Consider the following processes
(i) Breakdown of extra-cellular materials by releasing enzymes into the surrounding medium.
(ii) Providing nourishment during starvation.
(iii) Help during remodelling of the bone.
(iv) Massive production of membrane glycoproteins, ribophorins -I and II for the stabilization of lysosomal investment.
Which of the above is/are function (s) of lysosomes ?

Options

A. (i) only
B. (i), (ii) and (iv)
C. (i), (ii) and (iii)`
D. (ii), (iii) and (iv)

Answer

To determine which processes are functions of lysosomes, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Process (i): Breakdown of extracellular materials by releasing enzymes into the surrounding medium.**
- Lysosomes contain hydrolytic enzymes (also known as hydrolases) that can break down various biomolecules. They release these enzymes into the surrounding medium to digest extracellular materials. This process is known as autophagy and is a key function of lysosomes.
- **Conclusion:** This statement is correct.

2. **Process (ii): Providing nourishment during starvation.**
- During starvation, lysosomes can break down their stored materials (such as proteins and lipids) to provide nutrients to the cell. This process helps the cell survive when external nutrients are scarce.
- **Conclusion:** This statement is correct.

3. **Process (iii): Help during remodeling of the bone.**
- Bone remodeling involves the resorption of bone tissue, which is carried out by osteoclasts. Osteoclasts are cells that contain numerous lysosomes, which release enzymes to break down bone matrix. Therefore, lysosomes play a crucial role in this process.
- **Conclusion:** This statement is correct.

4. **Process (iv): Massive production of membrane glycoproteins, ribophorins -I and II for the stabilization of lysosomal investment.**
- This statement is incorrect because the production of membrane glycoproteins and ribophorins occurs in the Golgi apparatus, not in lysosomes. Ribophorins are specifically involved in the attachment of ribosomes to the rough endoplasmic reticulum, which is unrelated to lysosomal function.
- **Conclusion:** This statement is incorrect.

### Final Answer:
The correct functions of lysosomes are represented by statements (i), (ii), and (iii). Therefore, the answer is that statements 1, 2, and 3 are functions of lysosomes.