The secondary response involves mainly memory cells, this is the response that occurs on the second entrance of a microorganism or virus that has been encountered before and dealt with by the primary response.he primary immune system is also called innate immunity or auxiliary immunity because it is unspecific and present in everyone. These include physical and chemical barriers t â¦ hat protect the body from many different microscopic organisms. --Skin (and hair) acts as a large physical barrier.
The twin towers of the World Trade Center (WTC) collapsed on September 11, 2001, as a result of being struck by jet airliners hijacked by terrorists affiliated with al-Qaeda during the September 11 attacks.
The September 11th Attack. WTC 1, or the North Tower, was the first of the Twin Towers to be completed, the first to be hit by one of the trans-continentially fuelled flights on September 11th, and the last to be destroyed.