Asexual Reproduction Animals and Plant
Reproduction in organisms mitosis and meiosis
Sexual Reproduction In Animals
Plants , unlike animals grow through out their life. Some reproduce sexually and some reproduce asexually.When plants reproduces sexually means they produce seeds, from seeds new plant develop.
Plants generally shows alternative type of gametophyte means haploid and sporophyte means diploid.
In sexual reproduction in plants generally two main events are present .
1.fertilization ,2.Pollination.
Pollination: Pollination is the process of transfer of pollen grains from male reproductive organ (anther ) to female reproductive organ (stigma) .
Fertilization:The fusion of male nucleus and the female egg is called fertilization.
Plants are divided into flowering(angiosperms) and non flowering plants(gymnosperms).
Gymnosperms: the cone is the female reproductive part and the pollen is the male reproductive part .gymnosperms produces two types of cones. the male cone is called the pollen cone .The larger female cone is the seed cone . A single tree usually produces both pollen and seeds cones.
Angiosperms: Here flower is the sexual organism. it has male and female reproductive organisms.
If flower has only male or female reproductive organs that is called unisexual flowers. example: papaya, palm
If both male and female reproductive organ in single flower is called bisexual flowers.examples:most of the plants are bisexual flowers, Hibiscus.
A flower has male parts called stamen and female parts are called carpels.
Stamen(male reproductive organ): each stamen has anther and filaments. Each anther consists of pollen sacs that contains millions of pollen grains, which are equal to sperms in animals.
anther
stamen{
filaments
Carpels(female reproductive organs):the carpel consists of a swollen stigma at the top ,a slender tube called style, over at bottom. inside the over ovules which contains a embryo sac.in side the sac egg cells are present.
stigma
carpel{ style
ovary
Pollination:pollination happens in two ways , artificial and natural
Natural Pollination:Natural pollination again divide in to 1.cross pollination, 2.self pollination ,
1.Cross pollination:pollen are transfer from an anther of one flower to the stigma of a flower in another plant.Large number of pollen grains,flowers are large . insect, wind and animal pollination are comes under this process.
2. Self pollination: pollens transfer from anther of the flower to the stigma of the same flower or stigma of the same plant.less number of pollen grains ,flower is small.
a.Insect pollination: bees and flies carry pollen from anther of one plant to the stigma of the other plants flower .
b.Wind pollination:wind helps to transfer of pollens from anther to stigma.
Fertilization: The fusion of male nucleus to female egg is called fertilization.
fertilized egg divides into a ball of cell that forms an embryo. Embryo is center of ovule.The surrounding tissue called the endosperm supplies the embryo with food. the ovule develops into seed.After fertilization the ovary wall develops into a fruit which encloses the seed .
Outer coat called testa, protects seed from damage,this is the points seed attaches to wall of fruits. Near the one end of the attachment tiny hole ,the micropyle. cotyledons are the seed leaves which found inside the seed coat . baby plant form in between cotyledons. Embryo has baby roots called radicle and baby shoot called plumule The space between radicle and plumule called hypocotyl .
According to number of cotyledons plants are divide into two types, 1.Monocotyledons, 2.Dicotyledons.
1.Monocotyledons: seeds that have a single seed leaves. examples: rice ,wheat
2.Dicotyledons:Seeds have two seed leaves.examples:beans ,groundnut
Germination:the process of a seed to produce a seedling is known as Germination.
The rest period between seed and seedling is called Dormancy.
Germination again divide into two types, Hypogeal ,Epigeal.
Hypogeal Germination:in this process cotyledons remaining underground at the germination.
Hypogeal germination implies that the cotyledons stay below the ground. The epicotyl (part of the stem above the cotyledon) grows, while the hypocotyle (part of the stem below the cotyledon) stays the same length. In this way, the epicotyl pushes the plumule above the ground.pisum sativum(pea)
Epigeal: in this process cotyledons emerge above the ground at the germination
Epigeal germination implies that the cotyledonsare pushed above ground. The hypoctyl (part of the stem below the cotyledon) grows, while the epicotyl(part of the stem above the cotyledon) stays the same length. In this way, the hypocotyl pushes the cotyledon upward.
