Q4. What is the difference between the IUCN categories Extinct and Extinct in the Wild? Give NCERT’s example of where the second kind survives.
Extinct: no reasonable doubt that the last individual has died, based on appropriate evidence and surveys. Extinct in the Wild: known only in captivity, cultivation or naturalised populations well outside its past range; appropriate surveys support its absence from the wild historic range (IUCN, facts in our words). NCERT notes that many animals that have become extinct in the wild continue to be maintained in zoological parks (NCERT page 225).
Q5. Why is Data Deficient not a threat category?
Because it records a lack of information, not a level of risk: there are too few data on the species’ numbers or distribution to judge its risk of extinction. Further study may show that it belongs in a threatened category, or that it does not (IUCN, facts in our words).
Q6. Name the five criteria by which the IUCN decides whether a species is critically endangered, endangered or vulnerable.
(A) a reduction in population size; (B) a small geographic range; (C) a small population that is declining; (D) a very small or very restricted population; (E) a quantitative analysis of the probability of extinction. Meeting one complete criterion, including required thresholds and subconditions, can qualify the taxon; merely having a small range or a decline is not enough (IUCN, facts in our words).
Q7. Using NCERT’s IUCN figures, what share of the 784 recorded extinctions of the last 500 years are vertebrates, and how many more invertebrates than vertebrates were lost?
338 ÷ 784 ≈ 0.43, about 43 per cent; invertebrates exceed vertebrates by 359 − 338 = 21 species (our arithmetic from NCERT page 221).
Q8. Which Indian organisation published the Red Data Book of Indian Plants, and in how many volumes?
Beyond the NCERT text: the Botanical Survey of India, in three volumes (1987, 1988 and 1990), edited by M. P. Nayar and A. R. K. Sastry (Journal of Threatened Taxa, CC BY 4.0, facts in our words). The Zoological Survey of India published The Red Data Book on Indian Animals (Internet Archive catalogue, facts only).
Q9. NCERT says “organisms facing a very high risk of extinction in the wild in the near future” are endangered or threatened. How do the IUCN’s terms differ?
In the IUCN’s scheme a very high risk of dying out in the wild marks one category, Endangered; threatened is the name for three categories together, Critically Endangered, Endangered and Vulnerable (IUCN, facts in our words; NCERT page 224).