Plant Kingdom

A gametophyte is the plant that produces gametes. The fern gametophyte is a small, bisexual, heart- shaped plant called a prothallus. Sporophyte is the asexual and usually diploid phase that produces spores from which the gametophyte arises. A fern gametophyte prothallus is independent from sporophyte.

The gametophytic generation represents the dominant phase in the life cycle of bryophytes. The sporophyte phase is dependent on the gametophyte. This is the reason the plant body of Funaria moss is predominantly gametophytic with dependent sporophyte.

Azolla is a pteridophyte and used as a biofertilizer because it has association with nitrogenfixing cyanobacteria Anabaena azollae.

In Gymnosperms, ovule lacks ovary and ovary wall that forms fruit after maturation in Angiosperms.

Gymnosperms are seed bearing vascular plants, such as cycads, ginkgo, yews and conifers in which the ovules or seeds are not enclosed in an ovary. 

About 70 Genera and 730 species of gymnosperms exist. Therefore, option 'c' is the nearest to 730 and should be considered correct.

Turpentine is a fluid obtained by the distillation of resin from Pinus pinaster trees.

Spirulina is a blue-green algae. Spirulina platensis is one of the richest source of protein, containing 40-50 percent crude protein on dry weight basis which under favourable condition may reach upto 70 percent. Its protein has balanced composition containing all essential amino-acids and lysine and tryptophan being present in sufficient quantities.

It is also rich in vitamins, particularly Vit. B₁₂ which is not common in plant products and contains considerable amounts of fats, carbohydrates and minerals. It's lipids are made up of unsaturated fatty acids that do not form cholesterol.

Lycopodium, a pteridophyte is commonly known as 'club moss'.

Maximum solar energy is trapped by algae and hence they evolve maximum amount of oxygen by the process of photosynthesis. Therefore, algae are useful because they purify the atmosphere by releasing oxygen.

Pneumatophores are the aerial roots that grow vertically upwards in swampy plants like rhizophora to obtain oxygen as swampy plants are constantly submerged under water. Their main function is respiration, hence, they are also called as respiratory roots.