Name the following:

(a) The cells which transport oxygen to the different parts of the human body.

Red blood cells or erythrocytes

Explanation: Red blood cells carry out the task of picking up & delivering oxygen. The factors which enable them to be efficient oxygen carrier are – the absence of nucleus, mitochondria & endoplasmic reticulum. The absence of nucleus makes them biconcave & thus increase the surface area for absorbing more oxygen. The absence of mitochondria means that the red blood cells won't be able to use oxygen for themselves. The absence of endoplasmic reticulum means increased the flexibility of red blood cells for their movement through narrow capillaries (endoplasmic reticulum serves as a skeletal framework for the cells).