The amount of exercise done by the typical teenager tends to decline between ninth and twelfth grade

Jesse served in the Gulf War in the field hospital

He seemed to cope well until, during the tenth anniversary of his deployment, he had a minor car accident in which he sustained a head injury. Soon after, he began re-experiencing the horrible sights, sounds and smells from the hospital and having nightmares in which he was back trying to save critically injured patients. Which of the following is correct? a) This is not PTSD because it happened 10 years after the catastrophic events. b) Only if the event directly threatened him could Jesse be diagnosed with PTSD. c) Jesse meets the criteria for PTSD, which can occur years later and for which the risk is increased when the brain is made more vulnerable. d) Because of the head injury, the cause is not PTSD but brain damage.

The skin, sense organs, and the brain develop from which of the following layers of cells present in the embryo?

a. ectoderm b. mesoderm c. endoderm d. zygoderm