Mendelian inheritance of a single-locus transgene insert in self-pollinated crops:

• The primary transformant ($T_0$) is hemizygous ($T/-$). Upon selfing, the $T_1$ generation segregates in a $1:2:1$ ratio: $1\,TT$ (homozygous with transgene) : $2\,T/-$ (hemizygous with transgene) : $1\,-/-$ (null segregant, lacking transgene).
• Among the $T_1$ plants expressing/carrying the transgene, the ratio of genotypes is $1\,TT : 2\,T/-$ (i.e. 1 out of 3 is homozygous $TT$, and 2 out of 3 are hemizygous $T/-$).
• Upon selfing these 3 positive plants:
• The 1 homozygous ($TT$) plant breeds true, producing $100\%$ progeny with the gene.
• The 2 hemizygous ($T/-$) plants segregate in the $T_2$ generation ($3:1$).

Endotoxins produced by Bacillus thuringiensis (Bt):

• During sporulation, Bacillus thuringiensis forms parasporal crystalline protein inclusions known as $\delta$-endotoxins (delta-endotoxins, encoded by cry and cyt genes).
• Upon ingestion by susceptible insect larvae, the alkaline pH of the midgut dissolves the protoxin crystals, and insect midgut proteases cleave them into toxic active peptides that bind to cadherin/aminopeptidase N receptors, forming pores and causing cell lysis.

Differentiation and effector function of B lymphocytes:

• Upon antigen encounter and T-helper cell activation, naive mature B cells proliferate and differentiate into two distinct cell populations: memory B cells and plasma cells.
• Plasma cells (effector B cells) develop extensive rough endoplasmic reticulum and specialized Golgi apparatus to secrete thousands of antigen-specific immunoglobulin (antibody) molecules per second into circulation.
• Memory cells persist long-term for secondary immune responses, but do not actively secrete mass antibodies.