Sexual Reproduction

• Sexual reproduction - involves two separate parents that belong to the opposite sex.
• Sexual reproduction - Both plants and animals exhibit this kind of reproduction
• Flowering plants undergo sexual reproduction.
• Flower - is the sexual reproductive organ in plants.
• Flowers - often the most attractive structures of a plant.
• Flower’s anatomy can be divided into following parts:

  • Calyx
  • Corolla
  • Androecium
  • Gynoecium
• Calyx - green petal-like structures located right above the receptacle called the base of the flower.
• Calyx - made up of sepals.
• Calyx - their primary task is to safeguard the flower while it is still in the bud process.
• Corolla - the name given to the collective colorful petals of the flower.
• The petals of various flowers are found in different colors and are often fragrant much of the time.
• It is the petals that attract the pollinating agents.
• Corolla - is found above the calyx layer.
• Androecium - the male reproductive section of a flower.
• Androecium - it is made up of a series of stamens.
• Each stamen at the top of it consists of a filament and anther.
• The anthers are lobed structures that produce the male gamete-containing pollen.
• The gynoecium is the female reproductive organ of the flower.
• Gynoecium is composed of the ovary, style, and stigma.
• The style is a slender filament on top of which lies the stigma that works to retain pollen grains that are transferred.
• Once the pollen lands on the stigma, it is moved downward to the ovary via the style.
• The ovary is lobed and composed of the female gamete-containing ovules.
• The pollen grains and ovules by themselves cannot travel from one place to another.
• There are other factors such as wind, water, or animals that enable the pollen grains to travel to reach the stigma of the same or another flower.
• In plants, fertilization, which occurs after pollination and germination, is a sexual reproduction process.

   
• Fertilization can be defined as the fusion of the male gametes (pollen) to form a diploid zygote with the female gametes (ovum).
• Types of Fertilization

  • Porogamy
  • Chalazogamy
  • Mesogamy
  • Double Fertilization
• Porogamy - it is the common type of fertilization carried out in all angiosperms or flowering plants.
• Porogamy - In this type of fertilization, the pollen tube enters the ovule through the micropyle.
• Chalazogamy - this type of fertilization is carried out on all Casuarina species of plants.
• Chalazogamy - in this condition, the pollen tube enters the ovule through the pollen tube.
• Mesogamy - this type of fertilization is seen in all Cucurbit plants, such as pumpkin, ridge gourds, bitter gourd and other gourd plants.
• Mesogamy - in this type of fertilization, the pollen tube enters the ovule through its middle part or through the integuments of the ovule.
• Double fertilization is a fertilization process characterized by the fusion of two male gametes with a female gametophyte.
• Double Fertilization - One sperm cell in this process fuses with the egg-producing zygote, and the other fuses to create the endosperm with the two polar nuclei.
• Both angiosperm plants undergo a dual process of fertilization.
• In human beings, reproduction is by sexual reproduction in which both male and female gametes fertilize to give birth to a zygote that develops into an embryo.
• Fertilization takes place within the female's body thus, called internal fertilization.
• The penis is the male organ for sexual intercourse and urination.
• Semen and urine leave the penis through the urethra.