402: The acidification of oceans is increasing. Why is this phenomenon a cause of concern?
1. The growth and survival of calcareous phytoplankton will be adversely affected.
2. The growth and survival of coral reefs will be adversely affected.
3. The survival of some animals that have phytoplanktonic larvae will be adversely affected.
4. The cloud seeding and formation of clouds will be adversely affected.
Which of the statements given above is /are correct?
(a) 1, 2 and 3 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2, 3 and 4
Explanation:
Ocean acidification is the name given to the on-going decrease in the pH of the earth's oceans, caused by the uptake of anthropogenic carbon dioxide (CO2) from the atmosphere. About a quarter of the carbon dioxide in the atmosphere goes into the oceans, where it forms carbonic acid.
Although the natural absorption of CO2 by the world's oceans helps mitigate the climatic effects of anthropogenic emissions of CO2, it is believed that the resulting decrease in pH will have negative consequences, primarily for oceanic calcifying organisms. These span the food chain from autotrophs to heterotrophs and include organisms such as coccolithophores, corals, foraminifera, echinoderms, crustaceans and molluscs. As described above, under normal conditions, calcite and aragonite are stable in surface waters since the carbonate ion is at supersaturating concentrations. However, as ocean pH falls, so does the concentration of this ion, and when carbonate becomes under-saturated, structures made of calcium carbonate are vulnerable to dissolution. Even if there is no change in the rate of calcification, therefore, the rate of dissolution of calcareous material increases.
There is also suggestion that a decline in the coccolithophores may have secondary effects on climate, contributing to global warming by decreasing the Earth's albedo via their effects on oceanic cloud cover.
Aside from calcification, organisms may suffer other adverse effects, either directly as reproductive or physiological effects 9e.g. CO2-induced acidification of body fluids, known as hypercapnia), or indirectly through negative impacts on food resources. Ocean acidification may also force some organisms to reallocate resources away from productive endpoints such as growth in order to maintain calcification.
403: Neem tree has acquired industrial importance as a source of
(a) biopesticide and anti-fertility compound
(b) anti-fertility compound, biofertilizer and anti-cancer drug
(c) biofertilizer, biopesticide and anti- fertility compound
(d) anti-cancer drug, biopesticide and biofertilizer
Explanation:
Neem (Azadirachta indica) acquired industrial importance as a source of biofertilizer (Neem coated urea), biopesticide (Neem guard, 4% Neem seed kernel extract) and antifertility compound (Against insect pest multiplication).
404: In the balanced dietaries for a day of an adult working man, weights of carbohydrate food and total protein food (both superior and inferior) should be in order of
(a) 600 gm and 420 gm respectively
(b) 600 gm and 600 gm respectively
(c) 420 gm and 600 gm respectively
(d) 420 gm and 420 gm respectively