Cervical pregnancies are extremely rare. Women undergoing cervical pregnancies often experience unusual vaginal bleeding. In extreme cases, they may require a hysterectomy (removal of the uterus). Why do you think the symptoms and risk occurs with this type of ectopic pregnancy?

Ectopic pregnancy can cause the burst of fallopian tube. If previous ectopic pregnancy occured then again onset of this type of pregnancy may lead to life threatening bleeding. Having the abdominal surgery before may also proved as a risk.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.