Lab 7: Mitosis, Factors Affecting Cell Division of Allium Roots AP Biology INTRODUCTION Recall that mitosis is the division of cells that involves replicating the nuclear DNA and then subsequently distributing it to two daughter cells. We can investigate the occurrence of this phenomenon using model organisms such as frog embryos, fish embryos, or plants. It should be noted that the most rapidly growing part of a plant is the root. The root contains a specialized tissue known as apical meristem that contains cells that grow rapidly, which is why the roots of any plant are ideal study subjects for investigating the process of mitosis. The plant of choice when studying mitosis is the common onion. Onions germinate easily without soil so the chemicals provided to the plant can be easily controlled. Onion root tips also grow quickly and are only a few cells thick.1 Many mitosis labs involve creating a root tip squash, but in this investigation we will determine as a class how we will measure mitotic activity using an alternative way to measure its occurrence. We will then design a procedure to determine if various substances will affect mitotic activity of the roots of our onion plants. image source: http://bodell.mtchs.org/OnlineBio/BIOCD/text/chapter20/20images/20-13.gif General Procedure Each Group will place onions in their own test tubes. 3 will be control, 3 will be experimental. You will cut off all the existing roots from the bulb with a scalpel, and submerge it in your test tube 2 inches from the bottom. Use your toothpick to hang it. The experiment you design will test the affects of environmental factors on mitotic rate. Choose one of the below listed chemicals to test. If you have another idea or chemical you would like to bring, please ask your teacher. You will have the following materials available to you: Green onion (Allium) distilled water black tea Clear wrap Miracle Gro Pellets caffeine test tubes test tube rack graduated pipets scalpel graduated cylinder toothpicks Safety concerns for this lab: ● Do not eat the onions. ● Be careful when cutting the roots with the scalpel. DEVELOPING THE PROCEDURE: 10 Pre-Lab Questions ● ● ● ● ● ● What is your research question? What will your control group look like? How will you ensure that you are able to collect an adequate amount of data for analysis? How frequently will you collect data? What factors will you control to ensure that you collect high quality data? How will you measure the occurrence of mitosis? In other words, how will you measure your dependent Factors Affecting Cell Division of Allium Roots 2017 Modified by Lee Ferguson from a lab by Karen Davis, Canyon HS 1 Flinn Bio-Fax, “Environmental Effects on Mitosis” ● ● ● ● variable? What type of data will you collect? What kind of statistical testing will you conduct to analyze your data? How will you display your data--what kind of graphs will you produce? What will your hypothesis be? What will your Null Hypothesis be? Once the specific procedure is developed as a group, be sure you complete your pre-lab by answering the above questions. WHAT YOU WILL TURN IN: THE DELIVERABLE Your final product for this lab will be turned in as individuals--this is not a group assignment. Individuals will be selected to present their final product on Monday March 5. You will turn in a CER for this lab that includes the following: ● Your research question. ● The hypothesis you tested. ● Your claim about the onion you investigated. Remember that the claim answers the original research question-you don’t state the claim BEFORE investigation takes place, you state it AFTER it is finished. ● Evidence, to include: ○ Processed data (properly constructed graphs with explanation of data, statistical analysis) ○ Photos of the onions during the growth period ● Reasoning that supports your claim which includes showing the relationship between the outcome of your investigation and the biological concepts explored. This should use the data you collected and processed to support the claim you stated. ● You will submit your work as a Google Slides in Schoology. Be sure you have shared it appropriately so your teacher can view your work. Factors Affecting Cell Division of Allium Roots 2017 Modified by Lee Ferguson from a lab by Karen Davis, Canyon HS 1 Flinn Bio-Fax, “Environmental Effects on Mitosis”
