Questions: These models show two of the body systems that you were introduced to in this unit. Identify, in your science notebook, the two systems, and list all of the ways they are related. Be sure to include both the things you can see and the things you cannot see. Use your list to answer the following questions: 1. Why would an organism with both of these body systems be considered living?

To answer the question, we need to identify the two body systems being referred to and then explain how they are related. Since the specific models are not provided in the text, I will assume two common body systems that are often studied together: the circulatory system and the respiratory system.

1. Circulatory System: This system includes the heart, blood, and blood vessels. It is responsible for transporting oxygen, nutrients, and other essential substances to cells and removing waste products.
2. Respiratory System: This system includes the lungs, trachea, and other structures involved in breathing. It is responsible for taking in oxygen and expelling carbon dioxide.

• Oxygen Transport: The respiratory system brings oxygen into the lungs, where it diffuses into the blood. The circulatory system then transports this oxygen to cells throughout the body.
• Carbon Dioxide Removal: Cells produce carbon dioxide as a waste product. The circulatory system transports this carbon dioxide back to the lungs, where it is expelled by the respiratory system.
• Energy Production: Oxygen transported by the circulatory system is used in cellular respiration to produce energy (ATP) in cells. This process also produces carbon dioxide, which is then removed by the respiratory system.
• Homeostasis: Both systems work together to maintain the body's pH balance and overall homeostasis. The removal of carbon dioxide helps regulate the pH of the blood.
• Interdependence: The efficiency of the circulatory system depends on the respiratory system's ability to oxygenate the blood, and vice versa.

1. Why would an organism with both of these body systems be considered living?

An organism with both the circulatory and respiratory systems would be considered living because these systems are essential for sustaining life. They work together to ensure that cells receive the oxygen they need for cellular respiration, which is crucial for energy production. Additionally, they remove waste products like carbon dioxide, helping to maintain homeostasis. Without these systems, the organism would not be able to perform vital functions such as energy production, waste removal, and maintaining internal balance, all of which are characteristics of living organisms.

The two body systems in question are the circulatory and respiratory systems. They are interrelated through their roles in oxygen transport, carbon dioxide removal, energy production, and maintaining homeostasis. An organism with these systems is considered living because they are essential for performing vital life functions.