Cells that perform similar functions combine to form: a) organ systems b)organs c)organisms d)tissues

Which best explains why viruses do not have special structures or enzymes that allow them to make their own food? viruses can use energy in living cells that they infect. viruses can replicate inside a host that they infect. viruses can cause contagious illnesses in host cells. viruses integrate their rna or dna into infected cells.

The breakdown of food is accomplished by enzymes. a. physical b. chemical c. mechanical d. none of the above

What are antigens and antibodies? how are they involved in the body’s response to incompatible blood?