Ask a Teacher

1.Write the odd one in each of the following:

i.Purkinje fibres, AV bundle, AV valve, SA node.

          Ans: AV valve (because others are related with conduction of waves of     contraction).

ii.Mitral valve, tricuspid valve, semilunar valve, venous valve.

           Ans: Venous valve (it is not associated with heart)

iii.Aorta, pulmonary artery, carotid artery, dorsal aorta.

           Ans:  Pulmonary artery (it alone carries deoxygenated blood).

2.Distinguish between the following pairs of words.

3.What is the benefit of keeping deoxygenated and oxygenated blood separately in our heart?

Keeping of deoxygenated and oxygenated blood separately ensures highly efficient supply of oxygen to the body.

4.Why should bleeding or leakage of blood be stopped?

Bleeding should be stopped to minimize the loss of nutrients and oxygen present in the blood. In addition, loss of blood leads to reduction of pressure which inturn reduces the efficiency of pumping system.

5.Why RBC are considered as efficient carrier of oxygen?

RBC contains haemoglobin which binds with oxygen and form oxyhaemoglobin. In addition to that, RBC lacks nucleus which provide large space for oxygen and also lacks mitochondria, absence of which indicates that it does not use oxygen for its own activity and transfer oxygen to the right place.

6.Give one point of difference between RBCs and WBCs with regards to their structure.

RBCs are round and biconcave ,(because it provides large surface area ,allowing rapid diffusion  of oxygen) while WBCs are amoeboid and shapeless.

7. What is a pacemaker?

A patch of modified heart muscle that initiates a wave of contraction in the heart.