Blood Groups
(i) The concept of blood grouping was discovered by Karl Landsteiner. He identified blood groups A, B and O. AB blood group was recognized by Decastello and Steini.
(ii) Human blood contains certain specific substances called agglutinogens or antigens (Ag) and agglutinins or antibodies (Ab). Antigens are found on the membrane surface of RBC. Antibodies are present in blood plasma. Based on the presence or absence of antigen and antibodies human blood group is classified into four groups called A, B, AB, and O. An individual has one of the four blood groups.
(iii) 'A' group individuals: Antigen 'A' is present on the surface of RBC and antibody b (anti-b) is present in the plasma.
(iv) 'B' group individuals: Antigen 'B' is present on the surface of RBC and antibody an (anti-a) is present in the plasma.
(v) 'AB' group individuals: Antigens A and B are present on the surface of RBC and antibodies are absent in the plasma.
(vi) 'O' group individuals: No antigen A or B are absent on the surface of RBC. However, the plasma contains both antibodies 'a' and 'b' (anti a and b).
Blood donation :
(i) In blood transfusion one must consider the antigen and antibody compatibility (matching) between the donor and the person receiving blood (recipient). When an individual receives a mismatched blood group from the donor agglutination (clumping) of blood occurs in the body which leads to death.

(i) Rh factor was discovered by Landsteiner and Wiener in 1940. It was named so because it was first discovered in Rhesus monkey.

Valves are the muscular flaps that regulate the flow of blood in a single direction and prevent back flow of blood.

Definition: Transpiration is the evaporation of water from the aerial parts of the plant especially through stomata in the leaves.
Importance of Transpiration:
(i) Creates transpirational pull for transport of water.
(ii) Supplies water for photosynthesis.
(iii) Transports minerals from soil to all parts of the plant.
(iv) Cools the surface of the leaves by evaporation.
(v) Keeps the cells turgid; hence, maintains their shape.

(i) There are millions of root hairs on the tip of the root which absorb water and minerals by diffusion
(ii) Root hairs are thin walled, slender extension of epidermal cell that increase the surface area of absorption.
Pathway of water absorbed by roots:
(i) Once the water enters the root hairs, the concentration of water molecules in the root hair cells become more than that of the cortex.
(ii) Thus, water from the root hair moves to the cortical cells by osmosis and then reaches the xylem.
(iii) From there, the water is transported to the stem and leaves.

The upward movement of water and minerals from roots to different plant parts of the plant is called ascent of sap.

It occurs when water moves out of the cell and resulting in the shrinkage of cell membrane awayfrom the cell wall

(i) Neutrophils
(ii) Eosinophils
(iii) Basophils

(i) It transports oxygen from lungs to tissues.
(ii) It transports carbon dioxide from tissues to lungs