Sexual Reproduction in Flowering Plants: Germination of Seeds (For CBSE, ICSE, IAS, NET, NRA 2022)

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Germination of Seeds

  • The seed germination begins the moment seed absorbs water, swells, and bursts through the seed coat.
  • When the seeds are obtained from a plant, they are in dry and dormant state.
  • These seeds begin to grow as soon as they get water, air, soil, etc.
  • In simple germination can be defined as the beginning of the growth of a seed.
  • The enzymes function in the seed with the help of water.
  • The enzymes perform a function of digesting stored food thereby making it soluble.
Common Garden Bean

Functions of a Flower

  • The main function is the reproduction of individual species.
  • They also help in development of pollen tube, formation of gametes and fertilization.
  • The large and colored petal helps in attracting insects.
  • The filaments support the anther.
  • Angiosperms of the flowers help in diverse modes of pollination.
  • Flowers are also used as tokens of love or esteem.
  • Brightening decorations at home.
  • For worship purpose.

Megasporangia and Megasporogenesis

  • Megasporangia is also known as female sporangia.
  • It produces megasporocytes (megameiocytes) that yield megaspores.
  • The sporangia may be borne in:
    • Specialized structures such as sori in ferns.
    • Cones (strobili) in some pteridophytes.
    • Most gymnosperms
    • Flowers in angiosperms
Plant Ovules with Megasporocytes

Inflorescence

  • The collective cluster of flowers is termed an inflorescence in those species that have more than one flower on an axis.
  • Most members of the very large composite (Asteraceae) group is the common example.
  • It may include specialized stems and modified leaves known as bracts.
  • A single daisy or sunflower, for example, is not a flower but a flower head.

Floral Diagrams and Floral Formulae

  • Floral diagrams are used to represent the structure of a flower.
  • The diagrams may show important features of flowers, including the relative positions of the various organs.
  • A way to represent the structure of a flower using specific letters, numbers, and symbols is known as floral formula.

Self-Pollination

The pollen from the anther is deposited on the stigma of the same flower or another flower on the same plant.

Cross-Pollination

  • The transfer of pollen from the anther of one flower to the stigma of another flower.
  • Cross-pollination occurs on a different individual of the same species.
Cross-Pollination

FAQs

Q 1. What are the various important parts of a flower?

Answer:

The various important parts of a flower are:

i) Receptacle

ii) Sepals

iii) Petals

iv) Stamen

v) Carpel

Q 2. What are the three agents of Pollination?

Answer:

Three agents of Pollination are:

i) Anemophily, which occurs due to the impact of wind.

ii) Hydrophily, which occurs due to the impact of water.

iii) Zoophily, which occurs due to the impact of creatures.

Q 3. What is Double Fertilization?

Answer:

  • The process of fertilization occurring in angiosperms is called Double fertilization.
  • Here one vegetative and two generative cells form into a male gamete with the development of pollen grains.

Q 4. What is the difference between Self-pollination and Cross-pollination?

  • Answer: Self-pollination takes place when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant.
  • Cross-pollination occurs when there is a transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species.