Define the following: Amenorrhea

The menstrual cycle in the body of a female is a cyclic process of 28 days. In this process, one egg is released from one of the ovaries in the body of a female. This is composed of four phases these are menstruation, the follicular phase, ovulation, and the luteal phase. Amenorrhea can be best defined as a condition in which the menstrual cycle gets stopped. This condition may arise due to many reasons. The lactating mother sometimes exhibits this phenomenon.

Define life span. Give the life span of an elephant.

The period from birth to the natural death of an organism is called life span. Life span of an organism may be few minutes to several thousand years. The life span of Mayfly is one day, while Ocean Quahog is considered the longest living animal (405-410 years). It includes four stages: i) juvenile stage, ii) maturity stage, iii) senescence and iv) death. The life span of elephant is 60-75 years.

Name the terminal stage of ageing in the life cycle of plants.

There are three phases in the life cycle of an organism. These are the juvenile phase, reproductive phase and senescent phase. The juvenile phase is the period of growth between the birth of an individual up to reproductive maturity. The terminal stage of ageing in the life cycle of plants is called senescence. It begins at the end of the reproductive phase when degeneration sets in the structure and functioning of the body. It ultimately leads to death.

Name a plant which flowers every twelve years.

The flower is the reproductive organ of angiosperm plants. The appearance of flowers in higher plants indicates the sexual maturity of plants. Certain plants show unusual flowering behaviour. Strobilanthes kunthiana (Neelakurinji) flowers once in 12 years. The last time this plant flowered was during September-October 2018. It is found in hilly areas of Kerala, Tamil Nadu and Karnataka.

Give a significant point of difference between the oestrous cycle and menstrual cycle.

Features Menstrual Cycle Oestrus Cycle Fate of endometrium In the menstrual cycle, the endometrium is shed and expelled through the menstrual blood. In the oestrous cycle, the endometrium shed is reabsorbed by the walls of the uterus. Bleeding is not occur. Examples Primates such as humans, apes, etc. Nonprimates such as cow, dog, etc.