Identify the component responsible for the humoral immune response.

Transplantation of tissues or organs often fails because the patient's body rejects them. Which type of immune response is responsible for this rejection?

In the structure of an antibody,the heavy chains and light chains are held together by which type of bond?

Memory cells are .........

$T$-lymphocytes differentiate in which of the following organs?

Primary lymphoid organs $- P$
Secondary lymphoid organs $- Q$
$I -$ Appendix, $II -$ Peyer's patches of small intestine,
$III -$ Thymus, $IV -$ Spleen, $V -$ Lymph node, $VI -$ Bone marrow, $VII -$ Tonsils
Select the correct option for $P$ and $Q$.
$\quad P \quad \quad Q$