Enzymes can either help break a substrate molecule down to smaller ones or help substrate molecules join to form a larger one. They work as catalysts by reducing the activation energy of the reaction by providing an alternate pathway for it. The enzymes are specific with their substrates.
Plasmodium is a monocellular parasite causing malaria to humans. The parasite's life cycle always includes two hosts, an insect host and a vertebrate host. The parasite's cells are injected into the vertebrate's (human in our case) bloodstream by the insect host (mosquito). There are several stages in its life cycle but the sexual reproduction occurs only in the insect. In the insect, gametocytes (haploid gametes) merge and form a zygote which in turn becomes an oocyst. Oocysts divide multiple times and that way a great number of sporozoites is produced. These sporozoites travel to the salivary gland of the mosquito and are injected into the bloodstream of the second host, the human. In humans, sporozoites infect liver cells and red blood cells.
According to this information, the four statements about Plasmodium which are true are:
-Plasmodium cells are transferred to human cells through mosquito saliva.
-The complete life cycle of Plasmodium requires two hosts.
-Plasmodium cells infect two specific types of cells in humans.
- Inside an infected mosquito haploid gametes fuse, forming a haploid zygote that develops into an oocyst.
answer
Explanation:
The stages of fertilization can be divided into four processes: 1) sperm preparation, 2) sperm-egg recognition and binding, 3) sperm-egg fusion and 4) fusion of sperm and egg pronuclei and activation of the zygote.
