Pls answer q.no 6:

6. Given a scientific reason for the following. 
(i) Large central vacuoles in a plant cell.
(ii) Ribosomes attached to the surface of Endoplasmic reticulum.
(iii) Enzymes in the lysosome. 

Dear student,
The answer to question 6 is as follows:
(i)Large central vacuoles are present in plant cell because of the following reasons:
1. For storing food and water: Since plants cannot move from one place to another to obtain nutrition, therefore, they need to store a large amount of food for their survival.

2. To manage the turgor pressure changes across the cell wall: The vacuoles maintain the turgor pressure by gaining or losing water depending on the availability of water to plants.Thus, this evolutionary feature of large central vacuole helps the plants to survive in unfavorable conditions and to maintain the turgor pressure changes.

(ii) Ribosomes are attached to the surface of the endoplasmic reticulum to form Rough endoplasmic reticulum (RER).The ribosomes are formed in the nucleus into larger and smaller subunits.These subunits are then transported to the cytoplasm where they attach to ER. The main function of RER is to synthesize and store protein. Many of the proteins formed by attached ribosome on ER pass into RER and then are transported to other parts of the body. Thus, ribosomes are attached to the surface of ER.

(iii) Enzymes are present in the lysosomes to digest foreign materials along with the ingested bacteria and viruses by phagocytosis. It also destroys damaged cells and organelles by autolysis. It also helps in digestion of proteins from the surface of the cell by endocytosis.Thus, lysosomes contain 40 different types of digestive enzymes.