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.

1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. If the assertion is true but the reason is false
4. If both the assertion and reason are false

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   :       Heart of fish contains only deoxygenated blood.

Reason      :       Oxygenated blood do not return back to the heart in fishes.

Assertion   :       Blood flows at a very slow velocity in the lacunae and sinuses of prawn.

Reason      :       This happens because of the absence of heart in the prawn.

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   :       Blood pressure is arterial blood pressure.

Reason      :       It is measured by sphygmomanometer.

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.

Assertion   :       Total count of RBC comes out to be very low in polycythemia.

Reason      :       Number of erythrocytes get reduced in the condition of polycythemia.

Assertion   :       Serum can not be coagulated.

Reason      :       Serum lacks the protein fibrinogen.