This property of water allows for the Water Strider to walk on water. Esta propiedad del agua permite que el Water Strider camine sobre el agua.

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?

The part of the skeleton that protects the spinal cord is the \( \begin{array}{lll}\text { (a) rib cage } & \text { (b) skull } & \text { (c) backbone } \\ \text { The } & \text { is the part of the skeleton that protects the heart. } \\ \begin{array}{lll}\text { (a) skull } & \text { (b) rib cage } & \text { (c) backbone }\end{array}\end{array} \)

D. Answer the questions. 1. What tissues hold bones together? 2. How do hinge joints work? 3. What kind of joint can move in a complete circle?

A. Write the letter for the correct answer. \( \begin{array}{lll}\text { 1. The muscular system has } & \\ \begin{array}{lll}\text { (a) two } & \text { (b) three } & \text { (c) ten }\end{array} \\ \text { 2. Muscles are made of muscles. } \\ \begin{array}{lll}\text { (a) cells } & \text { (b) tendons } & \text { (c) ligaments }\end{array}\end{array} \).

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?