PROBLEM-BASED LEARNING IN THE SCIENCES. A Problem about Endangered Species and Animal Ecosystems. Shelagh A. Gallagher Dana L. Plowden.

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1 PROBLEM-BASED LEARNING IN THE SCIENCES Ferret It Out A Problem about Endangered Species and Animal Ecosystems Shelagh A. Gallagher Dana L. Plowden Problem Log Royal Fireworks Press Unionville, New York

2 Reflective Moment: Deeper Analysis Briefly respond to one of the questions below. Place an x by the question answered. Select one article and identify: (1) the main purpose, (2) three key facts, and (3) an inference or speculation made by the author(s). Then discuss: Is the author trying to be objective or persuasive? Is the article effective in making you think differently about some aspect of the problem? How? Compare information you gathered from a video and information you gathered from a print source. Describe the two sources, and then discuss: What is the value of each? What are the limitations of each? A quality response: (1) addresses the question, (2) stays on topic, (3) is plausible or reasonable, and (4) gives enough detail to make your ideas clear. Ferret It Out Problem Log 12

3 Ingredients for an Ecosystem Biomes: Seven Kinds of Ecosystems. The earth has thousands of different kinds of plants and animals, but unlike humans, plants and animals can t live anywhere they choose they need to have the proper environment in order to survive. That environment is called an ecosystem. There s another way to look at the regions of the earth that shelter different kinds of animals. A biome is a large geographic region with distinct land and climate features. It s hard to say how many biomes exist on earth, since scientists tend to categorize them in different ways. Some say there are only five biomes: aquatic, desert, forest, grassland, and tundra. Others create subdivisions within each of these major categories. For example, some separate the aquatic biome into freshwater, freshwater wetlands, marine, coral reef, and estuaries (freshwater rivers and streams). Each biome contains similar kinds of ecosystems, even though a single biome may be on several different continents. The grassland biome, home of the black-footed ferret, is on the map below; it s on five separate continents! Grassland Biomes of the World Source: 13 Ferret It Out Problem Log

4 Components of an Ecosystem. Have you ever made cookies from scratch? If you have, then you know that even though different kinds of cookies look and taste different, they all have a common set of ingredients: eggs, flour, sugar, etc. Different kinds of cookies are made by varying the ingredients the kind of sugar, the number of eggs, or by adding chocolate chips or oatmeal. There are lots of possible variations, but the basics always have to be there. Just try making cookies without sugar! Biomes work the same way. Each biome is different, with unique land features, different climates, and different plants and animals. But even though the specific animals and plants in each biome s ecosystem are different, biomes all have the same basic components, or ingredients. Each ingredient plays a unique, necessary role. Two Major Ecosystem Ingredients. The ingredients that make up an ecosystem are divided into two categories: abiotic, or non-living, and biotic, or living. Abiotic elements can be further divided into two more categories. Climatic elements have to do with the weather and atmosphere, including how much light and shade the land receives, the temperature cycle, the amount of wind, and the amount humidity in the air. Edaphic elements have to do with the land, including its level of acidity (ph) and whether it holds or drains water. Composition is another edaphic feature of soil whether the soil is made up of sand, like a desert or beach, or of dirt, like a wheat field or forest. Biotic features fall into three categories: autotrophs, heterotrophs, and saprotrophs. Autotrophs are producers; the word literally means self-feeder. They use organic elements of the land in combination with energy from the sun to grow. Rooted plants are the primary form of land-based autotrophs; algae are water-based autotrophs. Autotrophs are the foundation of the biotic elements of an ecosystem because they produce the first level of food and because they can exist independently of other biotic elements. Heterotrophs are consumers. Unlike autotrophs that draw on soil and sunlight for food, heterotrophs must eat another biotic element in order to survive. Some heterotrophs are herbivores, eating only plants. Other heterotrophs are carnivores, or animals that eat other animals. Carnivores are divided into two more categories. Primary carnivores are animals that eat herbivores. Secondary carnivores eat primary carnivores. Saprotrophs are the final category of biotic elements in an ecosystem. They are the decomposers of an ecosystem. Recyclers by nature, saprotrophs break down different organic elements of the ecosystem left by dead plants and animals. They break down dead matter by secreting a special kind of juice called an enzyme. The enzyme combines with the dead material and transforms it into compost. The saprotrophs can then absorb nutrients from the compost. Plants like fungi and mushrooms are examples of saprotrophs. Animals like earthworms, millipedes, burying beetles, and even fiddler crabs are saprotrophs, too. Each biome has an ecosystem with these same elements. However, the specific parts are not interchangeable; they are unique to each region. A fiddler crab would not be a useful saprotroph in the desert because it needs water to survive. Likewise, an earthworm would have a hard time living in the ocean. Ferret It Out Problem Log 14

5 My, What Big Words You Have. You now have the vocabulary to describe an ecosystem in two ways. You could say: An ecosystem is made up of land, climate, and animals. Land composition and climate provide the setting for plants to grow. Herbivores eat the plants, and carnivores eat other animals. Decomposers like worms and fungi break down dead matter so it becomes soil again. or you could say: An ecosystem has abiotic elements, including climatic and edaphic features. It also has biotic elements, comprised of autotrophs, heterotrophs, and saprotrophs. Abiotic elements support the growth of autotrophs, autotrophs provide food for heterotrophs, and heterotrophs provide food for saprotrophs. The job of the saprotrophs is to break down dead matter so the autotrophs can continue to grow. The two statements are pretty much the same, although the second will make you sound more like an animal biologist. It s more impressive, too! 15 Ferret It Out Problem Log

6 Prairie Ecosystem Template Directions: Complete the template with pictures or descriptions of each element of the prairie ecosystem. Include the black-footed ferret and the prairie dog, along with at least one predator and one food source. Label elements using scientific terminology. Ferret It Out Problem Log 16

7 The Prairie Ecosystem: A Grassland Biome Directions: In order to work effectively, the black-footed ferret s prairie ecosystem needs all of the necessary elements that create a grassland biome. Write the elements of the prairie ecosystem in the spaces provided below. Abiotic Elements Climatic: What is the weather like (temperature, rainfall, wind, etc.)? Edaphic: What are the qualities of the soil in the shortgrass prairie? Biotic Elements Autotrophs: What animals or plants are self-feeders? Heterotrophs: Herbivores: What prairie animals eat plants? Carnivores: Primary carnivores: What prairie animals eat herbivores? Secondary carnivores: What prairie animals eat other carnivores? Saprotrophs: What animals or plants are decomposers? 17 Ferret It Out Problem Log

8 Problem Definition: Problem Resolution Grid Directions: List the criteria for a good problem solution in the left-hand column. List your options across the top row (only use the number of rows necessary). Next, rate how well each solution option addresses the different criteria using a 3-point scale, in which 1 is Matches Very Well and 3 is Matches Very Poorly. Total the ratings for each solution option. Solution Options Solution Criteria Total Ferret It Out Problem Log 22

9 Reflective Moment: Defining the Problem Briefly respond to one of the questions below. Place an x by the question answered. What happens to a system when one element of the system changes? Does the same thing happen in other kinds of systems (friendship systems, government systems, communication systems)? How can this knowledge help you think about problems beyond the current problem of the black-footed ferret? How can a system continue to function when new input is introduced? How can a system function smoothly and efficiently again after this has happened? A quality response: (1) addresses the question, (2) stays on topic, (3) is plausible or reasonable, and (4) gives enough detail to make your ideas clear. 23 Ferret It Out Problem Log