.
Organisms exhibit complex properties due to interactions between their
constituent parts.
1. Interactions and coordination between organs provide essential
biological activities.
2. Interactions and coordination between systems provide essential
biological activities. Such as:
a. Nervous and muscular
b. Plant vascular and leaf
V.
Communities are composed of populations of organisms that interact in
complex ways.
1.
The structure of a community is measured and described in terms of
species composition and species diversity.
2.
Mathematical or computer models are used to illustrate and
investigate population interactions within and environmental impacts
on a community. Know at least one of the following:
a. Symbiotic relationship
b. Graphical representation of field data
c. Predator/prey relationships
3.
Mathematical models and graphical representations are used to
illustrate population growth patterns and interactions. Know each of
the following:
a. Reproduction without limiting factors resulting in exponential
growth (J-curve)
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b. A population can produce a density of individuals that exceeds the
system’s resource availability
c. When density dependent and density independent factors are
imposed, a logistic growth model generally follows (S-curve)
d. Demographics data with respect to age distributions and
reproductive capacity can be used to study human populations.
VI.
Interactions among living systems and with their environment result in the
movement of matter and energy.
1.
Energy flows but matter is recycled
2.
Changes in regional and global climates and in atmospheric
composition influence patterns of primary productivity
3.
Organisms within food chains and food webs interact
4.
Food webs and food chains are dependent on primary productivity
5.
Models allow the prediction of the impact of change in biotic and
abiotic factors. Understand each of the following:
a. Competition leads to logistic growth
b. Competition for resources, territoriality, health, predation,
accumulation of wastes and other factors contribute to density
dependent population regulation
6.
Human activities impact ecosystems on local, regional and global
scales. Know the following:
a. As human populations have increased in numbers, their impact on
habitats for other species has been magnified resulting in reduced
numbers of other species, habitat destruction, and in some cases
extinction
7.
Many adaptations of organisms are related to obtaining and using
energy and matter in a particular environment
VII.
Interactions between molecules affect their structure and function.
1. Change in structure of a molecular system may result in a change in
function of the system.
2. The shape of enzymes, active sites and interaction with specific molecules
are essential for basic functioning of the enzyme. Know each of the
following:
a. The substrate must fit into the enzyme’s active site for proper
enzyme function.
b. Cofactors and coenzymes affect enzyme function; this interaction
relates to a structural change that alters the activity rate of the
enzyme. The enzyme may only become active when all the
appropriate cofactors or coenzymes are present and bind to the
appropriate sites on the enzyme.
c. Allosteric molecules can enhance or inhibit enzyme activity
d. The change in enzyme function can be measured from data
regarding the concentrations of product or substrate as a function
of time. These representations demonstrate the relationship
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between an enzyme’s activity, the disappearance of a substrate,
and/or presence of a competitive inhibitor
VIII.
Cooperative interactions within organisms promote efficiency in the use of
energy and matter.
1. Organisms compartmentalize functions related to energy and matter and
these parts contribute to the whole. Understand each of the following:
a. At the cellular level, the plasma membrane cytoplasm and for
eukaryotes, the organelles contribute to the overall specialization
and functioning of the cell.
b. Within multicellular organisms, specialization of organs
contributes to the overall functioning of the organism. Such as:
i. Exchange of gases
ii. Digestion of food
c. Interactions among cells of a population of unicellular organisms
can be similar to those of multicellular organisms, and these
interactions lead to increased efficiency and energy use. Know the
following:
i. Bacterial community in the guts of animals
IX.
Interactions between and within populations influence patterns of species
distribution and abundance.
1. Interactions between populations affect the distributions and abundance
of populations. Understand each of the following:
a. Competition, parasitism, predation, mutualism and commensalism
can affect population dynamics
b. Relationships among interacting populations can be + and – an can
be modeled mathematically (predator/prey, disease patterns,
invasive species)
c. Many complex symbiotic relationships exist in an ecosystem, and
feedback control systems play a role in the functioning of these
ecosystems.
2. A population of organisms has properties that are different from those of
the individuals that make up the population. The cooperation and
competition between individuals contributes to these different
properties.
3. Environmental catastrophes, geological events, and the sudden
influx/depletion of abiotic resources or increased human activities affect
species distribution and abundance. Such as:
a. Loss of a keystone species
b. Kudzu or Dutch elm disease
X.
Distribution of local and global ecosystems changes over time.
1.
Human impact accelerates change at local and global levels. Know at
least one of the following:
20
2.
a. An introduced species can exploit a new niche free of predators or
competitors, thus exploiting new resources
b. Logging, slash and burn agriculture, urbanization, monocropping,
dams, transmission lines, roads and global climate change
threaten ecosystems on earth
Geological and weather events impact ecosystem distribution.
Understand the following:
a. Biogeographical studies illustrate these changes.
i. El Nino
ii. Continental drift
iii. Meteor impact on dinosaurs
XI.
Variation in molecular units provides cells with a wider range of functions.
1.
Variations within molecular classes provide cells and organisms with
a wider range of functions. Understand at least one of the following:
a. MHC proteins
b. Molecular diversity of antibodies in response to an antigen
c. Chlorophylls
2.
Multiple copies of alleles or genes (gene duplication) may provide
new phenotypes. Understand each of the following:
a. A heterozygote maybe more advantageous than a homozygote
under particular conditions, since with two different alleles, the
organism has two forms of proteins that may provide functional
resilience in response to environmental stresses
b. Gene duplication creates a situation in which one copy of the gene
maintains its original function, while the duplicate may evolve new
function. Example:
i. The antifreeze gene in fish.
XII.
Environmental factors influence the expression of the genotype in an
organism.
1. Environmental factors influence many traits both directly and indirectly.
Examples:
a. How human height and weight has changed since colonial times.
b. Adding of lactose to a bacterial culture
c. Seasonal fur color in arctic animals
d. Density of plant hairs as a function of herbivorous predators.
2. An organism’s adaptation to the local environment reflects a flexible
response of its genome. Examples:
a. Darker fur in cooler regions of the body in certain mammals
b. Alterations in timing of flowering due to climate changes.
XIII.
The level of variation in a population affects population dynamics.
1.
Species and populations with little genetic diversity are at risk of
extinction. Know at least one of the following:
a. Potato blight causing the potato famine
21
2.
3.
XIV.
b. California condors
Genetic diversity allows individuals in a population to respond
differently to the same changes in environmental conditions. Know
the following:
a. Not all individuals in a population in a disease outbreak are
equally affected; some may not show symptoms, some may have
mild symptoms, or some may be naturally immune and resistant
to the disease.
Allelic variation within a population can be modeled by the HardyWeinberg equation(s).
The diversity of species within an ecosystem may influence the stability of
the ecosystem.
1.
Natural and artificial ecosystems with few component parts and with
little diversity among the parts are often less resilient when
confronted with a changing environment.
2.
Keystone species, producers and essential abiotic and biotic factors
contribute to maintaining the diversity of an ecosystem. When
keystone species are removed from the ecosystem, the ecosystem
often collapses.