The 13 laboratory experiments that are included in the AP Biology curriculum are covered in this chapter.
AP Biology involves hands-on lab work and understanding the process of science.
You can review the work you did on the labs by reading the summaries.
If you missed one of these labs in class, or just don't feel comfortable with the material after reading this chapter, ask your teacher to go over the lab with you.
The 13 lab experiments that are included in the AP Biology curriculum are examined in this chapter.
We summarize the major objectives from each experiment and the major skills and conclusions that you should remember.
If lab experiments aren't your cup of tea, don't just brush this chapter aside.
Data analysis will be emphasized in both the multiple choice and the essay sections.
The questions will not be an exact duplicate of the experiment, but they will test your understanding of the objectives and main ideas that are discussed in this chapter.
The opportunity for you to create your own investigation is one of the parts of the investigations in this chapter.
We don't know what kind of mad-scientist experiment you might design, so we will focus on the more 237 19_Anestis_ch19_p237-260.qxd.
Look at the Wisconsin Fast Plants that you'll be working with.
It should not be something that is easy to say yes to or no to.
Only the top 10 percent of your plants have this trait, and only the lucky few are allowed to reproduce.
Once the seeds develop, plant and grow your second generation of plants, you will transfer pollen between this pool of "winners".
You will measure your chosen trait again in this second population.
You are choosing which genes will be passed on to the next generation.
The next generation will inherit the purpley genes if you artificially select only the purplest of the plants.
The second population of plants will hopefully show an increase or decrease in your chosen trait.
One of the requirements of this class is your ability to graph and analyze data, so creating a bar graph to compare the quantity of your trait between these two generations would be an excellent idea.
Data can be used to show how a measurable trait is changing.
The idea of Big Idea 1 natural selection and how it changes a population can be learned from this investigation.
If you wanted to see if a popula Evolution tion was evolving, you would track the frequencies of alleles and how they change from generation to generation.
If the allelic frequencies are changing in your population, this information can be used as a point of comparison.
The laboratory review is about stasis or not evolving.
You will use a computer model to model how allele frequencies change in a generation of an imaginary population.
The idea is to understand how the fitness of an allele affects the population.
There are two alleles for a gene.
If a population is in the equilibrium of the Hardy-Weinberg equilibrium, one half of the alleles in the population's pool is the dominant A form.
The point of this lab is evolution.
You can model how a hypothetical gene pool will change from generation to generation using tools such as computer programs and spreadsheets.
When you get to tinker with your non-evolving population, the real investigation begins.
If any of the conditions do not hold true, the population will experience microevolution and the frequencies of the alleles will change.
Imagine if an individual with a condition does not reproduce.
The shift in allele frequencies will be caused by the fact that the offspring wouldn't survive to reproduce.
There is a situation in which being Heterozygous for a condition provides some benefit.
The allele will still decrease, but not as fast as in the selection example.
Imagine if 60 percent of your population were killed in an environmental disaster.
The remaining 40 percent would continue to breed and give genes to the next generation.
It is difficult because the allele is hidden in the population and can only be used against genes that are expressed.
Some people who are Heterozygous are getting some benefit.
People with a trait that protects them against Malaria.
The positive benefit helps keep the condition alive in the population.
Data from a changing population can be used to analyze it.
Data from this equation shows the effects of selection.
If you find a brand-new creature buried in your backyard, you want to find its closest living relative.
If you identified a single gene that causes disease in Big Idea 1 hedgehogs, you would like to know if that same gene is found in humans.
The use of BLAST as a tool to answer such questions has evolved.
The use of cladograms is included.
A cladogram shows the evolutionary relatedness of a species.
In this investigation, you will use BLAST to create a cladogram.
If you have a genetic sequence, you need to use the online BLAST software to compare it to other genes already in their database.
The ranking of the most closely related organisms will be shown in the results.
No, you won't have to know how to use BLAST if you don't have a computer during the exam, just like in the previous lab.
You will most likely need to analyze data obtained from a hypothetical BLAST query and generate a cladogram depicting evolutionary relatedness.
To show evolutionary relatedness, you should be able to determine the percent similarity of an unknown gene with those from other organisms.
The table shows the percent similarity of "gene X" in humans versus four other species.
Figure 19.1 is an example of a cladogram showing the evolutionary relationship.
The two species are close to each other.
Draw or analyze a cladogram that shows evolutionary relationships.
Chapter 6 Cells is the subject of this investigation.
This lab will show how the ratio of surface area and volume affects the rate of cell movement.
Your cell model is a block of agar that has an indicator dye that changes color when the pH drops.
You're given a chunk of blue agar to carve into blocks with different surface area-to-volume ratios.
As the liquid diffuses into the agar, the pH causes a change in the color of the agar.
You can easily track the amount of time it takes to complete the project.
A large surface area-to-volume ratio is what it's all about.
The block with the biggest SA:V ratio won the race.
You should be able to calculate the volume and surface area for each block.
Blocks 2 and 3 have the same volume, but their surface areas are different.
diffusion takes longer in block 2 than it does in block 3.
A high SA:V ratio is important for a cell that has a high diffusion rate.
In order to create the highest surface area possible in the smallest amount of space, the linings of your small intestine and lungs have many folds.
You will be able to create a model of a cell using the tubing.
The tubing is impermeable to water and some solutes.
The purpose of the lab investigation is to use different solutions to model how water potential affects osmosis.
If you filled your bag with a 1 Molar (1 M) sucrose solution, weighed it, and placed it in a beaker of 1 M NaCl solution, you would know.
The ionized constant is the deciding factor because the molarities are equal for both solutions.
I am 2 for NaCl and 1 for sucrose.
Water will diffuse out of the bag.
The environment of a cell allows you to make predictions.
You can use potato cores to figure out the relative concentrations of the sucrose solutions, which range from 0.0 M up to 1.0 M. You can use the percent change in weight of your potato cores to determine the water potential of the potato tissue.
You can arrange the potatoes according to their percent change in weight for each of the unknown solutions.
A significant loss of water is indicated by a super negative percent change in weight.
It's the same for positive percent change in weight.
The potato cores gained a lot of water in a hypotonic solution.
If the water potential of the solution is the same as the cells, there is no net change in weight.
The axis shows the molarity when there is no net change in weight.
One final thought about your data is that qualitative observations are still very important.
The cells lost water because they were in a hypertonic solution.
Water flowed into the cells, increasing their turgor pressure, which would suggest that it was in a hypotonic solution.
A high surface area-to-volume ratio increases the rate of diffusion.
A cell with a high SA:V ratio would evolve.
All living cells use cellular form.
Some of the best experiments are the simplest, so let's watch little pieces of a leaf float in water as oxygen is produced as a by-product of photosynthesis.
The amount of oxygen produced can be used to measure photosynthetic rates.
The little leaf disks are put in a large syringe with some soapy water.
The challenging part of the lab is getting the disks to sink.
The mesophyll layer in the leaf tissue contains atmospheric gases that need to be pulled out by a vacuum.
The disks will slowly drift to the bottom of the syringe once this is accomplished.
The contents of the needle are dumped into a cup filled with a solution and put under light.
The little disks will begin to rise to the top slowly once enough oxygen is produced.
It is possible to get an alternative source of carbon dioxide from the ionization of water.
The investigative part of the lab allows you to look at variables that you think might affect photosynthesis.
In both your control and experimental groups, perform the same leaf disk analysis and compare the amount of time it takes for half of your disks to rise and the amount of time it takes 50 percent of the disks to float.
A lot of oxygen production is a result of a lot of photosynthesis.
The rate of photosynthesis is increased by light.
Carbon dioxide was provided.
The respiration rate of seeds can be tracked with a cellular microrespirometer.
This experiment looks at germinating peas by measuring the volume of gas that surrounds them at certain intervals in order to determine the rate of respiration.
O2 and CO2 are gases that contribute to the volume around the pea.
Something needs to be done with the CO2 released.
We don't get a true representation of how much the volume is changing because of oxygen consumption.
The CO2 would make it appear as if less O2 was being consumed.
K2CO3 can be produced by adding potassium hydroxide, which reacts with CO2 to make it.
Aerobic respiration requires change in the pressure of the atmosphere.
As respiration occurs, one would expect the volume of oxygen around the pea to decline.
To calculate the change in volume that occurs with these peas, one first has to measure the initial volume around the peas.
A control group must be set up that consists of peas that are not germinating and will have a lower rate of respiration than seeds.
The baseline will be used to compare the respiration rate of the germinating seeds.
Since temperature and pressure can affect the volume around the peas, it is important to set up another control group that can calculate the change in volume that is due to temperature and pressure.
The changes in the control group should be subtracted from the changes in the germinating seeds to determine how much of the volume change is due to oxygen consumption and respiration.
I've been researching for seven years.
It's time to tally up the last generation of peas.
They have more reactions going on.
You can determine how much oxygen is consumed by watching how much water is drawn into the pipettes.
This water is drawn in because of the drop in pressure caused by the consumption of oxygen.
Warming conditions speed up cellular respiration, while cold slows it down.
This experiment is based on information found in Chapter 9.
The goal is to see if there is a greater number of cells that are affected by lectin.
You can either prepare 19_Anestis_ch19_p237-260.qxd or you can review the knowledge you need to score.
If you need a point of comparison, you will do the same counts with root cells that have not been treated with this chemical.
For your control, of 300 cells examined, 268 are in interphase and 32 are in one of the stages of mitosis.
The cell spent almost all of its time in interphase.
Almost all of the cells are in interphase.
There's a way to get that number.
The result was 0.893.
The percentage is 89.3 percent if you move the decimal point two places to the right.
According to the same logic, these data also show that more than one percent are in the disease.
For comparison, let's say the slide had a total of 250 cells examined.
It's not that bad, even though it may seem intimidating.
You would expect the same percentage of cells in your treated group as in your control group.
If you didn't expect that chemical to do its job, the remaining 223 cells are in interphase.
You can use chi-square analysis to compare what you actually saw in your treated cells to see if there are more cells stuck in mitosis.
Your hypothesis is that the treatment didn't make a difference.
The chi-square value is 0.758 + 6.26 The number of groups minus one is equal to the degrees of freedom.
There are two groups in this lab, interphase and mitosis.
The degrees of freedom are based on the chi-square table that will be provided for you on the AP exam.
The chemical increased the number of cells.
Chi-square analysis is used to analyze data.
You can be certain that the AP exam will ask you to do this.
This lab is very good for such a question.
It is a haploid ascomycete fungus.
The final part of the experiment looks at the meiosis of this fungus and briefly discusses how the data can be used to create maps.
Four black and four tan ascospores will be contained in the asci if the two strains come together and undergo meiosis.
The ratio will change to either 2:1 or 2:1.
Chapter 10, Heredity, discusses gene maps.
The percentage of asci that showed crossover would be used to build the map.
Take the number of 2:2:2 and 2:4:2 asci and divide it into the total number of offspring.
The result will give a percentage.
The number can be used to determine how far away the gene is from the centromere.
The distance is determined by the percentage of the spores in each ascus.
Explain how crossing over leads to increased genetic diversity.
This kind of experiment can make you feel like a junkie.
Chapter 11 contains all this information.
We are not going to let you know what those things are.
You should do that on your own.
This is possible because of the presence of a small amount of proteins on the surface of cells that grab pieces of DNA from around the cell.
The goal of the experiment is to transfer the resistance to a strain that dies when exposed to ampicillin.
The experimenter can check to see if the transformedbacteria were successful by growing them on a plate with ampicillin.
The transformation has succeeded if it grows as if all is well.
Something has gone wrong if nothing grows.
One tube has a solution that contains a plasmid that is resistant to ampicillin, the other does not.
After 15 minutes on ice, the two tubes are quickly heated in an effort to shock the cells into taking in the foreign DNA.
The colonies are spread out on the agar plate after the tubes are returned to ice.
They are sent to sleep in the incubator and grow on the plate.
Two of the plates are without ampicillin.
Thebacteria from the test tubes should grow on the plates.
There is no growth on the ampicillin-coated plate that is spread withbacteria from the nontransformed tube.
The ampicillin-coated plate that is spread withbacteria from the attempted-transformation tube shows growth.
The cells are treated with calcium or magnesium.
Don't worry about how this business works.
Just know thatbacteria are capable of transformation.
Both pro and eukaryotic cells work the same.
You can change how it looks by adding a gene.
The lac operon will turn on.
In this lab, there are three activities that work together to analyze and compare DNA.
A palindrome is a sequence that reads the same from either direction.
If a restriction enzyme cuts in the center of the restriction site, it will create blunt ends and pieces with exposed hydrogen bonds.
The basis of many biotechnological wonders is a recombinant DNA molecule.
You could glue the human gene into the plasmid if you isolated it with a restriction enzyme and cut it open.
You want to identify someone based on his or her genetics.
You can cut up a sample of DNA and look at the sizes of the different pieces you have created using those restriction enzymes.
Everyone has a different pattern of DNA fragments.
RFLPs are unique DNA fragments.
Gel electrophoresis is a biotechnological tool.
Gel electrophoresis is a lab technique used to separate genes.
When there is an electric current running from one end of the gel to the other, the fragments of DNA dumped into the wells.
The DNA will migrate in the opposite direction if you reverse the flow of the current.
The positive charge is what the DNA wants to go towards.
Smaller DNA travels faster than larger DNA.
When the current is running, the DNA migrates.
The faster the DNA migrates, the faster the voltage that runs through the gel.
The longer the current runs through the gel, the longer the DNA goes.
Understand how to use restriction and gel electrophoresis to create genetic profiles.
Each individual will have a different pattern made by RFLP.
You will create a simple model with a single producer and a single consumer.
Energy can be converted into a form that can be used by non-photosynthetic organisms.
The second law of thermodynamics says that energy transfer is not always efficient.
The lab tracked energy as it traveled through the food chain.
You get to mass the frass in this lab, which is the best procedure direction for the entire year.
At the beginning of the investigation, you will determine the total weight of your caterpillar and then weigh them again after three days of feeding.
Their change in mass was caused by the plants they ate.
If you take into account the amount of food that wasn't used, then you're left with the amount of the producer's energy that was used.
If you knew the amount of plant energy used by the caterpillar and subtracted from that the amount of energy lost in the poop and energy used for the caterpillar's increase in mass, what you're left with is the energy used in respiration.
Energy transfer isn't perfect.
All of the plant's energy was not used by the caterpillar.
The idea of how living organisms use free energy relates to this lab.
The mass of living tissue is called the "biomass".
This experiment takes the concepts found in Chapter 6 of the text and applies them to the material in Chapter 14 Plants.
Before you start, there are interactions and vascular tissue.
Water moves from the soil to the leaves and branches of a plant.
Capillary action, osmosis, and root pressure are three minor players in the transport of water.
Osmosis draws water into the xylem.
The osmotic driving force is created by the absorption of minerals from the soil.
The water is pushed a small way up the superhighway by the root pressure in the xylem.
transpiration is the main driving force for the movement of water in a plant.
The water in the xylem is pulled toward the shoots by an upward tug on the remaining water.
The driving force of water through the xylem of the plants is due to the cohesive nature of water molecule.
When one of the water molecule is pulled in a certain direction, the rest follow.
Environmental factors that affect the rate of transpi ration are examined in this experiment.
Increased air movement, decreased humidity, increased light intensity, and increased temperature increase the rate of transpiration.
Think about how much more you sweat when it's hot.
It makes sense that decreased humidity would increase transpiration.
There is less water in the air when it is less humid.
Imagine standing with a 40- watt bulb shining on your neck, and then a 100 watt bulb shining on your neck.
The higher wattage bulb will cause you to sweat more.
The higher the intensity of the light, the more transpiration occurs.
Air movement is not obvious.
If there is good air flow, evaporated water on leaves is removed more quickly, increasing the amount of water that leaves the plant.
One easy way to measure water loss is to measure the mass of the plant every day for a week.
The "whole plant" method requires you to tightly seal a plastic sandwich bag around the root ball to keep water out of the leaves.
Think about the variables that may affect transpiration.
One plant will be your control, and every other plant will be assigned a variable.
For as long as your teacher says, measure the weights again 24 hours later.
If a leaf falls off during this experiment, it has to stay with the plant for subsequent weighings.
The best way to compare results between treatments is when your data collection is over.
If the initial plant weights were different, it's hard to compare the total change in weight.