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Apomixis is a special mechanism found in flowering plants to produce seeds without fertilisation. It is a type of asexual reproduction which mimics the sexual reproduction and is commonly found in Citrus varieties.

Tapetum is the inner layer of microsporangium (anther) which provides nourishment to developing pollen grain after meiotic cell division.

Double fertilisation is the characteristic feature of angiosperms. In this type of fertilisation one male gamete fuses with an egg and forms zygote. The second male gamete fuses with diploid secondary nucleus of central cell to form a triploidy primary endosperm nucleus.

In angiosperms, functional magaspore develops into an embryo sac. The functional megaspore is the first cell of female gametophyte.

Dioecious flowering plants contain unisexual flower. In dioecious condition two types of unisexual flowers occur on different plants. Hence, it does not favour autogamy and geitonogamy because autogamy takes place in bisexual flowers and geitonogamy takes place between different flower of the same plant.

Attractants and rewards are required for entomophily (insect pollination). Flowers produce specific odour and nectar to attract the insect for effective pollination. Entomophilous flowers are large with bright colours.

Endosperm is formed from the primary endosperm nucleus. Its formation starts before the formation of embryo. Primary endosperm nucleus is produced by fusion of secondary nucleus and second male gamete. The endosperm is thus tripled (3n).

Pollination by insect is termed as entomophily. Insect pollinated flowers are usually bright coloured. Scented and have nectar that attracts insects towards them.

The process of pollination by wind is termed as anemophily. Such flowers are called as anemophilous flowers.

The process of fusion of egg with male pro-nucleus is called as fertilization. In it, haploid male and female gametes fuse to form a normal diploid offspring.

Those flowers which are pollinated by wind are called Anemophilous flowers. Such flowers are small, colourless and inconspicuous.

Endosperm contain three sets of chromosome i.e. they are triploidy (3 n ) in nature. It is formed by fusion of second male gamete with the two polar nuclei or secondary nucleus in the central cell.

Hydrophilic pollination occurs in both eichornea and hydrilla, while in lotus pollination is performed by insects.

Aril is a edible part of annona. In orange, it is mesocarp while in apple, it is thalamus.

The central cell of embryosac is called as secondary nucleus. This nucleus fuses with second male gamete during fertilization to from triploidy primary endosperm nucleus (PEN), that give rise to endosperm of seed.

Cleistogamy is a type of automatic self pollination of certain plants that can propagate by using non-opening, self-pollinating flowers.

The edible part of apple is thalamus. In orange, it is mesocarp while in annona it is aril.

The central cell of embryosac is called as secondary nucleus. This nucleus fuses with second male gamete during fertilization to from triploidy primary endosperm nucleus (PEN), that give rise to endosperm of seed. Thus (b) is correct option.

Cleistogamy is a type of automatic self pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. It is more common in grass family. Other examples are peanuts, peas etc. Thus (a) is correct option.

The edible part of apple is thalamus. In orange, it is mesocarp while in annona it is aril. Thus (b) is correct option.