Which of the following is incorrect about the function of the immune system?

• A. Phagocytes are large cells that can ingest pathogens and other infected cells.
• B. All T cells can attach to infected cells and kill them.
• C. B cells produce antibodies that can attach to antigens.
• D. After recovering from an infection, some B and T cells become memory cells.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the role of phagocytes in the immune system. Phagocytes are large cells that engulf and digest pathogens and infected cells, which is a correct statement about their function.
2. Step 2: Review the function of B cells. B cells produce antibodies that specifically bind to antigens on pathogens, helping to neutralize or mark them for destruction, which is also correct.
3. Step 3: Examine the role of memory cells. After an infection, some B and T cells become memory cells, which help the immune system respond faster if the same pathogen invades again. This is a true statement.
4. Step 4: Analyze the statement about T cells. Not all T cells can attach to infected cells and kill them. Only cytotoxic T cells have this ability, while other T cells have different roles such as helping other immune cells. Therefore, the statement 'All T cells can attach to infected cells and kill them' is incorrect.
5. Step 5: Conclude that the incorrect statement is the one about all T cells being able to kill infected cells, because T cells have diverse functions and only a subset are cytotoxic.