State four features of flowers pollinated by insects.

Insects are the major biotic agent of pollination. Insect pollination is termed entomophily. The adaptations of insect-pollinated flowers are as follows: These flowers are large and colourful. They produce fragrance and nectar to attract insects. The flowers produce sticky pollen grains that are attached to the body of the insects during their visit. Some species provide a safe place for insects to lay eggs in flowers.

Give a reason for the following. Pollen grains of wind pollinated flowers are produced in large quantities.

Pollination is the transfer of pollen from an anther of a plant to the stigma of another plant, later enabling fertilisation and the production of seeds. The method of pollination can be biotic or abiotic. Biotic pollination relies on living pollinators to move the pollen from one flower to another, whereas abiotic pollination relies on wind, water or even rain. Wind pollinated flowers produce pollen grains in a huge quantity because much pollen may be wasted on the way. So to ensure the chance of pollination, pollen grains of wind-pollinated flowers are produced in large quantities.

Define parthenocarpy.

Parthenocarpy, also called stenospermocarpy, refers to natural or artificially induced production of fruit without fertilisation of ovules, whose result is the formation of seedless fruits. Naturally, it occurs as a result of mutation. Parthenocarpy can be valuable also as these fruits can serve as a "decoy defence" against seed predation. It also provides foods for the plant's seed dispersers. Parthenocarpy is of two types, which are vegetative parthenocarpy and stimulative parthenocarpy.

Draw a labelled diagram of the mature embryo sac of angiosperms.

A mature embryo sac consists of three cells in the micropylar region, known as egg apparatus. It consists of one egg cell or a female gamete and two synergids. Three cells are present in the chalazal region are called antipodals. The central cell is the largest cell in the embryo sac that contains two polar nuclei which later fuse to form a diploid secondary nucleus.

What is emasculation?

Emasculation can be best defined as the removal of male reproductive parts (anthers) from a bisexual flower without affecting the female parts (pistil) before the anthers mature. This method is used for preventing self-pollination (transfer of pollen grains from the anther to the stigma of the pistil of the same flower) in a bisexual flower.