Short Notes

   Reproduction in lower and Higher Animals  (Part 2) Menstrual Cycle : The menstrual cycle is a characteristic of primates.  It starts at the time of puberty and the period is called menarche. The menstrual cycle in humans lasts for 28 days. The days are numbered from the first day of blood flow in the menstrual period. A series of events occur regularly in females after every 26 to 30 years. The menstrual cycle includes four phases:- I) Menstrual  ovulation phase/Menstrual cycle phases : It is also called as bleeding phase this phase extends from the 1st to the 4th day of the menstrual cycle.  When the ovum is not fertilized, the high-level progesterone inhibits the secretion of luteinizing hormone, and the LH level decreases in the level of progesterone from the corpus leuteum.  After 14 days of ovulation, if the ovum is not fertilized, the lining of the uterus degenerates, and menstruation begins. This phase lasts about 4 days. The days when bleedi...

  Reproduction in lower and Higher Animals   (part 1) Reproduction:- Reproduction is defined as the biological process of formation of new life forms from pre-existing similar life. Asexual reproduction:- Asexual reproduction is a common method of reproduction among lower animals. It does not involve the fusion of two compatible gametes or sex cells. It is a process resulting in the production of genetically identical progeny from a single organism and inherits the genes of parents. Such morphologically and genetically identical individuals are called clones. Lower animals generally reproduce asexually either by gemmule formation, budding, or fragmentation. Gemmule formation:- Sponges reproduce asexually via. gemmule formation. Gemmule is an internal bud formed only in sponges to overcome unfavorable conditions.  The structure of the gemmule includes the micropyle, spicule, inner layer, archaeocytes, and outer layer. It possesses an asexually produced mass or aggregation ...

Reproduction in lower and higher plants Reproduction:  - Reproduction is the production of young ones like a parent.  - Reproduction is an essential process as it leads to the continuation of species as well as maintain the continuity of life.  - Each organism has its own particular method of reproduction.  - All these methods generally fall into two categories:  1) Asexual reproduction   2) Sexual reproduction 1) Asexual Reproduction: - It does not involve the fusion of two compatible gametes or sex cells. - It is a process resulting in the production of genetically identical progeny from a single organism and inherits the genes of parents. - Such morphologically and genetically identical individuals are called clones. - Organism choose to reproduce asexually by different modes or ways :      1) Fragmentation :  - Multicellular organisms can break into fragments due to one or other reasons. - These fragments grow into new indi...