Reproductive Organs in Plants MCQ Quiz in தமிழ் - Objective Question with Answer for Reproductive Organs in Plants - இலவச PDF ஐப் பதிவிறக்கவும்

Key Points

• A flower is the reproductive unit of angiosperms.
• It can be colourful, bright, shiny, conspicuous, and a rich source of nectar.
• The flower is of two types - complete and incomplete flower.
• A complete flower contains four important whorls- calyx, corolla, androecium, and gynoecium.
• An incomplete flower is one that devoids one or more of these structures.
• Calyx and corolla are the vegetative whorls of the flowers and androecium and gynoecium are the reproductive whorls.
• The female reproductive part of a flower is the gynoecium.
• It comprises the ovary, style, and stigma.
• The ovary is the enlarged basal part, on which
  lies the elongated tube, the style, and contains the eggs or the ovules.
• The stigma is usually at the tip of the style and is the
  receptive surface for pollen grains.

Additional Information

• Androecium-
  • ​The male reproductive part of a flower is the androecium.
  • It consists of a stalk or a filament and an anther.
• Pollen sac-
  • ​These are cavities the anther that produce pollen grains.
• Stamens- 
  • ​The androecium is composed of stamens.

Hence, the correct option is (1) gynoecium.

The correct answer is Exine.

Explanation-

• Sporopollenin is a tough and resistant biopolymer that makes up the outer layer of pollen grains, known as the exine.
• The exine is the outermost layer of the pollen grain wall and is composed primarily of sporopollenin, which provides protection to the pollen grain during its journey from the anther to the stigma.
• Sporopollenin helps pollen grains withstand harsh environmental conditions, such as desiccation, UV radiation, and microbial attack.
• Inside the exine is the inner layer of the pollen grain wall, called the intine, which is composed of cellulose and pectin and is responsible for pollen tube growth during fertilization.
• The pollen cytoplasm contains the organelles and cellular components necessary for pollen function, while the tapetum is a layer of nutritive cells surrounding the pollen sac (anther) that supports pollen development.

Therefore, sporopollenin is primarily found in the exine layer of pollen grains.

Concept:

• In angiosperms,  all the reproductive parts are located in the flower.
• Different parts of the flowers are- petals, sepals, stamens and carpels.
• Stamens and carpels are the reproductive parts of the flower
• They contain germ cells and are the parts responsible for gamete formation.
•  The male reproductive organ is Stamen
  • Stamen is made up of a stalk or filament and an anther at the tip.
  • Pollen grains are produced in the anther which is yellowish in colour.
  • These pollen grains are the ones which contain the male gamete inside them.
• The carpels form the female reproductive organ.
  • It consists of three parts stigma, style and ovary.
  • The basal swollen part is called the ovary, which contains the ovules.
  • The middle elongated part extending from the top of the ovary is style.
  • The style ends to form a sticky terminal part called a stigma.
  • The ovule in the ovary contains the egg cell which is the female gamet

​Explanation:

• The pollen grains are transferred from the stamen to the stigma through pollination.
• The male gamete or the germs cell reaches the ovary by passing through the pollen tube
• The pollen tube is formed from the pollen grain and extends up to the ovule.
• The male gamete fuses with the female gamete in the ovary and this is called fertilization.
• After the event of fertilization, the zygote is formed.
• The zygote divides several times to form an embryo. inside the ovule.
• Now the ovule forms a tough coat and is gradually developed into a seed.
• The ovary also grows and ripens forming a fruit.
• Therefore the steps involved in the events of sexual reproduction in a flower are

 Gamete→ pollination→ fertilization→ zygote →embryo→ seedling.

Concept:

• In angiosperms,  all the reproductive parts are located in the flower.
• Different parts of the flowers are- petals, sepals, stamens and carpels.
• Stamens and carpels are the reproductive parts of the flower
• They contain germ cells and are the parts responsible for gamete formation.
•  The male reproductive organ is Stamen
  • Stamen is made up of a stalk or filament and an anther at the tip.
  • Pollen grains are produced in the anther which is yellowish in colour.
  • These pollen grains are the ones which contain the male gamete inside them.
• The carpels form the female reproductive organ.
  • It consists of three parts stigma, style and ovary.
  • The basal swollen part is called the ovary, which contains the ovules.
  • The middle elongated part extending from the top of the ovary is style.
  • The style ends to form a sticky terminal part called a stigma.
  • The ovule in the ovary contains the egg cell which is the female gamet

​Explanation:

• The pollen grains are transferred from the stamen to the stigma through pollination.
• The male gamete or the germs cell reaches the ovary by passing through the pollen tube
• The pollen tube is formed from the pollen grain and extends up to the ovule.
• The male gamete fuses with the female gamete in the ovary and this is called fertilization.
• After the event of fertilization, the zygote is formed.
• The zygote divides several times to form an embryo. inside the ovule.
• Now the ovule forms a tough coat and is gradually developed into a seed.
• The ovary also grows and ripens forming a fruit.
• Therefore the steps involved in the events of sexual reproduction in a flower are

 Gamete→ pollination→ fertilization→ zygote →embryo→ seedling.

Concept:

• Pollen grains are the male gametophytes of higher plants.
• They develop from microspores that are formed from pollen mother cells by meiosis.
• Thus pollen grains are haploid in nature.
• They are mostly spherical in shape and about 20-25µm in diameter.

Important Points

• Pollens undergo mitotic divisions to form one vegetative cell and one generative cell.
• Pollens are usually shed at this 2-celled stage.
• Vegetative cell -
  • It is used as a food reserve for the developing male gametes and may also be called as tube cell.
• Generative cell -
  • It is smaller in size compared to the vegetative cell and floats in the cytoplasm of the vegetative cell.
  • It is a spindle-shaped cell that undergoes mitosis to form 2 male gametes.

Additional Information

• In Angiosperms, the embryo sac is the female gametophyte, which is formed from a single megaspore.
• The embryo sac is 8-nucleate and 7-celled at maturity.
• It consists of the following cells:
  • Antipodal cell - There are 3 of these uninucleate cells present at the chalazal end that degenerate after fertilization.
  • Central cell - It is centrally located covering most of the embryo sac and contains 2 polar nuclei.
  • Egg cell - It is the female gamete that undergoes fusion with a male gamete.
  • Synergids - There are 2 synergid cells at the micropylar end with the filiform apparatus at their base.
• Filiform apparatus - consists of finger-like projections that assist the entry of pollen tube into the embryo sac.

Concept:

• The flower is the main reproductive organ of the angiosperms.
• Petals, sepals, stamens and carpels together form the parts of the flower.
•  The main reproductive parts of the flower are Stamens and carpels 
• They contain germ cells and are the parts responsible for gamete formation.

Stamens

• It is the male reproductive organ
• It consists of a stalk or filament and an anther at the tip.
• Pollen grains are produced in the anther which is yellowish in colour.
• These pollen grains are the ones which contain the male gamete inside them.

Carpels

• The carpels form the female reproductive organ.
• It consists of three parts stigma, style and ovary.
• The basal swollen part is called the ovary, which contains the ovules.
• The middle elongated part extending from the top of the ovary is style.
• The style ends to form a sticky terminal part called a stigma.
• The ovule in the ovary contains the egg cell which is the female gamete.

Explanation:

• The pollen grains are transferred from the stamen to the stigma through pollination.
• The male gamete present inside the pollen grain or the germs cell reaches the ovary by passing through the pollen tube
• The pollen tube is the one which provides the path for the male gamete to pass through and then fuses with the female gamete present in the ovary.
• Therefore, the pollen tube formed should be of the length that can reach the ovule and help in the transportation of the male gamete.
• The length of the pollen tube is determined by the distance to be covered by the male gamete to reach the ovule.
• Hence, the length of the pollen tube depends on the distance between the pollen grain on the upper surface of the stigma and the ovule in the ovary.

Concept:

• Angiosperms are the most advanced and widely distributed plants in the plant kingdom.
• Angiosperms have seeds enclosed within their fruits, in contrast to gymnosperms which have naked seeds.
• These are flowering plants and have four whorls - Two accessory whorls - calyx and corolla and Two essential whorls - androecium and gynoecium.
• Angiosperms reproduce through sexual reproduction. The two essential whorls of the flower are involved in sexual reproduction in angiosperms.
• Androecium:
  • The androecium is the male reproductive whorl.
  • It contains the male gametophyte - pollen grains.
  • An individual member of androecium is known as a stamen.
  • Each stamen is made up of 3 parts - Anther, Filament and Connective.
• Gynoecium (Pistil):
  • The gynoecium is the female reproductive whorl. 
  • It contains the female gametophyte within the ovule.
  • Individual members of the gynoecium are called carpels.
  • Each carpel is made of three parts - Style, Stigma and Ovary.

Explanation:

• Option 1: Corolla - INCORRECT
  • ​Corolla is an accessory whorl of an angiosperm.
  • It is a floral whorl that is variously colored.
  • Individual members of the corolla are called a petal.
  • The main function of the corolla is to aid in pollination by attracting pollinators.
• Option 2: Style - INCORRECT
  • Style is a part of the female reproductive whorl - gynoecium.
  • It is a narrow thread-like structure that connects the stigma with the ovary.
  • During fertilization, the pollen grains deposited on the stigma are transported to the ovary through the style.
• Option 3: Stigma - INCORRECT
  • Stigma is a part of the female reproductive whorl - gynoecium.
  • Stigma is the part of the carpel that receives pollen grains during pollination.
  • It helps in the germination of a pollen grain.
• Option 4: Anther - CORRECT
  • ​The anther is a part of the male reproductive whorl - androecium.
  • Pollen grains are produced in anther by the process known as microsporogenesis.

So the correct answer is option 4 (Anther).