If you want to print this document out, here’s a link to this same document as an easier-to-print google doc.
- Introduction / How to use this outline.
- Unit 1: Molecules of Life
- Unit 2: Cell Structure and Function
- Unit 3: Cellular Energetics
- Unit 4: Cell Communication, Feedback, Cell Division
- Unit 5: Heredity
- Unit 6: Gene Expression
- Unit 7: Evolution
- Unit 8: Ecology
- Science Practices
I wrote this outline for you: an AP Bio student who’s studying for the upcoming AP Bio exam. My goal was to give you an easy-to-use study outline that you can use to assess your familiarity with key AP Bio concepts and skills.
My main source was the College Board’s AP Biology Course and Exam Description. However, based on my own experience preparing students for the AP Bio exam and consultation with other AP Bio teachers, I’ve combined some topics, changed the order of topics, and (rarely) added or cut topics.
If you want to go see the sources upon which I based this study outline, here are two ways to do that.
- AP Biology Course and Exam Description. This is the official College Board Document. Including its introductory material and appendices, it’s over 200 pages. Filled with illustrative examples, learning objectives, and key concepts, it’s a fantastic design document. But if you’re studying for the AP Bio exam, it can be a bit much.
- My reformatted Google Doc version of the CB document. By cutting and pasting, I was able to get the College Board’s original document to fit into 40 pages. However, the language can still be confusing, which is why I wrote the study outline below.
How to Use this Study Outline
Use this document to do retrieval practice. That means recalling information from memory (as opposed to just reading). As you move through the outline below, look at the numbered learning objective, and say (or write down) everything you know. If you can’t respond to an objective, mark that as a topic that you’ll need to review.
Where possible and feasible, I’ve put brief bullet points below the learning objective so you can tell if you’re on the right track. However, to keep the length of this document reasonable, many objectives have no bullets.
Links in the lists of topics or objectives go to interactive tutorials on Learn-Biology.com’s AP Biology curriculum.
Other Resources for Studying
The best material for you to use to study are questions created by the College Board. You can download the FRQs and scoring guidelines from the 2021 exam here. You can access FRQs from previous years at this link (but remember that the course was redesigned in 2019: skip questions relating to topics that are no longer on the exam, such as the immune system or the nervous system).
You’ll be able to access high-quality multiple-choice questions from the College Board through your teacher, who can give these to you directly or make them available through AP Classroom.
In addition to the outline below, please look at these review resources that I’ve created to help you review for the AP Bio exam.
- AP Bio Review Flashcards (more than 400: great for retrieval practice)
- AP Bio Review Multiple Choice Questions (over 300: wrong answers give you corrective feedback and hints)
- AP Bio Review Free Response Questions (over 100 prompts with sample responses)
Unit 1. Chemistry of Life
Unit 1 Topics at a Glance
- 1.1. Structure of Water and Hydrogen Bonding
- 1.2. Elements of Life
- 1.3. Monomers and Polymers
- 1.4. Carbohydrates and Lipids
- 1.5. Proteins
- 1.6. Nucleic Acids
Unit 1 Learning Objectives and Tutorials
Topic 1.1. Structure of Water and Hydrogen Bonding
- Describe water’s molecular structure.
- Explain the key physical and chemical properties that result from water’s molecular structure.
- Describe cohesion, adhesion, and surface tension, and explain how these key properties of water result from hydrogen bonding.
- List examples of ways in which living things depend on water’s physical and chemical properties
Topic 1.2 – 1.4
- Carbon and Life’s Key Elements;
- Functional Groups;
- Monomers and Polymers;
- The four biomolecule families;
- Describe the key roles of carbon, nitrogen, and phosphorus in the molecules found in living things.
- Carbon is the key structural atom in all biomolecules
- Nitrogen is in proteins and nucleic acids; phosphorus is in ATP, nucleic acids, and phospholipids.
- Compare and contrast dehydration synthesis and hydrolysis reactions.
- Dehydration synthesis reactions are endergonic and are used to build the complex molecules in living things.
- Hydrolysis reactions are exergonic and are used to release energy and digest polymers into monomers.
- Describe the structure and function of carbohydrates.
- Simple sugars (monosaccharides) are the monomers of carbohydrates. These monomers are combined to create more complex carbohydrates.
- Glucose (a six-carbon simple sugar) is used to power the synthesis of ATP during cellular respiration.
- Describe the structure and function of lipids
- Differences in saturation determine the differences between fats and oils.
- The structure of phospholipids gives them polar/hydrophilic regions and nonpolar/hydrophobic regions.
Topics 1.4, 1.5, 1.6:
- Describe the role and structure of amino acids.
- Amino acids are the monomers of proteins
- They have a central carbon, a hydrogen atom, an amine group, a carboxyl group, and a variable R-group/side chain
- List the types of R groups/side-chains
- hydrophobic, hydrophilic, basic, or acidic.
- Explain how proteins are directional,
- They have an amino terminus and a carboxyl terminus.
- Explain how the four levels of protein structure give rise to a protein’s 3D shape and function
- primary: the sequence of amino acids.
- secondary: interaction between carbonyl and amino residues leading to alpha-helices and beta-pleated sheets.
- tertiary: interactions between R-Groups
- Quaternary: interactions between polypeptide chains.
- Compare and contrast the structure of DNA and RNA.
- Both are polymers of nucleotides, which have 5-carbon sugar, a phosphate group, and a nitrogenous base.
- Both encode information in their sequence of nucleotides.
- In DNA, the sugar is deoxyribose, and the bases are A, T, C, and G.
- In RNA the sugar is ribose, and the bases are A, U, C, and G.
- DNA is a double helix in which the complementary strands are antiparallel; RNA is single-stranded.
- Explain the directionality of DNA, and connect directionality to DNA replication
- DNA (and RNA) has a 5′ to 3′ orientation. During replication, new nucleotides can only be added to the 3′ end of a growing strand.
Unit 1 Cumulative Review: Flashcards and Quizzes
Unit 2. Cell Structure and Function
Unit 2 Topics at a Glance
- 2.1-2.2. Cell Parts: Introduction; Animal Cells; Plant Cells
- 2.3. Cell Size
- 2.4-2.5. Plasma Membranes
- 2.6-2.7, 2.9: Membrane Transport
- 2.8. Tonicity and Osmoregulation.
- 2.10. Cellular Compartmentalization
- 2.11.Origins of Cell Compartmentalization
Unit 2 Learning Objectives and Tutorials
Topics 2.1 and 2.2: Cell Structure and Function
- Explain the basic ideas of the cell theory
- Cells are the basic units of life, all living things are made of cells, and cells come from other cells.
- Compare and contrast the basic features of prokaryotic and eukaryotic cells.
- Describe the structure and functions of the following cell parts
- cell membrane
- Rough endoplasmic reticulum
- Smooth endoplasmic reticulum
- Golgi complex
- cell wall
Topic 2.3: The Size of Cells (surface area to volume relationships)
- Explain how surface-area-to-volume ratios affect the ability of biological systems (cells, organisms, and groups of organisms) to obtain resources; eliminate wastes; or absorb or dissipate heat or other forms of energy from the environment.
- Explain how membrane surface area influences the size and shape of cells and organisms. Specifically:
- Why are cells small?
- Cells are small because a smaller size enables cells to increase their surface-area-to-volume ratio to more efficiently exchange materials and energy with their environment.
- Explain how, despite the limitation described above, organisms were able to increase in size.
- Multicellularity required various adaptations to increase internal surface area to allow for the diffusion of nutrients and wastes into or out of cells, or to control heat exchange with the environment.
- Explain various adaptations to increase or decrease surface area-to-volume ratios.
- Increase: branch vessels or flat surfaces to increase the efficiency of exchange.
- Decrease: opposite of above.
- Why are cells small?
Topics 2.4 – 2.9: Membrane Structure and Function; Osmosis
- Topic 2.4: Cell Membrane Structure
- Topics 2.5 -2.7, 2.9: Membrane Transport
- Topic 2.8: Osmosis and Water Potential
- Describe the fluid mosaic model of the cell membrane. Descriptions should include
- The overall function of the membrane
- The role of phospholipids (and how their structure results in the formation of phospholipid bilayers).
- The role of embedded proteins (how they fit into the bilayer, and their various roles)
- The functions of cholesterol, glycolipids, and glycoproteins.
- Define selective permeability.
- Explain how selective permeability arises from the fluid mosaic structure of the membrane.
- How small, nonpolar molecules like N2, CO2, and O2 can pass across the membrane
- through simple diffusion through the phospholipid bilayer.
- How ions and large polar molecules move across the membrane
- facilitated diffusion through embedded protein channels
- How small polar molecules (like water) pass through the membrane
- Water passes through aquaporins.
- How small, nonpolar molecules like N2, CO2, and O2 can pass across the membrane
- Compare and contrast passive transport, active transport, and facilitated diffusion. Connect each process to membrane structure.
- Protein pumps use energy for active transport
- Protein channels allow for facilitated diffusion.
- Compare and contrast endocytosis and exocytosis.
- Explain membrane potential
- A charge is created by an imbalance in ions across a membrane.
- Connect membrane potential to processes such as ATP synthesis.
- Proton gradients are used to drive ATP synthesis through chemiosmosis (more on this below in Topics 3.5 and 3.6.
- Define the term osmosis, and be able to predict and explain the flow of water into or out of cells in hypotonic, hypertonic, and isotonic environments.
- Explain the movement of water into or out of cells (and entire organisms) in relationship to water potential
- Water always flows from high water potential to lower water potential.
- Be able to understand and use (but don’t memorize) the two water potential equations
- the general water potential equation (Ψ = ΨS + ΨP : water potential = pressure potential + solute potential)
- The equation for solute potential: ΨS = – iCRT.
Topics 2.10 – 2.11: Cellular Compartmentalization and its origins
- Topic 2.10: The Endomembrane System: ER, Golgi, and Lysosomes
- Topic 2.11: Origins of Cellular Compartmentalization
- Define the term “endomembrane system,” and describe that system’s overall function. Descriptions should include:
- Creating cellular compartments that segregate cellular functions such as hydrolysis, export of cell materials through exocytosis, import of materials through endocytosis, the capture of food or pathogens in phagocytosis, and assembly of macromolecules.
- Creating compartments with optimal conditions for enzymatic reactions
- Increasing surface area for membrane-bound enzymatic reactions (in the E.R. and Golgi).
- List the key membrane-bound organelles found within eukaryotic cells, and describe the structure and function of each.
- The list should include rough E.R., smooth E.R., Golgi, lysosomes, vacuoles, vesicles, mitochondria, and chloroplasts.
- Explain how compartmentalization is different in eukaryotic and prokaryotic cells
- Extensive compartmentalization is primarily a feature of eukaryotic cells.
- Prokaryotic cells do have some internal compartments (such as the thylakoids in cyanobacteria)
- Explain the evolutionary origins of mitochondria and chloroplasts, with supporting evidence.
- Both mitochondria and chloroplasts arose through endosymbiosis. Free-living bacterial ancestors of mitochondria and chloroplasts were taken up by and took up residence inside a larger archaeal cell.
- All eukaryotic cells originate from the uptake/incorporation of mitochondria into a larger cell.
- Plants and algae originate from an early eukaryotic uptake of a photosynthetic cyanobacterium.
- Describe the evidence for the endosymbiotic theory.
- Both mitochondria and chloroplasts have bacteria-like chromosomes, with their own DNA.
- Both have a double membrane (the inner one a vestige of their own ancestral membrane; the outer one a vestige of an ancient endocytotic vesicle)
- Both reproduce themselves through binary fission.
Unit 2 Flashcards and Cumulative Quizzes
Unit 3. Cellular Energetics
Unit 3 Topics at a Glance
- 3.1 – 3.3. Enzyme Structure and Function
- 3.4. Cellular Energy
- 3.5. Photosynthesis
- 3.6. Cellular Respiration
Unit 3 Learning Objectives and Tutorials
Topics 3.1 – 3.3: Enzymes
- Topics 3.1 – 3.3, Part 1: Enzyme Structure and Function; Environmental Impacts on Enzymes
- Topics 3.1-3.3, Part 2: Enzyme Inhibition and Regulation
- Describe the key properties and function of enzymes. This description should include the following:
- Enzymes are complex, large proteins that facilitate chemical reactions by reducing activation energy.
- Enzymes are highly specific and generally interact with only one substrate.
- Enzyme specificity is based on the complementary shape and charge between the enzyme’s active site and the substrate.
- Explain how changes in an enzyme’s shape affect the enzyme’s function. Connect this explanation to the idea of denaturation.
- Because enzymes are proteins, their shape is stabilized by internal bonds that can be disrupted by changes in the enzyme’s environment.
- Denaturation is when a change in an enzyme’s shape reduces its ability to bind with its substrate.
- Denaturation can be reversible or irreversible.
- Explain the effect of moderate and extreme changes in temperature on enzyme activity
- At moderate temperatures, the temperature increase will increase enzyme-substrate collisions, increasing enzyme activity. Temperature decrease will (for the opposite reason) decrease enzyme activity.
- At high temperatures, enzymes can denature, reducing their activity
- Explain the effect of changes in pH or ion concentration on enzyme activity.
- Because enzymes are proteins and because protein shape is a function of various internal bonds, enzymes have a pH and ion concentration optimum.
- Environmental changes that move the pH and ion concentration above or below that optimum will disrupt the enzyme’s internal bonds, changing the shape of the enzyme’s active site, and reducing its activity.
- Explain the effects of enzyme and substrate concentration on enzyme activity
- Enzyme activity will increase with increased enzyme and substrate activity until the enzymes’ active sites are saturated. At that point, enzyme activity reaches its maximum rate.
- Explain the role of competitive and non-competitive inhibitors on enzyme activity
- Competitive inhibitors reduce enzyme activity by competing with substrates for the enzyme’s active site.
- Non-competitive inhibitors bind at a region away from the active site (an allosteric site). However, that binding changes the shape of the active site, reducing the enzyme’s activity.
- *Explain how cells can regulate enzyme activity through feedback inhibition and allosteric regulation.
- In feedback inhibition, the product of an enzymatic reaction acts as a competitive or non-competitive inhibitor of enzyme activity, creating negative feedback that reduces enzyme activity.
- In allosteric regulation, a substance produced by a metabolic pathway binds with an enzyme at an allosteric site. This can inhibit or stimulate enzyme activity.
Topic 3.4: Cell Energy
- Explain how living things create and maintain their complex order.
- Through a constant input of energy.
- For autotrophic organisms, that energy input is almost always energy from the sun (the exceptions are chemoautotrophs, which get energy by oxidizing inorganic compounds).
- For heterotrophs, the energy is from organic compounds that are eaten or absorbed.
- Describe the energy input/output balance required for life to be maintained.
- For life to be maintained, energy input has to exceed energy loss.
- Using the terms endergonic and exergonic, describe energy coupling.
- In energy coupling, energy-requiring processes (endergonic processes) are typically coupled with energy-releasing (exergonic) processes.
- Describe the structure of ATP.
- ATP is adenosine triphosphate. It consists of the 5-carbon sugar ribose, connected to three phosphate groups on one side and the nitrogenous base adenine on the other side.
- Describe some common coupled reactions.
- Oxidizing food or food by-products in order to reduce electron carriers.
- Oxidizing electron carriers to power proton pumping during chemiosmotic production of ATP.
- Hydrolyzing ATP to ADP and phosphate (an exergonic reaction) to power any endergonic process (synthesis, movement, or any other kind of work).
- Describe the ATP/ADP cycle.
- In an endergonic reaction powered by chemiosmosis or energy from an organic substrate, ATP is made from ADP and phosphate. The breakdown of ATP to ADP and phosphate makes energy available to power cellular work.
Topic 3.5: Photosynthesis
- Topic 3.5, Part 1: Introduction to Photosynthesis
- Topic 3.5, Part 2: Chloroplasts and the Two Phases of Photosynthesis
- Topic 3.5, Part 3: Light, Pigments, and Photosynthesis
- Topic 3.5, Part 4: The Light Reactions
- Topic 3.5, Part 5: The Calvin Cycle
- Describe the cellular location of the reactions of photosynthesis
- Chloroplasts are the organelle that carries out photosynthesis.
- Within chloroplasts are thylakoids: membrane-bound sacs, organized into stacks called grana.
- The photosystems and electron transport chain involved in the light reaction are located in the thylakoid membranes.
- The carbon-fixing reactions of the Calvin cycle occur in the stroma.
- Describe key evolutionary milestones in the evolution of photosynthesis
- Photosynthesis first evolved in photosynthetic bacteria (cyanobacteria)
- Prokaryotic photosynthesis created Earth’s oxygen-rich atmosphere.
- Chloroplasts are endosymbionts, descended from a cyanobacterium that took up residence inside a eukaryotic cell. These cells evolved to become the cells making up algae, then plants.
- Explain the light reactions of photosynthesis
- Light energy is converted into electron energy by two chlorophyll-rich photosystems. (PS II and PS I)
- Electron flow through the electron transport chain of photosystem II is used to create a proton gradient that powers ATP synthesis. The mechanism (pumping protons to a compartment, followed by chemiosmotic flow through ATP synthase) parallels what happens in mitochondrial ATP synthesis.
- Electron flow through the ETC of Photosystem 1 is used to reduce NADP+ into NADPH.
- Explain the key reactions of the Calvin cycle
- The Calvin cycle is responsible for carbon fixation (bringing organic carbon into the biosphere)
- The inputs are the products of the light reactions (NADPH and ATP), and carbon dioxide
- NADPH provides reducing power (for hydrogenating CO2)
- The reduction of carbon dioxide into carbohydrates is endergonic. Hydrolysis of ATP provides the energy to drive this reaction forward.
- Rubisco is the key enzyme involved in carbon fixation (and is the most abundant protein on Earth).
Topic 3.6: Cellular Respiration
- Topic 3.4: ATP and Cell Energy
- Topic 3.6, Part 1: Cellular Respiration Overview
- Topic 3.6, Part 2: Glycolysis
- Topic 3.6, Part 3: The Link Reaction and the Krebs Cycle
- Topic 3.6, Part 4: The Electron Transport Chain and Chemiosmosis
- Topic 3.6, Part 5: Anaerobic Respiration and Fermentation
- Explain the overall pathway of aerobic cellular respiration
- Glycolysis, link reaction, Krebs, and the electron transport chain.
- Explain what happens during glycolysis
- Oxidation of glucose is coupled to the reduction of NAD+ to NADH, and the phosphorylation of ADP to ATP.
- The end product is pyruvic acid, an energy-rich 3-carbon compound that powers the link reaction and Krebs cycle.
- Explain what happens during the link reaction
- Pyruvic acid enters the mitochondria and gets converted to acetyl CoA.
- Oxidation of pyruvate generates NADH.
- Explain the key reactions of the Krebs cycle
- Oxidation of acetyl-CoA to power the reduction of NAD+ and FAD to NADH and FADH2;
- Phosphorylation of ADP to ATP
- Release of carbon dioxide.
- Regeneration of the four-carbon compound oxaloacetate.
- Explain the roles of NADH and FADH2 in cellular respiration
- Electron energy from the oxidation of these two electron carriers is used to power proton pumping to create a proton gradient between the intermembrane space and the mitochondrial matrix.
- Describe what happens in chemiosmosis
- Diffusion of protons through the ATP synthase channel is used to power ATP synthesis from ADP and P.
- Explain the role of oxygen in the electron transport chain.
- Final electron acceptor
- Compare and contrast lactic acid and alcohol fermentation.
- Both reduce pyruvate so that NAD+ can be regenerated, allowing glycolysis to continue to yield two ATPs/glucose.
- Connect the structure of the mitochondrion to the key processes of aerobic respiration
- Krebs occurs in the mitochondrial matrix;
- The ETC happens along the inner membrane;
- Protons are pumped to the intermembrane space;
- Inner membrane folding increases surface area, allowing for more ETC components and more ATP synthases
- Explain how the pathways of cellular respiration can be used for thermoregulation
- Uncoupling electron flow from oxidative phosphorylation allows electron flow to generate heat.
Unit 3: Cumulative Objectives, Flashcards, and Quizzes
Unit 4: Cell Communication, Cell Cycle, Feedback
Unit 4 topics at a Glance
- 4.1. Cell Communication
- 4.2 – 4.4. Signal Transduction
- 4.5. Feedback
- 4.6. Cell Cycle
- 4.7: Regulation of the Cell Cycle
Unit 4 Learning Objectives and Tutorials
Topics 4.1.-4.4: Cell Signaling, Cell Communication, and Signal Transduction
- Topic 4.1: Introduction to Cell Communication
- Topics 4.2 – 4.4, Part 1: Introduction to Signal Transduction
- Topics 4.2 – 4.4, Part 2: Reception
- Topics 4.2 – 4.4, Part 3: Signal Transduction
- Topics 4.2 – 4.4 Part 4: Signaling Hormones and Gene Regulation
- Topics 4-1 – 4.4: Cell Communication and Signal Transduction Cumulative Quiz
- Describe three ways that cells communicate with one another, and provide examples of each one.
- Cell-to-cell contact (examples: immune signaling, plasmodesmata)
- Short-distance signaling using local regulators (examples: neurotransmitters, quorum sensing, morphogens during embryonic development)
- Long-distance signaling (examples: endocrine signaling)
- Describe the function of signal transduction
- linking signal reception with a cellular response)
- List the three components of signal transduction systems
- reception, transduction, response
- Describe the key features of reception
- specific receptors — usually membrane proteins — bind with ligands.
- Describe the key features of signal transduction
- ligand binding leading to changes in the intracellular domain of a membrane protein; propagation of the signal to and through second messengers such as cyclic AMP; amplification of the signal through phosphorylation cascades.
- List examples of cellular responses that result from signal transduction
- Examples: cell division, secretion of molecules, gene expression, apoptosis.
- Explain how changes in the components of a signaling system (ligand, receptor, transduction components) can alter cellular responses.
- Mutations in receptors (changes in shape or number) can affect downstream signal transduction.
- Chemicals interfering with any part of a signaling system component can change transduction.
Topic 4.5: Feedback and Homeostasis
- Topic 4.5, Part 1: Homeostasis and Regulation (using thermoregulation as an illustrative example)
- Topic 4.5 Part 2: Feedback Loops
- Topic 4.5, Part 3: Blood Glucose Regulation (Illustrative Example)
- Topic 4.5, Part 4: Understanding Diabetes (Illustrative Example)
- Describe the function of feedback mechanisms
- Maintaining internal environments and responding to internal and external environmental changes.
- Define the physiological concept of a set point.
- The value around which a physiological process fluctuates. For example, the temperature set point in humans is 37 degrees C.
- Explain how negative feedback helps to maintain homeostasis
- Returning a perturbed system to its target set point.
- Explain how positive feedback works
- Amplifying responses and processes in a way that increases the initial stimulus, which further activates the response.
Topic 4.6: Cell Division, the Cell Cycle
- Compare and contrast cell division in prokaryotes and eukaryotes
- binary fission v. mitosis
- Describe the functions of cell division in eukaryotes
- Asexual reproduction, growth, and repair.
- List the phases of the cell cycle, and explain what happens during each phase
- List: interphase, G1, S, G2, M
- Explain the importance of the G0 phase.
- Describe, on a big-picture level, what happens in mitosis
- Cloning of a parent cell’s entire genome into two genetically identical daughter cells
- List and describe the phases of mitosis.
Topic 4.7: Cell Cycle Regulation, Cancer, Apoptosis
- Describe how the cell cycle is regulated
- answers should include a general description of internal checkpoints, and how these checkpoints work to control progression through the cycle
- Explain how interactions between cyclins and cyclin-dependent kinases control the cell cycle.
- Describe how disruptions to the cell cycle can lead to cancer.
- Cancer can result from any process that increases cell division, removes inhibition of cell division, or both.
- Processes that increase cell division are connected to mutations in oncogenes. Processes that remove cell division inhibitors are connected to mutations in tumor suppressor genes.
- Define apoptosis
- A regulated process resulting in cell death.
Unit 4 Cumulative Objectives, Flashcards, and Quizzes
Unit 5. Heredity
Unit 5 topics at a Glance
- 5.1 – 5.2. Meiosis and Genetic Diversity
- 5.3. Mendelian Genetics
- 5.4. Non-Mendelian Genetics
- 5.5. Environmental Effects on Phenotype
- 5.6. Chromosomal Inheritance
Unit 5 Learning Objectives and Tutorials
TOPICS 5.1, 5.2, and 5.6: Meiosis, Chromosomal Inheritance, and Genetic Diversity
- Topics 5.1 – 5.2, Part 1: Meiosis Basic Concepts
- Topics 5.1 – 5.2, Part 2: Meiosis 1 v. Meiosis 2
- Topics 5.1 – 5.2, Part 3: How Meiosis Creates Variation
- Topics 5.1 – 5.2, Part 4: Meiosis, Step by Step
- Topic 5.6, Part 1: Sex Determination
- Topic 5.6, Part 2: Part 2: Nondisjunction and Human Chromosomal Variation
- Topic 5.1, 5.2, 5.6: Meiosis, Sex Determination, and Nondisjunction Cumulative Flashcards and Multiple Choice Speed Challenge
- Explain how meiosis transmits genetic material from one generation to the next.
- Compare and contrast diploid and haploid cells, and explain how these terms connect to somatic cells and germ cells.
- Diploid: two chromosome sets (one maternal, one paternal). Haploid: one set
- Somatic: body cells. Germ cells: gametes.
- Compare and contrast mitosis and meiosis (the types of daughter cells, the number of cell divisions)
- Mitosis: 2 diploid daughter cells that are clones of the parent.
- Meiosis: 4 genetically unique haploid daughter cells.
- Explain how meiosis generates genetic diversity.
- By creating genetically unique offspring that are genetically distinct from their parents, and siblings who are genetically distinct from each other.
- Define “homologous” chromosomes (their origin, their relationship in terms of genetic information) and explain what happens to homologous pairs during meiosis
- Homologous pairs are the matched chromosomes inherited from each parent. They have the same genes, but possibly different alleles.
- During meiosis 1, homologous pairs independently assort, creating gametes with unique combinations of maternal and paternal chromosomes.
- Explain what crossing over is, and how it generates genetic diversity.
- Homologous pairs exchange pieces of DNA, creating unique, never-before-seen recombinant chromosomes.
- Explain fertilization (in terms of haploid and diploid chromosome numbers), as well as fertilization’s contribution to genetic diversity.
- Compare meiosis 1 and meiosis 2, and explain what happens during each process.
- Meiosis 1: diploid to haploid, independent assortment.
- Meiosis 2: sister chromatids are pulled apart.
- Connect the events of meiosis and fertilization to how sexual reproduction creates variation.
- Through independent assortment; crossing over, and fertilization.
- Connect the events of meiosis to Mendel’s laws of segregation and independent assortment; and to recombination of linked alleles.
- Explain how certain aspects of human genetic variation (Down’s syndrome, etc.) can be explained by chromosomal changes resulting from meiosis (nondisjunction).
Topic 5.3. Mendelian Genetics (includes sex-linked alleles)
- Topics 5.3 – 5.5, Part 1: Mendelian Genetics and Punnett Squares
- Topics 5.3 – 5.5, Part 2: Solving ABO Blood Type inheritance problems
- Topics 5.3 – 5.5, Part 3: Sex-linked alleles, and a few human genetic conditions to know
- Topics 5.3 – 5.5, Part 4: Dihybrid Crosses
- Explain Mendel’s laws of segregation and independent assortment, and connect them to what happens during meiosis.
- Explain relevant rules of probability that apply to genetics.
- The rule of multiplication is the most important of these.
- Be able to solve genetics problems involving
- Monohybrid and dihybrid crosses with autosomal genes;
- Multiple alleles, with blood type (A, B, O system) as an illustrative example. Note that while blood type isn’t explicitly in the College Board’s standards, it can show up in problems related to inheritance patterns that involve multiple alleles.
- Explain the inheritance patterns of sex-linked genes, and be able to solve genetics problems involving sex linkage.
- Sex-linked genes are on the X chromosome
- Males (who much more frequently express these genes) always inherit sex-linked genes from their mothers.
- Explain non-XY sex determination systems, such as the ZZ/ZW system in birds, haplodiploidy in bees, and temperature-dependent sex determination in certain reptilian clades.
Topics 5.4 – 5.5. Non-Mendelian Genetics
- Topics 5.3 – 5.5, Part 5: Linkage and Recombination
- Topics 5.3 – 5.5, Part 6: How to do the χ2 (Chi Squared) Test
- Topics 5.3 – 5.5, Part 7: Mitochondrial Inheritance, Incomplete Dominance, and Genotype-Environment Interaction
- Explain the chromosomal basis of linkage and recombination. When given data about linkage, be able to determine the distance (in map units) between linked alleles.
- Genes on nonhomologous chromosomes independently assort.
- Genes on the same chromosome are linked but can recombine because of crossing over.
- Define polygenic traits, and describe why these usually have a bell-curve-shaped distribution pattern.
- Explain non-nuclear inheritance
- Inheritance of genes in mitochondria of chloroplasts.
- Gene transmission is exclusively maternal.
- Explain how the interaction between genotype and environment is a major determinant of phenotype.
Unit 5 Cumulative Objectives, Flashcards, and Quizzes
Unit 6. Gene Expression and Regulation
Unit 6 topics at a Glance
- 6.1 – 6.2. Structure of DNA and RNA; DNA Replication
- 6.3. Transcription and RNA Processing
- 6.4. Translation
- 6.5. Regulation of Gene Expression (Operons)
- 6.6. Gene Expression and Cell Specialization (Eukaryotic Gene Regulation)
- 6.7. Mutation
- 6.8. Biotechnology
Unit 6 Learning Objectives
Topic 6.1: DNA and RNA Structure and Function
[note: some of this is also covered in 1.6 above]
- Compare and contrast the functions of DNA and RNA
- DNA is the molecule of heredity in organisms. RNA can play that role in viruses.
- In organisms, RNA’s function is information transfer related to protein synthesis (mRNA, tRNA, and rRNA)
- RNA also has a catalytic role in certain processes (splicing out introns, influencing gene expression).
- Compare and contrast DNA in eukaryotic and prokaryotic organisms.
- Prokaryotes have circular chromosomes. Eukaryotes have multiple linear chromosomes.
- Plasmids are small circles of double-stranded DNA found in prokaryotes (and in some eukaryotes)
- Describe the features of DNA that make it suited to be the molecule of heredity.
- The stability of the double helix allows for information storage.
- Base pairing rules allow for accurate replication.
- Complementary nitrogenous bases pair through hydrogen bonding.
- In DNA, A (adenine) bonds with T (thymine); C (cytosine) bonds with G (guanine)
- Purines (G and A) have two rings and bind with pyrimidines (C, T, U), which have a single ring.
Topic 6.2: DNA Replication
- Describe the overall process of DNA replication
- DNA polymerase adds new nucleotides at the 3’ end of a growing strand (5′ to 3′ synthesis)
- Because DNA polymerase can only add to an existing strand, an RNA primer is required.
- Explain how DNA replication is semiconservative
- One strand acts as the template for the synthesis of a new complementary strand.
- List the key enzymes involved in DNA Replication (and describe the function of each)
- Helicase breaks hydrogen bonds to unwind the strands.
- Topoisomerase prevents supercoiling
- Polymerase (see above)
- Ligase creates sugar-phosphate bonds between adjacent DNA fragments.
- Explain the concept of leading and lagging strands, and explain how replication is different on each.
- Leading strand: continuous replication.
- Lagging strand: discontinuous replication (Okazaki fragments).
Topic 6.3: Transcription
- Describe the flow of genetic information within cells (AKA the central dogma)
- DNA makes RNA makes protein
- Describe what happens during transcription
- RNA polymerase uses the sequence of DNA nucleotides in the template strand (AKA the noncoding strand, minus strand, or antisense strand) to synthesize complementary RNA.
- RNA polymerase binds at a promoter, a DNA sequence just upstream of the transcription start site.
- The binding of RNA polymerase can be regulated by transcription factors (see topics 6.5 and 6.6 below)
- The template strand varies depending on the gene that’s being transcribed.
- RNA polymerase synthesizes in the 5’ to 3’ direction as it reads DNA in the 3’ to 5’ direction
- Describe the roles and key features of the 3 types of RNA in protein synthesis
- mRNA carries information from DNA to the ribosome. Information is encoded in codons: 3 RNA nucleotides that specify a particular amino acid.
- tRNAs have an amino acid binding site and an anticodon (a sequence complementary to a codon). The specific binding of anticodon to codon ensures that the amino acid sequence in a polypeptide matches the sequence specified in mRNA
- rRNA is the catalytic part of the ribosome, connecting amino acids in a polypeptide chain.
- Describe the additional RNA processing that occurs in eukaryotic cells
- Addition of a poly-A tail.
- Addition of a GTP cap.
- Excision of introns and splicing together and retention of exons.
- Explain how the organization of eukaryotic genetic material into introns and exons can increase phenotypic variation.
- Through alternative splicing, exons can be spliced together in alternative ways allowing for the production of multiple protein versions from the same mRNA transcript.
Topic 6.4. Translation and the Genetic Code
- Topic 6.4, Part 1: The Genetic Code
- Topic 6.4, Part 2: Translation/Protein Synthesis
- Topic 6.4, Part 3 (extension): Protein Targeting to the Rough E.R.
- Compare translation in prokaryotes and eukaryotes
- In all cells, translation occurs at ribosomes. In eukaryotes, some ribosomes are embedded into the rough E.R. (“bound ribosomes”) while other ribosomes float freely in the cytoplasm (“free ribosomes”)
- In prokaryotes, translation and transcription can occur simultaneously. In eukaryotes, transcription is in the nucleus, and translation in is the cytoplasm.
- Define the genetic code, describe its key features, and use a genetic code chart to predict the amino acid sequence that will be generated by a given sequence of mRNA.
- The genetic code is a set of 3-letter sequences of nucleotides called codons that code for specific amino acids.
- The code is redundant, with many codons coding for the same amino acid.
- The code is nearly universal, with only a few variants throughout the living world.
- The code includes punctuation: codons that signal for translation to start and stop.
- Describe the process of translation.
- Initiation: the small subunit of a ribosome binds with the start codon. A tRNA with an anticodon matching the start codon binds, bringing the first amino acid. The large subunit binds the small subunit.
- Elongation: As specified by the codon on the mRNA, tRNAs with the designated amino acid bind with the mRNA at the ribosome. The ribosome catalyzes a peptide bond between the newly arrived amino acid and the growing polypeptide chain.
- Termination: when a stop codon is reached, a release factor causes the polypeptide to be released, and the ribosome dissociates from the mRNA.
- Explain how retroviruses violate the central dogma (note: this is covered in the 6.7 extension topic below).
- Retroviruses use RNA as their genetic code.
- Reverse transcriptase uses RNA as a template for creating DNA, which is then incorporated into the host’s chromosome. The incorporated virus (a provirus) then exploits the host cell’s replication, transcription, and translation machinery for the replication of new retroviruses.
Topics 6.5 and 6.6. Regulation of Gene Expression and Cell Specialization
- Topics 6.5 – 6.6, Part 1: Gene Regulation in Bacteria through Operons
- Topics 6.5 – 6.6, Part 2: Eukaryotic gene regulation through regulation of chromatin, Epigenetics
- Topics 6.5 – 6.6, Part 3: Eukaryotic gene regulation through control of transcription
- Topics 6.5 – 6.6, Part 4: Eukaryotic Gene Regulation — Coordinated Control Mechanisms, and microRNAs
- Topics 6.5 – 6.6, Part 5: Eukaryotic Gene Regulation and Development
- Topics 6.5 – 6.6, Part 6: Eukaryotic gene regulation and evolutionary change in the threespine stickleback
- Define regulatory sequences.
- Regulatory sequences are segments of DNA that control the expression of genes, usually by increasing or decreasing the rate of transcription.
- Describe how prokaryotic cells use operons to control gene expression.
- Operons are clusters of genes under the control of a single promoter.
- The expression of operons is under the control of a regulatory protein, which binds to an operator region that is just downstream from the promoter.
- Explain the role of transcription factors in regulating eukaryotic gene expression.
- Transcription factors are proteins that bind near or at the promoter to regulate the binding of RNA polymerase.
- Transcription factors can promote, block, or inhibit transcription.
- Negative regulatory molecules (including small RNAs) inhibit gene expression by binding to DNA and blocking transcription.
- Explain how the phenotype of a multicellular organism is determined by gene expression.
- All cells in a eukaryotic organism have the same DNA.
- Cells differentiate into specific tissues because they express genes for tissue-specific proteins.
- These tissue-specific genes are activated through the induction of transcription factors during embryonic development.
- Induction and gene activation unfold in a hierarchical sequence.
- Small RNAs also play a role in the regulation of transcription and translation.
- Explain how gene expression can be coordinated in eukaryotes
- In eukaryotes, genes in different tissues can share regulatory sequences that can be activated or repressed by transcription factors to coordinate gene expression.
- Define epigenetics.
- Epigenetics involves reversible modifications to DNA that influence gene expression without changing the DNA sequence.
Topic 6.7 extension: Viruses
Note from Mr. W: With two exceptions, the objectives below are not in the College Board’s Course and Exam description. In the context of the COVID-19 Pandemic (not to mention AIDS and other viral diseases), teaching AP Bio without teaching about viruses is unimaginable. Here’s a set of objectives for teaching and learning about viruses. Also, because of the objectives about horizontal gene transfer that are in topic 6.7, it makes sense to teach or learn this material about viruses first.
- Topic 6.7, Part 1: Virus Structure and Viral Life Cycles (Lytic, Lysogenic, and Retroviral)
- Topic 6.7, Part 2: SARS-CoV-2 and Covid 19
- Topic 6.7 Part 3: mRNA Vaccines and Rapid Antigen Testing
- Explain what a virus is, and how viruses straddle the boundary between living and non-living.
- Describe the basic structure of viruses, starting with phage, and including animal viruses.
- Describe, compare, and contrast the lytic and lysogenic cycles.
- As an illustrative example of a retrovirus, describe the life cycle of HIV. This covers the learning objective about retroviruses from Topic 6.4, above.
- Explain how viruses develop their own genetic diversity through recombination and mutation, and how they introduce variation into other species through transduction. This covers part of the learning objective from Topic 6.7 below.
- Describe the life cycle and overall biology of SARS-CoV-2.
- Explain how mRNA vaccines work to provide protection against virtual infection.
- Explain how Rapid Antigen Tests work.
Topic 6.7. Mutation and Horizontal Gene Transfer
- Define mutation
- Compare and contrast somatic and germline mutations: where they occur, and what their consequences are.
- Describe various types of point mutations
- silent (no change in protein coded for by the mutated gene)
- missense (one amino acid is substituted for another one)
- nonsense (a stop codon is substituted for an amino acid)
- insertions and deletion errors leading to a frameshift (change in reading frame), causing extensive missense (or nonsense).
- Explain how mutations come about.
- Causes can include radiation, reactive chemicals, or errors in DNA replication or DNA repair.
- Explain how mutations can be harmful, beneficial, or neutral.
- Harmful: results in a protein that is nonfunctional or harmful (illustrative examples include mutations in the CFTR gene leading to cystic fibrosis)
- Beneficial: improves the function of a protein (illustrative examples include the MC1R mutation that leads to adaptive melanism, or the mutation leading to lactase persistence in certain human populations).
- Neutral: the resulting protein is the same (silent mutation) or similar (because of the type of amino acid substitution).
- Explain the overall importance of mutation to evolution.
- Mutation provides the raw material upon which natural selection acts.
- Connect the events of mitosis or meiosis to mutation (see related topics in Unit 5)
- Changes in chromosome number (polyploidy) resulting from mitosis or meiosis can create new species.
- Changes in chromosome number caused by nondisjunction during meiosis result in a variety of human developmental disorders (Down syndrome), or chromosomal differences (Turner Syndrome)
- Define horizontal gene transfer, and describe various types of mechanisms of horizontal gene transfer
- Horizontal gene transfer is the uptake of genetic information (as opposed to the inheritance of genetic information from a parent.
- It occurs primarily in prokaryotes and viruses via transformation, conjugation, and transduction.
- When two viruses infect the same cell, their genetic information can be combined, leading to viral progeny with novel gene sequences
Topic 6.8. Biotechnology
- Topic 6.8, Part 1: Genetic Engineering through Plasmids
- Topic 6.8 Part 2: Gel Electrophoresis, Restriction Fragment Length Analysis, and DNA Fingerprinting
- Topic 6.8, Part 3: Amplifying DNA by PCR (the Polymerase Chain Reaction)
- Topic 6.8, Part 4: A Few More Genetic Engineering Techniques to Know About: Sequencing and CRISPR
- Explain the basic goals of genetic engineering.
- Analyzing or manipulating DNA.
- Describe the basic method and purpose of electrophoresis
- Separating molecules of DNA, RNA, or protein according to size and charge, usually for analytical purposes.
- Describe the polymerase chain reaction (PCR)
- During PCR, DNA or RNA fragments are amplified (small amounts are made into larger samples that can be analyzed).
- Describe the purpose of bacterial transformation
- Introduces DNA into bacterial cells, usually to get these cells to express desired proteins (such as with genetically engineered insulin or clotting factor)
- Transformation is usually preceded by inserting novel genes into plasmids, which are then used as a vector to introduce these genes into bacterial cells where these genes can be replicated and expressed.
- Describe the purpose of nucleic acid sequencing
- Determining the order of nucleotides in DNA or RNA.
Unit 6 Cumulative Objectives, Flashcards, and Quizzes
Unit 7. Evolution
Unit 7 topics
- 7.1 – 7.3. Natural and Artificial Selection
- 7.4- 7.5. Population Genetics and Hardy-Weinberg
- 7.6 – 7.8 Evidence of Evolution and Common Ancestry
- 7.9. Phylogeny
- 7.10 – 7.12. Speciation and Extinction
- 7.13. Origin of Life
Unit 7 Learning Objectives
Topics 7.1 – 7.3: Natural Selection, Artificial Selection, and Sexual Selection
- Define adaptation.
- Explain how while evolution is non-random, the mutations that lead to adaptation are themselves random.
- Selection is non-random. But If it weren’t for mutation (which is random), all that selection could do would be to cull the population of less adaptive phenotypes. Mutation is what makes the process of natural selection creative and open-ended.
- Explain how natural selection works:
- Inherited variation, followed by selection for beneficial traits and against harmful traits, shifts the average phenotype in a population, leading to adaptation.
- Describe how evolutionary fitness can be measured
- As an organism’s ability to survive and reproduce
- Explain the importance of phenotypic variation to natural selection.
- Natural selection acts on phenotypic variation in populations. If selective pressure is maintained in the same direction over multiple generations, different phenotypic variations will become more or less common, depending on fitness.
- Explain how artificial selection works.
- During artificial selection, humans select favored phenotypes within plant or animal gene pools, shifting the average phenotype in the desired direction.
- Explain how natural selection acts on phenotypes to shift allele frequencies within populations.
- The result of selection (artificial or natural) is a shift in allele frequencies. But what’s being selected are phenotypes.
- Explain the relationship between environmental change and selective pressure
- As environments change, so do selective pressures. If selective pressure continues in the same direction, there’s directional selection for specific phenotypes. If change is fluctuating, then so will the average phenotype in a population.
- Explain sexual selection, and compare intersexual selection with intrasexual selection.
- Distinguish between directional, disruptive, and stabilizing selection*
Topics 7.4 and 7.5: Population Genetics and Hardy Weinberg
- Define gene pool
- Define allele frequency
- Describe evolution in terms of a population’s gene pool.
- Evolution is a change in the genetic makeup of a population over time.
- Describe the Hardy-Weinberg equilibrium model.
- The Hardy-Weinberg model is a mathematical model of a non-evolving population. That means a population in which allele frequencies stay constant over time.
- Be able to solve problems related to the two Hardy-Weinberg equations. [Note: you’ll be giving the formulas, so you don’t need to memorize them). The formulas are:
- p + q = 1, and
- p2 + 2pq +q2 = 1
- State the five conditions associated with non-evolving populations in Hardy Weinberg equilibrium
- Large population size
- isolation (no outside alleles coming into or leaving the gene pool)
- no net mutation
- random mating (no sexual selection or assortative mating).
- no beneficial or harmful alleles
- Define genetic drift.
- Genetic drift is a change in gene frequencies caused by random sampling of alleles in small populations.
- List and describe two ways in which genetic drift can occur.
- The founder effect
- The bottleneck effect.
- State the conditions that lead to evolution (change in allele frequencies). These are all violations of the Hardy-Weinberg conditions listed above
- Violate large population size, and you have genetic drift, shown either by population bottlenecks or by the founder effect.
- Violate isolation, and you have gene flow.
- Violate no net mutation, and you have alleles changing frequency as they mutate from one form to another.
- Violate random mating, and you have evolution caused by sexual selection or assortative mating.
- Violate no harmful or beneficial alleles, and you have evolution caused by natural selection.
Topic 7.6: Evidence for Evolution, Continuing Ancestry, and Continuing Evolution
- Explain what fossils are, and how fossils can be dated.
- Radioactive decay can show the age of igneous rocks in sedimentary strata adjacent to fossils.
- The decay of carbon-14 can show the age of relatively recent fossils.
- Geological strata and the use of index fossils can show relative dates.
- Describe homologous structures
- Structures that show evidence of common ancestry because of similarity in structure or similar embryological origin.
- Describe vestigial structures
- Structures that have lost their function, and only exist because of their inheritance from a common ancestor.
- Describe molecular homologies and vestigial features at the molecular level.
- Shared sequences in proteins and nucleic acids that show evidence of common ancestry.
- Pseudogenes are inactive gene sequences that persist in the genome.
- List and describe the molecular homologies that indicate that all living things share a common ancestor.
- DNA, RNA, ribosomes, the genetic code, and shared metabolic pathways (chemiosmosis)
- List and describe the cellular and genetic homologies that indicate that all eukaryotes share a common ancestor.
- Membrane-bound organelles, linear chromosomes, genes with introns, mitochondria
- List and describe the evidence that evolution continues
- Changes in the fossil record
- The ongoing evolution of resistance to antibiotics, pesticides, herbicides, antiviral drugs, and chemotherapy drugs.
- Newly emerging pathogens and diseases.
Topic 7.9: Phylogeny
- Describe the types of evidence that can be used to infer evolutionary relationships.
- Morphological similarities that show homology
- DNA and RNA sequences
- Be able to construct and analyze phylogenetic trees and cladograms. The key things to be able to identify are
- Common ancestors
- Which clades are most closely related (and why)
- With regards to phylogenetic trees, define (and be able to identify) clades, shared derived features, ancestral features, outgroups, nodes, and common ancestors.
- Understand what phylogenetic trees represent in terms of evolutionary understanding.
- Phylogenetic trees and cladograms are hypotheses about evolutionary relatedness that need to be revised in light of new information.
- Compare the value of sequence data and morphological data in terms of constructing phylogenetic trees.
- Molecular data typically provide more accurate and reliable evidence than morphological traits
- Explain how molecular clocks work.
- Nodes are dated based on correlation with the fossil record. This enables the extrapolation of divergence times in other branches of the same phylogenetic tree.
Topics 7.10-7.12: Speciation, Variation, and Extinction
- Explain the biological species concept (what it is, and what its limits are)
- A species is a population that can interbreed to produce viable, fertile offspring.
- Doesn’t work for fossil species or asexual species
- Describe prezygotic and postzygotic reproductive isolating mechanisms
- Explain what speciation is, and the mechanisms by which it occurs
- Definition: when an ancestral species splits into two or more reproductively isolated daughter species.
- Mechanisms: allopatric and sympatric
- Compare punctuated equilibrium with gradualism
- Punctuated equilibrium: long periods of stasis, followed by rapid change.
- Gradualism: slow evolution at a steady pace over long periods.
- Define adaptive radiation and describe its importance
- Definition: Multiple speciation events from a common ancestor.
- Importance: it’s the key pattern of life’s reemergence following mass extinction. Also a key pattern on island chains.
- Connect a population’s genetic diversity with its ability to withstand environmental pressures.
- Populations with more genetic diversity are better able to respond to environmental change.
- Populations with little genetic diversity (because of genetic drift or human manipulation) are at higher risk of extinction.
- **Connect variation at the molecular level with fitness
- Molecular variation can increase fitness.
- Example: Multiple chlorophylls enhance photosynthesis
- Example: Multiple hemoglobins (fetal vs adult) maximize oxygen absorption at different developmental stages
- Distinguish between extinction and mass extinction.
- Extinctions occur at a regular background rate.
- During mass extinction events (of which there have been very few), geological or astronomical events increase extinctions well beyond the background rate.
- Explain how human activity is related to extinction
- Currently, humans are modifying ecosystems to a degree that’s creating a human-caused mass extinction event (see Topic 8.7 below).
- Explain the connection between extinction and biodiversity
- In any particular ecosystem, the level of diversity results from the rate of speciation and the rate of extinction.
- Mass extinctions create vacant ecological niches that are filled during subsequent adaptive radiation (such as the adaptive radiation of the mammals following the extinction of the dinosaurs).
Topic 7.13: Origin of Life
- List the key dates for the emergence of life on Earth.
- Based on geological evidence, Earth formed about 4.5 bya.
- Based on biological and geological evidence, life was well established by 3.5 bya.
- Based on geological and biological evidence, life probably first emerged on Earth about 3.8 bya.
- Explain some of the key steps associated with the origin of life on Earth.
- Conditions in a few locations on the early Earth would have made the abiotic formation of biological monomers possible.
- A likely spot for that to have happened is alkaline hydrothermal vents.*
- Additional prebiotic molecules could have come down from space via meteorites (but this is not nearly as plausible as the hydrothermal vents)
- The formation of monomers would have to be followed by the formation of polymers.
- Next would be the formation of self-replicating polymers. *
- At some point, the encapsulation of self-replicating polymers within a lipid bubble led to the formation of cells.*
- Describe the progress that’s been made in verifying theories related to the origin of life.
- Organic monomers, including nucleotide precursors and amino acids, have been synthesized in laboratories under abiotic conditions designed to simulate the conditions on the early Earth.
- The next step —creating complex self-replicating polymers — has not yet been achieved, but there are promising approaches.
- Describe the RNA world hypothesis.
- The RNA world hypothesis promotes the idea that RNA, rather than DNA, served as the first genetic material.
Unit 8. Ecology
Unit 8 topics
- 8.1. Responses to the Environment
- 8.2. Energy Flow through Ecosystems
- 8.3 – 8.4. Population Ecology
- 8.5 – 8.6. Community Ecology and Biodiversity
- 8.7. Disruptions to Ecosystems
Unit 8 Learning Objectives
Topic 8.1: Responses to the Environment
[Note from Mr. W]. In terms of understanding how organisms respond to their environments, these exclusion statements by the College Board tell you what you don’t have to know.
- In relation to how changes in the environment are related to physiological or behavioral changes, no specific physiological mechanism is required.
- In relation to communication and behavioral systems, the details of these systems are outside the scope of the exam and course.
As a result, telling you what to study is difficult. The College Board’s objectives are very open-ended (and somewhat obvious). So, while there are bound to be questions on the AP exam that relate to animal behavior and responses to the environment, it’s hard to advise you on what specific terms or concepts you need to know.
Here are the key ideas from the CB outline.
- Based on cues in the environment, organisms change their behavior and physiology.
- Communication between organisms in response to internal or external changes can change behavior.
- Signaling changes the behavior of other organisms and is subject to natural selection.
- A variety of signals (visual, auditory, tactile, chemical, and electrical) are used to indicate social dominance, find food, and induce or solicit mating.
- Learned and innate behaviors are subject to natural selection.
- Cooperation between members of the same population can increase fitness.
One strategy might be to familiarize yourself with illustrative examples. However, don’t overdo it. You don’t need to memorize anything. If these examples show up on the AP exam, they’ll be used as parts of data sets or scenarios that you’ll have to analyze and explain (with no previous knowledge expected).
- Photoperiodism and phototropism in plants
- Taxis and kinesis in animals
- Nocturnal and diurnal activity
- Pack behavior in animals
- Herd, flock, and schooling behavior in animals
- Predator warnings
- Colony and swarming behavior in insects
- Kin selection
- Parent and offspring interactions
- Courtship and mating behaviors
- Foraging in bees and other animals
- Fight-or-flight response
- Predator warnings
- Plant responses to herbivory
- Compare and contrast endotherms and ectotherms.
- Endotherms use thermal energy generated by metabolism to maintain homeostatic body temperatures.
- Ectotherms lack efficient internal mechanisms for maintaining body temperature. Their temperature can fluctuate widely, though they may regulate their temperature behaviorally by moving into the sun or shade or by aggregating with other individuals.
- Describe the relationship between metabolic rate and size.
- Generally, the smaller the organism, the higher the metabolic rate.
- Describe the relationship between energy gain or loss and growth/survival/reproduction
- Net energy gain results in energy storage or the growth of organisms or populations.
- Net energy loss results in loss of mass, death, and population decline.
- Describe how energy flow through ecosystems can be graphically represented.
- Through food chains, food webs, and energy pyramids.
- *Define biogeochemical cycle, and (as a representative example) explain the carbon cycle.
- Explain the effects of changes in energy availability on trophic levels and ecosystem structure.
- Changes in energy availability can affect the number and size of the trophic levels. Specifically, a change in the producer level can affect the number and size of other trophic levels.
- Compare autotrophs and heterotrophs
- Autotrophs capture energy from physical or chemical sources in the environment;
- Heterotrophs capture energy by eating or absorbing chemical energy in organic compounds.
- Compare photoautotrophs with chemoautotrophs
- Photoautotrophs use light to synthesize organic compounds. Plants, algae, and cyanobacteria are photoautotrophs.
- Chemoautotrophs power the creation of organic compounds by oxidizing small inorganic molecules (such as iron). This process can occur in the absence of oxygen. All chemoautotrophs are bacteria or archaea.
Topics 8.3 – 8.5: Population Growth and Community Ecology
- Explain the general factors behind population growth, and the general equation for this growth (dN/dt = B – D)
- Explain what exponential growth is and when it occurs, and be able to use its relevant equation (dN/dt = rmaxN)
- Define limiting factors.
- Compare and contrast Density Dependent and Density Independent Limiting Factors
- Define carrying capacity.
- Be able to use the Logistic Growth equation (dN/dt = rmaxN (K-N/K))
- Explain how population growth can be influenced by resource availability and predator-prey interactions.
- Explain how communities change over time during the process of ecological succession.
- Describe the key Interactions that occur between the species in a community. This includes the following interactions and being able to describe the positive and negative effects on each species.
- Commensalism, amensalism
- Competition (leading to niche partitioning and character displacement)
- Predator/Prey interactions (leading to evolutionary arms races)
- Explain what keystone species are, and what happens when keystone species are removed from their ecosystems.
- An organism whose activity defines the structure of the entire ecosystem.
- Often these are carnivores that control herbivores, increasing productivity and overall biodiversity.
- When keystone species are removed, ecosystems can collapse.
Topic 8.6-8.7: Biodiversity and Disruptions to Ecosystems
- Define Biodiversity, and describe its key components.
- Species composition and richness.
- Know how to use the Simpson’s Biodiversity index.
- Explain the connection between biodiversity and ecosystem resilience.
- Less biodiversity and less ecosystem complexity often equate to less resilience to environmental change.
- List and describe the traits that predispose a species to become an invasive species.
- High reproductive rates, tolerance of a wide range of conditions, generalist ecological niche.
- Explain how invasive species affect ecosystem dynamics and biodiversity.
- When invasive species enter a new habitat, they tend to grow exponentially.
- As invasive species are freed from control by their former predators or competitors, they can outcompete or overexploit the species in their new environment, or overrun their new habitat.
- The overall effect is a decrease in biodiversity.
- Describe the human activities that lead to changes in ecosystem structure and/ or dynamics.
- Destruction or degradation of habitat, habitat fragmentation, the introduction of invasive species,
- The introduction of new diseases can devastate native species.
- Climate disruption is altering habitats worldwide.
- Explain how geological and climatic changes can change ecosystem structure and/or dynamics.
- Changes in geology and climate can alter habitats and change ecosystem distribution.
[This is word-for-word from the College Board’s Course and Exam Description]
- Concept Explanation: Explain biological concepts, processes, and models presented in written format.
- 1.A. Describe biological concepts and/or processes.
- 1.B. Explain biological concepts and/or processes.
- 1.C. Explain biological concepts, processes, and/or models in applied contexts.
- Assessment on the AP Exam: Students will need to identify or pose a testable question, state the null and alternative hypotheses or predict the results of an experiment, identify experimental procedures, and/or propose new investigations.
- Visual Representations: Analyze visual representations of biological concepts and processes.
- 2.A. Describe characteristics of a biological concept, process, or model represented visually.
- 2.B. Explain relationships between different characteristics of biological concepts, processes, or models represented visually
- In theoretical contexts.
- In applied contexts.
- 2.C. Explain how biological concepts or processes represented visually relate to larger biological principles, concepts, processes, or theories.
- 2.D Represent relationships within biological models, including
- a. Mathematical models.
- b. Diagrams.
- c. Flowcharts.
- Assessment on the AP exam: Students will need to describe characteristics of a biological concept, process, or model represented visually, as well as explain relationships between these different characteristics. Additionally, students will need to explain how biological concepts or processes represented visually relate to larger biological principles, concepts, processes, or theories.
- Questions and Methods: Determine scientific questions and methods.
- 3.A. Identify or pose a testable question based on observations, data, or a model.
- 3.B. State the null and alternative hypotheses or predict the results of an experiment.
- 3.C. Identify experimental procedures that are aligned to the question, including
- a. Identifying dependent and independent variables.
- b. Identifying appropriate controls.
- c. Justifying appropriate controls.
- 3.D. Make observations or collect data from representations of laboratory setups or results. (Lab only; not assessed)
- 3.E. Propose a new/next investigation based on
- a. An evaluation of the evidence from an experiment.
- b. An evaluation of the design/methods.
- Assessment on the AP Exam: Students will need to identify or pose a testable question, state the null and alternative hypotheses or predict the results of an experiment, identify experimental procedures, and/or propose new investigations.
- Representing and Describing Data: Represent and Describe Data
- 4.A. Construct a graph, plot, or chart (X, Y; Log Y; Bar; Histogram; Line, Dual Y; Box and Whisker; Pie).
- a. Orientation
- b. Labeling
- c. Units
- d. Scaling
- e. Plotting
- f. Type
- g. Trend line
- 4.B. Describe data from a table or graph, including
- a. Identifying specific data points.
- b. Describing trends and/or patterns in the data.
- c. Describing relationships between variables.
- Assessment on the AP exam: Students will need to identify specific data points, describe trends or patterns, and describe relationships between variables
- 4.A. Construct a graph, plot, or chart (X, Y; Log Y; Bar; Histogram; Line, Dual Y; Box and Whisker; Pie).
- Statistical Tests and Data Analysis: Perform statistical tests and mathematical calculations to analyze and interpret data.
- 5.A. Perform mathematical calculations, including
- a. Mathematical equations in the curriculum.
- b. Means.
- c. Rates.
- d. Ratios.
- e. Percentages.
- 5.B. Use confidence intervals and/ or error bars (both determined using standard errors) to determine whether sample means are statistically different.
- 5.C. Perform chi-square hypothesis testing.
- 5.D Use data to evaluate a hypothesis (or prediction), including
- a. Rejecting or failing to reject the null hypothesis.
- b. Supporting or refuting the alternative hypothesis.
- Assessment on the AP exam: Students will need to perform mathematical calculations, use confidence intervals, perform chi-square hypothesis testing, and use data to evaluate a hypothesis or prediction.
- 5.A. Perform mathematical calculations, including
- Argumentation: Develop and justify scientific arguments using evidence.
- 6.A. Make a scientific claim.
- 6.B. Support a claim with evidence from biological principles, concepts, processes, and/or data.
- 6.C. Provide reasoning to justify a claim by connecting evidence to biological theories.
- 6.D. Explain the relationship between experimental results and larger biological concepts, processes, or theories.
- 6.E. Predict the causes or effects of a change in, or disruption to, one or more components in a biological system based on
- a. Biological concepts or processes.
- b. A visual representation of a biological concept, process, or model.
- c. Data.
- Assessment on the AP exam: Students will need to make scientific claims, support claims with evidence, and provide reasoning to justify claims. Additionally, students will need to explain relationships between experimental results and larger biological concepts, processes, or theories. Finally, students will need to predict the causes or effects of a change in, or disruption to, one or more components in a biological system.
* Not explicitly in the standards, but recommended
** The College Board put this concept in Cellular energetics, which looks like a mistake.