Question

Define (a) Juvenile Phase
(b) Reproductive phase
(c) Senescent phase

Answer 1

Hint: The above mentioned phases are different phases in the life cycle of humans,animals and plants. Every Organism has a life span through which the generation continues. The process of passing the genes from one generation to another happens through Reproduction.

Complete Answer:
A) Juvenile Phase : This phase is the growth phase.In an individual organism juvenile phase is considered as the growth period that happens after the birth and before the organism meets the reproductive maturity.
B) Reproductive Phase : As the name suggests this phase is the time when the individual organism attains reproductive maturity and is sexually active.The reproduce and give birth to offspring.
C) Senescent Phase : This marks the end of the reproductive phase where the organism gets older and loses the capacity to reproduce.

Additional information:
The end of juvenile phase in animals is marked by the happening of morphological and physical changes before the reproductive activity.In the reproductive phase plants are classified into two types.They are
1. Monocarpic Plants
2. Poly-carpic Plants
1) Monocarpic plants produce only one flower in their lifetime. The flowering or fruiting marks the death of the plant.
Example:Rice
2) Poly-carpic Plants produce flowers seasonally every year. Example :China Rose
The senescent phase is marked by the slow metabolism which in turn leads to the last stage death.

Note: In plants the juvenile phase is mentioned as vegetative phase.In few viviparous organisms the embryo development from the fertilized eggs are carried out inside the uterus of the female and the resulting offspring is called juvenile. The nourishment to the embryo is through the placenta. The appearance of flowers in plants marks the reproductive phase.