Choose the correct option:
$(1)$ Depolarization of the ventricles induces the $QRS$ / $T$ waves.
$(2)$ Incomplete double circulation is seen in reptiles / birds.

Which of the following figures correctly represents the path of a closed circulatory system?

Newborn babies generally do not shiver despite low temperatures because of:

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

Consider the following four statements regarding the human circulatory system:
$(a)$ Arteries have thick walls and a narrower lumen compared to veins.
$(b)$ Angina is a sudden chest pain.
$(c)$ In the $ABO$ blood grouping system,a person with blood group $AB$ can donate blood to anyone.
$(d)$ Calcium ions play a significant role in blood clotting.
Which two of the above statements are correct?

Which of the following is a characteristic of pernicious anemia?