Answer: The nervous system
Explanation:
The first part of the embryo to develop is the neural tube, which will become the spinal cord and brain. As the nervous system starts to develop, the tiny heart starts to pump blood, and other parts of the body—such as the digestive tract and backbone—begin to emerge.
Answer:
The immune system is made up of special organs, cells and chemicals that fight infection (microbes). The main parts of the immune system are: white blood cells, antibodies, the complement system, the lymphatic system, the spleen, the thymus, and the bone marrow.
Explanation:
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The respiratory system gives the blood oxygeb
