Plasmodium undergoes its life cycle in two different hosts. The asexual phase occurs in the _______ host, while the sexual phase occurs in the _______ host. 

A human and female Anopheles mosquito 

 Plasmodium, the parasite that causes malaria, completes its life cycle in two hosts. The asexual phase of the life cycle occurs in the human host, while the sexual phase occurs in the female Anopheles mosquito.

The malarial cycle, also known as the malaria life cycle, refers to the series of events that occur during the transmission and development of the malaria parasite within humans and mosquitoes. There are several stages in the malarial cycle, involving different forms of the parasite and different hosts. Here is an overview of the malarial cycle:

1. Transmission to humans: The cycle begins when an infected female Anopheles mosquito bites a human and injects sporozoites, which are the infective form of the malaria parasite, into the person's bloodstream.
2. Liver stage: The sporozoites travel to the liver, where they invade liver cells and develop into a different form of the parasite called merozoites. During this stage, the infected person does not experience any symptoms.
3. Blood stage: The merozoites are released from the liver cells and invade red blood cells (RBCs). Inside the RBCs, the merozoites multiply rapidly and eventually rupture the RBCs, releasing more merozoites into the bloodstream. This causes the characteristic symptoms of malaria, including fever, chills, and flu-like symptoms.
4. Gametocyte formation: Some of the merozoites differentiate into sexual forms of the parasite called male and female gametocytes. These gametocytes can be taken up by another mosquito during a blood meal.
5. Transmission to mosquitoes: When a mosquito feeds on an infected human, it ingests the gametocytes along with the blood. Inside the mosquito's gut, the male and female gametocytes undergo sexual reproduction, forming a zygote.
6. Mosquito stage: The zygote develops into a motile form called ookinete, which penetrates the mosquito's gut wall and forms an oocyst. Inside the oocyst, the parasites multiply and develop into sporozoites.
7. Salivary gland stage: The mature sporozoites migrate from the oocyst to the mosquito's salivary glands. When the infected mosquito bites another human, it injects these sporozoites into the person's bloodstream, starting the cycle anew.

The malarial cycle continues as long as there are infected mosquitoes and susceptible humans in an area. Effective control measures aim to interrupt this cycle by targeting either the mosquitoes or the parasites at different stages of their development, thereby reducing transmission and the burden of malaria.