How do organisms regulate complex systems through chemical interactions?
The heating system of a house works to keep the temperature constant. If the house gets too cold, then the heat automatically turns on to warm the house. The heat stops when the preset temperature is reached. This is an example of a feedback mechanism. Organisms use many feedback mechanisms to either maintain or amplify important chemical systems. This could happen at a molecular level to coordinate the function of a single enzyme or it could happen throughout the body to regulate the organism’s internal temperature.
Model 1 – Positive and Negative Feedback
Signal is sent.
Signal is sent.
Stimulus is decreased.
Stimulus is increased.
1. What two types of feedback mechanisms are illustrated in Model 1? 2. Define the words below as they are used in everyday language. Stimulus Signal Response 3. Identify at least three similarities in the two types of feedback mechanisms in Model 1.
4. Imagine that you have just gotten a puppy. In the course of playing with the puppy you throw a ball and the puppy chases after it. You then say “Good job!” and rub the puppy’s head to show him he did what you wanted him to do.
a. Is the puppy likely to chase the ball the next time you throw it? Justify your reasoning.
b. Identify the portions of the scenario as stimulus or response.
Puppy chases the ball.
“Good Job” and head rub.
c. Is this scenario an example of positive or negative feedback? Justify your reasoning using the words “stimulus” and “response.” 5. Later that day your puppy urinates on the couch. You then say “No, bad dog!” and place the puppy outside.
a. Is the puppy likely to urinate on the couch again? Justify your