Question

Activity of phagocytosis occurs through?
A. Neutrophils and monocytes
B. Basophils and monocytes
C. Eosinophils and monocytes
D. Lymphocytes and neutrophils

Answer 1

Hint: Phagocytosis is a process by which a cell swallows-up by using its plasma membrane and it is promoted by phagocytes and the process has four basic steps. It is of two types- endocytosis and exocytosis.

Complete answer:
The process of phagocytosis is consists of four steps:
-The first step involves chemotaxis. In this step, the cells of the organism travel towards the area with a high concentration of molecules that need to be ingested. The movement of these cells is stimulated and regulated by those molecules only.
-The next step is binding. The surface receptors of the organism bind to those molecules' surfaces. It is a crucial step for ingestion and so for phagocytosis. There are different types of receptors present on the surface of organisms. They bind to different molecules which need to be ingested.
-Some of them include:
Scavenger receptors- These receptors bind to various molecules present on the surface of bacteria.
Opsonin receptors- Opsonin receptors are receptors which bind to molecules that have immunoglobulin G present on their surface.
Antibodies- These cells have the ability to produce antibodies that permit them to attach to some antigens.
Toll-like receptors- These receptors bind to certain specific molecules present on the surface of bacteria, fungi, and viruses.
-The third step results in the expansion of cells. The cell now surrounds the foreign molecule. This process utilizes the formation of vesicles around the molecule once it is completely ingested.
Sometimes the enzyme in the vesicle cleaves the molecule itself and breaks it into simpler components. -Waste materials that are not used by the organism are then removed from the cell through the process called exocytosis.

Phagocytes are mostly white blood cells. they help the ingestion of molecules and prevent the ingestion of harmful or dead cells. One such phagocyte is neutrophils. Neutrophils have the ability to secrete products which stimulate monocytes and macrophages. Neutrophil secretions increase the activity of phagocytosis. The formations of compounds having reactive oxygen which are used in the intracellular killing are also promoted.
Hence option A is correct.

Note: The other phagocytes include dendritic cells, mast cells and macrophages. They bind to foreign molecules and internalize them into a phagosome. They acidify and fuse with lysosomes present in the cell in order to destroy the contents.