Plant Module 1 Final

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Washington State University *

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106

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Biology

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Feb 20, 2024

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Laboratory 1 (There are 4 parts to this lab) Introduction & Plant Growth Biology 106 Plant Module: LAB 1 of 3 ( This document has been modified from the original protocol written by Dr. Lisa Carloye and her group of Biol 106 instructors at WSU ) 1. Plant Module Case Study – Introduction 2. Scientific investigation – designing experiments to answer questions about the role of nutrients in increasing plant biomass for a canola farm. 3. Data management: ± Using spreadsheets to organize data. ± Analyzing data using statistics ± Visually representing data using bar graphs. 4. Getting started – experiment set up. PART 1: PLANT MODULE CASE STUDY Trade wars with China have dominated the political and economic news lately as President Trump slaps tariffs on Chinese goods and China retaliates with tariffs on targeted US goods. Amidst this economic bad news for farmers, one crop produced here on the Palouse may benefit from the restrictions created by this trade war: Rapeseed ( Brassica napus ). One of the commodities hard hit by China’s tariffs is US-grown soybeans, so China has been increasing their demand for rapeseed to help offset the lost oil they extract from soybeans. Rapeseed is grown for the oil produced in the seeds. In the spring, the intense yellow of rapeseed ( Brassica napus ) covering select fields around Pullman is a stunning display, attracting photographers from around the world. Depending on the variety grown, rapeseed is harvested for use in cooking (canola oil), and as an ingredient in margarine and soap. Its oils have long been used as an industrial lubricant for jet engines and marine engines due to its ability to work at high temperatures. It is also used in plastics such as bread wrappers and garbage bags. It can be made into biodiesel as well. Furthermore, after the oil is extracted, the plant residue can be used in feed for livestock and the plant can be grown as forage for cattle to graze. Rapeseed is a highly versatile commodity. Q. Based on this list of uses, categorize the ways in which we use rapeseed. Give between 3 and 4 types (categories) of uses (e.g., “Food production”): In order to make the most of this increased demand for rapeseed in China (and around the world), local producers want to maximize their yield and produce a high-quality product. Plants, like animals, require resources from the environment to grow and produce healthy offspring. Over the next three labs you will investigate factors important for plant growth and maximizing yield. You will then draw conclusions and write a report to communicate your findings to the Canola Council of Canada (and earn a grade for Bio 106). _ cooking (canola oil) _ , ___ Jet engine lubrican __ , __ Plastics (wrappers ____ , Forage for cattle ___________

Biology 106: 2022 Summer 2 ± Please list below 4 resources you think plants require for growth: PART 2: SCIENTIFIC EXPERIMENTATION Because one common way farmers produce quality crops is to increase soil nutrients by applying fertilizers, we will focus our efforts in BIOL 106 on determining just how much fertilizer is necessary to impact plant biomass and, potentially, increase yield. Furthermore, we will investigate whether increasing access to nutrients also increases herbivory on the plant tissues since this might just negate any benefits seen with add fertilizer to the growing crop. In this lab, you will gather data to answer two key questions using a fast-growing relative of Brassica napus , Brassica rapa (the data you will use in this experiment was obtained by Dr. Lisa Carloye and her group of Bio 106 instructors who previously conducted the study to produce data for your use) : ± Question 1: Will adding nutrients (fertilizer) to the growth medium increase Brassica growth? If so, how much is optimal? ± Question 2: Will increased nutrients affect the amount of feeding on the leaves by primary consumers (herbivores)? In order to answer these questions, we need to know how to design and conduct a valid, scientific experiment. Exercise 1: The scientific approach to answering questions Step 1: Formulate a testable hypothesis, often referred to as the alternative hypothesis, (also formulate its companion null hypothesis). In science, questions are investigated through the process of hypothesis testing. A hypothesis is a testable explanation for a set of observations based on the available data and guided by inductive reasoning (Campbell Biology, 2014). Note that hypotheses are testable explanations constructed as statements, not if/then sentences which are more like predictions. For example, “Water is necessary to rehydrate carbohydrates in seeds in order to trigger germination,” is a hypothesis (we know water is necessary for seeds to germinate and think it is logical they facilitate seed germination by freeing up carbohydrates to use for growth). Experiments are conducted and the information collected (data) is used to test a pair of complementary hypotheses: the null hypothesis ( H 0 ) and the alternative hypothesis ( H 1 ). For question #1 above, the null hypothesis (H 0 ) would be “adding nutrients will have no effect on plant yield”. The alternative hypothesis (H 1 ) could be, “adding nutrients will increase plant yield.” Note how the alternative hypothesis is the plausible hypothesis you have developed and want to test. 1. Sunlight 2. Water 3. Nutrients 4. CO2 e 3. t How can w e t whether or not the items listed above are important? As scientists, we do this by developing testable 4. hypotheses and designing experiments to test them.

Biology 106: 2022 Summer 3 Step 2: Design an experiment that will answer the question. Experiments change one (and usually only one) variable at a time so that any changes observed in the test subjects can be attributed to that one specific variable. The manipulated variable you change in an experiment is called the independent variable . Q. In the experiment investigating the effect of nutrients on plant yield, what is the independent variable? That is, what variable is the research scientist manipulating? Adding Nutrients Apart from the independent variable all other conditions in the experiment should be kept the same. These are sometimes called controlled variables (not to be confused with the Control Treatment ). Q. List some things that should be held constant: Amount of Water Amount of Soil Amount of seeds Q. Why should these things be held constant? If not held constant then that would not determine the effect nutrients has on plant yield and the study would then be invalid. During, and at the end of, the experiment, the research scientist will measure the effect of the manipulation (independent variable). This measured variable is called the dependent variable . The value of the measurement depends on the independent variable. Q. In the above experiment, what is the dependent variable? That is, what variable will the research scientist measure? Plant yield (size and number of plants) The Scientific Control: In a well-designed experiment, a scientist has a scientific control that isolates the independent variable and assures that changes in the dependent variable are ONLY from the independent variable you manipulated. For example, identical plants in group 1 are sprayed from a sprinkler with a chemical dissolved in water. In group 2, the plants are sprayed with the exact same sprinkler in the exact same way, but with ONLY water. Why? That design eliminates the possibility there is an un-anticipated effect from (1) water and/or (2) some mysterious effect of a sprinkler that might occur for unexpected reasons. Q. What will be the experimental (scientific) control in the experiment investigating the effect of fertilizer on plant mass? the control is the use of sprinklers when distributing fertilizer vs without fertilizer The experiment: Now think through the details of how you would design this experiment. ± Make a sketch below of how you would set it up.

Biology 106: 2022 Summer 4 ± Label each component to make it clear what you would use, how you would use it, and what it will tell you. Q. Can you get meaningful results from just using 1 plant per treatment? Why or why not? Discuss the importance of replication in an experiment. It would not be as meaningful because the treatment working for one plant could be an outlier. The more plants you have the more valid the results. Being able to replicate the study helps determine its validity. Q. For this experiment, each pot will house 4 seeds. Why do you think we chose 4 instead of fewer, or more? 4 Seeds were chosen in order to determine replicability of the experiment however still give the seeds room to grow and receive nutrients. If there was less than 4 seeds the study may not be as valid and reliable. Step 3: Make a prediction! Predicting results provides a critical analysis of the experimental design. A prediction is always based on a particular experiment designed to test a specific hypothesis. Predictions are written in the form of if/then statements: “ If the hypothesis is supported, then the results of the experiment will be…” Please write an if/then statement for the alternative hypothesis (H 1 ) above and your predicted outcome: Exercise 2: Preparing the Plants Brasica rapa seeds were planted in pots containing nutrient-free soil and watered with deionized (DI) water by BIOLOGY 106 Lab Manager Kara . Over the course of 3 weeks, Kara photographed the plants to record their growth. METHODS: ± Each pot was planted with 6-8 Brassica rapa seeds. ± After seed germination, Lab Manager Kara identified the 6 healthiest looking plants, and removed all other seedlings, leaving these 6 plants undisturbed. You will measure 4 of these and they will be your experimental subjects. ± At the start of the study each pot was randomly selected for a given treatment and fitted with 1 label tag: 1. Four pots were labeled “ +fertilizer-HIGH ” 2. Four pots were labeled “ +fertilizer-MEDIUM ” 3. Four pots were labeled “ +fertilizer-LOW ” 4. Four pots were labeled “ ±± fertilizer-CONTROL ” ± Each pot was then photographed at eye-level. These photographs capture the seedlings before they receive their experimental or control treatment and serve as the baseline. ± One plant from each pot was measured (in mm) and that number was recorded. This measurement allowed Drs. Hellmann and Carloye to scale the

Biology 106: 2022 Summer 5 online ruler you will use to measure the plants. The ruler is found in the Powerpoint slides showing the potted plants from which you will obtain your measurements – do not resize the ruler so that you obtain accurate measurements! Exercise 3: Data Collection PROCEDURE : 1. Open the document “ Lab 1 Brassica Plants, bio 106, f2022.pptx , ” posted on Canvas. This has pictures of the plants. 2. Look carefully at the little seedlings that have sprouted in the pots. Q. How many plants are growing in the Control-Pot 2 (the second photo in the row)? __ 5 _____ Q. How many plants are growing in the LOW-pot 1 (the first photo in the row)?__ 6 ____ 3. Use the ruler provided on the page to measure each of the 4 plants indicated in each CONTROL pot in millimeters. ± The ruler should be able to be “grabbed” and moved to each plant in turn. ± Measure from the vermiculite surface to the tallest part of the plant as best you can. ± Record the heights for your potted plants here, and give the units: Plant 1: 1mm Plant 2 2mm Plant 3 2mm Plant 4 1.8mm Q. What factors make it challenging to accurately measure these plants? List them all: Accurately measuring size, leaf size, measuring consistently across plants, using power point software, making sure to measure from the 0 of the ruler, distance distortion 4. Open the Plant Data Excel Spreadsheet posted on Canvas, file, “ Plant Module lab 1 Excel Data Sheet, bio 106, f2022 master.xlsx .” Record the data by entering the plant heights into the appropriate cell, one plant height per cell (only numbers, do not include units ), in the “Raw Data” sheet, based on the treatment, pot and plant: Type in the number you measured for the Control treatment, Pot 1, and one of the plants. Then continue on until you have entered all of the plants in all of the treatments with one plant per cell

Biology 106: 2022 Summer 6 5. Save the file to your laptop or to your cloud – you will need this file in future labs so be sure you know where to find it later. PART 3: Data Analysis The point of randomizing the pots when assigning plants to different treatment groups at the start of the study is to ensure that we are not skewing, or biasing, the data in some way, e.g., by unconsciously selecting all of the most-robust-looking seeds for the control treatment. Q . What are 2 scenarios where the final results might be biased if we didn’t start out by randomly assigning which treatment a particular pot of plants would get. In order to determine whether or not the plants in the treatments are starting out the same , we must analyze our data. To objectively analyze our data, we will use statistics as outlined below: A. The purpose of statistics is to organize, summarize, and compare data. In science, statistics are used to draw conclusions. Organisms are variable and can respond differently to changes in conditions. Additionally, measurements are not always precise. Therefore, reaching conclusions about a group based on a study done on one individual is not possible and of very little value, because no one individual will be, or can be, representative of the entire group (remember from the blurb we are trying to understand Brassica growth for all farmers in the Palouse, not just your lab subjects). However, when many individuals in a group are studied, the impact of inherent deviation from the typical plant by any one individual subject is minimized. This usually results in the generation of large amounts of data. Statistics are used to summarize such large sets of data. B. Types of Statistics that will be used for the Plant Module: ± Mean = a single number used to typify a set of numbers. The mean is calculated by adding all the values, then dividing by the number of values (same as average). Here’s an example: A sample of 5 plant heights ( 1 cm + 2 cm + 3 cm + 4 cm + 5 cm )/5 plants = 15/5 = 3 cm which is the mean height. Q. What is the LOW Fertilizer treatment’s mean? ____ 16mm ___ Q. What is the MEDIUM Fertilizer treatment’s mean? ___ 15.4mm _____ Q. What is the HIGH Fertilizer treatment’s mean? ___ 17mm ____ Q. What is the Control treatment’s mean? ____ 1.4mm ______ ± Variance = a measure of how far a set of numbers is spread out. o Zero variance indicates that all the values are identical. o Small variance indicates data points tend to be very close to the mean. Scenario 1: Plants adhering to hypothesis receiving extra treatment leading to bigger plants\ Scenario 2: Delivering less water treatment to plants without fertilizer

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