Assertion             :       In mollusca, circulatory system is of closed type.

Reason               :       The blood of mollusca contains haemoglobin

Assertion  :       Histamine is involved in allergic and inflammatory reactions.

Reason     :       Histamine is a vasodilator

Assertion   :       Heart valves resemble swing doors in action.

Reason      :       Valves are present in the heart chamber, at the opening of the heart into large arteries and veins.

Assertion   :       Cardiac output rises during exercise.

Reason      :       Cardiac output helps in less oxygen consumption.

Assertion    :       EEG is of immense diagnostic value in the cardiac diseases.

Reason      :       Defects in cardiac functions can be reflected in changes in the pattern of electrical potentials recorded in the EEG. 

Assertion   :       An artificial pacemaker can replace the sinoatrial node of heart.

Reason      :       This is because, an artificial pacemaker is capable of stimulating the heart electrically to maintain its beats.

Assertion   :       Mixing of oxygenated and deoxygenated blood occurs in reptilian and amphibian hearts.

Reason      :       This happens because of the incomplete partitioning of the auricle.

Assertion   :       Left ventricle of heart has a thinner wall than that of the right ventricle.

Reason      :       Left ventricle needs to pump blood to nearby lungs only.

Assertion   :       The increased permeability of the lymph capillaries is easily altered.

Reason      :       The increased permeability of the capillary walls leads to oedema or swelling.

Assertion: Electrocardiogram is record or electrical activity of the heart which shows certain waves called P, Q, R, S and T waves.

Reason: It gives important information concerning the spread of excitation to the different parts of heart and it is of value in the diagnosis of cases of abnormal cardiac rhythm and myocardial damage.