Exponential growth is shown by

Options

A. Unicellular forms
B. A cell in tissue culture
C. Embryo
D. Multicellular plants

Answer

### Step-by-Step Solution:

1. **Understanding Exponential Growth**:
- Exponential growth refers to a situation where the growth rate of a population or cells is proportional to its current size, leading to the population increasing rapidly under ideal conditions.

2. **Conditions for Exponential Growth**:
- For exponential growth to occur, certain ideal conditions must be met:
- Unlimited availability of nutrients and food.
- Optimal living conditions without any environmental stressors.

3. **Analyzing the Options**:
- The question presents several options: unicellular forms, tissue in cell culture, embryo, and multicellular plants.
- We need to determine which of these options can exhibit exponential growth.

4. **Evaluating Each Option**:
- **Unicellular Forms**: While unicellular organisms can grow rapidly, they typically exist in environments where resources are limited, leading to logistic growth rather than exponential growth.
- **Tissue in Cell Culture**: Cells in tissue culture are maintained in controlled environments with a constant supply of nutrients and optimal conditions, allowing them to grow exponentially.
- **Embryo**: Embryos also rely on limited resources and environmental factors, which can restrict their growth to logistic patterns.
- **Multicellular Plants**: Similar to embryos, multicellular plants face competition and resource limitations in natural environments, leading to logistic growth.

5. **Conclusion**:
- Based on the analysis, the only option that consistently shows exponential growth is **tissue in cell culture**, as it is maintained under ideal conditions with no shortage of nutrients.

### Final Answer:
**Exponential growth is shown by tissue in cell culture.**

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