The pro B-cells develop in the fetal liver cells during embryogenesis and then later on mature in Bone Marrow. In infants and adults, both development and maturation takes place in bone marrow.

The naming of antibody classes is based on the heavy chain naming: IgA- alpha heavy chain, IgD- delta heavy chain and so on.

Leucine zippers are exclusively involved in protein-protein dimerization, while they ineract with DNA’s sugar and phosphate molecules in an induced way, rather than direct binding.

The IgA of external secretion like tears, colostrums, mucus, etc. consists of a dimer or tetramer with a J-chain and a polypeptide chain called secretory component.

The genes for MHC-I and MHC-II are located closely on chromosome-6 of humans, and these are transferred as a set to the next generation in order to maintain the MHC compatibility.

The myeloid progenitor hematopoietic stem cells are: monocytes, WBC, RBC, platelets and mast cells.

Progenitor cells develop as stem cells in the bone marrow and migrate to thymus for maturation into T-Lymphocytes. Option 1 is correct as migration to thymus is neccessary for T-cells to mature. An experiment is performed with professional human and chicken cell lines. The chicken cells are subjected to a mutant that will destroy the function of bursa of fabricius and human cell lines are genetically induced with the gene encoding for bursa of fabricius. Both the cell lines are kept in high hygiene conditions.

From cytosol of one cell to mitochondrial matrix of other cell, there will be total of 4 membranes and each membrane is double layered (inner and outer phospholipid bilayer). Therefore, total layers will be 4*2 = 8.

Active immunity is stimulated by exposure to pathogens but Ab and Ig mediated immune response is passive as it is not directly implemented by pathogens.

Lineweaver-Burk is a plot of “1/v v/s 1[S]”. Hanes-Woolf is the “[S]/v v/s [S]" and Lineweaver-Burk plot is “v v/s v/[S]”.

Monocytes migrate through the blood stream to various tissues where they undergo further differentiation into variety of histological forms. Kupffer cells in liver, osteoclasts in bones, splenic cells in white pulp of spleen and mesangial cells in kidneys.

BOF is present in birds near cloaca, and is the site of B-cell production and maturation. While in humans it is absent, its function is performed by bone marrow. Removal of BOF in birds will be fatal in case of infections while humans will not be affected. In due course of evolution, humans adapted to bone marrow instead of BOF, but both avian and human B cells are the same. Therefore, BOF in humans will also be a site of B-Cell development and thus, the human immune system will be enhanced. The answer 2 can also be considered to be correct, as the current research supports the 3 answer but books still believe in 2.