Q1. Activation of T cells requires that antigens be presented from antigen-presenting cells, not simply by exposure to the antigen in solution. What biological rationale may underlie this requirement – consider both from the perspective of how this can aid in generation of a cytotoxic T cell response, and how […]

Q1. In a continuous culture of a bacterium running at D=0.345 hr-1 glucose is the limiting substrate with a residual concentration of 0.01 g/l. The yield coefficient based on glucose is 0.5 g cell/g glucose. What will occur if the feed glucose is increased by 0.5 g/l while the dilution […]

Industrial melanism refers to the dark pigmentation that evolved in some insects giving them protective coloration on vegetation darkened by soot in heavily industrialized areas prior to air pollution regulation.  In one heavily polluted area near Birmingham, England in 1956, 87% of the moths of the species Biston betularia were black […]

Q1. In animal cells and in the meristem cells of land plants the nuclear envelope disintegrates during mitosis. This disintegration does not occur in the cells of most protests and fungi. According to our current knowledge of plant evolution, which group of organisms should feature mitosis most similar to that […]