Increase in mass and increase in number of individuals are twin characteristics of which character of living organisms?

Answer

### Step-by-Step Text Solution

1. **Understanding the Question**: The question asks about the characteristics of living organisms that involve an increase in mass and an increase in the number of individuals.

2. **Identifying Key Terms**: The terms "increase in mass" and "increase in number of individuals" are crucial. These terms are often associated with the concept of growth in living organisms.

3. **Defining Growth**: Growth in biological terms refers to the increase in size (mass) and number of cells in an organism. This can be observed in both unicellular and multicellular organisms.

4. **Examples of Growth**:
- **Increase in Mass**: For example, consider a human being. A baby grows into an adult, and during this process, its mass increases significantly. A newborn baby has a much lower mass compared to an adult.
- **Increase in Number of Individuals**: In a population, as organisms reproduce, the number of individuals increases. For instance, a single pair of rabbits can produce multiple offspring over time, leading to an increase in the population.

5. **Conclusion**: Based on the understanding of growth and the examples provided, we conclude that the twin characteristics of an increase in mass and an increase in the number of individuals are indeed associated with the concept of growth in living organisms.

### Final Answer
The twin characteristics of increase in mass and increase in number of individuals are associated with **growth** in living organisms.

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