Must Know About AP Biology Labs

The example AP Biology investigations and variations of these investigations will be discussed with curriculum content and science practice connections. It is recommended that lab work take at least 25% of your class time. Many AP exam questions will provide you lab data in the prompt and ask you questions about the data set.

There is no separate AP Biology lab practical or required-lab section on the exam. Instead, laboratory reasoning is embedded throughout the multiple-choice and free-response sections through experimental design, data analysis, graphing, statistical reasoning, and evidence-based explanation.

AP Biology requires at least 25% of course time in hands-on, inquiry-based lab work, but the College Board does not require one fixed set of named labs; teachers may use different investigations to build the same science practices and concepts. Also, on the AP Biology Exam, students are not tested on whether they performed a specific named lab; instead, they are expected to analyze biological scenarios, experiments, data tables, graphs, models, and investigations using the course concepts and science practices.

On the current AP Biology Exam, students are assessed through 60 multiple-choice questions and 6 free-response questions in 3 hours total. Lab-based thinking appears throughout the exam, especially when students must interpret experimental results, analyze or graph data, evaluate investigations, propose follow-up experiments, and justify claims with evidence. Students are not expected to memorize a required list of official labs, but they are expected to apply course concepts and science practices to unfamiliar investigations.

In the current AP Biology course, laboratory experiences are meant to build the six AP Biology science practices assessed throughout the course and exam: concept explanation, visual representations, questions and methods, representing and describing data, statistical tests and data analysis, and argumentation. Students should prepare for lab-based questions by practicing these skills across many biological contexts rather than by memorizing procedures from a fixed list of official labs.

Also, virtual labs and simulations will be referenced for extra practice and content review if needed. You may consider using the virtual labs or simulations for additional review and practice over topics you may have not done in your class.

There are several key ideas from all the lab investigations and simulations that you did in your class.

1. Be able to make observations, collect data, make the proper graph and evaluate the data collected.
2. Review and understand the conclusions from each lab.
3. Answer “what if” questions that may test your understanding and answer questions like “Based on these results, what would your follow up question be?” Or “Predict what would happen if…” Or “Propose what your next investigation would be…”
4. Perform calculations from the lab results or data sets.
5. Be able to write a prediction or hypothesis; identify the independent and dependent variables for the experiments.
6. Be able to identify and justify appropriate controls for the experiment.

Science practices you should connect to labs and lab-based questions

1. Explain biological concepts and processes in written and applied contexts.
2. Analyze and interpret visual representations such as models, diagrams, tables, and graphs.
3. Identify testable questions, variables, controls, and appropriate methods; predict results and state a null hypothesis when appropriate.
4. Construct and describe graphs and data displays using correct labels, units, scales, and error bars when appropriate.
5. Perform calculations and data analysis, including rates, ratios, percentages, percent change, confidence intervals/error bars, and chi-square testing when appropriate.
6. Make and justify scientific claims using evidence and reasoning.

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Unit 1: Chemistry of Life

There are no fixed official AP Biology labs for this unit, but teachers often use short inquiry activities to build core lab skills early in the year. Knowledge of basic chemistry such as elements, molecules, compounds are essential to learn. Properties of water are an important concept of this unit.

Knowing basic information about the four types of macromolecules or biological molecules is important too. These molecules are the: 1) Carbohydrates 2) Proteins 3) Lipids 4) Nucleic Acids.

Often at the start of the year, you were taught about a lab write format including how to write a proper question to investigate; how to write a hypothesis or prediction; how to properly draw and label a graph; and how to properly analyze the data collected. Also, you may have been taught about CER in AP Biology and improving your skills in argumentation.

• An activity to review macromolecules is Pattern Matching.
• An activity to review water properties is Water Molecule - Model Building
• A tutorial for Biomolecules: Biomolecules -----

Unit 2: Cell Structure and Function

This unit teaches about the cell, the basic unit of life. Cells are a key component to life’s organization and provide conditions for our cell organelles to function. Cell organelles provide what is often referred to as “compartmentalization”, and this concept helps with cellular organization.

Cells have selectively permeable membranes that regulate what enters and exits the cell. By controlling exchange of water, ions, and other substances, membranes help cells maintain stable internal conditions and support homeostasis.

One common classroom investigation that helps build AP Biology science practices in Unit 2 explores diffusion, osmosis, membrane transport, and surface area-to-volume relationships. This investigation often has several parts. In the first procedure, you will be asked to study the relationship between surface area and volume by varying the size of artificial cells. This lab is often done with agar. Your teacher makes agar cubes with an indicator of different sizes and you place the cubes into a solution of vinegar (an acid) for about 10 minutes and the indicator in the cube will change color. Surface area and volume related calculations are done. These calculations are done to determine what happens to the surface area to volume ratio as a cell gets larger. You should see that as cell size increases, the surface area-to-volume ratio decreases. Smaller cells therefore have relatively more membrane surface area available for exchange compared with their volume.

In the second procedure you may use a model of a living cell, dialysis tubing, and study osmosis and diffusion. As a student you fill your dialysis bags with different solutions and weigh before and after to measure the change in mass. (usually leave overnight) The dialysis tubing acts like a selectively permeable membrane. A selectively permeable membrane allows some substances to cross more easily than others. Substances may cross passively by diffusion or osmosis, while active transport requires specific membrane proteins and an energy input.

An example might be you placed in the dialysis tubing different “concentrations of sugar” and place them in beakers of distilled water overnight. Water moves by osmosis from regions of higher water potential to regions of lower water potential across a selectively permeable membrane. In many classroom examples, this corresponds to movement from a solution with lower solute concentration to one with higher solute concentration. In this case, the tubing with the highest concentration of sugar will gain the most mass.

In the third procedure, you may observe osmosis in living cells. You cut out potato cores for example and weigh them and place them in different concentrations of a solution, (usually salt or sugar) and weigh them before and after to determine the percent change in mass. Percent change in mass compares the change in mass to the initial mass. Use: percent change in mass = ((final mass - initial mass) / initial mass) x 100. Cores are left overnight.

You should notice some cores will gain mass and others will lose mass. In potatoes water will move from areas of high water concentration to areas of lower water concentration through a semipermeable membrane the "potato cells.” Water movement in potato cells is determined by differences in water potential across the cell membrane, which are caused by differences in solute concentration between the potato cells and the surrounding solution.

This investigation models how materials move across selectively permeable membranes and how surface area-to-volume relationships affect exchange with the environment. The movement in and out of the cell is limited by the cell membranes and organelle membranes because they are selectively permeable. Water moves through membranes by a special type of diffusion called osmosis.

Water moves across membranes by osmosis. In many cells, water movement is facilitated by channel proteins called aquaporins, which increase the rate of osmosis across the membrane. Most other substances like (Na+ or K+) ions also move through different protein channels. Carbohydrates and other larger molecules will require movement through transport proteins.

Water moves from areas of high water concentration (high water potential) to areas of low water concentration (low water potential). Water has high water potential when it has low solute (like salt) dissolved in it and therefore has a high free water concentration. Water has low water potential when it has high solute concentration and therefore a low free water concentration.

A hypertonic solution has a higher effective solute concentration than the cell, so water tends to move out of the cell. A hypotonic solution has a lower effective solute concentration than the cell, so water tends to move into the cell. An isotonic solution results in no net water movement.

Water moves from high water potential to low water potential or hypotonic solution to a hypertonic solution. In terms of free energy and water potential, water moves from high free energy to areas of low free energy.

Some tutorials and virtual labs include:

• Biomembranes I Tutorial: Membrane Structure and Transport
• Osmosis and Diffusion Lab: Osmosis and Diffusion

The following are simulations by Jon Darkow. These are excellent reviews of content and help you work on your science practice skills. Worksheets are provided. You can now run these simulations on your phone.

1. Diffusion and Surface area/volume: Diffusion and SA/V
2. Water Potential and Osmosis: Water Potential

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Unit 3: Cellular Energetics

This unit tends to be one of the harder units for students because it covers a lot of complex topics. This unit focuses on cellular energetics, showing how energy is captured and used by organisms. You will learn about enzymes and how they lower the activation energy for chemical reactions and how the environment can influence the effectiveness of enzyme activity. Finally, you study “cellular respiration and photosynthesis” and how energy is used to drive these processes.

There are several example investigations often done with this unit. The first is about enzymes. Enzymes are organic catalysts (usually proteins) that control many of the reactions that occur in living organisms. Enzymes are used in all metabolic reactions to control the rate of reactions and decrease the amount of activation energy necessary for the reaction to take place. Enzymes are specific for each reaction and are reusable.

The chemical an enzyme works on is called the substrate. An example of a substrate is hydrogen peroxide. An example of an enzyme is catalase. Many biological enzymes end in “ase.” Enzymes have an area called the active site to which a specific substrate will bond temporarily while the reaction is taking place. The substrate binds temporarily at the enzyme’s active site. In the induced fit model, substrate binding causes a slight change in the enzyme’s shape that helps catalyze the reaction.

This lab looks at how abiotic (nonliving) or biotic (living) factors can change or influence enzymatic reactions. There are many forms of this lab using many different types of equipment. One version uses hydrogen peroxide as the substrate that is broken down by the enzyme catalase. A couple of the variables chosen to test are varying the amount of substrate, varying the amount of enzyme, and varying the temperature or pH. A control is set up for each lab. One way is to substitute water for the enzyme.

An enzyme virtual lab review:

1. Enzyme Catalysis Lab: Enzyme Catalysis

The following are simulations by Jon Darkow. These are excellent reviews of content and help you work on your science practice skills. Worksheets are provided. You can now run these simulations on your phone.

1. Enzyme Diversity: Enzymes
2. Lactase Enzyme: Lactase

The second common investigation is about photosynthesis. In eukaryotes, photosynthesis takes place in the chloroplast. There are two general processes of photosynthesis: 1) Light-dependent reaction (often called the light reaction) and this takes place in the thylakoid membranes 2) Light Independent reaction (often called the dark reaction or Calvin cycle) and this takes place in the stroma or fluid area of the chloroplast.

Photosynthesis includes light-dependent reactions, in which light energy is captured by photosystems in the thylakoid membrane, and the Calvin cycle, in which enzymes help use ATP and NADPH to fix carbon dioxide into carbohydrates. During photosynthesis, light energy is captured to build carbohydrates that are full of energy stored in the chemical bonds. Autotrophs capture free energy either from sunlight through photosynthesis or from inorganic chemical reactions through chemosynthesis. Heterotrophs obtain chemical energy from organic molecules produced by other organisms.

Living systems require free energy and matter to grow and to reproduce.

A balanced summary equation for photosynthesis is: 6 CO2 + 6 H2O + light energy -> C6H12O6 + 6 O2.

There are multiple versions of this lab. A common version is called the floating disc lab. In your classroom, you may have used ivy or baby spinach leaves and punched out discs and used a syringe to sink the discs and timed how long it took for the discs to float again. As photosynthesis occurs, oxygen accumulates in the leaf tissue, making the disks more buoyant so they rise. The time required for disks to float is therefore used as an indirect measure of photosynthetic rate. You may have run this experiment by varying the amount of baking soda in water, “providing carbon dioxide”, varying the distance from a light source, or the color of light.

Photosynthesis tutorial and virtual lab review:

1. Photosynthesis tutorial: Photosynthesis
2. Photosynthesis lab: Photosynthesis

The following is a simulation by Jon Darkow. This is an excellent review of content and helps you work on your science practice skills. Worksheets are provided. You can now run these simulations on your phone.

1. Photosynthesis Simulation: Photosynthesis

The third common investigation is about cellular respiration. Living systems require energy to grow and reproduce. If organisms are lacking or deficient in energy, this deficiency can cause harm to the organism or to the population or even the ecosystem level. Different organisms use different strategies to store and preserve energy, often called free energy. Autotrophs capture free energy either from sunlight through photosynthesis or from inorganic chemical reactions through chemosynthesis. Heterotrophs obtain chemical energy from organic molecules produced by other organisms.

At the cellular level, the intake of oxygen gas and the output of carbon dioxide gas is associated with the production of ATP and this process is called cellular respiration. During cellular respiration, ATP is produced by processes that include glycolysis in the cytoplasm and, in eukaryotes, additional stages in the mitochondria. During cellular respiration, the energy stored within macromolecules such as glucose is released and utilized to phosphorylate (add a phosphate to) ADP, producing ATP.

In aerobic cellular respiration, glucose is oxidized and the process produces ATP, carbon dioxide, and water.

A balanced summary equation for aerobic cellular respiration is: C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + ATP (energy). You may also note that ATP is produced through glycolysis, the citric acid cycle, and oxidative phosphorylation.

Organisms that utilize oxygen for the breakdown of glucose are called aerobic organisms. Plants and animals are both examples of aerobic organisms.

In eukaryotes, glycolysis occurs in the cytoplasm, the citric acid cycle occurs in the mitochondrial matrix, and oxidative phosphorylation occurs at the inner mitochondrial membrane. Oxygen serves as the final electron acceptor in the electron transport chain, so aerobic respiration depends on oxygen overall.

There are many versions of this lab. One version uses respirometers you can make out of a syringe or other materials and place germinating, non-germinating seeds and beads as a control in them. You measure the respiration rate by measuring oxygen consumption.

A cell respiration tutorial or virtual lab review:

1. Cell Respiration tutorial: Cell Respiration

The following are simulations by Jon Darkow. These are an excellent review of content and help you work on your science practice skills. Worksheets are provided. You can now run these simulations on your phone.

1. Cell Respiration Accounting: Cell Respiration
2. Cell Respiration Multiple Dose Model: Cell Respiration Dose

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Unit 4: Cell Communication and Cell Cycle

In earlier units, you studied membrane transport proteins and how molecules cross membranes. In Unit 4, the focus shifts to cell communication, in which receptor proteins detect signals and trigger cellular responses through signal transduction pathways. Do not confuse membrane transport or photosynthetic light absorption with Unit 4 cell communication. In AP Biology, cell communication focuses on receptor proteins detecting signals and initiating signal transduction pathways that lead to cellular responses and feedback regulation.

You will learn how cells use energy, transfer information and replicate by using cellular communication. One basic pathway for this process is called the signal transduction pathway. There are three steps. 1) Reception -- a protein at the surface that detects a chemical signal 2) Transduction -- a conformational change at the protein surface causes change and starts a “transduction” of the signal through a series of steps and 3) Response -- the signal triggers a specific response.

The signal transduction process allows cells to maintain homeostasis by being able to respond to changes to the environment. Also, signal transduction plays a major role in regulating the cell cycle that is important for life.

Examples of cell communication include blood glucose regulation through insulin and glucagon signaling, neurotransmission at synapses, and signaling among immune cells. In AP Biology, the emphasis is on how signaling molecules interact with receptors and trigger pathways that regulate cell responses and feedback.

One common classroom investigation that helps build AP Biology science practices in this unit is about mitosis and regulation of the cell cycle. Meiosis is part of Unit 5: Heredity, even if some classes connect the topics when discussing cell division. For the mitosis investigation, a common version is to use onion root tips and by using different chemicals (lectin or caffeine are the common ones) to see if you can inhibit or stimulate onion root tip growth. One way is to cut the tips and stain them and count to see at what stage of mitosis the individual cells are or to have the root tips cut to the same length, measure them and see if there is a change in length over time.

Most teachers do the meiosis portion of the lab with Unit 5.

Cell Communication and Mitosis tutorials and lab review:

1. Mitosis tutorial: Mitosis
2. Biomembranes II and Cell Communication Tutorial: Cell Communication

The following simulations can help review signaling and regulation concepts; focus on receptor signaling and cellular responses rather than simple movement across membranes. These are excellent reviews of content and help you work on your science practice skills. Worksheets are provided. You can now run these simulations on your phone. Please note: Only two examples are provided here.

1. Cell Cycle Simulation: Cell Cycle
2. Insulin Secretion and Membrane Transport: Insulin

The following is a click and learn simulation from HHMI bio-interactive. One does a great job reviewing Cell Cycle Regulation and the other is about p53 genes and cancer.

HHMI Cell Cycle Regulation: Cell Cycle

HHMI The p53 Gene and Cancer: p53

The following are optional enrichment examples that can support understanding of communication, cell cycle, or bioethics, but they are supplementary and not required named AP Biology lab content.

A unique form of Cell Communication is called Quorum Sensing. It is used by bacteria.

HHMI Quorum Sensing: Quorum Sensing

Another extension your class may have done is to read the book(or sections of the book) The Immortal Life of Henrietta Lacks by Rebecca Skloot, do an activity and discuss the HeLa cells. The story of Henrietta Lacks is often discussed as a bioethics extension because HeLa cells were taken from her cervical cancer tissue and used in research without her informed consent.

If interested in the Henrietta Lacks story: Henrietta Lacks

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Unit 5: Heredity

You will learn about the concepts and processes associated with heredity. These include the passing on or transmission of genetic information using chromosomes from one generation to the next using the process of meiosis. Meiosis is a process that makes certain genetic diversity which is important for speciation to occur.

Meiosis is a process where a single cell divides two times to form four non-identical cells with half the original amount of genetic information. These particular cells are our sex cells; egg and sperm. They are haploid (n) which means they have half the number of chromosomes as the parent cell. The parent cell is called diploid (2n).

You study Mendelian and Non-Mendelian genetics and learn about patterns of inheritance. Meiosis is studied and its importance to our genetic variation. You also study environmental effects on phenotype, meaning that traits can be influenced by both genotype and environmental conditions. In addition, errors in chromosome separation such as nondisjunction during meiosis can produce gametes with abnormal chromosome numbers.

Mendelian genetics is often used to try to explain inheritance and biological diversity based on studying pea plants. In diploid organisms, individuals typically inherit two alleles for each gene, one from each parent. Mendelian genetics focuses on how alleles separate during gamete formation (law of segregation) and how different allele pairs assort independently when genes are on different chromosomes or far apart on the same chromosome (law of independent assortment). Dominant and recessive relationships describe one common pattern of inheritance, but not all traits show simple dominance.

Non-Mendelian genetics simply put do not follow Mendelian genetics laws. Listed below are a few examples:

1. Incomplete dominance: For example, Red and White flowers are crossed and form pink flowers.
2. Codominance: Both genes expressed equally. For example, ABO blood type shows codominance because IA and IB are both expressed in type AB individuals. Possible genotypes include IAIA or IAi for type A, IBIB or IBi for type B, IAIB for type AB, and ii for type O.
3. Polygenic Inheritance: Human height is controlled by many genes!
4. Sex-linked: Usually X linked which means the trait usually shows up in males. An example of this is red-green color blindness.

A virtual lab that reviews various Mendelian and Non-mendelian crosses. This will provide you data sets to evaluate and provide chi-square practice if needed. Included is a very short tutorial and questions so you can practice the types of crosses you need to review. In heredity investigations, chi-square is especially useful for comparing observed results to expected ratios and deciding whether to reject or fail to reject a null hypothesis.

1. Virtual Lab site: Virtual Fly Lab
2. Virtual Fly Tutorial: Virtual Fly Video tutorial
3. Virtual Fly Practice Problems: Virtual Fly Practice Problems

The following are simulations by Jon Darkow. These are excellent reviews of content and help you work on your science practice skills. Worksheets are provided. You can now run these simulations on your phone. Please note: Only two examples are provided here.

1. Drosophila-Apterous vs. Wild-type simulation: Apterous
2. Drosophilia-White-Eyed vs Wild-type simulation: White-Eyed
3. Gene Linkage and Recombination: Gene Linkage

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Unit 6: Gene Expression and Regulation

Gene expression examines the role of DNA and RNA (Nucleic Acids) in gene expression. You will study the differences in structure between DNA and RNA. Understanding protein synthesis (transcription and translation) is key to understanding how an individual genotype leads to phenotype gene expression. The regulation of gene expression is very important for survival which transitions into Unit 7 Natural Selection (Evolution).

The last topic discussed in the unit is biotechnology. You will study about all the advances in biotechnology and its importance to understanding biotechnology. Topics such as genetic engineering, GMO, gene cloning and transgenic organisms will be discussed.

DNA and RNA are the main sources of inherited information. Information is generally passed on from DNA-mRNA-Protein-(Expression). This process is often referred to as the Central Dogma. This information is stored in chromosomes and in eukaryotes the chromosomes are linear and in prokaryotes they are circular. Prokaryotes also contain small circular DNA molecules called plasmids.

During DNA replication, new DNA is synthesized in the 5’ to 3’ direction. Replication is semiconservative, meaning each daughter DNA molecule contains one original (parental) strand and one newly synthesized strand. When making proteins DNA is copied into mRNA and the mRNA leaves the nucleus and goes to a ribosome. During transcription, a DNA sequence is used to synthesize RNA. During translation, mRNA binds to a ribosome, and tRNA molecules bring amino acids that are linked together to form a polypeptide.

In eukaryotes, pre-mRNA can be processed by adding a 5’ cap, adding a poly-A tail to the 3’ end, and removing introns by RNA splicing. Introns are removed during RNA processing, and exons are joined together. In alternative splicing, different combinations of exons can be retained, producing different mRNA molecules and potentially different proteins from the same gene.

Transcription, Translation and Gene Regulation Tutorials and Lab Reviews

1. DNA Replication Tutorial: DNA Replication
2. Transcription Tutorial: Transcription
3. Translation Tutorial: Translation
4. The Lac Operon in Ecoli Tutorial: Lac Operon
5. Restriction Digest Tutorial: Restriction Digest
6. Molecular Biology Labs Tutorial (Gel Electrophoresis and Transformation)

The following are simulations by Jon Darkow. These are excellent reviews of content and help you work on your science practice skills. Worksheets are provided. You can now run these simulations on your phone.

1. Genotyping with Electrophoresis Simulation: Genotyping
2. Lac Operon with Diauxic Simulation: Lac Operon

The following is a click and learn simulation from HHMI biointeractive. These do a great job reviewing difficult topics in AP Biology. There are several. I will suggest two that may be the most helpful focusing on eukaryotic gene regulation that is difficult to explain. There is a worksheet provided to guide you for each.

1. Regulation of the Lactase Gene Click and Learn: Lactase Gene
2. RNA Interference: RNAi

The following is a nice overview of protein synthesis and its relationship to gene expression and RNAi. Petunias and RNAi. (The first half of it.)

The example investigations done with this unit are related to gene expression and biotechnology and there are numerous variations of these labs. They are also very expensive and therefore your school may not have been able to afford them. One usually focuses on genetic transformation.

In a common bacterial transformation investigation, one sample of bacteria receives a plasmid (+) and one does not (-). The plasmid typically carries both an antibiotic-resistance gene and a reporter gene under the control of a regulated promoter. On an LB plate, both + and - bacteria may grow if the cells are alive. On an LB/ampicillin plate, only bacteria that took up the plasmid should grow because they carry the antibiotic-resistance gene. On an LB/ampicillin/arabinose plate, transformed bacteria still grow, and arabinose activates expression of the reporter gene in systems such as pGLO, causing colonies to fluoresce.

Another common biotechnology investigation focuses on gel electrophoresis and the use of restriction enzymes to cut DNA at specific spots while running the DNA through a gel. The reference to the DNA Learning Center website explores several other topics including Gel Electrophoresis (restriction analysis). Gel electrophoresis is often used by forensic scientists to evaluate DNA evidence in real life and on TV shows like CSI.

Restriction enzymes in simple terms are DNA scissors. They cut DNA at specific places by looking for a specific DNA sequence. Gel electrophoresis is a method used to separate DNA fragments by size as they move through a gel in an electric field. You load DNA into wells in a gel and run electricity through it to help separate the DNA by size. The smaller pieces will travel farther than larger ones.

DNA is negatively charged and DNA will travel towards the positive electrode. Here is a sample of what a gel looks like.

1. Virtual Gel Electrophoresis: Gel Electrophoresis
2. DNA Learning Center Transformation

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Unit 7: Natural Selection (Evolution)

First, the unit 7 title is natural selection, which is the process by which organisms that are better adapted to the environment will tend to survive better. Charles Darwin developed and wrote about the theory of natural selection. In AP Biology, natural selection is one important mechanism of evolution, which is defined as change in the genetic composition of a population over time.

Natural selection is often discussed throughout your AP Biology course. Natural selection states that populations that are better to adapt to their environment tend to survive and are able to reproduce. During the unit, you will study about the different mechanisms of evolutionary change.

Also, the topic of artificial selection (like breeding racehorses) and how that affects variation in species is learned about. Another topic of study is Hardy-Weinberg equilibrium as a way to predict changes in allele frequencies for populations that are not evolving. This involves analyzing data sets and working on some mathematical skills to help justify a conclusion.

One other topic will be building and interpretation of cladograms or phylogenetic trees. You will look at the relationships and common ancestry of species. Finally, you will examine scientific hypotheses about the origins of life on Earth and evidence related to early biological evolution.

For more practice and understanding about topics associated with natural selection and evolution. Here are nice tutorials:

1. Evolution tutorial: Evolution 101

A lab tutorial for Hardy-Weinberg:

1. Hardy-Weinberg Lab Tutorial: Hardy-Weinberg

A simulation for Hardy-Weinberg Lab Simulation

1. Hardy Weinberg Simulation
2. Here is a worksheet to guide you on how to use it with some suggested practice simulations. Radford Worksheet.

Jon Darkow Simulations: These are excellent reviews of content and help you work on your science practice skills. Worksheets are provided. You can now run these simulations on your phone.

1. Evolution of Populations Simulations: Evolution of Populations
2. Guppy Evolution Simulation: Guppy Evolution
3. Ground Finch Evolution: Ground Finch

HHMI Click and learn. These are quick reviews of common in-class investigations.

1. Sorting Finches Click and Learn (Speciation): Finches
2. Creating Phylogenetic Trees Click and Learn (Evolutionary Relationships): Trees
3. Sorting Shells Click and Learn: Shells

These are examples of the kinds of investigations teachers may use; students are assessed on concepts and science practices rather than on memorizing a required named lab. Common investigations associated with natural selection or evolution include an artificial selection investigation, a Hardy-Weinberg investigation, and a bioinformatics/phylogeny investigation comparing DNA sequences.

The Hardy-Weinberg lab is commonly done in class. In general, Hardy-Weinberg law states that large, random mating populations will not be affected by evolutionary processes such as mutations or types of selection. The allele frequencies will not change from one generation to the next. Examples are mentioned earlier in this section.

The artificial selection lab is not done by students that often due to time. You choose a trait to measure (such as plant height or a number of trichomes or hairs on leaves) and plant a couple of strains of fast-growing plants such as a Wisconsin Fast Plant and grow them.

You artificially select which plants will grow until they flower after about two weeks (you remove the weaker, not as tall plants or plants with the most hairs or trichomes on the leaves) and allow more room for the ones you select to grow and allow them better access to the nutrients. You leave about 2 or 3 plants). You cross-pollinate the plants when they flower and when they grow to plant the seeds produced and compare the trait-like root hair number between the initial generation and second generation. Artificial selection investigations help students practice the kinds of data analysis, experimental design, and evolutionary reasoning that can appear in AP Biology free-response and multiple-choice questions.

A BLAST lab is used to study DNA and study genes of interest. The lab uses bioinformatics methodology to study similarities and differences in genomes. You learn to construct a cladogram or phylogenetic tree that is used to study the evolutionary relatedness of species. Phylogenetic trees and cladograms are important Unit 7 skills that are commonly assessed, so students should know how to interpret and construct them from evidence such as morphology or DNA sequence data.

There are many versions of the lab. The key is not understanding how to use BLAST but understanding the evolutionary relationships and the making of a cladogram.

HHMI Click and Learn Creating Phylogenetic Trees is a great practice.

If you want to physically make one and check your answers. Go here. Phylogenetic Trees.

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Unit 8: Ecology

Unit 8 Ecology is the last unit of your AP Biology course. It is the topic that brings the course together and helps you make connections to the rest of the course.

You look at how systems interact and how these systems respond to changes in the environment. The flow of energy through a system is a key topic of discussion and study as well as studying the interactions of species and what happens to species when the system is altered significantly.

Major topics in the unit include response to environmental changes, flow of energy, population ecology, energy/food pyramids, community ecology and disruptions to the systems (such as invasive species (zebra mussels), disease (smallpox, dutch elm disease), human activity (logging, urbanization (building of larger cities, markets, etc.)

There is lots of quantitative reasoning in this unit, especially with population growth, rates of change, percentages, percent change, and interpretation of graphs and data from ecological investigations. When working with ecology data, pay close attention to graph construction, units, rates, and whether error bars or confidence intervals suggest meaningful differences among samples or treatments.

There are several example investigations with this unit. One is not done very often and the other two there are many forms of. The first is Energy Dynamics. It looks at the flow of energy.

One version looks at a cabbage white butterfly life cycle and Wisconsin Fast Plants you study how to determine the net primary productivity. You end up learning to estimate the energy flow between the producers the Wisconsin Fast Plants and the White Cabbage Butterfly. There is a lot of math with this lab.

This is a virtual lab that reviews primary productivity. Attached also is a guide for it.

1. A simulation for Energy Dynamic Lab Tutorial: Energy Dynamics
2. Here is a worksheet that may help guide you through the tutorial: Worksheet

The second common investigation is about Transpiration. Transpiration is the process by which water is carried through plants to stomata, small pores located on the underside of a leaf. It is often described as evaporation from plant leaves. It helps create a negative pressure gradient that helps draw up water and minerals through plants from the roots.

This is a common lab done in AP Biology classes. There are many versions.

One of the most common ways is called the whole plant. You set up plants under different conditions (100% light, humidity (plant under a bag with water sprayed in it to simulate humidity), dark environment and wind for example). You weigh them initially and weigh them every day to see how much water they lost over a week’s time and determine which plant condition had the greatest % of water loss.

This lab is sometimes done with Unit 1: Chemistry of Life, because of water and its properties as a focus.

There are a couple of virtual labs that review transpiration. It uses photometers, which is a different version but covers the same concepts.

1. A simulation of Transpiration Lab: Transpiration
2. A different simulation using photometers and explains the procedure in a little more detail: Photometers

Optional older enrichment: Some legacy AP Biology resources include an animal behavior investigation. This is not a required named lab in the current AP Biology course. If used, treat it only as extra practice for designing investigations, analyzing data, and interpreting organismal responses to environmental stimuli.

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