(a) The cleistogamous flowers remain closed and never open. They are bisexual. Therefore, this condition of flowers i.e., cleistogamy ensures autogamy i.e., the transfer of pollen from the anther to the stigma of the same and single bisexual flower e.g., Commelina and Viola.
b) The main advantage of cleistogamy is that also guaranted or assured pollination and therefore, fertilization and seed setting.
The main disadvantage of cleistogamy is that variants cannot be produced due to autogamy. It results in poor crop yield and poor resistance to environmental stresses.

Sugar Cane

Functions of fruits
1.Protection of seeds in the early stages till they become fully mature.
2. Dispersal of seeds.
3. On their decay provide raw material for the benefit of new seedling.
4. Many fruits are consumed by human beings as food and is source of glucose and pectin.

Micropyle is the opening left by the integuments at the trip of the ovule; this remains as an opening on the seed coat.
It facilitates the entry of oxygen water during seed germination.

Biotic agents of pollination:
(i) Insects like butterflies, bees, wasps, etc.
(ii) Birds like humming bird.
(iii) Bats
(iv) Lemurs
(v) Arboreal rodents.

Tapetum is the innermost wall layer of the microsporangium.
It nourishes the developing pollen grains.
Characteristics of tapetal cells:
(i) They possess dense cytoplasm.
(ii) They have more than one nucleus.

1. Since geitonogamy involves two different flowers of the same plant, it is genetically similar to autogamy; both autogamy and geitonogamy do not result in genetic variation in the progeny.
2. Geitonogamy and cross-pollination involve different flowers and a pollinating agent.

A zygote is the product of syngamy, it is formed by the fusion of a haploid male gamete and a haploid female gamete, i.e., egg cell.
\(\underset { (n) }{ Male\quad gamete } +\underset { (n) }{ Egg } \rightarrow \underset { (2n) }{ Zygote } \)
A primary endosperm cell is the product of the fusion of a secondary nucleus (2n) and a haploid male gamete (n).
\(\underset { (2n) }{ Secondary\\ nucleus } +\underset { (n) }{ Male\\ gamete } \rightarrow \underset { (3n) }{ Primary\quad endosperm\quad nucleus } \)

Two species (Saccharum barberi and Saccharum officinarum) were crossed to get sugarcane varieties with high yield/thick stem/high sugar content) ability to grow in North India.

(a) A = Haustorium
B = Suspensor
C = Cotyledons
D = Plumule
E = Radicle
(b) Function of A is absorption of nourishment from embryosac and function of B is translocation of nutrients to the developing embryo.

(a) Ovary is superior
(b) Flower is hypogynous because all the floral arise from thalamus below the level of ovary
(c) Ovule is anatropous because it is completely inverted. The micropyle is near the hilum and faces down towards the placenta.The embryo sac is straight.
(d) The ovary of the flower gets converted into fruit after fertilization.
(e) A = Stigma, B = Style, C = Ovary and D = Ovule 

The three parts of a pistil and their functions are:
(i) Stigma - it acts as the platform where the pollen grains are lodged during pollination.
(ii) Style - it exposes the stigma for easy pollination.
(iii) Ovary - it encloses the ovule(s) inside which is the female gametophyte.

1. Embryo sac develops from a megaspore, which is formed after meiosis in a megaspore mother cell; so it is haploid.
2. Zygote is formed by the fusion of two haploid gametes (a male and a female); hence it is diploid.
3. Endosperm is formed by triple fusion, i.e. fusion of two haploid polar male gamete; hence it if triploid.

Vallisneria is pollinated by water.
Water lily is pollinated by insects.
In Vallisneria, the male flowers (later pollen grains) are released on the surface of water and keep floating.
The female flowers reach the surface of water by uncoiling of the long stalk
When the passively carried male flowers/pollen grains meet the female flowers, pollination is effected.
The stalk of the female flower coils and the flower is drawn inside the water column.

(a) In angiospermic embryo sac, two fusions, syngamy and triple fusion, occur. Therefore, this is known as double fertilization.
In this process, one of the male gametes moves towards the egg cell and fuses with it, this fusion is called syngamy and it results in the formation of a diploid cell, the zygote, that later develops into the embryo.
The second male gamete fuses with the secondary nucleus to form a triploid primary endosperm nucleus. This fusion is called triple fusion.
Ploidy of cells:
Endosperm cell - triploid
Fertilized egg cell - diploid
Synergids - haploid
Antipodals - haploid
(b)

Each cell of sporogenous tissue, functions as microspore mother cells  \(\rightarrow \) meiosis/ microsporogenesis,  \(\rightarrow \) microspore tetrad  \(\rightarrow \)  4-pollen grains (male gametophyte) 2-celled stage
See Quick Review  \(\rightarrow \) Microsporogenesis

(i) Keeping in view the market demands, same quality of product can be assured by vegetative propagation as there is no meiosis involved in this type of propagation.
(ii) As meiosis occurs in sexual reproduction, there is crossing over and new combinations are formed.These recombinations may have desirable traits from commercial point of view such as high yield, disease resistance, novel taste, shape etc.
(iii) Monu's father wanted to remove his son's misconcepts and , therefore, enhanced his knowledge by giving him scientific explanation.

A typical microsporangium is surrounded by four wall layers, i.e. the epidermis, endothecium, middle layers and the tapetum. The outer three wall layers are protective in function and help in dehiscence of anther to release pollen grains.
The innermost layer (tapetum) nourishes the developing microspores or pollen grains. The cells of tapetum possess dense cytoplasm and generally have more than one nucleus.

When the anther is young, a group of compactly arranged homogenous cells called the sporogenous tissue occupies the centre of each microsporangium.

(i) part that develops into seed coat integuments
(ii) part that develops into an embryo after fertilization-egg
(iii) that develops into endosperm in a albuminous seed-polar nuclei
(iv) through which pollen tube enters into embryo sac-micropyle
(v) that attaches the ovule to the placenta funiculus.

(a) Differences: 

(b) Pollen-Pistil Interaction.
The stigma/pistil has the ability to recognise the right type of pollen, i.e. the compatible pollen of the same species and rejects the wrong type of pollen grains.
It is the result of interaction between the chemical components of the pollen and those of stigma. - A compatible pollen grain starts its germination on the stigma.
The intine grows out through one of the germ pores as a protuberance.
The contents of the pollen move into this tube, i.e. the tube nucleus (nucleus of the vegetative cell) and the generative cell (or the two male gametes in those species where pollen is liberated in the three-celled stage).
The pollen tube grows through the tissues of stigma and style and enters the ovule through micropyle.
It enters the embryo sac through the filiform apparatus of one of the synergids to liberate the male gametes.
The events from the deposition of pollen on the stigma till the pollen tube enters the ovule, are collectively referred to as pollen-pistil interaction.