16. In some genetically engineered corn plants the dominant gene (BT) produces a protein that is lethal to certain flying insect pests that eat the corn plants. It was also found that the pollen could cause death in some flying insects. If the corn plant is heterozygous for BT, what proportion of the pollen would carry the dominant gene

50% of the gametes carry the dominant allele.

Explanation:

Economically important Bt crops include potato, cotton, corn and tobacco. Genetically engineered modified Bt crops were originally produced by introgressing genes from Bacillus thuringiensis (Bt) that conferred resistance to diverse pests including rootworm, corn earworm, tobacco budworm and bollworm. These transgenic crops produce Bt-derived Cry toxins that have a toxic effect in insects when the plant is eaten.

An organism that is heterozygous for one particular dominant locus has two alleles: one dominant and one recessive. These heterozygous organisms will express the dominant phenotype. Maize is a hybrid (highly heterozygous) crop, it means that they are the result of crossing two breeding lines. In consequence, transgenic Bt-resistant maize lines are heterozygous for the genes that encode Cry toxins, and since it is a dominant allele, all plants will express the dominant phenotype.