Goblet cells are glandular cells, or unicellular mucus-secreting glands, present in the epithelial lining of the mucous membranes of the respiratory tract and digestive system. The mucus produced by a goblet cell is secreted in the light of the tubule in question by exocytosis and diluted with water in order to coat the epithelium exposed to harmful actions present in the digestive or respiratory tubes. [1] It has an important function of keep moist and avoid desiccation of the epithelium, particularly in the airways.
It would be A. Vestigial Wing because of the vestigial genes that are carried by a fly, both have to be changed (a defect) to produce the bent wing shape.
The crossing over of homologous chromosomes occurs in meiosis. Meiosis is characterized by the lining up of homologous chromosomes close together to form a structure known as a tetrad.
