Reference no: EM133366564
In this project, you will design and conduct an investigation in order to provide evidence that a feedback mechanism helps a living organism maintain homeostasis.
Background
The internal and external environments of living organisms are constantly changing in many ways. To stay alive, a living thing must maintain homeostasis (internal stability). Feedback mechanisms help living systems maintain this stability. A feedback mechanism does this by sensing a change in a condition and causing a response. Thus, it keeps an organism's internal conditions within a tolerable range. A positive feedback mechanism is one that encourages the change that was detected. A negative feedback mechanism is one that discourages the change.
Both the stimulus for feedback and the response can be internal or external. For example, an increase in a person's heart rate while running is an internal response to an internal stimulus. The upward movement of tree sap in spring is an internal response to an external stimulus. A lizard running under a rock to cool off in hot weather and a leaf's stomata opening and closing as the humidity rises and falls are external responses to external stimuli.
Before You Begin
1. Access and carefully read the document Guidelines for Safely Using Live Animals in Investigations. It can be accessed here, via the link on the landing page of this activity, and in the Student Resources section of the course. Follow these guidelines as you design and conduct your investigation.
2. Select the type of animal or plant that you will investigate. The organism you select must have the following qualities:
It must be safe for you to handle (if necessary) and easy to care for.
It must display observable responses to external stimuli.
It must be observable without magnification or by using readily available tools (e.g., hand lens, light microscope, video magnifier, or binoculars).
It must be inexpensive, easy to obtain from a local source (such as your yard, a garden center, or a pet supply store), and easy to release or dispose of.
3. Research the appropriate methods for releasing or disposing of the organisms used in your investigation. You might need to do some research to discover examples of external stimuli and the responses that help organisms maintain homeostasis.
Part I: Design an Investigation
1. Write hypothesis that you will test with your investigation.
2. Design an experiment that can test your hypothesis. Describe your design, including the organism and materials you plan to use, the investigation's variables, and your step-by-step procedures.
3. Review your experimental design with your teacher. Verify the type of living organism you will study and materials you will need in order to conduct the experiment. Make sure the organisms and materials you need are readily available to you and that you have a plan to later dispose of the organisms and materials. You will also need a place to set up and conduct your experiment. Write a summary of the conversation you had with your teacher.
Part II: Conduct Your Investigation
After your design is approved, you will need to carefully describe and diagram your procedures and the types of data you plan to collect. Include the initial conditions, such as the source of your subjects, their activity level or location, and the temperature or amount of light or air present. Also include the final conditions of the subjects. Refine and repeat your experiment if your initial data do not provide evidence that your plants or animals responded to a stimulus. Determine whether a positive or negative feedback mechanism is involved. Submit a report to your teacher that includes the following:
Your final investigation design, including:
A list of materials you used during the investigation
A list of all the variables: independent variables, dependent variables, constants, and controls
A step-by-step procedure that includes at least three replications of each treatment
The data you collected, organized into tables and/or charts
The conclusions you were able to draw from your investigation