gen bio week 1a

• • Reproduction is the biological or natural process by which new individual organisms, called offspring, are produced from a single parent or from two parents.
• also referred to as procreation or breeding
• Two modes of procreation in plants and in animals: Asexual and Sexual
• Asexual reproduction is a living thing can reproduce without the involvement of another organism.
• In asexual reproduction, there is no exchange of genetic material with other individuals.
• Sexual Reproduction involves the fusion of gametes (egg cell and sperm cells) resulting in the formation of zygote.
• The main difference between sexual and asexual reproduction is that sexual reproduction requires the union of male and female sex cells while asexual reproduction does not require this union.
• Fertilization occurs when the egg cell and sperm cell fuse together.
• Zygotes develop into embryo through mitosis until it becomes a fully developed baby.
• The resulting new organism is naturally a clone of its parent.
• Sexual reproduction calls for  the  interaction  of  two  specialized  cells.
• referred  to as gametes or sex cells
• male   gamete   unites   with   a   female   gamete   of   the same species to create a fertilized egg, called zygote.
• Two ways that plants can propagate asexually:

  1.        Spore formation

  2.       Vegetative reproduction.

   
• Spore formation is a method of asexual reproduction which occurs in non-flowering plants.
• Spore is a reproductive cell which is capable of developing into a new individual plant without combining with another reproductive cell.
• It differs from sex cells because it does not need to pair with another cell to give rise to a new plant.
• Spores are considered as agents of asexual procreation in plants.
• Mosses and ferns propagate through spore formation.
• Spore-bearing organs - called sporangia - are often located underneath of leaves.
• Vegetative reproduction is a mode of procreation that occurs through the vegetative or body parts of a plant such as stems, leaves, and roots.
• Sexual reproduction in plants occurs in gymnosperms (cone-bearing) plants and  in angiosperms (flowering) plants.
• This mode of breeding requires the union of a male and a female gamete to produce a zygote (baby) called seeds
• In angiosperms, the flowers act as a sex organ.
•                             Stamen- male reproductive part in plants
• Pistil- female reproductive part in plants
• Stamen- has anther which contains pollen grains or male gametes.
• Pistil- has stigma, style, and ovary, the ovary consists of ovules.
• ·         The female gamete called ovum (ova – plural) lives in the ovule.
• ·         Flowers having both reproductive parts are bisexual
• ·         the flower with only one of the reproductive parts is unisexual.
• ·         hibiscus or gumamela flower is an example of a bisexual flower.
• ·         Cone is the female reproductive part in gymnosperms
• ·         Pollen is the male reproductive part in gymnosperm
• ·         Male cone called the pollen cone in pine trees or other gymnosperm
• ·         Female cone (larger) is the seed cone in pine trees and other gymnosperms
• Two steps in plants sexual reproduction:·         Pollination·         Fertilization
• Pollination is the transfer of pollen grains from the plant’s male reproductive structure to the female reproductive part.
• Two ways plants pollinate:  self-pollination or autogamy and cross- pollination or allogamy
• Ø  When the transfer of pollen grains occurs within the same plant, the process is called self-pollination.