SSC Selection Post 2025 PYQ — Question 25

Correct Answer

White blood cells

Explanation

White blood cells (WBCs), also scientifically known as leukocytes, are the primary cells of the human immune system responsible for fighting infections and defending the body against foreign pathogens such as bacteria, viruses, fungi, and parasites. They constantly circulate through the bloodstream and lymphatic system, identifying, attacking, and destroying harmful microorganisms that enter the tissues.

Regarding the other components, red blood cells (Erythrocytes) contain hemoglobin and are responsible for transporting oxygen from the lungs to the rest of the body. Platelets (Thrombocytes) are vital for blood clotting and stopping bleeding at wound sites. Plasma is the liquid component of blood that holds these cells in suspension and carries nutrients, hormones, and proteins throughout the body.

Key Points

White blood cells make up about 1% of the total blood volume in a healthy adult but their production increases rapidly during an active infection. There are five main types of white blood cells, each with specialized defense roles, including Neutrophils, Lymphocytes (B-cells and T-cells), Monocytes, Eosinophils, and Basophils. Lymphocytes produce specific proteins called antibodies to target and neutralize specific viruses and bacteria.

Important Questions and Answers

Question: What is the alternative scientific biological term used to refer to white blood cells?

Answer: Leukocytes.

Question: Which component of blood is primarily responsible for the mechanism of blood clotting to prevent excessive bleeding from an injury?

Answer: Platelets (Thrombocytes).