Predict the effect of increased competition for abiotic and biotic resources on a food web. colored pencils graph paper ruler

Transcription

1 Edit File QUICK LAB Effect of Abiotic and Biotic Factors No organism exists in isolation. Organisms depend on and compete for the abiotic, or non-living, factors in its environment. For example, organisms in marine ecosystems are affected by the amount of light available in the water, the salinity of the water, and the amount of oxygen dissolved in the water. Organisms in freshwater ecosystems are affected by the same abiotic factors that affect those in marine ecosystems. A change in an abiotic factor in a marine or freshwater ecosystem can affect the organisms and the populations of organisms in the ecosystem. For example, a decrease in the oxygen level of the water will increase the competition between the organisms and populations that depend on oxygen. This will cause problems for the organisms that are less successful at obtaining the oxygen they need. It may cause the size of one or more of the populations to decrease. OBJECTIVE Predict the effect of increased competition for abiotic and biotic resources on a food web. MATERIALS colored pencils graph paper ruler An organism also depends on and competes for the biotic, or living, factors in its environment. If the population of a producer in a terrestrial ecosystem decreases, less food is available for the consumers in that ecosystem. As a result, the consumer population also decreases. If more than one population of consumers depends on the same producer population, one or more of the populations may eventually disappear from the ecosystem. For example, if the population of plants decreases, it may impact populations of animals and insects that eat those plants, and the consumers that eat them. In this lab activity, you will investigate the relationships between producers and consumers in a food web for a terrestrial ecosystem. You will then investigate how these organisms and populations depend on and compete for biotic and abiotic factors in the ecosystem. You will use a food web as a model to predict how changes in the ecosystem will affect the organisms and populations in the ecosystem. You will represent these relationships on bar graphs. ScienceFusion 519 Unit 9, Lesson 1

2 Quick Lab continued PROCEDURE Study and analyze the terrestrial food web shown below. Use the food web to investigate ways in which organisms and populations depend upon and compete for biotic factors in their ecosystems. Which organisms in this food web are producers? Which organisms are consumers that depend on producers for food, also known as primary consumers? Which organisms are consumers that depend on primary consumers for food, also known as secondary consumers? ScienceFusion 520 Unit 9, Lesson 1

3 Quick Lab continued The table below shows the number of selected individual consumers in 5000 square meters of the terrestrial ecosystem. Use these data to construct a bar graph in your lab journal or notebook that represents the consumers in this ecosystem. Number of Consumers in 5000 m 2 Consumer rabbit chipmunk grasshopper fox bird deer mouse owl hawk Number Suppose an abiotic factor in the ecosystem changes. It is a dry summer, with much lower rainfall than average. Predict which consumer will be most affected by the decrease in the amount of rain. Explain how these organisms and populations will be affected. Also describe how competition between individuals and populations will be affected by this change. Next, suppose a biotic factor in the ecosystem changes. Because of the drought, grass and other plants are not plentiful. A population of thirty-five locusts enter the ecosystem, and they eat the same food as the grasshoppers. Predict which organisms and populations will be most affected by the arrival of the locusts. Explain how these organisms and populations will need to compete for resources. Predict which organisms and populations will be least affected by the arrival of the locusts. Explain your prediction. ScienceFusion 521 Unit 9, Lesson 1

4 Quick Lab continued After investigating how the organisms in the food web might be affected by the locusts, make another bar graph similar to the one you made in Step 4. On your new graph, the height of the bars should reflect your prediction of the numbers of the organisms likely to be present one year after the arrival of the locusts. Write a brief description of your predictions. Predict how your new graph might change if the amount of rain increases significantly. Include the effects of competition in your predictions. Draw a new bar graph or modify your existing graph to show how this abiotic factor would affect organisms and populations in the ecosystem. ScienceFusion 522 Unit 9, Lesson 1

5 Edit File QUICK LAB The Effect of an Abiotic Factor on Yeast Yeast is a microscopic unicellular fungus found in many natural environments. Yeast is present in the human body and in the bodies of many other organisms. It is found in marine environments, especially near coastlines and in sediments. Freshwater yeasts are as plentiful and diverse as marine yeasts. In general, yeast is able to exist in many different environments because it can use food sources from those environments to create yeast biomass. Sometimes in a marine, freshwater, or terrestrial environment the food source comes from another living organism, and in that case the yeast acts as a parasite. All species of yeast have certain characteristics in common. To grow and reproduce, yeast must have a food source as well as a heat source that keeps the temperature appropriate for yeast growth. The dry yeast that you will be using in this lab is dormant, which means that it is living, but is not active or awake. Under the right conditions, this type of yeast will wake up and will start feeding. Once this happens, they begin to produce carbon dioxide as a waste product. You can tell this is taking place by observing bubbles or fizz. Yeast will also begin to reproduce under the right conditions, which leads to even more fizzing and bubbling as even more organisms release carbon dioxide. In this activity, you will use appropriate tools to investigate the effect of temperature, an abiotic factor, on the growth of a population of yeast. Other abiotic factors, such as oxygen and water, are also involved in instances where organisms must compete to survive. You will prepare four samples of a solution that contains live yeast and a source of food for the yeast. You will then heat two of them on a hot plate and cool one with ice, leaving the third at room temperature. After letting the samples rest for several minutes, you will then observe the samples under a microscope to see how much activity occurred in each sample. You will use your observations to draw conclusions about how an abiotic factor, temperature, affects the yeast. You will use safety precautions when collecting and analyzing information with the hot plate and microscope, and you will use goggles and gloves when handling samples. OBJECTIVE Determine how the abiotic factor of temperature affects a yeast population. MATERIALS For each group clock or timer droppers, medicine (4) sugar grease pencil or marker hot plates (2) ice cubes in a bowl beakers, small (5) stirring sticks (5) balance filter paper heat-resistant gloves thermometers (4) water, roomtemperature yeast, active dry, baking microscope microscope slide ScienceFusion 525 Unit 9, Lesson 1

6 Quick Lab continued PROCEDURE Label the side of one beaker Stock. Label the sides of the four other beakers Cold, Control, Warm, and Hot. Add 3.5 g of sugar, 200 ml of water, and 3.5 g of yeast to the Stock beaker. Stir the mixture with a stirrer until it is well mixed. Sugar, which the yeast use for food, is a biotic factor in their ecosystem. Why does your plan include adding sugar in this step of the procedure? Pour equal amounts of the Stock mixture into each of the other four beakers. Be sure to stir just before each pour, so that the same amount of yeast and sugar is added to each beaker. Place the Cold beaker in the bowl of ice to cool it to approximately 10 C. Place the Warm beaker on the hot plate (on warm) to adjust the temperature to approximately C. Place the Hot beaker on another hot plate and bring it to a boil. Use caution while using the hot plates. Measure the temperatures of the liquids regularly. Stir the contents of the beakers while they are cooling or heating. Use caution when heating the beakers with the hot plate. After each sample reaches its target temperature, let the beakers and their contents sit for 20 minutes. Explain why this step is necessary. ScienceFusion 526 Unit 9, Lesson 1

7 Quick Lab continued After 20 minutes, investigate each of the four samples and analyze them under a microscope. Sketch what you see in each beaker and describe what each sample looks like in the table below. Then write what you think happened in the last row of the table. Sample Control Sample Cold Sample Warm Sample Hot Sample Temperature of sample Sketch of sample Description of sample Explanation Which samples that you examined with the microscope had the most bubbles? Which had the least? Analyze what this tells you about how the yeast reacted to the temperature differences in the samples. ScienceFusion 527 Unit 9, Lesson 1

8 Quick Lab continued How were populations dependent on temperature, an abiotic factor? The bubbling of the samples is a good indication of whether the yeast is reproducing and its population is growing. Based on this information, think about this population of yeast living in the wild. What temperature ecosystem would this type of yeast grow most successfully in? Based on the yeast s response to heat, what do you predict would happen to a parasitic yeast organism living on a live host if the host died? Explain your answer. Suppose a freshwater pond contains a population of yeast. Predict what will happen to the yeast population if the pond freezes over. Explain your answer. Include a description of how the yeasts would be affected if there were one part of the pond where the temperature remained warm. ScienceFusion 528 Unit 9, Lesson 1

9 Edit File FIELD LONG LAB The Effect of Adaptations on Predator and Prey Populations The survival of a predator depends on how easily the predator can catch prey after finding it. Just as prey have adaptations (such as camouflage) that help them survive, predators have adaptations that help them capture and kill prey after finding it. For example, small fish are quick and can swim away from predators. However, a successful predator, such as a piranha in a freshwater ecosystem or a shark in a marine ecosystem, has sharp teeth that enable the predator to hold onto and kill the smaller fish. A marine or freshwater predator with a small mouth or no teeth would not have the adaptations needed to capture and kill these prey. Food is a biotic factor for which organisms within a population or among populations may be in competition. If two species of predators are in competition for the same prey, the population of the species that can more effectively capture and kill prey will increase, and the population of the other species will decrease because of lack of food. In this lab activity, you will investigate how organisms and populations depend upon, and compete for biotic factors in an ecosystem. You will model several different adaptations of predators and determine how effective each adaptation is in capturing prey. You also will model several adaptations of prey and determine how these adaptations affect their survival rate. Be sure to follow the safety guidelines for field investigations while taking part in the lab activity, and report any accidents or hazards to your teacher immediately. OBJECTIVE Determine how adaptive features of predators and prey affect the predator/prey relationship. MATERIALS clock or timer chopsticks (1 set) dried beans (3 or 4 different types and colors) paper or plastic cups (3) plastic fork (1) plastic spoon (1) colored pencils PROCEDURE ASK A QUESTION In this activity, you will work in groups of three to investigate how adaptations of predators and prey affect how easily a predator can find, capture, and kill prey. Each member of your group models a different predator. Each member chooses one of the objects chopsticks, plastic fork, or plastic spoon to model the way that particular predator captures and kills prey. Fill in the following table to show specifically what adaptation you think each of the items represents. Object chopsticks plastic fork spoon Adaptation ScienceFusion 535 Unit 9, Lesson 1

10 Field Long Lab continued Each type of dried bean models a type of prey that the predators try to catch. Use the following table to sketch each type and color of bean. Show each type of bean used for your class. Your pictures will probably be larger than the actual bean, but you should make each bean diagram the correct size relative to each other (make big beans big and small beans small). You may even want to include a scale next to your diagram to show how the the size of the drawings compare to the real thing. For example, your scale may show that 1 centimer in real life is equivalent to 3 centimeters in your drawings. You might not fill every column. Labeling each type of bean with a letter will help you later in the activity. Picture of bean A B C D Color of bean FORM A HYPOTHESIS Think about the adaptations of predators and prey. Form a hypothesis about which predator/prey (adaptation/bean) combination will be the most successful for the predator. Explain your reasoning. TEST THE HYPOTHESIS To investigate how organisms and populations in an ecosystem compete for prey (a biotic factor), go to the area outside marked off by your teacher. You will take with you your predator adaptation, the data tables for this activity, a pencil, and a cup. When the teacher signals the beginning of the one-minute hunting period, you will use your adaptation to capture any of the prey in the area and put it into your cup. The beans in the cup represent prey that have been caught and eaten. Demonstrate safe practices and follow the safety guidelines for field investigations. Report any accidents or hazards to your teacher immediately. ScienceFusion 536 Unit 9, Lesson 1

11 Field Long Lab continued When the teacher signals the end of the hunting period, gather with your group. Fill out the following table for your group, showing the number of each type of prey captured by each predator. After your table is complete, report the results of your investigation to your teacher. Hunting Period 1 Chopsticks Plastic fork Plastic spoon Bean A Bean B Bean C Bean D After hunting period 1, your teacher will add one more bean to the hunting area for each surviving bean to model reproduction of the prey. Then, complete three more hunting periods (just like the first), recording your results below and reporting them to your teacher. Hunting Period 2 Chopsticks Plastic fork Plastic spoon Bean A Bean B Bean C Bean D Hunting Period 3 Bean A Bean B Bean C Bean D Chopsticks Plastic fork Plastic spoon Hunting Period 4 Bean A Bean B Bean C Bean D Chopsticks Plastic fork Plastic spoon ScienceFusion 537 Unit 9, Lesson 1

12 Field Long Lab continued At the end of hunting period 4, return to your classroom, bringing with you all materials you used. If your teacher directs you to, collect all the remaining beans you can find in the hunting area. Return all the beans and other materials to your teacher. Complete the following table, which shows the total number of prey captured by each predator adaptation. For example, if the student with the chopsticks captured 3 of bean A during hunting period 1 and captured 2, 5, and 3 of bean A during hunting periods 2, 3, and 4 respectively, report a total of 13 in the Bean A column for the chopstick adaptation. Total Chopsticks Plastic fork Plastic spoon Bean A Bean B Bean C Bean D ANALYZE THE RESULTS Evaluating Hypotheses Compare your group s results with your hypothesis. Do your results support your hypothesis? Explain your answer. DRAW CONCLUSIONS Explaining Conclusions Examine your group s results. Which predator/prey combination was most successful for the predator? Draw conclusions to explain these results. In your conclusions, include the effects of both predator and prey adaptations. ScienceFusion 538 Unit 9, Lesson 1

13 Field Long Lab continued Applying Concepts In this investigation you explored how adaptations affected competition between organisms and populations for a biotic factor (food) in their ecosystem. Identify an adaptation and explain how it could affect how organisms and populations compete for an abiotic factor, such as water or sunlight. Developing Methods How would you investigate the interaction you identified above? TO THE ESSENTIAL QUESTION Applying Conclusions Predators and prey are connected parts of an ecosystem. Describe how biotic factors influence the relationship between predators and prey. ScienceFusion 539 Unit 9, Lesson 1

14 FIELD LONG LAB The Effect of Adaptations on Predator and Prey Populations If two species of predators are in competition for the same prey, the population of the species that can more effectively capture and kill prey will increase, and the population of the other species will decrease because of lack of food. The survival of a predator depends on adaptations that the predator has that enable it to catch and kill prey after finding it. The success rate of prey depends on adaptations that the prey have that help them avoid capture by predators. For example, small fish are quick and can swim away from predators. However, a successful predator, such as a piranha in a freshwater ecosystem or a shark in a marine ecosystem, has sharp teeth that enable the predator to hold onto and kill the smaller fish. A marine or freshwater predator with a small mouth or no teeth would not have the adaptations needed to capture and kill these prey. In this lab activity, you will describe the relationships between predators and prey that occur in food webs. You will also investigate how organisms and populations depend upon and compete for biotic factors in an ecosystem. You will model a predator/prey relationship. You will play the role of a predator and will choose a predator adaptation that you think will help you capture prey. By hunting, you will determine how effective your adaptation is in capturing prey. You will also use models of several adaptations of prey and determine how these adaptations affect their survival. Be sure to demonstrate safe practices and follow the safety guidelines for field investigations while taking part in the lab activity. Report any accidents or hazards to your teacher immediately. OBJECTIVE Determine how adaptive features of predators and prey affect the predator/prey relationship. MATERIALS clock or timer dried beans (3 or 4 different types and colors) objects that represent adaptations that predators might use to catch prey (3) paper or plastic cups (3) colored pencils PROCEDURE ASK A QUESTION In this activity, you will work in groups of three to investigate how adaptations of predators and prey affect how easily a predator can find, capture, and kill prey. Object Each member of your group models a different predator. Each member chooses an object to model the way that particular predator captures and kills prey. Fill in the following table to show what object was chosen by each group member and what specific adaptation you think each object represents. Adaptation ScienceFusion 540 Unit 9, Lesson 1

15 Field Long Lab continued Each type of dried bean models a type of prey that the predators try to catch. Use the following table to sketch each type and color of bean. Show each type of bean used for your class. Your pictures will probably be larger than the actual bean, but you should make each bean diagram the correct size relative to each other (make big beans big and small beans small). You may even want to include a scale next to your diagram to show how the size of the drawings compare to the real thing. For example, your scale may show that 1 centimeter in real life is equivalent to 3 centimeters in your drawings. You might not fill every column. Labeling each type of bean with a letter will help you later in the activity. Picture of bean A B C D Color of bean FORM A HYPOTHESIS Think about the adaptations of the predators and the prey. Form a hypothesis about which predator/prey (adaptation/bean) combination will be the most successful for the predator. Explain your reasoning. TEST THE HYPOTHESIS To carry out the investigation, you will have four one-minute hunting periods during which you will use your adaptation to capture any of the prey in the area and put it into your cup. The beans in the cup represent prey that have been caught and eaten. Make a table you can use to show each predator adaptation in your group and how many of each type of prey is captured. You will need five copies of this table: one for each hunting period, and one for the total of the hunting periods. Go to the area outside marked off by your teacher. You will take with you your predator adaptation, your data tables, a pencil, and a cup. When the teacher signals the beginning of the one-minute hunting period, you will use your adaptation to capture any of the prey in the area and put it into your cup. The beans in the cup represent prey that have been caught and eaten. Demonstrate safe practices and follow the safety guidelines for field investigations. Report any accidents or hazards to your teacher immediately. ScienceFusion 541 Unit 9, Lesson 1

16 Field Long Lab continued When the teacher signals the end of the hunting period, gather with your group. Fill out the table you made for hunting period 1 for your group. After your table is complete, report the results of your investigation to your teacher. After hunting period 1, your teacher will add one more bean for each surviving bean to model reproduction of the surviving prey. Then, complete the other three hunting periods (just like the first one), recording your results in your tables and reporting them to your teacher. At the end of hunting period 4, return to your classroom, bringing with you all materials you used. If your teacher directs you to, collect all the remaining beans you can find in the hunting area. Return all the beans and other materials to your teacher. Complete the table for the total number of prey captured by each predator adaptation. For example, if the student with the chopsticks captured 3 of bean A during hunting period 1 and captured 2, 5, and 3 of bean A during hunting periods 2, 3, and 4 respectively, report a total of 13 in the Bean A column for the chopstick adaptation. ANALYZE THE RESULTS Evaluating Hypotheses Compare your group s results with your hypothesis. Do your results support your hypothesis? Explain your answer. DRAW CONCLUSIONS Explaining Conclusions Examine your group s results. Which predator/prey combination was most successful for the predator? Draw conclusions to explain these results. In your conclusions, include the effects of both predator and prey adaptations. ScienceFusion 542 Unit 9, Lesson 1

17 Field Long Lab continued Applying Concepts In this investigation you explored how adaptations affected competition between organisms and populations for an biotic factor (food) in their ecosystem. Identify an adaptation and explain how it could affect how organisms and populations compete for an abiotic factor, such as water or sunlight. Developing Methods How would you investigate the interaction you identified above? TO THE ESSENTIAL QUESTION Applying Conclusions Predators and prey are connected parts of an ecosystem. Describe how biotic factors influence the relationship between predators and prey. ScienceFusion 543 Unit 9, Lesson 1