| 1. | At what age (after fertilization) do blood vessels appear? A) 2 weeks B) 3 weeks C) 4 weeks D) 5 weeks E) None of the above |
| 2. | When does the heart begin to beat? A) 2 weeks B) 4 weeks C) 6 weeks D) 8 weeks E) None of the above |
| 3. | Name the 3 main sections of the brain 3 weeks after fertilization. A) membrane, frontbrain, cerebral cortex B) forebrain, midbrain, hindbrain C) ectoderm, endoderm, mesoderm D) spine, brainstem, medulla oblongata E) none of the above |
| 4. | Name the first body system to achieve a functional state. A) Nervous system B) Gastrointestinal system C) Cardiovascular system D) Respiratory system E) None of the above |
| 5. | At what age does the body plan emerge? A) 2-3 weeks B) 3-4 weeks C) 4-5 weeks D) 5-6 weeks E) None of the above |
| 6. | The heart begins to beat _______________ after fertilization. |
| 7. | At what age does the heart begin to beat? |
| 8. | At what age does the body plan emerge? |
| 9. | Which germ layer forms a significant portion of the pancreas? |
| 1. | B. 3 weeks |
| 2. | E. None of the above The heart begins to beat 3 weeks, 1 day (or 22 days) after fertilization. |
| 3. | B. forebrain, midbrain, hindbrain |
| 4. | C. Cardiovascular system The Cardiovascular system is the first body system to achieve a functional state as the heart begins to beat 3 weeks, 1 day after fertilization and blood cells and blood vessels begin forming at 3 weeks in the yolk sac and throughout the embryo. |
| 5. | B. 3-4 weeks The body plan emerges between 3 and 4 weeks through the rapid growth and folding of the embryo. These processes form the chest and abdominal body cavities. By 4 weeks, the head, chest, abdomen, and upper and lower limb buds are easily recognizable. |
| 6. | 3 weeks, 1 day |
| 7. | 3 weeks, 1 day (22 days) post-fertilization |
| 8. | Between 3 and 4 weeks, the body plan emerges as a direct result of the rapid growth and folding of the embryo. |
| 9. | ENDODERM forms a significant portion of the pancreas and other organs such as the liver and the lining of the gastrointestinal and respiratory tracts. The pancreas first appears during Carnegie Stage 13 (about 28 days postfertilization). |