Interphase is the part of the cell cycle when :

Options

A. mitosis proceeds
B. a cell grows and duplicates its DNA
C. a germ cell forms its spindle apparatus
D. a cell ceases to function

Answer

To answer the question "Interphase is the part of the cell cycle when:", we need to analyze the options provided and understand what happens during interphase.

### Step-by-step Solution:

1. **Understanding Interphase**: Interphase is the longest phase of the cell cycle, during which the cell prepares for division. It consists of three main sub-phases: G1 (Gap 1), S (Synthesis), and G2 (Gap 2).

2. **Analyzing the Options**:
- **Option A: Mitosis proceeds**: This is incorrect because mitosis occurs after interphase, not during it.
- **Option B: A cell grows and duplicates its DNA**: This is correct as interphase includes cell growth (G1 phase) and DNA replication (S phase).
- **Option C: A germ cell forms its spindle apparatus**: This is incorrect because the spindle apparatus forms during mitosis, not during interphase.
- **Option D: A cell ceases to function**: This is incorrect as cells are active and performing functions during interphase.

3. **Conclusion**: The correct answer is **Option B: A cell grows and duplicates its DNA**. This accurately describes the activities that occur during interphase.

### Final Answer:
Interphase is the part of the cell cycle when **a cell grows and duplicates its DNA**.

---