The correct order of stages in life cycle of plasmodium is

Options

A. Gametocytes - gametes - ookinete oocyst - sporozoite
B. gametocytes - gametes - ookinete oocyst - merozoite
C. gametocytes - gametes - oocyst ookinete - sporozoite.
D. gametocytes - gametes - oocyst - sporozoite - ookinete

Answer

To determine the correct order of stages in the life cycle of Plasmodium, we will follow the sequence of events as the parasite transitions between its hosts, which are humans and female Anopheles mosquitoes.

### Step-by-Step Solution:

1. **Gametocyte Formation in Humans**: The life cycle of Plasmodium begins in humans, where the parasite exists in the form of gametocytes. These gametocytes are found in the red blood cells (RBCs) of infected individuals.

**Hint**: Remember that gametocytes are the sexual stage of Plasmodium and are crucial for the next steps.

2. **Mosquito Feeding**: When a female Anopheles mosquito bites an infected human, it ingests blood that contains these gametocytes.

**Hint**: This step highlights the role of the mosquito as a vector for the transmission of Plasmodium.

3. **Gamete Formation in Mosquito**: Inside the mosquito's gut, the gametocytes develop into gametes. This process is essential for sexual reproduction.

**Hint**: Focus on the transformation from gametocyte to gamete, which is a key part of Plasmodium's life cycle.

4. **Fertilization**: The male and female gametes fuse to form a zygote within the mosquito's intestine. This fertilization is a critical step in the life cycle.

**Hint**: Remember that fertilization leads to the formation of the next stages in the life cycle.

5. **Oocyst Development**: The zygote develops into an oocyst, which is a protective structure that allows the parasite to mature.

**Hint**: Oocysts are important for the survival of the parasite in the mosquito.

6. **Sporozoite Formation**: Inside the oocyst, the parasite undergoes division and eventually produces sporozoites, which are the infective form of Plasmodium.

**Hint**: Sporozoites are crucial because they are the stage that will infect the next human host.

7. **Migration to Salivary Glands**: The mature sporozoites migrate to the salivary glands of the mosquito, ready to be transmitted to a new human host during a subsequent bite.

**Hint**: This step is essential for the continuation of the life cycle, as it allows the sporozoites to enter a new host.

8. **Infection of New Human Host**: When the mosquito bites another human, the sporozoites are injected into the bloodstream, initiating a new cycle of infection.

**Hint**: This marks the beginning of the cycle again, as the sporozoites will eventually develop into gametocytes in the new host.

### Conclusion:
The correct order of stages in the life cycle of Plasmodium is:
1. Gametocyte (in human)
2. Mosquito feeding (ingests gametocytes)
3. Gamete formation (in mosquito)
4. Fertilization (in mosquito)
5. Oocyst development (in mosquito)
6. Sporozoite formation (in mosquito)
7. Migration to salivary glands (in mosquito)
8. Infection of new human host (by sporozoites)

Thus, the correct answer is option A, which follows this sequence accurately.