How do Organisms Reproduce?

• Organisms reproduce in two ways

  1. Asexual Reproduction

  2. Sexual Reproduction
• Sexual Reproduction in Plants

  Angiosperms have both male and female reproductive organs. Pollen grains produce male gametes which fuse with the egg cell. Fertilization leads to the formation of a zygote, embryo, seed, and fruit
• Regeneration

  If organisms like Hydra and Planaria are cut into several pieces, each part grows into a new organism. Specialized cells proliferate and produce a large number of cells, leading to the development of different cells and tissues
• Multiple Fission


  • Unicellular organisms reproduce by multiple fission when conditions are unfavourable. Plasmodium and Entamoeba undergo this process
• Asexual Reproduction

  1. Fission

  2. Budding

  3. Vegetative propagation

  4. Regeneration

  5. Spore formation
• Fission


  1. Binary Fission

  2. Multiple Fission
• Budding


  An outgrowth is produced from the cell from which a new organism is developed. The developed organism remains attached to the parent organism and detaches only when it matures, leaving behind scar tissue. Prominent in yeast and hydra
• Asexual Reproduction


  Only a single parent is involved and no gamete formation takes place
• Sexual Reproduction in Humans

  Testes in males and ovaries in females produce sperm and eggs respectively. Fertilization results in the formation of a zygote which develops into an embryo, seeking nutrition from the mother through the placenta
• Spore Formation


  Organisms form sporangium during unfavourable conditions. Spores develop into new individuals when conditions become favourable
• Sexual Reproduction


  Two parents are involved and gamete formation takes place. Meiosis is an important step in sexual reproduction
• Binary Fission

  • Organisms reproduce by binary fission only when adequate amounts of food and moisture are available. Amoeba divides by binary fission
• Vegetative propagation


  A new plant grows from the fragments of the parent plant or a specialized reproductive structure. Offspring are exact clones of the original plant with no mixing of DNA. Common forms include grafting, layering, cutting, tuber, tissue culture, etc.
• Sexual Reproduction


  Natural way of reproduction involving two individuals to produce offspring. Male and female gametes fuse together to give rise to a new cell