Important Questions for Class 12 Biology 2nd Chapter Sexual Reproduction in Flowering Plants MCQ, Very Short, Short Type, Long Type
CBSE Class 12 Important Questions for Class 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants all MCQ Type, Very Short Type, Assertion Reason Type, Case Study, Short Type and Long Type Questions with Answers by Expert. Important Questions for Section A, B, C, D Class 12 Biology Chapter 2.
- Answer in one sentence
Q.1) What are pollen grains?
Ans. The male gametophytes are represented by pollen grains. A plasma membrane surrounds the cytoplasm of pollen grains. The vegetative cell and the generative cell are found in the mature pollen grain.
Q.2) Describe the various arrangements of pistils in a flower.
Ans. The gynoecium can be monocarpellary or multicarpellary. When there are several pistils, they may be fused together (syncarpous) or free (apocarpous)
Q.3) What is difference between Microsporogenesis and microspore tetrad?
Ans. Microsporogenesis is the process of producing microspores from a pollen mother cell (PMC) via meiosis. The microspores are generated in a cluster of four cells known as the microspore tetrad.
Q.4) What is apomixis?
Ans. Apomixis is a phenomenon occurring in various angiosperms, particularly grasses. It leads to the production of seeds that are not fertilized. In horticulture and agriculture, apomicts have various advantages.
Q.5) Define: pollination
Ans. Pollination is the transfer of pollen grains from the anther to the stigma of a pistil for fertilization.
Q.6) Enlist the different types of pollination.
Ans. The different types of pollination are as follows Autogamy, Geitonogamy and Xenogamy
Q.7) define: perisperm
Ans. Nucellus remains can be found in various seeds, such as black pepper and beet, on rare occasions. The perisperm is the remaining, persistent nucellus.
Q.8) how does the pericarp develop?
Ans. The ovary grows into a fruit at the same time as the ovules mature into seeds, i.e., the ovules mature into seeds and the ovary develops into a fruit at the same time. The ovary wall develops into the pericarp, which is the fruit wall.
- Answer in Short
Q.1) Describe the components of pistil.
Ans. 1.) The stigma, style, and ovary are all components of the pistil.
2.) Pollen grains land on the stigma as a landing pad.
3.) The extended, slender section underneath the stigma is the style.
4.) The ovary is the bulged, basal part of the pistil.
5.) The ovarian cavity can be found inside the ovary (locule). The ovarian cavity houses the placenta.
Q.2) What is tapetum?
Ans. 1.) The tapetum is the microsporangium’s innermost wall layer.
2.) It nurtures the pollen grains as they grow.
3.) Tapetum cells have a thick cytoplasm and usually have more than one nucleus.
Q.3) Explain the following terms: Emasculation, Bagging, Rebagging
Ans a.) Emasculation: If the female parent bears bisexual flowers, forceps must be used to remove anthers from the flower bud before the anther dehisces. Emasculation is the term for this process.
b.) Bagging: To prevent undesired pollen from contaminating the stigma of emasculated flowers, they must be covered with a sufficient size bag, usually made of butter paper. Bagging is the term for this procedure.
c.) Rebagging: When the stigma of a bagged flower reaches receptivity, mature pollen grains from the male parent’s anthers are dusted on it, the flowers are rebagged, and the fruits are allowed to develop.
Q.4) Short note: A typical dicotyledonous embryo
Ans. 1.) An embryonal axis and two cotyledons make up a normal dicotyledonous embryo.
2.) The epicotyl is the section of the embryonal axis above the cotyledons that ends with the plumule or stem tip.
3.) The hypocotyl is the cylindrical section of the plant below the cotyledons that ends in the radicle or root tip.
4.) A root cap protects the tip of the root.
Q.5) What is difference between non-albuminous or ex-albuminous seeds?
Ans. 1.) Non-albuminous or ex-albuminous mature seeds are the 2 types of seeds that are usually formed.
2.) Endosperm in nonalbuminous seeds is totally consumed during embryo development, hence there is no leftover endosperm (e.g., pea, groundnut).
3.) Because endosperm is not totally used up during embryo development, albuminous seeds retain some of it (e.g., wheat, maize, barley, castor).
Q.6) What are true and false fruits?
Ans. 1.) Other floral components in most plants deteriorate and fall off by the time the fruit develops from the ovary.
2.) The thalamus does, however, play a role in fruit production in a few species such as apple, strawberry, cashew, and others. This type of fruit is called False fruits.
3.) True fruits, on the other hand, emerge exclusively from the ovary.
- Answer in Brief
Q.1) Why is the typical angiosperm embryo sac, at maturity called 8-nucleate and 7-celled?
Ans. 1.) Within the embryo sac, the cells are distributed in a certain pattern.
2.) The egg apparatus is made up of three cells packed together at the micropylar end.
3.) the egg apparatus is made up of two synergids and one egg cell.
4.) Filiform apparatus, which are distinctive cellular thickenings near the micropylar tip of synergids, play a crucial role in guiding pollen tubes into the synergid.
5.) The antipodals are three cells located at the chalazal end. The big central cell has two polar nuclei.
6.) As a result, a normal angiosperm embryo sac is said to be 7-celled at maturity, despite being 8-nucleate.
Q.2) Give detailed explanation of how wind acts as an agent of pollination.
Ans. 1.) Abiotic pollination by wind is more common than biotic pollination.
2.) Pollen grains must also be light and non-sticky in order to be transported in wind currents during wind pollination.
3.) They frequently have exposed stamens (allowing pollen to be easily transported in wind currents) and big, typically feathery stigmas to capture pollen grains in the air.
4.) Wind-pollinated flowers typically have a single ovule in each ovary and a large number of flowers packed into an inflorescence; a common example is the corn cob, where the tassels are simply the stigma and style, which swing in the wind to trap pollen grains.
5.) In grasses, wind pollination is extremely common.
Q.3) Describe the structure of a typical angiosperm ovule
Ans. 1.) The ovule is a tiny structure that is linked to the placenta via a funicle stalk.
2.) In the hilum area, the ovule’s body unites with the funicle.
3.) As a result, the hilum indicates the point where the ovule and funicle meet.
4.) Integuments are protective envelopes that surround each ovule.
5.) The nucellus is completely surrounded by integuments, with the exception of a small aperture called the micropyle near the tip.
6.) The chalaza, which represents the ovule’s basal half, is located opposite the micropylar end.
7.) The nucellus is a clump of cells found within the integuments.
8.) The nucellus has an abundance of reserve food resources.
9.) The embryo sac, also known as the female gametophyte, is found in the nucellus.
10.) A single embryo sac is generated from a megaspore in most ovules.
Q.4) State the adaption in plants to facilitate pollination by insects/animals.
Ans. 1.) The majority of flowers pollinated by insects are big, colorful, fragrant, and nectar-rich. 2.) Flowers are gathered into inflorescences when they are small to make them more visible.
3.) Flowers attract animals because of their colour and/or scent.
4.) To attract flies and beetles, flowers pollinated by them emit unpleasant odors.
5.) Flowers must present incentives to the animals in order to keep them coming back.
6.) The usual floral incentives are nectar and pollen grains.
7.) The animal visitor comes into contact with the anthers and stigma while gathering the reward(s) from the flower.
8.) Pollen grains coat the animal’s body, which are sticky in pollinated flowers pollinated by animals.
9.) When a pollen-carrying animal comes into touch with stigma, it causes pollination.
Q.5) How do plants encourage cross-pollination in them?
Ans. 1.) Pollen release and stigma receptivity are not always synchronized in some species.
2.) Either the pollen is released before the stigma is receptive, or the stigma is responsive long before the pollen is released.
3.) Pollen cannot come into contact with the stigma of the same flower in other species because the anther and stigma are situated at different places.
4.) Both of these techniques work to keep autogamy at bay.
5.) Self-incompatibility is the third method of preventing inbreeding. Self-pollen (from the same flower or other blooms on the same plant) is prevented from fertilizing the ovules by suppressing pollen germination or pollen tube growth in the pistil.
6.) The formation of unisexual flowers is another method of preventing self-pollination.
7.) Autogamy is prevented but not geitonogamy when both male and female flowers are present on the same plant, such as castor and maize (monoecious).
8.) Male and female flowers are seen on different plants in various species, such as papaya, indicating that each plant is either male or female (dioecy).
9.) Both autogamy and geitonogamy are prohibited by this circumstance.
- MCQs
(1) Assertion: Xenogamy is a type of pollination
Reason: Pollen grains from the anther are transferred to the stigma of another flower of the same plant
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.
(2) Assertion: Pollination by water is quite rare in flowering plants.
Reason: This pollination is limited to about 30 genera, mostly dicotyledons.
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.
(3) Transfer of pollen grains from anther to the stigma of a different plant is called
(a) Xenogamy
(b) Geitonogamy
(c) Autogamy
(d) Polygamy
(4) Seedless fruits develop by the process of
(a) Apomixis
(b) Parthenocarpy
(c) Isogamy
(d) Parthenogenesis
(5) The process of removal of anthers from female flower bud before the anther dehisces using a pair of forceps is called
(a) Emasculation
(b) Bagging
(c) Rebagging
(d) Autogamy
(6) Assertion: Hydrophily pollination is accomplished through the agency of water
Reason: Water pollination is uncommon in flowering plants, occurring in only around 30 genera, predominantly monocotyledons.
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.
(7) Assertion: Exine is the soft inner layer which is made up of sporopollenin.
Reason: Sporopollenin is one of the weakest organic materials known.
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false
(8) A few flowering plants such as some species of Asteraceae and grasses, have evolved a special mechanism, to produce seeds without fertilization is called
(a) Amphimixes
(b) Apomixes
(c) Both a) and b)
(d) None of the above
(9) Assertion: The gynoecium represents the female reproductive part of the flower
Reason: it is made of ovule, style and stigma
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false
(10) Assertion: A typical anther is bilobed, dithecous and tetrasporangiate.
Reason: Pollen grains develop inside the megaspores
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false