Which phenomenon inhibits the formation of tumors in the human body? Class 9

Which phenomenon inhibits the formation of tumors in the human body? Class 9

Question 1.

Which phenomenon inhibits the formation of tumors in the human body? Can plants also develop tumors? Explain. Class 9

Answer:

(a) Phenomenon that inhibits tumors:

1. The phenomenon is contact inhibition.
2. In this process, cells stop dividing when they come in contact with neighboring cells, preventing uncontrolled growth.

(b) Can plants also develop tumors?

1. Yes, plants can develop tumors, but they are different from animal tumors.
2. Plant cells do not show contact inhibition due to their rigid cell wall.
3. As a result, abnormal growth can occur, forming tumor-like structures (e.g., plant galls).

Question 2.

The cell membrane of a cell is made up of proteins and lipids. Which cell organelles help in the synthesis of cell membrane? Write the path of these compounds from their site of synthesis to the cell membrane and show this through a labelled diagram. Class 9

Answer:

Organelles involved: Ribosomes, Rough ER (RER), Smooth ER (SER), and Golgi apparatus Path of proteins:

1. Ribosomes (attached to RER) → synthesise proteins
2. Proteins enter the RER → undergo initial processing
3. From RER → Golgi apparatus (via transport vesicles) → further modification, sorting, and packaging
4. Golgi packages proteins into vesicles that travel to and fuse with the cell membrane

Path of lipids:

1. Smooth ER (SER) → synthesises lipids (fats)
2. Lipids move to the Golgi apparatus → packaged into vesicles
3. Vesicles travel to and fuse with the cell membrane → add new lipid molecules

So the full path is:

Ribosomes / SER → RER / SER → Golgi apparatus → Vesicles → Cell membrane