Question

Assertion : In cells engaged in active secretion, as in pancreas, the rough endoplasmic reticulum is well developed.

Reason: Ribosomes attached to endoplasmic reticulum are actively engaged in protein synthesis.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

Answer 1

The correct option is: (b)

Explanation:

Rough endoplasmic reticulum has rough membrane because a number of ribosomes are attached to their outer surfaces. RER is, therefore. also called granular endoplasmic reticulum. The membrane of the endoplasmic reticulum bears a fine pore in the area of attached ribosome to pass the synthesised polypeptide into the channel of endoplasmic reticulum for transport. RER contains two types of glycoproteins (ribophorin I and ribophorin II) for attachment to ribosomes. On account of the presence of ribosomes, the rough ER is engaged in synthesising proteins and enzymes. It is, rich in cells which are actively engaged in protein synthesis and secretory activity. e.g., pancreatic acinus cells. plasma cells, fibroblasts, goblet cells.