When studying the immune system in class, Peta concluded that T-cells are more specific to the pathogen than inflammation is. What did Peta most likely learn that led to this conclusion? T-cells are made to identify antibodies, while inflammation starts a fever. T-cells are made to identify antigens, while inflammation starts to make antibodies. T-cells make antibodies that cause a fever, while inflammation identifies antigens on the pathogens. T-cells are made to identify antigens, while inflammation fights anything in the affected area.

B. Write the letter for the correct answer. \( \begin{array}{lll}\text { 1. A vertebra is part of the } \\ \begin{array}{lll}\text { (a) skull } & \text { (b) backbone } & \text { (c) rib cage }\end{array} \\ \begin{array}{lll}\text { 2. The ribs are attached to the }\end{array} \\ \begin{array}{lll}\text { (a) skull } & \text { (b) brain } & \text { (c) backbone }\end{array} \\ \begin{array}{lll}\text { 3. A group of bones that protects the brain is the } \\ \text { (a) skull } & \text { (b) backbone } & \text { (c) rib cage }\end{array} \\ \begin{array}{lll}\text { 4. The backbone is made up of many cords } & \text { (b) ribs } & \text { (c) vertebrae }\end{array}\end{array} \).

C. Answer the questions. 1. What part of your skeleton can bend without breaking? 2. What do blood vessels do in the bones? 3. Where do new red blood cells come from? 4. What is an unborn baby's skeleton made of? 5. What shapes and supports your arms and legs?

C. Answer the questions. 1. What is the important job of the rib cage? 2. What are the bones of the backbone called? 3. Name the important job of the skull. 4. What could happen if your spinal cord were injured? 5. What is the important job of the backbone?

A. Answer True or False. 1. The skull is shaped like a cage. 2. The backbone is made up of many vertebrae.

Answer True or False. 1. Cartilage is harder than bone. 2. You have the same amount of cartilage in your body all your life. 3. Bones can repair themselves. 4. Red blood cells are made in marrow. 5. Bones always stay the same size. 6. Some cartilage changes to bone.