CBSE Class 12 Biology Sexual Reproduction in Flowering Plants Worksheet Set A

Multiple Choice Questions (MCQs)

Question. The anther contains :
(a) sepals
(b) ovules
(c) carpel
(d) pollen grains

Answer : D

Question. Which of the following method of contraception protects a person from acquiring a sexually transmitted disease ?
(a) oral pills
(b) condom
(c) copper-T
(d) surgery

Answer : B

Question. In which one of the following birth control methods, a small portion of oviducts of a woman is removed by surgical operation and the cut ends are ligated ?
(a) copper-T
(b) tubectomy
(c) vasectomy
(d) diaphragm

Answer : B

Question. One of the following is a surgical method which prevents the sperms from reaching the ovum and pregnancy does not occur. This method is :
(a) IUCD
(b) vasectomy
(c) condom
(d) tubectomy

Answer : B

Question. Fertilisation results immediately in the formation of :
(a) a zygote
(b) an embryo
(c) a placenta
(d) a foetus

Answer : A

Question. Which of the following is not a part of the female reproductive system in human beings ?
(a) ovary
(b) uterus
(c) vas deferens
(d) oviducts

Answer : C

Question. One of the following is not a part of the human male reproductive system. This is :
(a) testis
(b) oviduct
(c) seminal vesicle
(d) prostrate gland

Answer : B

Question. Which of the following is not a sexually transmitted disease ?
(a) gonorrhoea
(b) hepatitis
(c) syphilis
(d) AIDS

Answer : B 

Question. The advantage that internal fertilisation has over external fertilisation is that in internal fertilisation :
(a) new off-springs are exactly like the parent
(b) production of large numbers of gametes is unnecessary
(c) copulation and fusion of gametes is passive
(d) fewer individuals are produced

Answer : D

Question. The figure given alongside shows the human male reproductive organs. Which structures make sperms and seminal fluid ?
(a) V makes sperms and X makes seminal fluid
(b) W makes sperms and Y makes seminal fluid
(c) X makes sperms and W makes seminal fluid
(d) Y makes sperms and V makes seminal fluid

Answer : D

Question. In a flower, the parts that produce male and female gametes are respectively :
(a) sepal and anther
(b) filament and stigma
(c) anther and ovary
(d) stamen and style

Answer : C

Question. Characters that are transmitted from parents to offspring during sexual reproduction show :
(a) only similarities with parents
(b) only variations with parents
(c) both similarities and variations with parents
(d) neither similarities nor variations with parents

Answer : C

Question. The male gametes in a flower and in a human are produced respectively in :
(a) stigma and ovary
(b) anther and style
(c) ovary and testes
(d) anther and testes

Answer : D

Question. The ratio of number of chromosomes in a human zygote and a human sperm is :
(a) 2 : 1
(b) 3 : 1
(c) 1 : 2
(d) 1 : 3

Answer : A

Question. The normal body cell of an organism contains 28 pairs of chromosomes. The number of chromosomes present in its germ cell will be :
(a) 28
(b) 14
(c) 56
(d) 42

Answer : A

Question. The number of chromosomes in parents and offsprings of a particular species remains constant due to :
(a) doubling of chromosomes after zygote formation
(b) halving of chromosomes during gamete formation
(c) doubling of chromosomes after gamete formation
(d) halving of chromosomes after gamete formation

Answer : B

Question. The length of pollen tube depends on the distance between :
(a) pollen grain and upper surface of stigma
(b) pollen grain on upper surface of stigma and ovule
(c) pollen grain in anther and upper surface of stigma
(d) upper surface of stigma and lower part of style

Answer : B

Question. Which of the following is the correct sequence of events of sexual reproduction in a flower ?
(a) pollination, fertilisation, seed, embryo
(b) seed, embryo, fertilisation, pollination
(c) pollination, fertilisation, embryo, seed
(d) embryo, seed, pollination, fertilisation

Answer : C

Question. The characteristics transmitted from parents to offspring are present in :
(a) cytoplasm
(b) ribosome
(c) golgi bodies
(d) genes

Answer : D

Question. Which one of the following best describes the function of the umbilical cord ? It :
(a) feeds the embryo with digested substances.
(b) conveys nutrients and wastes to and from the embryo respectively
(c) removes waste matter from the embryo to the mother’s blood.
(d) supplies oxygenated blood from the mother to the embryo.

Answer : B

Question. The sexually transmitted disease which is caused by bacteria is :
(a) malaria
(b) diarrhoea
(c) gonorrhoea
(d) AIDS

Answer : C

Question. Which among the following statements are true for unisexual flowers ?
(i) They possess both stamen and pistil
(ii) They possess either stamen or pistil
(iii) They exhibit cross pollination
(iv) Unisexual flowers possessing only stamens cannot produce fruits
(a) (i) and (iv)
(b) (ii), (iii) and (iv)
(c) (ii) and (iii)
(d) (i), (iii) and (iv)

Answer : B

Question. Which of the following statements are true for sexual reproduction in flowering plants ?
(i) it requires two types of gametes
(ii) fertilisation is a compulsory event
(iii) it always results in the formation of zygote
(iv) offsprings formed are clones
(a) (i) and (iv)
(b) (i), (ii) and (iv)
(c) (i), (ii) and (iii)
(d) (ii), (iii) and (iv)

Answer : C

Question. One of the following process does not lead to the formation of clones. This is :
(a) fission
(b) fertilisation
(c) fragmentation
(d) tissue culture

Answer : B

Question. AIDS is a deadly disease which is caused by :
(a) a protozoan
(b) a fungus
(c) a bacterium
(d) a virus

Answer : D 

Question. Which of the following statements are true for flowers ?
(i) flowers are always bisexual
(ii) they contain sexual reproductive organs
(iii) they are produced in all groups of plants
(iv) after fertilisation they give rise to fruits
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (ii) and (iv)

Answer : D

Question. The correct sequence of organs in the male reproductive system for the transport of sperms is :
(a) testis → vas deferens → urethra
(b) testis → ureter → urethra
(c) testis → urethra → ureter
(d) testis → vas deferens → ureter

Answer : A

Question. In human males, the testes lie in the scrotam outside the body because it helps in the :
(a) process of mating
(b) formation of sperms
(c) easy transfer of sperms
(d) all the above

Answer : B

Question. Which among the following are not the functions of testes at puberty ?
(i) formation of germ cells (ii) secretion of testosterone
(iii) development of placenta (iv) secretion of estrogen
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iv)
(d) (iii) and (iv)

Answer : D

Question. During adolescence, several changes occur in the human body. Mark one change from the following associated with sexual maturation in boys :
(a) loss of milk teeth
(b) increase in height
(c) cracking of voice
(d) weight gain

Answer : C

Question. In human females, an event that indicates the onset of reproductive phase is :
(a) growth of body
(b) change in hair pattern
(c) change in voice
(d) menstruation

Answer : D

Question. The offsprings formed as a result of sexual reproduction exhibit more variations because :
(a) sexual reproduction is lengthy process
(b) genetic material comes from two parents of different species
(c) genetic material comes from two parents of same species
(d) genetic material comes from many parents

Answer : C

Question. One of the following occurs in the reproductive system of flowering plants as well as that of humans. This is :
(a) vas deferens
(b) anther
(c) ovary
(d) style

Answer : C

Question. In the figure given alongside, the parts marked A, B and C are sequentially :
(a) cotyledon, plumule and radicle
(b) plumule, radicle and cotyledon
(c) plumule, cotyledon and radicle
(d) radicle, cotyledon and plumule

Answer : C

Question. The correct sequence of reproductive stages occurring in flowering plants is :
(a) gametes, zygote, embryo, seed
(b) zygote, gametes,embryo, seed
(c) seed, embryo, zygote, gametes
(d) gametes, embryo, zygote, seed

Answer : A

Question. The part of a seed which grows and develops into root on germination is :
(a) cotyledon
(b) plumule
(c) follicle
(d) radicle

Answer : D

Very Short Answer Questions

Question. State the function of filiform apparatus found in mature embryo sac of an angiosperm.
Answer. The filiform apparatus guides the pollen tube into the synergid.

Question. What is funiculus?
Answer. Funiculus is the stalk of ovule that attaches it to the placenta.

Question. How many germ pores are there in the pollen grains of monocots and dicots?
Answer. There are three germ pores in dicots and one in monocots.

Question. Who discovered double fertilisation in angiosperms?
Answer. S. G. Nawaschin (1897) discovered double fertilisation in angiosperms.

Question. Name a plant in which dichogamy is found.
Answer. Magnolia

Question. Why do pollen grains of some flowers trigger ‘sneezing’ in some people?
Answer. They result in an allergic reaction.

Question. What is nucellus?
Answer. The body of the ovule consists of a mass of parenchymatous cells rich in reserve food material which is called nucellus.

Question. Name the tissue present in the fertilised ovules of angiospermic plants that supplies food and nourishment to the developing embryo.
Answer. Endosperm

Question. How many cells are found in a typical embryo sac?
Answer. There are seven cells in a typical embryo sac. These are one egg cell, two synergids, three antipodal cells and a central cell.

Question. What is self-incompatibility?
Answer : It is a genetic mechanism which prevents self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.

Question. How is pollination carried out in water plants?
Answer : (a) In many aquatic plants with emergent flowers, pollination occurs by wind and insects.
(b) In water plants if pollination occurs below the surface of water is called hypohydrophilly, e.g., Ceratophyllum.
(c) In water plants if pollination takes place over the surface of water is called epihydrophily, e.g., Vallisneria spiralis.

Question. What is the function of the two male gametes produced by each pollen grain in angiosperms.
Answer : One male gamete unites with egg forming embryo.This process is called fertilisation or syngamy. Another male gamete unite with two polar nuclei resulting in the formation of endosperm triple fusion.

Question. Name the type of pollination in self-incompatible plants.
Answer : In self-incompatible plants, (while self-pollination is incompatible) cross-pollination is occurs.
Note Self-incompatibility is a genetic mechanism which prevents self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.

Question. Draw the diagram of a mature embryo sac and show its eight-nucleate,seven-celled nature. Show the following parts-antipodals, synergids, egg, central cell, polar nuclei.
Answer : 

Question. Name the parts of pistil which develop into fruit and seeds.
Answer : Pistil is the female reproductive organ that receives pollen to fertilise the egg located in ovary. A pistil has three parts, i e . ., stigma (receives pollen), which grows down through style to ovary. Ovary contains ovules, which contain an egg. The ovary develops into the fruit and ovule develops into a seeds.

Question. In case of polyembryony, if an embryo develops from the synergid and another from the nucellus which is haploid and which is diploid?
Answer : Embryo developed from the synergid is haploid as the ploidy of the synergid is haploid.Embryo developed from the nucellus is diploid as the ploidy of the nucellus is diploid.

Question. Which is the triploid tissue in a fertilised ovule? How is the triploid condition achieved?
Answer : Endosperm is the triploid tissue. It results from triple fusion involving union of one male gamete and two haploid polar nuclei.

Question. Are pollination and fertilisation necessary in apomixis? Give reasons.
Answer : Pollination and fertilisation are not necessary for apomixis. The reasons in support of this are given below
(i) Embryo sac can develop from megaspore without reduction division the egg is diploid and develops into embryo.
(ii) Embryo sac can also develop from diploid nucellus cells in which case egg is diploid that develop into embryo parthogenetically.

Question. Identify the type of carpel with the help of diagrams given below
Answer : (a) If a gynoecium has multiple carpels fused into a single structure, it is syncarpous. In this given diagram, the type of carpel is syncarpous (e.g.,poppy).  

(b) If a gynoecium has multiple carpels in free form, it is apocarpous. In this given diagram, the type of carpel is apocarpous. (e.g., michelia)

Short Answer Questions

Question. Explain any two devices by which autogamy is prevented in flowering plants.
Answer. (i) Male and female flowers are present on different plants.
(ii) The stamens and stigma of a bisexual flower mature at different times.
(a) Anthers mature earlier than the stigma and release pollens.
(b) The stigma matures earlier than the anther.
(iii) Flowers are self-sterile or self-incompatible.
(iv) Chasmogamous flowers are present with exposed stamens and stigma which facilitate crosspollination.
(Any two)

Question. What is polyembryony and how can it be commercially exploited?
Answer : Polyembryony is the occurrence of more than one embryo in a seed. In many citrus and mango varieties, some of the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into embryos. In such species, each ovule contains many embryos.
Polyembryony plays a main role in plant breeding and horticulture. The plantlets obtained from these embryos are virus free and has more vigour. Hybrid varieties of several food and vegetable crops are being extensively cultivated and these hybrid cultivars possess high productiviy.

Question. Are parthenocarpy and apomixis different phenomena? Discuss their benefits.
Answer : Yes, parthenocarpy and apomixis are different phenomenon.
Importance of Parthenocarpy
(i) The fruit production without fertilisation of the ovary is called parthenocarpy. This phenomenon is applied for the commercial production of seedless fruits. e.g., banana, grapes.
(ii) This is more useful far the juice industries.
Importance of Apomixis
(i) During apomixis, chromosomal segregation and recombination does not occur. So, characters are stable for several generations.
(ii) It simplifies commercial hybridised production because isolation is not necessary to produce F1 or maintain parental generation.
(iii) Adventive embryony is being used in the production of uniform root-stock and virus free varieties.

Question. Given below are the events that are observed in an artificial hybridisation programme. Arrange them in the correct sequential order in which they are followed in the hybridisation programme (a) Re-bagging (b) Selection of parents (c) Bagging (d) Dusting the pollen on stigma (e) Emasculation (f) Collection of pollen from male parent.
Answer : The correct sequential order of artificial hybridisatian is as following
(a) Selection of parents.
(b) Emasculation (removal of anthers from the flower bud before the anther dehisces).
(c) Bagging (process to cover the emasculated flower with a bag made up of butter paper).
(d) Collection of pollen from other male plant.
(e) Dusting of pollen on stigma.
(f) Re-bagging
Note If the female parent produces unisexual flowers, there is no need of emasculation.

Question. Vivipary automatically limits the number of offsprings in a litter. How?
Answer : Vivipary is defined as the seed germination, while the fruit is still attached to the mother plant. Plants which grow in marshy places are called Mangroves. In these plants when seeds fall on marshy places, they cannot germinate, because of high salinity and more water conditions.
So, in those plants, seeds germinate when they are still attached to the mother plant. Litter is the off spring at one birth of animal usually 3-8 in number.
Vivipary automatically limits the number of offspring in litter due to the reason that limited number of egg or ovum are produced and fertilised during reproductive cycle of female.

Question. List three strategies that a bisexual chasmogamous flower can evolve to prevent self-pollination (autogamy).
Answer : A bisexual chasmogamous flower can evolve the following (three) strategies to prevent self-pollination (autogamy).
(a) Dichogamy In this mechanism, pollen release and stigma receptivity are not synchronised. In sunflower, the pollen is released before the stigma becomes receptive (protandry). In Datura, Solanum, the stigma becomes receptive much before the release of pollen (protogyny) leads to cross-pollination.
(b) Herkogamy The male and female sex organs are placed at different positions or in different directions is called Herkogamy. In these plants, the pollen cannot came in contact with the stigma of the same flower. It has undergone cross pollination, e.g., Hibiscus, Gloriosa.
(c) Self-sterility It is a genetic mechanism which prevents the self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil, e.g., Abotilon.
Note Another device to prevent self-pollination is the production of unisexual flowers, but this is not beneficial as above mentioned strategies. It prevents autogamy but not geitonogamy in monoecious plants such as castor and maize.

Question. Geitonogamous flowering plants are genetically autogamous but functionally cross-pollinated.
Justify. Give similarity of geitonogamy with autogamy and xenogamy. 
Answer. Geitonogamous flowers are genetically autogamous because both male and female flowers are borne on the same plant. They are functionally cross-pollinated because the pollen from one flower is transferred to the stigma of a different flower.

Question. Double fertilisation is reported in plants of both, castor and groundnut. However, the mature seeds of groundnut are non-albuminous and castor are albuminous. Explain the postfertilisation events that are responsible for it. 
Answer. The development of endosperm (preceding the embryo) takes place from primary endosperm nucleus (PEN) in both, castor and groundnut.
The developing embryo derives nutrition from endosperm.
PEN undergoes repeated division to give free nuclei. Subsequently cell wall is formed and endosperm becomes cellular. At this stage endosperm is retained in castor or is not fully consumed  but in groundnut endosperm is consumed by growing embryo.

Question. (a) You are given castor and bean seeds. Which one of the two would you select to observe the endosperm?
(b) The development of endosperm precedes that of embryo in plants. Justify.
Answer. (a) Castor
(b) Endosperm stores reserve food materials. It provides nutrition to the developing embryo, therefore its development precedes that of embryo.

Question. How does the Mediterranean orchid Ophrys ensures its pollination by bees? 
Answer. The petals of the Ophrys resemble the female of a bee species in size, colour and odour. Male bee mistakes the Ophrys for female bee and tries to copulate. Few pollen grains adhered to the body of the male bee fall over stigma of the flower thereby leading to pollination showing sexual deceit.

Question. Why should a bisexual flower be emasculated and bagged prior to artificial pollination?
Answer. A bisexual flower is emasculated to prevent self-pollination in the flower and it is bagged after emasculation to prevent contact of unwanted pollen grain with the stigma of the flower.

Question. Write the cellular contents carried by the pollen tube. How does the pollen tube gain its entry into the embryo sac? 
Answer. Pollen tube carries two male gametes.
Pollen tube, after reaching the ovary, enters the ovule through the micropyle and then enters one of the synergids through the filiform apparatus which guides the entry of pollen tube into egg cell.

Question. If you squeeze a seed of orange you might observe many embryos of different sizes? How is it possible? Explain. 
Answer. In orange, the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into a number of embryos of different sizes.

Question. In a flowering plant a microspore mother cell produce four male gametophytes while a megaspore mother cell form only one female gametophyte. Explain. 
Answer. Male gametophytes are formed by meiosis of single microspore mother cell whereas female gametophytes are formed by meiosis of single megaspore mother cell to produce 4 megaspores, out of which 3 degenerate and only one survives. The surviving megaspore undergoes mitotic division to form the female gametophyte.

Question. Banana is a parthenocarpic fruit whereas oranges show polyembryony. How are they different from each other with respect to seeds?
Answer. Banana develops from an ovary without fertilisation having non-viable seeds so it is called parthenocarpic fruit. An orange contain seeds with more than one embryo thus, it shows polyembryony.

Long Answer Type Questions

Question. Starting with the zygote, draw the diagrams of the different stages of embryo development in a dicot.
Answer : 

Question. What are the possible types of pollinations in chasmogamous flowers. Give reasons.
Answer : There are two types of pollinations (chasmogamy) in chasmogamous flowers, i e . ., self- -pollination and cross-pollination.
(a) Self-pollination(Autogamy) The transfer of pollen grains from anther to stigma of the same flower is called self-pollination. It is found in both cleistogamous and chasmogamous flowers.
(b) Cross-pollination (Allogamy) The transfer of pollen grains from anther to stigma of another flower is called a cross-pollination. It is of two types (i) Geitonogamy It is the transfer of pollen grains from anther to the stigma of another flower of the same plant. It is functionally a type of cross-pollination involving a pollinating agent, genetically. It is similar to autogamy.
(ii) Xenogamy The transfer of pollen grains from the flower of one plant to the stigma of another plant. This is the only type of pollination, which brings genetically different types of pollen grains to the stigma.

Question. With a neat, labelled diagram, describe the parts of a mature angiosperm embryo sac. Mention the role of synergids.
Answer : After the 8-nucleate stage, cell walls are laid down leading to the organisation of the typical female gametophyte or embryo sac.
Six of the eight nuclei are surrounded by cell walls and organised into cells. Three cells present towards the micropylar end grouped together, constitute the egg apparatus. The egg apparatus, in turn consists of two synergids and one egg cell.
Three cells of the chalazal end are called the antipodals. The large central cell is formed by the fusion of 2-polar nuclei. Thus, a typical angiospermic embryo sac, at maturity consists of
eight nuclei and seven cells. This embryo sac is formed from, the single megaspore, so it is called ‘monosporic embryo sac.
Role of Synergids
The synergids have special cellular thickenings at the micropylar tip called filiform apparatus, which play an important role in guiding the pollen tubes into the synergid.

Question. Draw the diagram of a microsporangium and label its wall layers. Write briefly about the wall layers?
Answer : The diagram representation of a microsporangium is shown below  

In a transverse section, a typical microsporangium is circular in outline and is surrounded by four wall layers.
(a) Epidermis The epidermis is the outermost protective layer. It is composed of tangentially flattened cells. The cells are closely fitted and have thick walls which is helpful in the dehiscence of anther.
(b) Endothecium It is present below the epidermis and expands radically with fibrous thickenings, at maturity these cells loose water, at contract and help in dehiscence of
pollen sac.
(c) Wall Layers It is present between well marked endothecium and tapetum. These are thin walled layers, arranged in one to five layers, which also help in dehiscence of
anther.
(d) Tapetum It is the innermost wall layer with large cells, thin cell walls, abundant cytoplasm and have more than one nuclei. Tapetum is a nutritive tissue which nourishes the developing pollen grains.
The centre of the microsporangium consists of sporogenous tissue, which undergoes meiotic divisions to form microspore tetrads. This process is known as microsporogenesis.

Question. Embryo sacs of some apomictic species appear normal, but contain diploid cells. Suggest a suitable explanation for the condition.
Answer : Replacement of the normal sexual reproduction by asexual reproduction without fertilisation is called apomixis. e.g., replacement of the flower by bulbils and replacement
of the seed by a plant.
Apomitically produced offsprings are genetically identical to the parent plant. In flowering plants, apomixis is used in a restricted sense to mean angiosperm, i.e., asexual reproduction through seeds. In some plant species it is common, e.g., Asteraceae, Poaceae. In some species, the diploid egg cell is formed without reduction division and develops into embryo without fertilisation. It is an asexual reproduction in the absence of pollinators such as in extreme environments.
In some species like citrus, some of the nucellar cells surrounding the embryo sac start dividing and develop into embryo. It occurs in the megaspore mother cell does not undergo
meiosis, thus produces diploid embryo sac through mitotic divisions.
Thus, it explains that, embryo sacs of some apomictic species appear normal, but produce diploid cells.
Vegetative cell
(i) It is bigger in size.
(ii) It has food reserves.
Generative cell
(i) It is smaller and floats in the cytoplasm of vegetative cell.
(ii) It gives rise to two male gametes

Very Short Answer

Question. How the exine is made up of?
Answer : The exine is made up of sporopollenin which is one of the most resistant organic materials.

Question. What is intine?
Answer : The inner wall of the pollen grain is called intine

Question. What are the two parts of a typical stamen?
Answer : The two parts of the stamen are filament and anther

Question. Define microsporogenesis?
Answer : The process of formation of microspores from a pollen mother cell through meiosis is called microsporogenesis.

Question. What is pollen grain?
Answer : Pollen grains are microscopic structures that carry the male reproductive cell of plants

Short Answer

Question. What do you understand by the double-fertilisation?
Answer : Flowering plants undergo a unique process called double fertilization. After pollination brings a pollen grain to a flower's female reproductive structure (carpel), a pollen tube releases two sperm cells. One of these sperm cells unites with an egg cell to produce a diploid zygote.

Question. What is the structure of microsporangium?
Answer : Microsporangium is the sporangial structure which contains microspores which are the pollen sacs giving rise to male gametes in an angiosperm. A microsporangium is circular in outline in transverse section and is usually surrounded by four wall layers. The outermost is the single layer of the epidermis

Question. What do you mean by the pollen-pistil interaction?
Answer : Pollen−pistil interaction is a dynamic process involving pollen recognition, followed by promotion or inhibition of the pollen. The pollen-pistil interaction begins with pollination, followed by pollen adhesion to the stigma. After it adheres, it imbibes water and gets hydrated which initiates pollen tube germination. This pollen tube penetrates through the stigma and the tube grows through the style and reaches the ovary

Question. What do you mean by artificial hybridisation?
Answer : Artificial hybridization is the process in which only desired pollen grains are used for pollination & fertilization. Artificial hybridization is achieved using the following techniques: Emasculation. Removal of anthers from bisexual flowers of female parent plant.

Question. How vegetative cell is different from generative cell?
Answer : The generative cell produces two sperm cells, or male gametes, whereas the vegetative cell produces an elongated pollen tube, a gametophytic cell, to deliver the male gametes to the embryo sac.

Long Answer

Question. Explain about pollination and its types?
Answer : Pollination process occurs when pollen grains from the male part of one flower anther are transferred to the female part (stigma) of another flower. Once the pollination occurs, the fertilized flowers produce seeds, which enable the associated plant to reproduce and / or form the fruit. The goal of every living organism, including plants, is to create offspring for the next generation. Depending on the source of pollen, pollination can be divided into three types:
1. Autogamy: In autogamy the pollen is transferred to the stigma of the same flower, transfer of the pollen grains from another stigma of the same flower. Autogamy in such flowers requires synchrony in pollen release and stigma and also the anthers and the stigma should lie close to the each other so that the self-pollination can occur. Autogamy in flowering plants and autogamy in unicellular species is fundamentally different, and plants and protists are not related, it is likely that both instances evolved separately.
2. Geitonogamy: Geitonogamy is the pollination of a flower by the pollen from another flower of the same plant. It is functionally cross-pollination since pollen is exported using a vector pollinator or wind from one flower to another flower, but genetically self-pollination as both the parents belong to the same plant and thus have same genetic makeup.
3. Xenogamy: Xenogamy is the fertilization of a flower by the pollen of a flower from a genetically different plant. This is the only type of the pollination which during pollination brings genetically different types of pollen grains to the stigma.

Question. Difference between apomixis and polyembryony?
Answer : 1. Apomixis refers to an asexual reproduction that occurs without fertilization and not involving meiosis whereas polyembryony refers to the formation of more than one embryo from a single fertilized ovum or in a single seed.
2. In apomixis fertilization does not occur whereas in polyembryony undergoes fertilization.
3. Apomixis is a type of asexual reproduction whereas polyembryony is a type of sexual reproduction.
4. Apomixis is genetically-identical to the parent whereas the plants produced by polyembryony are not genetically-identical to the parent.
5. Apomixis is not involved in the production of seeds whereas polyembryony is involved in the production of seeds.
6. Apomixis is also known as agamospermy, which occurs in gymnosperms, producing clonal seeds whereas polyembryony can occur in vertebrates, invertebrates, and plants.

Question. Distinguish between microsporogenesis and megasporogenesis?
Answer : 1. Megasporogenesis refers to a sporangium that develops only megaspores whereas microsporogenesis refers to a sporangium that develops only microspores.
2. Megasporogenesis is called the ovule in flowering plants whereas the microsporogenesis is called the anther.
3. Megasporogenesis produces female gametes or megaspores whereas microsporogenesis produces male gametes or microspores.
4. Megasporogenesis produces large, rounded gametes or spores whereas microsporogenesis produces small, sometimes motile gametes.
5. Megasporogenesis has only one megaspore of a spore tetrad is functional whereas microsporogenesis have all the four microspores of a spore tetrad are functional.
6. In megasporogenesis the arrangement in a microspores in a tetrad is generally known as tetrahedral whereas in microsporogenesis the arrangement of mega spores in a tetrad is commonly known as linear.

Question. Explain the post fertilisation events of flowering?
Answer : The post fertilization events of the flowering plants are:
1. Endosperm: The endosperm is a tissue produced inside the seeds of most of the flowering plants following fertilization. It is triploid in most species. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This can make endosperm a source of nutrition in animal diet. Endosperm is formed when the two sperm nuclei inside a pollen grain reach the inside of an ovule or embryo sac. One sperm nucleus fertilizes the egg, forming a zygote, while the other sperm nucleus usually fuses with the two polar nuclei at the center of the embryo sac.
2. Embryo: The plant embryo, sometimes called the seed embryo, is the part of a seed or bud that contains the earliest forms of a plant's roots, stem and leaves. The embryo develops after a fertilized adult plant flowers, and is generally contained within a seed or bud. The plant embryo develops from the apical (terminal) cell. The suspensor develops from the basal cell. The suspensor anchors the embryo to the endosperm and serves as a nutrient conduit for the developing embryo.
3. Seed: Seeds serve several functions for the plants that produce them. Key among these functions is nourishment of the embryo, dispersal to a new location, and dormancy during unfavourable conditions. They help in germination of the new plant. The seeds contain food reservoirs in the form of cotyledons and endosperm. The seed coat is protective in nature which protects the embryo inside.

Question. State the difference between androecium and gynoecium?
Answer : 1. Androecium refers to the male fertilizing organ of a flower, typically consisting of a pollen-containing anther and a filament whereas gynoecium refers to the female organs of a flower, comprising the stigma, style, and ovary.
2. Androecium is the male reproductive organ of the flower whereas gynoecium is the female reproductive organ.
3. Stamen is another name for Androecium whereas pistil or carpels are other names for gynoecium.
4. Androecium contains micro gametocytes whereas gynoecium contains mega gametophytes.
5. Androecium produces microspores whereas gynoecium produces macrospores.
6. Androecium has anthers and filaments whereas gynoecium has stigma, style, and ovary.

Please click on below link to download CBSE Class 12 Biology Sexual Reproduction in Flowering Plants Worksheet Set A