1. Self-incompatibility:  A condition wherein the pollen is ineffective in fertilizing the same flower or other flowers on the same plant usually due to inhibition of the growth of the pollen tube in the stigma and style, thereby preventing delivery of male gametes to the ovules.
2. Maturation of pistil before that of stamen (protogyny) or maturation of stamen before that of the pistil (protandry) inhibit self-pollination.

The fruits selected to induce parthenocarpy can be watermelon, papaya, etc. It is because these fleshy fruits have a large number of seeds, which interfere with the preparation of jams, jellies, etc.

Apple is called a false fruit because it develops from the thalamus (enlarged structure at the base of the flower) instead of ovary.

1. Emasculation is the process of removal of stamens from a bisexual flower before they shed pollen in order to prevent self-pollination and permit cross-pollination of stigma with desired pollen. During breeding, the breeder wants to make sure that the desired pollen grains are used for pollination and the stigma is protected from contamination (from unwanted pollen).
2. A plant breeder employs this technique to select and incorporate specific traits in the progeny.

Self-incompatibility
It is the third device to prevent inbreeding. It is a genetic phenomenon of preventing the pollen from fertilising ovules of the same flower by inhibiting pollen germination or pollen tube growth in the pistil.

1. Chasmogamous flowers are the bisexual, open flowers with exposed anthers and stigma. 
2. Cross-pollination cannot occur in cleistogamous flowers because they remain in bud throughout their life and form seeds via self-pollination.

An embryo sac is called monosporic because it develops from one of the four megaspores formed from the division of megaspore mother cell.

1. Apomixis is a form of asexual reproduction that mimics sexual reproduction and seeds are formed without fertilisation.
2. Apomictic embryos are genetically identical to the female parent.
3. If hybrid seeds can be made apomictic, the desirable characters can be maintained in the progeny.
4. It is often associated with polyembrony.

There is an adaptation in angiospermic plants to provide assured nutrition to the developing embryo. Most zygotes divide only after certain amount of endosperm is formed. Therefore, zygote remains dormant for sometime in a fertilised ovule.

1. Male gametophyte - In the Anther (microsporangia) and later on the stigma and style.
2. Female gametophyte - inside the ovule.

Bagging The emasculated flower is covered by a bag of suitable size generally made up of butter paper, so as to prevent contamination of the stigma by unwanted pollen grains.
1.When the stigma of bagged flower becomes receptive, the collected pollen grains are dusted onto the stigma, the flower is rebagged and the fruits are allowed to develop.
2. If the female parent is unisexual, emasculation is not necessary. In this case, the female bud is directly bagged and when the stigma turns receptive, suitable pollen grains are dusted onto it so as to allow germination and the flowers are rebagged.

Tapetum is the innermost layer of the microsporangium. It produces the exine layer of the pollen grains, which is composed of the sporopollenin, the most resistant organic material. During microsporogenesis, the cells of tapetum produce various enzymes, hormones, amino acids and other nutritious materials required for the development of pollen grains.

Triple fusion:
It is  the process of fusion of three nuclei, two polar nuclei (fuse to form a diploid secondary nucleus) and a male gamete.
It occurs in the central cell of the embryo sac of the ovule of angiosperms.
Then nuclei involved are two polar nuclei and a male gamete.

(i) In coconut, endosperm formation is of nuclear type. The primary endosperm nucleus undergoes repeated nuclear division without cell wall formation.
(ii) Tender coconut is an endosperm. It is rich in nutrients like fats, proteins, carbohydrates, minerals, vitamins, etc. Hence, it is considered as a healthy source of nutrition.
(iii) Pea seeds are non-endospermic, while castor seeds are endospermic.

(i)

(ii)

(iii)

(iv)

1. The ovule is attached to the placenta by a short stalk called funiculus.
2. The junction between the funiculus and the ovule, is called hilum.
3. The primordium of the ovule grows into a mass of cells, forming the nucellus, the main body of the ovule.
4. It becomes surrounded by two protective envelopes called integuments, which leave a small opening called micropyle, at the tip of the ovule.
5. The basal part of the ovule (opposite to the micropyle) is called chalaza. Cells of the nucellus are rich in reserve food materials.
6. There is a single embryo sac/female gametophyte in the nucellus; it has developed from a megaspore.
7. The embryo sac contains the following cells:
(i) Three antipodal cells at the chalazal end.
(ii) Three cells at the micropylar end, forming egg apparatus, which consists of two synergids and a female gamete.
(iii) Two nuclei in the central cell, called polar nuclei, which fuse to form a diploid secondary nucleus.

Meiosis occurs during sporogenesis.
The structure formed at the end are microspores and megaspores respectively.

(a) A - Suspensor
B - Globular embryo
(b) (i) Zygote
(ii) Proembryo

(a) 200 ovules - each ovule becomes a seed after fertilisation; hence, 200 ovules will become 200 seeds.
(b) 200 megaspore mother cells- Though each megaspore mother cell forms four megaspores by meiosis, only one megaspore is functional and forms an embryo sac in an ovule.
(c) 400 male gametes - each ovule requires two male gametes for double fertilisation.

(a) A - Chasmogamous flower
B - Cleistogamous flower
(b) A - Autogamy, geitonogamy and xenogamy
B - Autogamy only.

(a) Megaspore
(b) Haploid
(c) (i) Filiform apparatus refers to the special cellular thickenings in the synergids, towards micropylar tip.
(ii) They play an important role in guiding the pollen tube to enter one of the synergids.

(a) Megasporangium
(b) (i) G. Funicle
(ii) B. Nucellus
(iii) E. Outer integument
(iv) A. Chalaza
(v)  C. Embryo sac.

(c) The body of the ovule consists of a mass of parenchymatous cells named nucellus. The nucellus is mostly consumed by the developing embryo sac or endosperm. But in some plants it persists in the mature seed as a nutritive tissue. The persistent nucellus is called perisperm.

(b) Both assertion and reason are true but reason is not the correct explanation of assertion

(c) The pollen wall comprises two principal layers, the inner one is called intine and the outer exine. The intine is pecto-cellulosic in nature as is the primary wall of the somatic cells. The exine is composed chiefly of a class of material called sporopollenin.

(b) Mostly all the four spores within a tetrad are completely isolated from one another and from the spores in other tetrads of the locule. Usually the microspores separate from one another shortly after meiosis. However, in some plants the spores tend to remain together in tetrads for longer period and develop into compound pollen grains. In many members of Orchidaceae and Asclepiadaceae all the microspores in a sporangium remains together to form what is called a pollinium.

(a) The sporogenous cells of anther may directly function as microspore mother cells (also called pollen mother cells or PMCs) or they may undergo a few mitosis to add up to their number before entering meiosis. Each PMC, by a meiotic division, gives rise to a group of four haploid microspores. The aggregates of four microspores are referred to as microspore tetrads.