CHAPTER 9 REPRODUCTION AND DEVELOPMENT

9.1 Asexual reproduction in plants and animals Learning Outcomes: At the end of this topic, students should be able to: Explain the following terms and give examples of each: i)Parthenogenesis ii)Sporulation iii)Budding iv)Binary fission v)Regeneration vi)Vegetative propagation in plants

1. Parthenogenesis 2.Sporulation 3.Budding 4.Binary fission 5. Regeneration 6. Vegetative propagation Asexual Reproduction Types of Asexual Reproduction

Definition: Reproduction that does not involve fertilization between male and female gametes. Occurs in both animal and plant; especially plants and lower animals. Rarely occur in higher animals. Asexual Reproduction

Parthenogenesis The development of an unfertilized eggs develops into an adult animal (Solomon & Berg 9 th edition) Females produce offspring from unfertilized eggs. Reproduction happens without fertilization of male gamete. E.g.: Certain species of bees, aphid, wasps and ants

Example of partenogenesis: Aphids

Type of reproduction that occurs in fungi, algae, and protozoa. Involves the formation of spores by the spontaneous division of a cell into four or more daughter cells. Each of which contains a part of the original nucleus E.g.: Ferns, moss, fungus and a few types of protozoa. Sporulation

Spores are usually microscopic and light, helping distribution by wind, water and animals. An important characteristic of this reproduction is spores are produced in large amounts to increase the chance of successful reproduction. The formation of a refractile body or resting spore, within certain bacteria that makes the cell resistant to unfavorable environmental conditions. In suitable condition, spores would grow into new individuals. Sporulation

Example of sporulation: Fern

A small part of the parent’s body separates from the rest and develops into a new individual.( Solomon & Berg 9 th edition) A method where an organism would develop an outgrowth, which upon detachment from the parent becomes a self supporting individual. These individuals may detach from the parent or remain on the parent. E.g.: Yeast, Hydra sp. Budding

Example of budding: Yeast

Equal division of a prokaryotic cells into two (Solomon & Berg 9 th edition) Division of an organism to produce two new individuals by simple division of nucleus and cytoplasm. Both individuals are similar to the parent cell. This asexual reproduction occurs in unicellular organisms E.g. : Amoeba sp., Paramecium sp. Binary fission

Example of binary fission: Paramecium sp. and Amoeba sp.

The body of the parent breaks into several pieces and each piece regenerates the missing parts and develop into a whole animal. (Solomon & Berg 9 th edition) Latin word : re = again; generate = to be get] Renewal of a portion of a body which has been injured or is lost. E.g.: Planaria sp., Lizards, Starfishes Regeneration

Example of regeneration: Planaria sp.

Example of regeneration: Lizard Example of regeneration: Star fish

In plants, new individuals develop from specialised multicellular structures (e.g.: tubers, bulbs, rhizomes, stolons) that will eventually detach from the parent plant. E.g.: The production of strawberry plants from runners Vegetative propagation

Example of vegetative propagation: Strawberry