Transitions between the juvenile, reproductive and senescent phases in both plants and animals is maintained by

Options

A. Enzymes
B. Hormones
C. Vitamins
D. All of the above

Answer

To answer the question regarding the transitions between the juvenile, reproductive, and senescent phases in both plants and animals, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Phases**:
- **Juvenile Phase**: This is the growth phase in both plants and animals. In animals, it is characterized by growth and development, while in plants, it is referred to as the vegetative phase where the plant grows but does not reproduce.
- **Reproductive Phase**: This phase begins when the juvenile phase ends. It is the period during which organisms are capable of reproduction.
- **Senescent Phase**: This phase starts after the reproductive phase and is characterized by aging. In this phase, metabolic processes slow down, leading to decline and eventual death.

2. **Identifying the Transitions**:
- The transitions between these phases are crucial for the life cycle of organisms. The question asks what maintains these transitions.

3. **Role of Hormones**:
- Hormones play a significant role in regulating these transitions. They are biochemical messengers that influence growth, development, and reproductive processes in both plants and animals.
- In plants, hormones such as auxins, gibberellins, and cytokinins are involved in regulating growth and development, while in animals, hormones like estrogen, testosterone, and growth hormones regulate the transitions between juvenile, reproductive, and senescent phases.

4. **Conclusion**:
- Therefore, the correct answer to the question is that the transitions between the juvenile, reproductive, and senescent phases in both plants and animals are maintained by **hormones**.

### Final Answer:
The transitions between the juvenile, reproductive, and senescent phases in both plants and animals are maintained by **hormones**.

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