Vegetative propagation in Pistia occurs by

Select the answer with correct matching of the structure, its location and function.

The haemoglobin content per 100 ml of blood of a normal healthy human adult is

Given below are four statements (i-iv) regarding human blood circulatory system.
(i)  Arteries are thick-walled and have narrow lumen as compared to veins.
(ii)  Angina is acute chest pain when the blood circulation to the brain is reduced.
(iii)  Persons with blood group AB can donate blood to any person with any blood group under ABO system.
(iv)  Calcium ions play a very important role in blood clotting.
Which two of the above statements are correct?