Is cell mediated or humoral immunity essential to control a mycobacterium infection ?

Cell mediated

Explanation:

The immune system protects the body against intracellular microbes using cell-mediated immunity(CMI). CMI refers to immune responses that are controlled by T-cells. Intracellular microbes enter into macrophages through phagocytosis.

this is true, assuming that the allele is completely recessive and incomplete dominance is not a factor.

answer: decrease

a limiting factor is the one which decrease the abundance, distribution and causes extinction of the population of species in a ecosystem. here, predators including hawks, owls and snakes are the limiting factor for the population of mexican free tailed bat.   although bats are nocturnal animals as they forge for food at night these predators also may remain active during night which can decrease the population of the mexican free-tailed bats. also, these bats eat only one type of insects that are moths. the food can also be a limiting factor as all 400 members are dependent upon same type of food needs that are moths. the decrease in the moth population can cause decrease in population size of the mexican free-tailed bats.

therefore, the scenarios will most likely to decrease the population size of the mexican free-tailed bats.