AP Biology Exam Review Plan
AP Bio Unit One: Chemistry of Life
Topic 1.1: Water and Hydrogen Bonding
Water is a polar molecule.
Forms hydrogen bonds (weak intermolecular bonds).
Acts as the universal solvent due to polarity and hydrogen bonding.
Key properties: cohesion, adhesion, surface tension, and high specific heat.
Hydrogen bonds are found in:
DNA
RNA (forming specific shapes)
Proteins
Intermolecular interactions
Topics 1.2 to 1.3: Elements of Life, etc.
Molecules of life are built from monomers that combine into polymers.
Dehydration synthesis: Combines monomers into polymers.
Hydrolysis: Takes polymers apart.
Carbohydrates:
Used for energy storage and structure.
Monosaccharides: Energy storage
Disaccharides: Energy transport
Polysaccharides: Store energy (starch) or create structures (cellulose in cell walls)
Lipids:
Non-polar
Key unit: fatty acid (saturated or unsaturated)
Saturated: More solid
Unsaturated: Have bends and kinks, more liquid
Functions:
Energy storage (fats and oils)
Waterproofing (waxes)
Membrane formation (phospholipids)
Signaling (steroids)
Phospholipids:
Dual nature: hydrophobic non-polar tail and hydrophilic polar head.
Forms a phospholipid bilayer in water (basis of membranes)
Proteins:
Diverse functions: motion, enzymes, building structures, transport, energy storage, and signaling.
Composed of amino acids (monomers).
Amino group, carboxy group, and R group (side chain that varies in chemistry).
Four levels of structure:
Primary: Genetically determined sequence of amino acids.
Secondary: Alpha helices and beta-pleated sheets (interactions between amino acids in the polypeptide backbone).
Tertiary: Complex turns and loops as R groups interact (hydrogen bonds, covalent bonds, hydrophobic interactions, and ionic bonds).
Quaternary: Aggregation of multiple polypeptide chains.
Nucleic Acids:
Molecules of heredity (DNA).
RNA: Information transfer molecule (messenger RNA); can catalyze reactions (ribozymes, splices, microRNAs).
Monomers: Nucleotides (five-carbon sugar, nitrogenous base, and phosphate group).
DNA vs. RNA: different sugar (deoxyribose versus ribose) and different bases (A, T, C, G in DNA; A, U, C, G in RNA).
DNA Structure:
Double-stranded (double helix).
Two sugar-phosphate backbones.
Base pairing: Adenine (A) bonds with thymine (T), cytosine (C) bonds with guanine (G).
Anti-parallel structure: One strand is 5' to 3', the other is 3' to 5'.
Unit 2: Cell Structure and Function
Prokaryotic vs. Eukaryotic Cells:
Differences in size, structure, and DNA packaging.
Cellular Geography:
Key parts related to animal cells and plant cells.
Plant cell differences are highlighted in bold.
Topic 2.3: Cell Size
Cells are small to maximize surface area to volume ratio.
Surface area to volume ratio decreases as objects get bigger.
Adaptations related to surface area:
Gills
Elephant ears
Inner folding of mitochondrial membrane
Lining of the intestine
Adaptations related to less surface area:
Whales being large to lose less heat
Topics 2.4 to 2.9: Membrane Structure and Function
Selective permeability: Controls what enters and leaves the cell.
Phospholipids form the framework.
Fluid mosaic model: Phospholipids, proteins, and cholesterol moving around the membrane.
Molecules and their functions:
Phospholipids: Framework of the membrane.
Cholesterol: Fluidity buffer (stabilizes at high temperatures, fluid at low temperatures).
Proteins: Transport, cytoskeleton attachment, membrane-embedded enzymes, signal transduction, and cell-cell recognition.
Membrane Transport
Diffusion: Movement of molecules from higher to lower concentration.
Spontaneous, no energy required (passive transport).
Molecules flow down their concentration gradients.
Simple diffusion: Small, non-polar molecules (oxygen, carbon dioxide), lipids (steroids, fats).
Facilitated diffusion: Polar molecules and ions through protein channels.
Active Transport: Requires energy (ATP to ADP) to pump molecules up a concentration gradient.
Bulk Transport:
Endocytosis: Membrane buckles in, bringing fluid and materials into a vesicle.
Exocytosis: Vesicles fuse with the membrane, dumping contents outside.
Osmosis: Diffusion of water from higher to lower concentration.
Water flows from hypotonic to hypertonic.
Predict the effect of osmosis on plant and animal cells.
Water Potential: Formal way to talk about osmosis and water movement.
Adding solute decreases water potential.
Adding pressure increases water potential.
Water flows from higher water potential to lower water potential.
Topics 2.10 through 11: Cellular Compartmentalization
Cells have internal compartments with special pH and chemistry for different functions.
Endomembrane system: Nuclear membrane, rough and smooth ER, vesicles, Golgi, and lysosomes.
Mitochondria and chloroplasts are not part of the endomembrane system; they're endosymbionts.
Descendants of once independent organisms.
Evidence: own circular DNA, replicate through binary fission, bacteria-like ribosomes, protein synthesis, two membranes.
AP Bio Unit 3: Cellular Energetics
Topic 3.1: Enzymes
Enzymes are protein catalysts; they lower the activation energy of reactions.
Enzymes are highly specific; they bind with substrates at an active site.
Sensitive to changes in pH or temperature (denaturation).
Denaturation: Shape of active site changes, preventing interaction with the substrate.
Inhibition:
Competitive: Molecule competes with the substrate for the active site.
Non-competitive: Molecule binds to an allosteric site, changing the shape of the active site.
Allosteric regulation can modulate enzyme activity.
Topic 3.4: Cell Energy
Metabolic pathways: Linked series of reactions controlled by enzymes, product of one reaction becomes the reactant for the next.
Linear (glycolysis) or cyclical (Krebs cycle, Calvin cycle).
Exergonic reactions: Release energy and drive cellular work.
Endergonic reactions: Require energy.
Reactions are often coupled through ATP.
ATP: Five-carbon sugar (ribose), nitrogenous base, and three phosphate groups.
Energy in (cellular respiration) powers ATP creation (endergonic).
ATP breakdown to ADP and phosphate releases energy for cellular work (exergonic).
Topic 3.5: Photosynthesis
Photoautotrophs use light energy to combine carbon dioxide and water to create carbohydrates; releases oxygen as a waste product.
Source of biomass and the basis of almost every food chain on this planet.
Two phases:
Light reactions: Light energy converted into chemical energy (ATP and NADPH).
Calvin cycle: Energy in ATP and NADPH converted into carbohydrate (G3P); fixes carbon dioxide.
The Light Reactions
Light powers an electrical current that powers proton pumps that pump protons into the thylakoid space.
Facilitated diffusion through ATP synthase generates ATP.
Photosystems take light energy and make it into a flow of electricity.
Chlorophyll molecules lose an electron, another part of this photosystem breaks apart a water molecule;
Oxygen released, additional protons enhance gradient; more ATP produced
Electron flow from one photosystem reducing to NADP+ to NADPH.
Calvin Cycle
Three phases enable carbon dioxide into G3P (glyceraldehyde 3-phosphate).
Carbon fixation: Incorporates to six-carbon, then broken to three-carbon compound.
Energy investment: Products of the light reactions, ATP and NADPH, used to energize compound.
Regeneration combined to RuBP, a five-carbon molecule.
Topic 3.6: Cellular Respiration
How cells take glucose and convert it ultimately into ATP.
Animals just do cellular respiration, but plants do both cellular respiration and photosynthesis.
Four stages/phases:
Glycolysis, the link reaction, the Krebs cycle, and the electron transport chain.
Oxidizing food.
Creating mobile electron carriers (NADH and FADH2).
Glycolysis and the Krebs cycle make a little bit of ATP.
Oxidative phosphorylation and the electron transport chain (most ATP).
Electron carriers power an electrical current that flows through an electron transport chain.
Electron energy is used to pump protons from the matrix to the intermembrane space.
Protons diffuse out through the ATP synthase channel.
As they do, their kinetic energy is used to combine ADP and phosphate into ATP.
Oxygen is the final electron acceptor.
Anaerobic respiration happens without oxygen (less ATP).
Glycolysis (2 ATPs) combined with fermentation.
Fermentation regenerates NAD+.
Lactic acid fermentation (muscle cells during anaerobic respiration) and yogurt.
AP Bio Unit 4: Cell Communication, Feedback, and the Cell Cycle
Cells constantly communicate with one another (direct contact or signals).
Signals are ligands complementary to receptors.
Binding leads to a cellular response.
Three phases of cell communication (ligands):
Reception of the ligand.
Signal transduction: Taking the initial signal and amplifying it.
Cellular response: Gene activation or enzyme activation.
G protein-coupled receptors are examples of cellular communication.
Steroid hormones can diffuse through the phospholipid bilayer and bind with cytoplasmic receptors, enter nucleus and activate genes.
Topic 4.5: Homeostasis and Feedback
Homeostasis: Maintaining internal conditions at a relatively constant optimal level.
Feedback: Output of a system is also an input to the system.
Negative feedback quiets the system.
Positive feedback accelerates internal changes.
Glucose homeostasis involves insulin and glucagon.
Insulin lowers blood sugar.
Glucagon raises blood sugar.
Breakdown results in diabetes.
Positive Feedback:
Oxytocin and Childbirth
Baby applying the stretch to the uteris, the stretch receptors in the uterus releases the oxytocin hormones, and increases the stretch receptors as contractions increase in the uterus towards childbirth.
Fruit ripening and ethylene.
Topics 4.6 to 4.7: The Cell Cycle
Phases mnemonic: I Put My Apple There, Charlie (Interphase, Prophase, Metaphase, Anaphase, Telophase).
Most of the cell cycle is interphase (growth one, synthesis of DNA, growth two).
G0 phase: Cells become highly specialized and leave the cell cycle.
Regulated by checkpoints where the cell checks conditions.
External and internal regulation.
Internal regulation: Cyclins and cyclin-dependent kinases.
Cancer: Caused by unregulated cell division.
Mutations, cells grow in one location, forming a tumor.
Metastasis: Spread to other sites.
Mutations in proto-oncogenes increase cell division rate.
Mutations in tumor suppressor genes remove cell division inhibitors.
AP Bio Unit 5: Heredity
Meiosis: Diploid germ cells create haploid sperm and egg cells with one chromosome set.
Meiosis begins with germ cells replicating their DNA.
Creates cells that are diploid with double chromosomes.
Meiosis 1: Homologous pairs are separated.
Meiosis 2: Sister chromatids are pulled apart.
Phases are doubled.
Prophase one: Homologous pairs pairing up, crossing over.
Chromosome pairs proceeding to the cell equator, every chromosome pair does so independently of every other pair
Homologous pairs separated in meiosis one.
Sister chromatids are separated for haploid gametes.
Diversity generated in three ways: independent assortment, crossing over and genetic recombination, and fertilization.
Mitosis vs. Meiosis: Daughter cells are clones vs having genetic variation.
Sex Determination:
Mammals XX/XY
Birds ZW/ZZ
Nondisjunction when either homologous pairs don't separate correctly or sister chromatids don't separate.
Trisomy: Three chromosomes.
Down syndrome.
Monosomy: One chromosome.
Turner syndrome.
Topics 5.3 to 5.5: Genetics
Gene: Basic unit of heredity, sequence of nucleotides that codes for RNA or protein.
Key concepts: Segregation of alleles, homozygous and heterozygous, dominant and recessive, genotype and phenotype.
Monohybrid crosses: Cross between two heterozygotes (3:1 phenotype ratio, 1:2:1 genotype ratio).
Sex-linked genes are on the X chromosome.
Independent assortment when there are two gene pairs; dihybrid crosses (9:3:3:1 phenotypic ratio).
Linked genes are mostly inherited together (on the same chromosome) but can be separated by crossing over.
Linked genes that are close together are inherited; genes farther apart are more likely to be separated by crossing over.
Non-nuclear inheritance: Genes are on mitochondria.
Incomplete dominance: Blending effect between the two alleles.
Genotype-environment interaction: Environment determines the phenotype more than the genes.
Chi-square is used to analyze the results of genetic crosses.
AP Bio Unit 6: Gene Expression
DNA and RNA structure (handled in Unit 1).
Topic 6.2: DNA Replication
Semiconservative: Original strand separates, each strand serves as a template for a new strand.
Enzymes: Helicase, DNA polymerase, primase, ligase.
DNA polymerase synthesizes in the 5' to 3' direction.
Continuous on the leading strand, fragmentary on the lagging strand (Okazaki fragments).
Topic 6.3: Transcription
Making of RNA from a DNA template.
Be able to take any sequence of RNA and translate it into amino acids using a genetic code dictionary, and explain the details of protein synthesis itself.
Topics 6.5 to 6.6: Gene Regulation
Operons are important gene regulation systems in prokaryotes.
All cells in the same multicellular eukaryote organism are genomically equivalent, they express different genes.
Acetylation turns genes on; methylation turns genes off.
Epigenetics: Changes in DNA expression but not changes in the DNA sequence.
Eukaryotic genes are interspersed with introns.
Exons are expressed sequences, introns are intervening sequences that get edited out.
Topic 6.7: Mutation
Point mutations are changes where one nucleotide changes to another.
Ranging from nothing (because there's redundancy in the genetic code)
Nonsense (A stop codon gets inserted)
Missense (Change the amino acid).
Frame shift mutations change the reading frame.
Mutations can be positive, negative, or neutral.
Horizontal gene transfer: One individual transmits genes to another organism of the same generation.
Conjugation in bacteria, transformation, transduction (involves viruses), viral recombination.
Topic 6.8: Genetic Engineering and Biotechnology
Techniques: PCR, Restriction enzymes and gel electrophoresis, Recombinant DNA and engineering plasmids, DNA sequencing.
Unit 7: Evolution
Two theories is natural selection, and a lot of that evolutionary change is not about natural selection.
Natural Selection:
Adaptations through survival of the fittest; artificial selection, in which humans select favored traits in our domesticated animals and plants; and sexual selection, which is selection for reproductive advantage.
Effects of Selection:
Directional Selection pushes the population's mean in one direction.
Stabilizing Selection occurs against the extremes.
Disruptive Selection occurs against the mean.
Topics 7.4 to 7.5: Population Genetics
Study of how allele frequencies change in gene pools.
Hardy-Weinberg principle if certain conditions are met, such as genetics, population bottlenecks, the founder effect
* Random change in small populations.Mutations where some alleles are harmful and beneficial.
Gene flow where genes move from one population to another.
Directional mutation, where one allele mutates into another.
Traits of Evolution
Mountain of evidence includes fossils, homologous features, molecular homologies
Vestigial features which no longer have a function
Phylogeny
* Key concepts include the concept of a clade. A group of organisms that is derived from a common ancestor
* Nodes
* Shared derived features, very important
* Ancestral features
* Outgroups
* Molecular clocks
Topics 7.10 to 7.12: Speciation, Variation, and Extinction
Can interbreed fertile offspring by the biological species concept
Reproductive isolating mechanisms and Prezygotic barriers when keeping a Zygote from forming.
Postzygotic barriers where if some confusion arose and these two did mate, then the zygote might not be able to develop, or if it did develop, it wouldn't be fertile.
Allopatric speciation which involves a kind of geographic barrier where there's differentiation on each side of the barrier. If it is not there, two subpopulations become so different they can no longer interbreed.
Sympatric speciation happens without a barrier.
Mass Extinctions
Caused by geological or astronomical factors that cause a mass die-off of huge numbers of species all at one time.
Mass extinctions cause vast decreases in biodiversity.
Subsequent adaptive radiation and reestablishment of biodiversity.
Topic 7.13: The Origin of Life
How did life naturally emerge in the absence of life after the Earth became habitable?
Geological processes and chemical processes led to the abiotic synthesis of monomers.
RNA became encapsulated within a membrane that forms a kind of protocell.
Last universal ancestor of all life, the last universal common ancestor (LUCA), and that gives rise to the three domains of life.
Miller-Urey experiment has become the model for subsequent experiments that have produced other monomers and more complex substances, but these experiments are still a long way from generating life in a test tube.
RNA was probably the first genetic molecule, not DNA; RNA is also catalytic and act as an enzyme to catalyze reactions.
AP Bio Unit: Ecology
Topic 8.1: Responses to the Environment
Learn how to be analytical and carefully read the question.
Topic 8.2: Energy Flow in Individual Organisms and Entire Ecosystems
Topics includes Metabolic rate and size and the relationship between the two
The flow of energy through food webs, including the concept of a trophic or feeding level, the idea of the pyramid of energy, and how only 10% of the energy gets passed from trophic level to trophic level; ecological pyramids, not limited to but including the pyramid of numbers.
Topics 8.3 and 8.4: Population Growth
Includes exponential growth model and the logistic model, which includes the idea of carrying capacity, biotic potential and limiting factors.
Topic 8.5: Species Interactions
Know all of the traits and definitions and the positive, negative, or neutral effects they have
Community Structure influenced key species act as keystone species.
Humans Impacts on Diversity have not been good.
Habitat destruction
Habitat fragmentation
Invasive Species that have been both intentional and unintentional
Logging to much overfishing ect.
This is creating an extinction vortex where populations are getting smaller and leading to genetic drift and inbreeding