Unit 1: Living Systems

Transcription

1 Biology is the study of life Unit 1: Living Systems Bio = life Logy = study of The scientific study of all forms of life, or all types of organisms Science means to know Science is a body of knowledge about the natural world In class Activity = lets propose an explanation for why it rains without including any scientific thinking. Clouds are raining Invisible rivers are crying Rain god pours water on earth when angry Suppose someone doesn t believe your explanation, could you supply evidence to support your explanation? No why not can t gather evidence Several features of science Science deals only with the natural world Scientists collect and organize information in a careful orderly way looking for patterns and connections between events Scientists propose explanations that can be tested by examining evidence Some explanations can be pseudoscience = fall outside the realm of scientific explanation, ex is astrology Section 1: Life in Earth Systems EVIDENCE 1 Make a claim about what defines a living system. Humans have used technology since early times. Technology includes even simple things such as a fork or a pen. Technology is any tool, process, or system that is designed to solve a problem.

2 If we are to compare a robot to a human we can say that they have a control center to guide their actions. They are both systems that can perform many of the same tasks. EVIDENCE 2 Imagine a company that sells robots like the one shown in figure1 on page 4. The company makes the claim This living machine is the perfect companion. Make a case to either support or refute this claim. How similar are living and nonliving systems? Systems and System Models One approach to understanding natural phenomena is called systems thinking. This way of thinking looks for links and interactions between the parts of a system to understand how the overall system works. Properties of Systems System a set of interacting components that work together. 1. Boundaries and Components

3 Boundaries define the space of the system to separate that system from the rest of the universe. Components are all the parts of the system that interact to help the system carry out specific functions. Any boundary can be assigned to a system. The boundary that is used for a model does not necessarily have to correspond to a physical boundary. For example, the Earth. You could use the Earth s surface or Earth s atmosphere as its boundary. 2. Inputs and Outputs Outputs are generated when the inputs are processed in some ways. EVIDENCE 3: what is the boundary of the human body? What is the boundary of a robot? Compare the inputs and outputs of humans and robots in terms of matter and energy. 3. Open and Closed Systems Systems can be categorized according to the flow of inputs and outputs. In an open system, the inputs and outputs flow into and out of the system. In a closed system, the flow of one or more inputs and outputs is limited in some way. An isolated system, all of the inputs and outputs are contained within the system. EVIDENCE 4: Is the human body an open, closed, or isolated system? What about a robot? Explain your answers. 4. Controls These help keep the system working properly by monitoring and managing the inputs and outputs. Controls can be manual, automatic, or a combination Feedback is information from one step of a cycle that acts to change the behavior of a previous step of a cycle. Feedback is output that becomes input A feedback loop is formed when an output returns to become an input in the same system that generated the output. An example is a thermostat. You input a temperature into the thermostat. The temperature starts to decrease and the thermostat senses a changes so it switches on. The temperature will increase until the target temperature is reached. Once reached it shuts off. It stays off until it

4 detects a decrease. This is an example of a feedback loop because it is all within one system. An example of something that you think a feedback loop would be is a hummingbird taking the nectar from a flower. The nectar is the output of a flower and input for the hummingbird. The energy given to the bird from the nectar allows the bird to continue taking nectar. This however is NOT a feedback loop because it is between two systems. System Organization Systems can range in size and in complexity. The more complex the system the more levels of organization make it up. EVIDENCE 5: How do your interactions with nonliving systems affect your environment? System Models Model a pattern, plan, representation, or description designed to show the structure or workings of an object, system, or concept. Examples of models are computer simulations, conceptual diagrams such as flow charts, mathematical equations, physical models

5 Systems Biology Systems thinking applied to Biology allows scientists to consider biological phenomena at different scales and examine how the components of a biological system. Emergent property a property that a system has but that its components do not have Example is a cell. Cells are self-contained systems that can function independently. When cells are combined with other similar cells they form tissues and perform unique functions that the individual cell could not do. The Earth System The Earth System is all of the matter, energy and processes within Earth s boundary. Matter stays within the Earths system, but energy enters the system in the form of sunlight and exits in the form of heat. Within the system, light energy is converted into other forms of energy that drive transformations of matter from one form to another as it cycles through the system. EVIDENCE 6: Is Earth an open, closed, or isolated system? Organization of the Earth System The Earth System is divided into four interconnected systems, or spheres 1. Geosphere all the solid features of Earth s surface, such as mountains, continents, and the sea floor. It also contains everything below the Earth s surface 2. Hydrosphere all of Earth s water, including water in the form of liquid water, ice, and water vapor. 3. Biosphere the area of Earth where life exists. 4. Atmosphere all of the air that envelops Earth s solid and liquid surface.

6 EVIDENCE 7: The model shown in figure 9 on page 13 shows the biosphere in the middle of the diagram with arrows connecting it to the other spheres. Why is the biosphere depicted this way? Organization of the Biosphere All living things and all the places they are found on Earth make up the biosphere. Every part of the biosphere is connected with every other part.

7 Hierarchy of Life Across the biosphere, the variety of life is called biological diversity or biodiversity. It generally increases from poles to the equator which means greater biodiversity is found in warmer areas. This is because more living things can survive in warmer temperatures and less temperature changes during the year.

8 Factors in an ecosystem Biotic Factors - The living components in an ecosystem Animals and plants Abiotic Factors the nonliving components in and ecosystem Rocks and soil The biotic and abiotic factors in an ecosystem interact and are interdependent EVIDENCE 8: Using figure 11 on page 11 identify the biotic and abiotic factors. Made a model to illustrate how these factors interact in this ecosystem. Characteristics of Living Things Remember that an Organism = ANY individual living thing All living organisms must have all 7 of the above characteristics or they will not survive. 1. Cellular structure and function All living things are made up of one or more cells The cell is the smallest unit capable of life Our bodies have 100 trillion cells, a paramecium has one cell 2. Reproduction It is the a process by which organisms make more of their own kind from one generation to the next

9 The rate of reproduction changes based on organism; some bacteria reproduce every 15 minutes but the bristle cone pine tree reproduces after every 5000 years. Remember that just because an individual can t reproduce it doesn t mean a species won t survive. (species wouldn t survive if all organisms couldn t reproduce) 3. Metabolism The sum of all chemical reactions carried out by an organism 4. Homeostasis A constant stable internal condition despite the external environment. If an organism is unable to balance the internal and external conditions then it will die. 5. Heredity The passing of traits to their offspring through genes from parent to offspring. 6. Evolution A change in inherited characteristics of species over generations 7. Interdependence Organisms are dependent on one another and their environment. EVIDENCE 9: Describe at least two biological systems. Explain how these systems are independent and interconnected with each other. EVIDENCE 10: Record evidence for whether the robot at the beginning of this lesson meets the criteria for a living system. Which criteria does it meet, and which does it not? Does a robot have emergent properties? Explain your answer.