ECOSYSTEMS Part 2 Joseph Priestly Joseph Priestly was an English clergyman and scientist. He noticed that if he put a burning candle in a jar, the candle went out after a few minutes and when he put a mouse in the jar, the mouse died. When Priestly added a green plant to the jar the candle did not go out as quickly and the mouse survived. 1
Producers If we wanted to pick the single most influential abiotic element that influences life on Earth it should probably be the Sun. Producers The Sun provides us with energy in the form of light and heat, both of which are important for most if not all forms of life either directly or indirectly. Plants need light to make food and in the Spring, it is the rising of temperatures that signals and triggers growth. 2
Producers The one thing that makes plants so amazingly important in all our lives is the fact that they can produce their own food from light, water and the gas carbon dioxide (CO 2 ). This is why we call them producers. Photosynthesis Water + carbon dioxide + light energy Sugar (glucose) + oxygen 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 You can see how mathematically, it balances the scale. 3
Cellular Respiration The process by which cells release the energy stored in sugars (obtained from food) is called cellular respiration. Sugar + oxygen carbon dioxide + water + energy 4
Bean Seeds and Germination Complete the Bean Seeds and Cellular Respiration worksheet. Remember that a hypothesis is a statement of what you expect to occur Remember that a test is how you determine the accuracy of the hypothesis Remember that a result is what actually occurs Producers In the end, almost all types of organisms on our planet (there are exceptions) either depend directly on the Sun, which means they are plants, or they eat plants or they eat things that have eaten plants or they eat things that have eaten plants, or well, you get the picture. 5
Food Chain This is a logical, singular way to examine the sources of food: Wheat mouse snake hawk Producer primary consumer secondary consumer tertiary consumer Ecological Pyramids All pyramids need a large base for ecological pyramids this is where we place the producers. Ex: grass, wheat, leaves, reeds The next level is smaller this is where we place primary consumers (also called an herbivore) Ex: mouse, cow, deer 6
Ecological Pyramids The third level on a pyramid is again smaller this is where the secondary consumers are placed (would include carnivores or omnivores) Ex: raccoon, human, lion, shark The next level is smallest this is where we place tertiary consumers (includes carnivores and omnivores that consume creatures that have already consumed another non-plant life). Ex: human, snake, owl, shark Ecological Pyramids An ecological pyramid is a graphic representation of the relationships among the different components of a food chain. It can illustrate The number of organisms at each level (pyramid of numbers) The amount of biomass (pyramid of biomass) at each level The energy lost at each level (pyramid of energy) Only a small percentage (approximately 10%) of the food energy is available to the next level of a food chain. 7
Ecological Pyramids 1 hawk (tertiary consumer) 3 snakes (secondary consumer) 20 mice (primary consumer) 200 grains of wheat (producer) What to Eat? Four hectares of corn will support 1000 people for one day. If those same hectares of corn were fed to cattle and then the cattle were eaten by people, there would only be enough beef to feed 50 people for one day. What are the implications of this knowledge to North America? What are the implications to countries where food is in short supply? 8
Transfer of Energy in an Ecosystem Using the diagram: 1. What would happen to the food chain if only 100 grains of wheat were available instead of 200? 2. What might cause a reduction in the amount of wheat available? 3. What other natural or human-caused events could take place, and what effect would they have on the ecological pyramid? 1 hawk (tertiary consumer) 3 snakes (secondary consumer) 20 mice (primary consumer) 200 grains of wheat (producer) Transfer of Energy in an Ecosystem Using the diagram: 1. What other food sources exist for mice, snakes, and hawks? 2. Why might it be useful to have more than one food source? 3. What statement can you make regarding the transfer of energy within an ecosystem and the implications of the loss of producers and consumers to this transfer? 1 hawk (tertiary consumer) 3 snakes (secondary consumer) 20 mice (primary consumer) 200 grains of wheat (producer) 9
10
Deadly Links Game Bioaccumulation or Biological Amplification The process that results in increasing concentrations of a harmful chemical at each higher level of a food chain. Discuss the pros and cons of using toxic chemicals, identifying perspectives from the various groups involved. 11
Mercury Bioaccumulation Mercury is a poisonous substance that can affect the functioning of body systems. Mercury levels in water have fluctuated in the past years. In the 1970s, there were high levels of mercury found in some areas due to discharges from pulp and paper mills. Laws have since been implemented to monitor and regulate the amount of mercury that can enter water systems. In addition, quotas have been imposed by the government on the number and type of fish that can be caught. These quotas are placed on large predatory fish only, and do not apply to small fish. Why do you think this is? 12
Scavengers and Decomposers Using the laptops, help create a class list of scavengers and decomposers. Investigate the purpose of scavengers and decomposers in an ecosystem. 13
Interactions within an Ecosystem We have discussed how producers are consumed by other organisms this creates what we call a parasitic relationship. This is when one organism benefits (the parasite ), while the other organism suffers (the host ). Interactions within an Ecosystem A second type of interaction is called mutualism. This is a type of interaction in which both organisms are benefiting. For example: A honeybee with a flower. The Honeybee gets food from the flower (nectar) while the flower gets the bee to distribute it s pollen. 14
Interactions within an Ecosystem The third interaction type is called commensalism. This is when one organism gains while the other organism is neither helped nor harmed. An example of this would be army ants and birds. The army ants go around attacking other insects. The insects capable of flight will fly away. As they leave, the birds swoop in and eat them. Symbiotic Relationship Some mutually beneficial interactions go so deep and are so prolonged that both species depend on one another in such a was that they are called symbiotic meaning living together 15
The clownfish feeds on small invertebrates that otherwise have potential to harm the sea anemone, and the fecal matter from the clownfish provides nutrients to the sea anemone. The clownfish is additionally protected from predators by the anemone s stinging cells, to which is it immune. Populations and Communities As we consider interactions in the environment, we are not only looking at the way that individual living things interact with one another but we will also consider entire populations and communities. 16
Populations Populations are collections of individuals that belong to the same species that live in the same area. An example would be all the geese of the same species in a pond. Species A species is the collection of all individuals that are so closely related genetically that they can produce fertile offspring. 17
Some organisms are able to reproduce, but their offspring are sterile, which means that the offspring cannot reproduce. Community A community is made up of populations of different species that live in the same ecosystem. The interactions between these populations and the local abiotic elements make up the ecosystem. 18
Community Consider a pond, for example. In that pond are a variety of insects and amphibians. Many of the different species of amphibians may compete for the same insects as a food source and may be subject to predation by snakes, raccoon and birds. All of these species use the pond as a source of water and many use it as their habitat. Microscope Carry microscopes by the arm and base Clean the ocular lens and objective with lens paper only 19
Microscope Place the slide on the stage and lower the objective carefully Look from the side when focusing while looking through the ocular lens and raising the objective lens Microscope Lower the stage before changing from a lower objective lens to a higher objective lens Watch from the side of the microscope to ensure that the objective does not hit the stage 20
Microscope Use the diagram to help identify the various parts of the microscope When using a microscope, always ensure that the magnification is on the lowest to start Micro-organisms Working in groups, we will be baking bread. Half the groups will be using the recipe as written Half the groups will be using the recipe without yeast Examine yeast under a microscope 21
Micro-organisms Mould is a micro-organism also. Help devise a set of experiments to determine what bread mould needs to grow and reproduce. Remember to test only one variable at a time. The Roles of micro-organisms Help to fill-in a t-chart comparing the Beneficial Roles and the Harmful Roles Select one item from the chart to research Use the research findings to prepare an information poster, to be posted on the class bulletin board 22
Food Preservation Techniques Refer to cookbooks, family and/or friends to identify past and present methods tof preserving foods. List the different food preservation techniques and indicate which of a micro-organism s basic needs is affected by each preservation technique. Record information in a chart and share it with the class. The Barbeque What s the cause? List all the food practices contained within the barbeque scenario and indicate whether they were safe. Use this information to identify and explain a possible cause for the illnesses, including an explanation of why Harry was extremely ill while Alice did not succumb to the illness her friends did. 23