What’s in a Tomato? Understanding our human impact on the environment: This lesson plan demonstrates the use of research, experimental design, writing and critical thinking skills by exploring linkages between tomato diversity and human impacts on the (food) environment. Subject/Course: Environmental Sciences: SVN3E Grade Level: Grade 11 Topic: The impact of human activities on the environment Specific Curriculum Expectations Met: A1.1 Formulate relevant scientific questions about observed relationships, ideas, problems or issues, make informed predictions and or formulate educated hypothesis to focus inquiries A1.6 Compile accurate data from laboratory and other sources and organize and record the data, using appropriate formats, including tables, flow charts, graphs and or diagrams A1.8 Synthesize, analyze, interpret and evaluate qualitative and or quantitative data to determine whether the evidence supports or refutes the initial prediction or hypothesis and whether it is consistent with scientific theory; identify sources of bias and or error and suggest improvements to the inquiry to reduce the likelihood of error A1.10 draw conclusions based on inquiry results and research findings and justify their conclusions with reference to scientific knowledge. B1. Analyse selected current environmental problems in terms of the role human activities have played in creating or perpetuating them, and propose possible solutions to one such problem; B2.1 use appropriate terminology relating to the environmental impact of human activity, including, but not limited to: carbon footprint, carbon neutral, biodegradable, biodiversity, carrying capacity, sustainability, and invasive and native species. B3.4 explain the concept of a “carbon footprint” and how it is used to measure the impact on the environment of a range of human activities Required Resources: Total of 4 tomatoes halves: 2 tomatoes halves from 2 different, locally grown in Ontario tomatoes and 2 tomatoes from 2 different imported tomatoes (Mexico, US) 1 plastic knife 1 ruler 1 measurement table (see below) 1 diagram of tomato cross section (see below) Paper Towel 1 Scenario: Michelle is shopping at a No Frills grocery store and is looking to buy some fresh tomatoes for tomato and cheese sandwiches. She notices a few choices when it comes to buying tomatoes. She can purchase 1 locally grown in Ontario tomato for $1.50 or 2 tomatoes imported from Mexico for $1.00. Michelle decides to purchases both types and returns home to make her sandwiches. As she begins to slice each tomato, she observes a difference between the two. The insides of the Ontario tomato (e.g. columella, septa) appear more red in colour; feels less firm; was easier to slice; and the tomato skin wall (e.g. pericarp wall) is less thick compared to the Mexican tomato. Mexican tomatoes appear more pale on the inside; feels more firm; and was harder to slice. Michelle also decides to taste a slice of each tomato and discovers that the imported tomato had less taste compared to the local tomato. Stricken by curiosity, Michelle takes both tomato slices to her high school’s science club, and seeks assistance from a group of interested environmental science and biology students. She asks for the students’ help in understanding the difference between the two tomatoes. She mentions that she is especially curious about the difference in each tomato’s skin wall. Working in smaller groups as part of the science club, you are asked to conduct the following investigation to help Michelle better understand the differences in tomato types. Activity and Answer Key: Part 1: Investigating differences Steps: 1) Watch the Story of Food as an introduction to the activity: http://usc-canada.org/storyoffood/ 2) Before proceeding with any dissection, discuss with your group and generate a hypothesis regarding the difference in the tomato skin wall. Either your group believes that there is a difference in the skin wall of the imported vs. local tomato or your group believes there is no difference and what Michelle witnessed was a coincidence. (A1.1) Ho: The pericarp wall in imported tomatoes (Mexico, US) will be thicker in diameter compared to those in local Ontario grown tomatoes. Ha: There is no difference in the diameter thickness of the pericarp wall of imported or locally Ontario grown tomatoes 3) n/a 4) With each tomato slice, measure the tomato’s pericarp wall in three different places (as shown in Figure 1). Record each measurement you take for each slice sample (using Table 1). When finished, calculate the sample’s average skin wall diameter. Record this average value in Table 1. Be sure to add the unit measurements into your table as well. (A1.6) 2 Table 1: Tomato pericarp wall measurements, with example Tomato Sample Measurement Measurement ID 1 2 Example 0.9cm 0.75cm Local 1 Local 2 Imported 1 Imported 2 Check the average calculations Measurement 3 1.1cm Average 0.92cm 5) Using the data that you’ve generated in Table 1, defend whether it supports or refutes your group’s original hypothesis described in step 1. (A1.8) Either the data (average calculations) supports that imported tomatoes have greater pericarp walls or that there is no relationship between tomato origin and pericarp wall. Some students (although rare) may find that local tomatoes have thicker pericarp walls. In this case, consider the student’s rationale as to why the opposite happened. Part 2: Relating differences Answer the following questions by identifying key findings from the above reading. In some cases, you will need to compare your results from Part 1 and interpret this with key findings from the above reading. 1) Explain why tomatoes are an essential ingredient for a healthy diet. (A1.6) Tomatoes are: rich in Vitamin A (for good eyesight, sexual reproductive health and body growth), Vitamin C (disease prevention, stress control, heal cuts and wounds), potassium, phosphorus, iron, calcium, and lyocpene (shown to suppress cancer). 2) How have tomatoes changed over the last 50 years? (A1.6) Today’s fresh tomato contains 30.7% less vitamin A;16.9% less vitamin C; 61.5% less calcium (required to maintain strong bones and teeth); 11.1% less phosphorus; 9% less potassium; 7.97% less niacin; 10% less iron and 1% less thiamine than its 1963 counterpart. Fat (lipid) content in tomato has increased by 65 percent since 1963, and sodium has increased upward of 200 percent. 3) What are some commonalities between the scientists and processing tomato experts’ desired traits in an ideal tomato? (A1.6) - Firmness, in terms of thickness and hardness of the outer pericarp wall (which provides the ability to withstand pressure and between 25 000 and 50 000 pounds of weight when bouncing along in a truck during shipment, thus increasing yield (in pounds per acre)) 3 - Firmness, provides the ability to withstand rough handling during mechanical harvesting Resistance to disease Heat tolerance Firmness 4) In Pawlick’s chapter one, he claims there is a connection between the thickness of a tomato skin wall and the tomato being imported. Can you explain why imported tomatoes have thicker skin walls compared to local tomatoes? (A1.6) - - Identified in both scientist and processing experts, firmness, in terms of thickness and hardness of the outer pericarp wall is desired in tomatoes, especially imported, since they need to withstand 25 000 to 50 000 pounds of weight when bouncing along a truck during shipment, or withstanding rough handling during mechanical harvesting Thicker tomatoes are desired because they more likely will survive transportation and harvesting, whereas local tomatoes do not have to travel as far and so no need for thickness 5) Are your findings from Part 1 supported by Pawlick’s claim identified in question 4? If not, can you explain reasons why you didn’t observe this claim in your results from Part 1? (A1.6) - Findings from part 1 should support Pawlick’s claim that imported tomatoes have a thicker pericarp wall. If findings do not support this, assess student’s explanation. Several factors include: mixing of the tomato samples (on student’s part), local grown tomatoes are of the same genetic type, local grown tomatoes are not actually local grown but imported and masked as being locally grown (e.g. this is very typical of produce purchased from farmer markets early in the season), difference in timing of the tomatoes (e.g. very ripe in season local tomatoes vs. picked before ready/ripe imported tomatoes) 6) Having conducting this experiment, what explanation should you be able to provide to Michelle regarding the differences between the pericarp wall in both tomatoes? (A1.8) (A1.10) - - Locally grown tomatoes stay on the vine for much longer, allowing them to ripen naturally, which gives flavour. These tomatoes do not have thick pericarp walls as it is not in their genetic make up. Imported tomatoes are selected for their thick pericarp wall characteristic, which takes away from flavour since this is not what they’re bred for. Imported tomatoes are picked earlier (while still green and not yet ripe) and sprayed with ethylene gas, a naturally produced gas, to speed up ripening during transportation. Part 3: Interpreting Differences To answer the questions in this section, you will need to consider key findings from chapter one and think broadly (e.g. in relation to the environment, which includes humans). 4 1) Assuming that your data from Part 1 supported the claim that imported tomatoes have thicker pericarp walls, can you explain how humans have played a key role in the dominance of these selected tomato types in supermarkets. (B1) - Consumers demand/expect tomatoes to be fresh year round Supermarkets address/meet this need by imported from US/Mexico during winter months This has skewed the desire for certain tomatoes (that have more desirable traits) over other types of tomatoes and explains why only 5 of approximately 5000 tomato varieties are commonly found in supermarkets. 2) Chapter one mentions that southern US states and Mexico are primarily tomato producers year round, while southern Ontario only has a presence during summer months. US and Mexico’s dominance is related to its climate and large scale greenhouse production systems. How might these large scale greenhouses influence water use (and other environmental problems, if any) in some of these southern regions? (B1) - - - In some southern regions such as California, fresh water is a scarce resource that may not be efficiently used for large scale agricultural production Use of scarce freshwater resources in warm or desert like regions reduces water availability for humans and other ecosystems (e.g. aquatic ecosystems), creating water starved conditions. This is exacerbated during drought-like conditions. As a result, water may be piped in from other regions or over pumped from groundwater resources. A piped waterline is associated with huge environmental costs (e.g. land lost to development) and over extraction of groundwater aquifers may collapse the aquifer/land Water may also be trucked in but at the costs of transportation, oil/gas needed as well as carbon/ greenhouse gas emissions 3) Because of Ontario’s colder climate, we cannot grow our own tomatoes during winter months. Instead, we import our tomatoes from the US and Mexico. Can you explain some environmental problems that result from the constant transportation of tomatoes into food supermarkets in Canada? (B1) - - - use of scarce crude oil and long distance transportation creates carbon and greenhouse gas emissions which contributes to climate change large scale food production in southern regions may degrade soil quality from pesticide/chemical use to protect crops. Use of these chemicals may run off into water sources and pollute the water over breeding due to selection of more desirable tomatoes ideal for shipping, reduces the diversity (biodiversity) of our food availability, which can influence the amount of nutrients that we receive, influencing human health food packaging (non recyclable plastic food containers) that store the tomatoes create unnecessary waste 5 4) What is a carbon footprint and how does the everyday transportation of tomatoes from international areas affect our carbon footprint, in terms of annual carbon emission produced? Assume that the daily distance from California or Mexico to Ontario is 5000km and that the car fuel efficiency is 1km/L. Assume that local grown tomatoes travel a daily distance of 50km with the same car fuel efficiency rate previously described. Graph the differences in terms of annual carbon produced and discuss. (B2.1) (B3.4) - Carbon footprint is a measure of how much carbon or greenhouse gas emissions we produced as a result of our daily activities/lifestyle choices By choosing to purchase imported over local, we create a larger carbon footprint as a family/community/city/province etc. The more transportation, especially from international destinations, the larger the footprint, as shown below in the graph Annual carbon emissions produced (kgC/year) per year from imported and local tomatoes Carbon emission produced (kgC/year) 40150000 45000000 40000000 35000000 30000000 25000000 20000000 15000000 10000000 5000000 0 401500 Imported Tomates from California Local Tomato from Ontario Tomato Source Annual Carbon (kgC/year)… Additional Teacher Notes: - SVN 3E students may find Pawlick’s reading a bit difficult. If this is the case, the teacher can synthesis Pawlick’s reading into a PowerPoint presentation or a 1-2 page summary. References: Nemose. 2011. Solanum lycopersicum, tomato. Retrieved Jan 11, 2011 from: http://www.geochembio.com/biology/organisms/tomato/#fruit Pawlick, T. 2006. The End of Food. Greystone Books. Vancouver, BC, Canada. 265pp. USC Canada. 2011. The Story of Food. Retrieved Jan 11, 2011 from: http://usccanada.org/storyoffood/ For more information, please contact: Jason Tran, OAC Liaison Officer, University of Guelph tranv@uoguelph.ca 519-924-4120 ext. 56812 6