Control of foods and droughts:
1. Forests control flood by trapping and absorbing the rain water and slowly releasing it later.
2. The roots of plants hold the soil particles firmly and prevent soil erosion.
3. The forest cover prevents water directly falling on open soil.

One can go to place like sea shore in tropical region as Kerala.

Use of biodiversity in agriculture
1.As a source of new crops.
2. As a source of material for breeding varieties.
3. As a source of new biodegradeable pesticides.
Only 20% of total plant species are cultivated to produce 85% of world's food.
Wheat, corn and rice, the three major carbohydrate crops, yield nearly two third of the food sustaining the human population. Fats, oils, fibres, etc. are other uses for which more and more new species need to be investigated.

Pyrolysis is burning without oxygen. It consumes a large amount of energy. It is a very costly means of disposing of the wastes.

Increased concentrations of phosphates and nitrates from industries, residential wastes as well as from agricultural run off water into the water bodies result in excessive growth of algae which form a mat on the surface of water. This phenomenon is called algal bloom or eutrophication.
It affects the ecosystem in following ways:
(i) It decreases light penetration thus affecting photosynthesis.
(ii)  It result in depletion of dissolved oxygen resulting in death of  aquatic life.
(iii) Nitrates contaminate drinking water leading to decrease in  oxygen capacity of haemoglobin in human beings.

Ecologists make a statistical comparison of the species richness of systematically studied groups of insects of the temperate and tropical regions and extrapolate this ratio to the other groups of animals and plants. This is how they calculate the gross estimate of the total number of species existing on this planet.

Hotspots are the regions with high endemism. The endemic species are mostly rare and its crucial to conserve them. Hence, the areas with high endemism are chosen as hotspots and given high protection.

National parks are the biosphere reserves maintained by the government for the betterment & protection of wildlife where grazing, cultivation & forestry is not allowed. While sanctuaries are the tracts of land where animals can take refuge & they are protected. In sanctuaries the activities like tilling of land harvesting of timber collection of forest product etc. are allowed.

Uses of biodiversity.
1. As source of food and improved varieties.
2. As source of drugs and medicines.
3. Aesthetic and cultural benefits.
Examples of aesthetic rewards include ecotourism, bird watching, wildlife, pet keeping, gardening, etc. Throughout human history, people have related biodiversity to the very existence of human race through cultural and religious beliefs.
4. Biodiversity is essential for the maintenance and sustainable utilization of goods and services from ecological system as well as from individual species.

Earth's rich biodiversity is vital for the very survival of mankind. The reasons for conserving biodiversity are narrowly utilitarian, broadly utilitarian and ethical. Besides the direct benefits (food, fibre, firewood, pharamaceuticals, etc.), there are many indirect benefits we receives through ecosystem services such as pollination, pest control, climate moderation and flood control. Each and every living being has some intrinsic value. We derive countless economic benefits from the living things. Living things play a major role in many ecosystems. All the species in the ecosystem are interlinked. When a species becomes extinct, the plant and animal species associated with it in an obligatory way also becomes extinct. When a host fish species becomes extinct, its unique assemblage of parasites also meets the same fate. Another example is the case of coevolved plant-pollinator mutualism where extinction of one leads to extinction of the other.