Question

Which of the following is/are true about P, Q and R?

A. P-transports oxygen, Q-kills bacteria, R-clots blood
B. P-transports carbon dioxide, Q-produces antibodies, R-clots blood
C. P-transports bacteria, Q-eats foreign material, R-clots blood
D. P-transports food, Q-develops immunity, R-clots blood

Answer 1

Hint:- Blood is a red, mobile and vascular connective tissue, consisting of two components- plasma and formed elements or blood corpuscles. Plasma forms the 55-60% of the blood volume and blood corpuscles form the remaining blood volume

Complete answer: In the given figure, P is red blood cells, Q is neutrophils and R is platelets.
Red blood cells or erythrocytes are the most numerous formed elements of the blood in the human body. They have a red, oxygen carrying pigment called haemoglobin in their cytoplasm. The shape of the RBCs vary in different vertebrates. In mammals they are circular, biconcave, denucleated discs. The hemoglobin in the blood carries about 97-99 percent of oxygen from the lungs to the body tissues as oxyhemoglobin. It also transports about 23 percent of carbon dioxide as carbamino-haemoglobin.
Leukocytes or White blood cells are rounded or amoeboid, nucleated, non-pigmented blood corpuscles. On the basis of cytoplasmic granule, they are divided into two types- granulocytes and agranulocytes.
Granulocytes include neutrophils, basophils and acidophils while agranulocytes include lymphocytes and monocytes. Neutrophils have quite large and many lobed nuclei and abundant fine granules in the cytoplasm. They are phagocytic in action and engulf microbes.
Blood platelets are the smallest sized blood corpuscles that are formed form the giant cells called megakaryocytes of bone marrow. They play a major role in the process of blood clotting.
So the correct answer is A. P-transports oxygen, Q-kills bacteria, R-clots blood.

Note:- The formation of red blood corpuscles is called erythropoiesis and the formation of white blood corpuscles is leukopoiesis. The WBCs have a life of 3-4 days only while the RBCs have a life of around 120 days.