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 iconic twin towers of downtown Manhattanâs World Trade Center were a triumph of human imagination and will. Completed in 1973, the towers stood at 110 stories each, accommodating 50,000 workers and 200,000 daily visitors in 10 million square feet of space. They were the hub of the bustling Financial District, a top tourist attraction and a symbol of New York Cityâsâand Americaâsâsteadfast devotion to progress and the future.