Describe the consumptive use value of biodiversity as food, drugs and medicines, fuel and fibre with suitable examples.
Biological resources are the basis of life forms on this planet. The countries with maximum biodiversity possess better potential to compete with the rest of the world. Biodiversity has great economic importance to mankind due to its many uses, some of, which with consumptive value are following
Food is obtained from biodiversity sources like livestock, forestry and fish. Biodiversity in modern agriculture is beneficial due as a source of new crops. e.g., just three cereals crop like wheat, rice and maize account for about $55 \%$ of protein and $60 \%$ of calories in humans.
Drugs such as morphine (Papaver somniferum), quinine (Cinchona ledgeriana), reserpine (Rauwolfia vomitaria), belladonna (Atropa belladonna), aconite (Aconitum, napellus), wintergreen and birth bark (Gaultheria procumbens) are derived from plants.
About $70-80 \%$ of entire population is dependent on plants or its extract for medicine. penicillin (Penicillium notatum), tetracycline (bacteria), digitalin (Digitalis) are some examples of medicinal plants.
Plant like Chorchorus, Gossypium are sources of fibre while Jatropha is a source of biofuels. Fossils fuels (e.g., petrolum) are obtained from fossils of organisms.
Species diversity decreases as we move away from the equator towards the poles. What could be the possible reasons?
Species diversity decreases as we move towards the poles, because
(i) Temperature decreases and conditions become harsh.
(ii) Both the amount and intensity of solar radiation decreases.
(iii) Vegetation decreases.
(iv) Less resources available to support species.
Speciation is generally a function of time and environmental stability, so if conditions are too harsh, it is difficult for the species to survive and adapt. This results in decrease in biodiversity towards the poles.
Explain briefly the 'rivet popper hypothesis' of Paul Ehrlich.
Ecologist Paul Ehrlich gave rivet popper hypothesis to help understand the contribution species richness. He compared each species with rivet in the body of an airplane.
(i) This hypothesis explains that ecosystem to be an airplane and the species to be the rivets joining all parts together.
(ii) If every passenger travelling in the airplane start taking rivets home (causing a species to become extinct), initially it may not affect flight safety (proper functioning of ecosystem), but over a period of time the plane becomes weak and dangerous (species become endangered and then extinct.
The relation between species richness and area for a wide variety of taxa turns out to be a rectangular hyperbola. Give a brief explanation.
According to AV Humboldt, a German scientist within, a region, species richness increased with increasing explored area (only upto a limit). Accordingly the relation between species richness and area for a wide variety of taxa (birds, bat, angiosperms, aquatic fishes) turns out to be a rectangular hyperbola.
The relationship depicts a straight line on a logaithimic scale described by the following equation
$$ \log S=\log C+Z \log A $$
Where, ' $S$ ' stands for species richness, ' $A$ ' is area and ' $Z$ ' and ' $C$ ' are slope of line (regression coefficient) and y intercept respectively.
