Draw a well-labelled diagram of an angiospermic ovule showing porogamous type of pollen germination.

The ovule is the megasporangium in the flowering plants. It contains an embryo sac, which is formed from the functional megaspore. The ovule is attached to the placenta through a stalk known as a funicle. The embryo sac is enclosed within the nucellus, which in turn is covered by the protective layers called integuments.

Give the characteristic features of anemophilous flowers.

The transfer of pollen grains from the anther to the stigma, a part of the carpel of the flower, taking place with the help of wind is called anemophily. The wind-pollinated plants are called anemophilous plants. Anemophilous plants possess certain adaptations in their flowers to favour this process. These are called floral adaptations for anemophily. These are as follows: The flowers of wind-pollinated plants are small without bright colours, sweet nectar, and fragrance. In the case of unisexual flowers, the male flowers are more numerous than females and are situated at a higher level. Stamens are with long filaments, versatile, and exposed anthers. Pollen grains are produced in extremely large numbers to compensate for their wastage. Pollen grains are light weighted and nonsticky. Flowers possess long style bears large feathery or hairy stigma to trap pollen grains.

Explain different types of endosperm with suitable diagrams.

The endosperm is the triploid structure that provides nourishment to the developing embryo. It is formed by the triple fusion of male gamete with two polar nuclei. Based on the process of development, there are three types of endosperms: i) Nuclear ii) Cellular and iii) Helobial endosperm i) Nuclear Endosperm— In this type of endosperm development, the primary endosperm nucleus forms many nuclei by free nuclear division. These nuclei get arranged on the periphery and a large vacuole is formed. It becomes cellular after some times by the formation of cell walls around the nuclei. The coconut water is an example of a nuclear type of endosperm. ii) Cellular Endosperm— In this type of endosperm development, the primary endosperm nucleus divides into two nuclei and a cell wall is formed between these two nuclei. Each subsequent nuclear division is followed by cell wall formation. Example: Members of Gamopetalae class ( Verbascum) . iii) Helobial Endosperm— This type of endosperm is of intermediate one of both the types of endosperms. In this type, the first division of the primary endosperm nucleus is followed by wall formation resulting in the formation of a large and a small cell. In the small cell, lying towards the chalazal end, free nuclear divisions take place and the cell wall formation does not occur. In the larger cell lying towards micropyle, each nuclear division is followed by cell wall formation. Thus, it is a mixed form of nuclear and cellular type of endosperm. Example: Members of the order Helobiales of monocot plants.

The formation of new plants from an embryo without meiosis and fertilization is called apomixis. According to Hans Winkler (1908), "Replacement of general sexual reproduction by any such method in which meiosis and fertilization do not occur is termed apomixis." In this method, the embryos are formed from haploid cells present in the embryo sac like egg, synergids, etc., or from diploid cells in the ovule like nucellus, integuments, etc. The plants formed by apomixis are either haploid or diploid in nature. Examples: Datura , Maize, etc.

What are the characters of flowers pollinated by insects?

The characteristics of flowers pollinated by insects are : Flowers are large. To attract insects, they are bright-coloured. Sticky or spiny nature of pollens enables them to be carried easily by insects. Emit scent/fragrance to attract insects. These flowers synthesise nectar that serves as food for insects.