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Frequently Asked Questions

Must Know About AP Biology Labs

23 min read•july 11, 2024

Mark Little

AP Biology 🧬

358 resources

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The AP labs and variations of these labs 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.

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.

Be able to make observations, collect data, make the proper graph and evaluate the data collected.
Review and understand the conclusions from each lab.
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…”
Perform calculations from the lab results or data sets.
Be able to write a prediction or hypothesis; identify the independent and dependent variables for the experiments.
Be able to identify and justify appropriate controls for the experiment.

Unit 1: Chemistry of Life

There are no College Board recommended labs for this unit. 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 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 membranes that separate the internal and external environment and these membranes control what enters and exits the cell and helps maintain a condition called homeostasis.

The major lab for Unit 2 is about Diffusion and Osmosis. The lab has three 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 with 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 as the surface area to volume ratio decreases, the cell will get larger.

In the second procedure you will 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 certain molecules or ions to pass through actively or passively.

An example might be you placed in the dialysis tubing different “concentrations of sugar” and place them in beakers of distilled water overnight. You should see water flow from areas of high water potential to areas of low water potential. In this case, the tubing with the highest concentration of sugar will gain the most mass. Water moves down the concentration gradient, meaning from areas of high water concentration “least amount of sugar” to areas of lower water “solutions with the most sugar.”

In the third procedure, you will 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 shows a direct relationship between the current mass and previous mass. 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.” The movement of water from higher concentration to lower concentration is determined by the starch and water concentration in the potato.

This lab looks at the movement of materials through the cell membrane and throughout the cytoplasm of the cell. 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 through special protein channels called aquaporins in the cell membrane. These special protein channels allow water to move more quickly than it would through osmosis. 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 solute concentration and a lower water potential. A hypotonic solution has a lower solute concentration and a higher water potential. Isotonic solutions have equal water potential.

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 and 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

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 three labs associated often done with this unit. The first lab 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. Many scientists call this temporary bond the induced fit model.

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:

Enzyme Catalysis Lab: Enzyme Catalysis

Enzyme Diversity: Enzymes
Lactase Enzyme: Lactase

The second lab 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.

The process of photosynthesis occurs in a series of steps regulated by enzymes. During photosynthesis, light energy is captured to build carbohydrates that are full of energy stored in the chemical bonds. Autotrophs are organisms that capture free energy from the sun through photosynthesis and chemosynthesis and heterotrophs from the carbon products (like carbohydrates) of other organisms.

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

The general summary equation for photosynthesis is

H2O + CO2 + light → carbohydrate (CH2O) + O2 + H2O

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. 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:

Photosynthesis tutorial: Photosynthesis
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.

Photosynthesis Simulation: Photosynthesis

The third lab 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 are organisms that capture free energy from the sun through photosynthesis and chemosynthesis and heterotrophs obtain energy from the carbon products (like carbohydrates) of other organisms. In the process of cellular respiration,

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. ATP is generated by mitochondria within the cell. 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 the presence of oxygen, glucose can release large amounts of energy. The process of cellular respiration also produces water and carbon dioxide gas as waste products.

C6H12O6 + 6 O2 -> 6H2O + 6CO2(g) + energy

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

Cell respiration takes place in the mitochondria in eukaryotic organisms and has three general steps: 1) Glycolysis (anaerobic -- no oxygen required) in the cytoplasm 2) Krebs or Citric Acid Cycle (aerobic -- requires oxygen) in the mitochondrial matrix and 3) Electron Transport Chain that is aerobic as well.

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:

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

Unit 4: Cell Communication and Cell Cycle

You have seen cell communication before. In Unit 2 the various types of carrier proteins involved in facilitated diffusion are an example of cell signaling. Also in unit 3, light is used to trigger a response to start the process of photosynthesis (light-dependent reaction).

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.

Blood sugar regulation (production of insulin and glucagon), neurotransmission, the immune system with helper and killer T cells are examples of cell communication you may know.

There is one major recommended lab. It is about cell division: mitosis and meiosis. For the mitosis lab, 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:

Mitosis tutorial: Mitosis
Biomembranes II and Cell Communication Tutorial: Cell Communication

Cell Cycle Simulation: Cell Cycle
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

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. This book is a fantastic read and is relevant today because she had some of her cervical cancer tissue removed with her knowledge.

If interested in the Henrietta Lacks story: Henrietta Lacks

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. Lastly, you learn about how the environmental factors (like lack of oxygen, alcohol, etc.) and nondisjunction (failure of one or more homologous chromosomes or sister chromatids to separate)

Mendelian genetics is often used to try to explain inheritance and biological diversity based on studying pea plants. He found out that genes come in pairs and are inherited in genes, one from each parent. Mendelian genetics studies three main ideas or laws.

1) Law of Segregation: the two alleles or forms of a trait will separate randomly, in which there is a 50% chance for either allele to show up in either gamete. 2) Law of Independent Assortment: One allele of one gene separates of an allele of a different gene. (This deals with two genes) 3) Law of dominance, which means one character or trait is dominant and the other is recessive, the dominant form of the trait will be expressed

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

Incomplete dominance: For example, Red and White flowers are crossed and form pink flowers.
Codominance: Both genes expressed equally. For example blood typing: AB blood typing is an example. (Types AA (Ai), BB (Bi), AB, ii or type O)
Polygenic Inheritance: Human height is controlled by many genes!
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 cross. 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.

Virtual Lab site: Virtual Fly Lab
Virtual Fly Tutorial: Virtual Fly Video tutorial
Virtual Fly Practice Problems: Virtual Fly Practice Problems

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

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 chromosomes called plasmids.

DNA is made (replication) in a 5’ to 3’ direction and is often called semiconservative, which means each strand is half new DNA and has the old strand. When making proteins DNA is copied into mRNA and the mRNA leaves the nucleus and goes to a ribosome. The mRNA attaches to the ribosome and tRNA brings amino acids to the mRNA and they make an amino acid chain through the process of transcription.

The mRNA can undergo modifications. A couple of things that can happen are the addition of a poly-A tail on one end of the addition of a GTP cap. Also, a phrase you may have been taught is “Exons are always expressed.” Introns are spliced out of the transcript and the exons are transcribed. This process of splicing or cutting and the keeping of exons can result in different forms of the mRNA sometimes called alternative splicing.

Transcription, Translation and Gene Regulation Tutorials and Lab Reviews

DNA Replication Tutorial: DNA Replication
Transcription Tutorial: Transcription
Translation Tutorial: Translation
The Lac Operon in Ecoli Tutorial: Lac Operon
Restriction Digest Tutorial: Restriction Digest
Molecular Biology Labs Tutorial (Gel Electrophoresis and Transformation)

Genotyping with Electrophoresis Simulation: Genotyping
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.

Regulation of the Lactase Gene Click and Learn: Lactase Gene
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 specific labs 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 and you insert a gene of interest into a bacteria and make it change color.

A sample procedure is you have a set up with 3-5 plates. Sometimes you can divide a plate in half to get more lab sets. You make two tubes with bacteria, usually labeled + for the bacteria with the plasmid with the gene of interest to insert into bacteria and one without the plasmid labeled -. The First of the 3-5 plates is LB, which has good bacteria food on it. It is a control plate to test if your bacteria are alive or not. You should expect growth on both plates.

The second plate is LBA. This plate has Ampicillin on it, an antibiotic. The + bacteria with the plasmid have antibiotic resistance will grow on the plate and the bacteria with - will not grow on the plate because they do not have the resistance to ampicillin.

The last plate is LBAA and you only put the + bacteria on it. This plate contains ampicillin and a sugar arabinose. Arabinose is needed for the gene to be turned on to change the color of the bacteria from white to green. You should notice that if the plasmid was taken up by the bacteria the bacteria will be a green or another bright color depending on the plasmid. See the image of the results.

The other usually focuses on gel electrophoresis, 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. It is a way to separate sequences of DNA by size. 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

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 thoroughly studies and wrote about natural selection and this process became the driving force of evolution.

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 look at different hypotheses about the formation of the Earth.

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

Evolution tutorial: Evolution 101

A lab tutorial for Hardy-Weinberg:

Hardy-Weinberg Lab Tutorial: Hardy-Weinberg

A simulation for Hardy-Weinberg Lab Simulation

Hardy Weinberg Simulation
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.

Evolution of Populations Simulations: Evolution of Populations
Guppy Evolution Simulation: Guppy Evolution
Ground Finch Evolution: Ground Finch

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

Sorting Finches Click and Learn (Speciation): Finches
Creating Phylogenetic Trees Click and Learn (Evolutionary Relationships): Trees
Sorting Shells Click and Learn: Shells

The three labs associated with natural selection or evolution are an artificial selection lab, a Hardy-Weinberg lab and a BLAST lab 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. These data are used on the AP Exam. Such as this in past free-response questions from 2014.

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. Cladograms ALWAYS so upon the AP Biology exam so it is an essential skill to learn how to make one and interpret a cladogram.

There are many versions of the lab. The key is not understanding how to use BLAST but they understand 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.

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 math in this unit with the Simpson Diversity Index, Population Growth Rates, Exponential Growth, Population Growth.

There are three labs with this unit. One is not done very often and the other two there are many forms of. The first lab 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.

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

The second lab 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.

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

The last lab is about Animal Behavior. This lab is one of the more common labs done in AP Biology and often done at the beginning of the year. There are many versions.

In most cases, students set up two choices in choice chambers and you place certain critters in to test (fruit flies, pillbugs, mealworms…) You place different foods (sweet like sugar or sour) or environments (light or dark) for the critters to choose from and see if the critter tested show a preference. It is possible to have more than two choices of environments for the critters to choose from.

You study to see if the critters are attracted to the environment or food or do they go away from it or is it random, no pattern. Kinesis is a movement with no pattern while taxis can be positive (towards it) or negative (away from it). There are different types of taxis (Phototaxis-towards or away from light for example).

Here is a simulation of the Animal Behavior Lab. This simulation covers the main concepts of the lab to review: