Reproduction in Plants MCQ Quiz in मल्याळम - Objective Question with Answer for Reproduction in Plants - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

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 Both (1) and (2)

Explanation:

• Endosperm, a product of double fertilisation in angiosperms.
• Endosperm may either be completely consumed by the developing embryo (e.g., pea, groundnut, beans,gram) before seed maturation or it may persist in the mature seed (e.g. castor and coconut) and be used up during seed germination.
• In gram seeds, the food for the later development of embryo is stored in cotyledons which becomes massive. Such seeds are non-endospermic or exalbuminous. 
• Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor).
• Some monocot seeds, e.g. Orchids, Sagittaria are also non-endospermic seeds.
• So, Both (1) and (2) are correct.

The correct answer is When pollen is shed at two-celled stage, double fertilisation does not take place.

Explanation:

When pollen is shed at two-celled stage, double fertilisation does not take place.

• Incorrect: When pollen is shed at the two-celled stage, it consists of the vegetative cell and the generative cell.
• The generative cell will subsequently divide to form two sperm cells once the pollen tube begins germination. Thus, double fertilization can indeed take place after the generative cell divides inside the pollen tube.

Vegetative cell is larger than generative cell.

• Correct: The vegetative cell is larger than the generative cell. The vegetative cell is responsible for the growth of the pollen tube, while the generative cell (which can divide to form two sperm cells) is smaller and enclosed within the vegetative cell.

Pollen grains in some plants remain viable for months.

• Correct: In some plant species, pollen grains can remain viable for several months under favorable storage conditions. This is particularly true for plants adapted to environments where pollination opportunities are limited or seasonal. In some cereals such as rice and wheat, pollen grains lose viability within 30 minutes of their release, and in some members of Rosaceae, Leguminoseae and Solanaceae, they maintain viability for months.

Intine is made up of cellulose and pectin.

• Correct: The intine, which is the inner wall of the pollen grain, is primarily composed of cellulose and pectin.

The correct answer is A, C, D

Explanation:

• The period for which pollen grains remain viable is highly variable and to some extent depends on the prevailing temperature and humidity.
• In some cereals such as rice and wheat, pollen grains lose viability within 30 minutes of their release. This short lifespan of pollen is an adaptation to the specific environmental conditions and ensures that pollination and fertilization occur quickly, which is crucial for successful reproduction in these annual plants.
• In some members of Rosaceae, Leguminoseae and Solanaceae, they maintain viability for months. This extended viability is beneficial for their pollination strategies, which usually involve insect pollinators that do not guarantee immediate transfer of pollen to the stigma.
• Pollen grains can be store for years in liquid nitrogen (-196⁰C).
• Such stored pollen can be used as pollen banks, similar to seed banks, in crop breeding programmes.

 Key Points:

• ​In anthers, microsporocytes go through meiotic divisions to produce microspores, which will form male gametophyte (pollen grain) by subsequent mitotic divisions.
• In an analogous scenario in ovules, megasporocytes produce megaspores by meiosis, which eventually form the female gametophyte (embryo sac).

Figure 1: Male and female gametophytes of angiosperms

Explanation:

Option 1: petals, corolla and stigma, style, ovary

• It lists parts of a flower, but not the microsporocyte and megasporocyte, which are parts of the plant reproductive system.
• Petals, corolla, stigma, style, and ovary are all parts of the flower that play a role in pollination and fertilization, but they are not related to the production of male and female gametes.

Option 2: antipodal cells, polar nuclei and vegetative cell, generative cell

• It lists the correct parts but in the wrong order.
• The antipodal cells and polar nuclei are parts of the megasporocyte, while the vegetative cell and generative cell are parts of the microsporocyte.

Option 3: vegetative cell, generative cell and antipodal cells, polar nuclei

• It represents the correct parts of the microsporocyte and megasporocyte, respectively.
•  In plants, the microsporocyte and megasporocyte are cells that undergo meiosis to produce haploid microspores and megaspores, respectively.
•  These spores eventually develop into male and female gametophytes.
•  Microspore becomes highly vacuolate and the haploid nucleus moves toward the periphery of the cell.
• The microspore then undergoes a highly unequal cell division producing a larger vegetative cell and a smaller generative cell. 
• While the antipodal cells and polar nuclei are parts of the megasporocyte that produce megaspores.

Option 4: stigma, style, ovary and vegetative cell, generative cell

• This option combines parts of the flower with parts of the microsporocyte and megasporocyte, which are not related to each other.
• Stigma, style, and ovary are parts of the flower that play a role in pollination and fertilization, while the vegetative cell and generative cell are parts of the microsporocyte that produce microspores, and the antipodal cells and polar nuclei are parts of the megasporocyte that produce megaspores.

The correct answer is Multinucleate

Concept:

• The tapetum is a specialized layer of nutritive cells within the anthers of flowering plants. 
• The tapetum provides enzymes, hormones, and other essential nutrients required for the maturation of pollen.
• It is characterized by its multinucleate condition, which means that the cells typically contain more than one nucleus.

Explanation:

• Nourishes the egg: This option is incorrect because the tapetum does not nourish the egg. Instead, it nourishes the developing pollen grains.
• Middle layer of megasporangium: This option is incorrect because the tapetum is not a part of the megasporangium. It is located in the anther of the stamen.
• Multinucleate: This is the correct answer. The tapetum cells are multinucleate. Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.

The correct answer is option 2.

Concept:

• The process by which the pollen grains shed by the anther reaches the stigma of the flower is called pollination.
• There are different factors that help in pollination such as wind, water, insects like bees, animals, humans, etc.

Explanation:

Vallisneria is an aquatic plant. To understand the kind of pollination in it, let us look at the different types of pollination in aquatic plants:

• Flowers emerge above the water surface, and pollen is carried by the wind or insects
  • This type of pollination occurs in aquatic plants like water hyacinth and water lily.
  • In this kind of pollination, the flowers reach above the surface of the water and pollen grains are either carried by the insects or by the wind.
• Male flowers are carried by water currents to female flowers at the surface of the water
  • In aquatic plants like Vallisneria, the female flower emerges out of the water by means of a long stalk.
  • The male flowers or the pollen grains are shed on the surface of the water and carried to the female flower by passive water currents.
  • Some of the pollen grains eventually reach the stigma of the flower.
• Pollination occurs in submerged conditions by water
  • ​In some aquatic plants like seagrasses, the female flowers remain submerged.
  • The pollen grains are released inside the water.
  • The pollen grains are long, ribbon-like, and are carried by water to the stigma of the flower.

So, the correct answer is option 2.

The correct answer is Bats.

Key Points

• Chiropterophily is a type of pollination that is carried out by bats.
• Bats are attracted to flowers that are often white or pale in color and emit a strong odor at night.
• During pollination, bats transfer pollen from the male parts of one flower to the female parts of another flower.
• This type of pollination is important for the survival of many plant species, especially those that are found in tropical and desert regions.
• Chiropterophily is a relatively rare form of pollination compared to other methods such as entomophily (pollination by insects) and anemophily (pollination by wind).

Additional Information

• The word "chiropterophily" comes from the Greek word "Chiroptera" meaning "hand-winged" (referring to bats) and "philia" meaning "love of".
• Bats are important pollinators for many fruits such as bananas, guavas, and mangoes, as well as for plants that are used to make tequila and other alcoholic beverages.
• The act of birds pollinating flowering plants is known as ornithophily or bird pollination.
• Pollination carried out by squirrels is called pollination by agents.
• Entomophily is a type of plant pollination in which insects, especially bees, Lepidoptera (butterflies and moths), flies, and beetles, spread pollen.

Key Points

• Artificial hybridization refers to the process of production of a new plant from the desired pollen grains that are selected for conducting the process of pollination and fertilization.
• The desired pollen grains are hand pollinated and used for fertilization.
• Crossing between plants of various genera and species is carried out to achieve a plant with desired characteristics.
• The hybrid plant so formed will have the characteristics of both the genera and species.
• It is a major approach to crop improvement programs.
• There are main two steps - 

1. Emasculation:

• Emasculation refers to the process of removing anthers from the flower bud before it releases the pollen grains.
• It involves the removal of anthers by employing forceps.
• This step is carried out in only bisexual flowers that have both the male and female reproductive whorls on the same flower. 
• This is because there is a danger of the stigma to be pollinated by the pollens from the same plant leading to contamination.

2.  Bagging:

• The flowers that are emasculated need to be protected to avoid contamination.
• This is done by covering it with a bag of a suitable size normally butter paper is used.
• This process is called bagging.
• Bagging helps prevent contamination of the stigma with unwanted pollen.
• When the stigma of the bagged flower attains receptivity, desired collected pollens are dusted on this stigma.
• The flowers are rebagged and the fruits are allowed to develop.
• In unisexual flowers, bagging is done before the flower is open.
• Similar to bisexual flowers that are emasculated, bagged unisexual flowers are too dusted with collected pollens on attaining receptivity.
• It is then rebagged and fruits are allowed to develop.

Explanation:

• ​Papaya is a dioecious plant and has unisexual flowers. Male and female reproductive whorls are present on different plants.
• Plants with unisexual flowers do not require the process of emasculation while carrying out artificial hybridization.
• This is because since the pistil and stamen are on a different plant, there is no chance of the stigma being pollinated by its own pollen.
• However, unisexual flowers are bagged to avoid contamination from other pollens.
• On the other hand, wheat, brinjal and potato all have bisexual flowers i.e., both male and female parts are on the same plant.
• This necessitates emasculation of the flowers in these plants during artificial hybridization experiments.

So the correct answer is option 1 (Papaya).​

The correct answer is option 3.

Concept:

• The gynoecium represents the female reproductive part in flowering plants.
• The gynoecium has pistils which consist of style, stigma, and ovary.

Explanation:

• The pollen grains land on the stigma, style is the slender tube below the stigma.
• The pistil has bulged part called the ovary.
• Inside the ovary, an ovarian cavity with a placenta is present.
• The ovules (megasporangium) arise from the placenta.
• Let us see some of the parts of the megasporangium:

So, the correct answer is option 3.