A host cell infected by a virus will activate the adaptive immune response through . (Select all that apply) Dendritic cell Macrophages MHC I molecules Cytotoxic T cell MHC II molecules Helper T cell

Cytotoxic T cell

Helper T cell

Explanation:

Adaptive immune system is a part of the immune system initiated only when there is an attack by a pathogen or foreign substance. The adaptive immune system is beckoned on when the infection is insurmountable for the body's first line of immunity, which is the innate immune system.

The adaptive immune response is triggered by the white blood cells called LYMPHOCYTES. Lymphocytes consists of T cells and B cells. T cells are either cytotoxic or helper T cells. The cytotoxic T cells kills the cells infected with the virus while the Helper T cells activate every other cell involved in the immune process.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.