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100 questions in this collection · Page 3 of 10
Question 21 of 100
📘 CLASS XII
Biodiversity And Conservation
Consider the value of the regression coefficient (Z) in species-area relationships under different spatial scales:
I. Regardless of the taxonomic group or region, the value of Z lies in the range of 0.1 to 0.2 for local or regional analyses. II. If the species-area relationship is analyzed across very large areas such as entire continents, the slope becomes much steeper. III. The Z value for continental-scale species-area relationships lies in the range of 0.6 to 1.2.
Which of the statements given above are correct?
All three statements are correct. Local or regional analyses generally yield Z values of 0.1 to 0.2, whereas continental-scale analyses produce much steeper slopes with Z values ranging from 0.6 to 1.2.
Question 22 of 100
📘 CLASS XII
Biodiversity And Conservation
Read the following statements regarding species-area relationship slope variations:
I. For frugivorous birds and mammals in the tropical forests of different continents, the slope of the species-area regression line is about 1.15. II. Steeper slopes (higher Z values) indicate that species richness increases much more slowly as the explored area expands. III. The slope of the regression line (Z) varies widely between 0.1 and 1.2 even within small, identical geographic boundaries depending on the plants studied.
Which of the statements given above is/are correct?
Statement II is incorrect because higher Z values indicate that species richness increases more rapidly with increasing area. Statement III is incorrect because within comparable local or regional areas, Z values are generally similar (0.1 to 0.2). Only statement I is correct.
Question 23 of 100
📘 CLASS XII
Biodiversity And Conservation
What are the key attributes of a stable biological community? Evaluate these statements:
I. A stable community must not show too much variation in productivity from year to year. II. It must be highly vulnerable to occasional natural disturbances to facilitate evolutionary turnovers. III. It must be highly resistant to invasions by alien species.
Which of the statements given above are correct?
Statement II is incorrect. A stable biological community should be resistant or resilient to occasional disturbances rather than highly vulnerable. Statements I and III are correct.
Question 24 of 100
📘 CLASS XII
Biodiversity And Conservation
Consider the findings of David Tilman's long-term ecosystem experiments:
I. Tilman used meticulously controlled indoor climate chambers for his long-term ecosystem plots. II. He discovered that plots with more species showed less year-to-year variation in total biomass. III. He demonstrated that increased diversity directly contributed to higher productivity.
Which of the statements given above are correct?
Statement I is incorrect because David Tilman conducted his long-term experiments using outdoor plots, not indoor climate chambers. Statements II and III are correct.
Question 25 of 100
📘 CLASS XII
Biodiversity And Conservation
With reference to the Rivet Popper Hypothesis proposed by Paul Ehrlich, identify the correct statements:
I. Paul Ehrlich, a Stanford ecologist, used this analogy to explain the importance of species diversity to ecosystems. II. In this analogy, the airplane represents the species, and the rivets represent the ecosystems. III. Popping rivets on the wings (key species driving major ecosystem functions) is a far more serious threat to flight safety than losing rivets on seats inside the plane.
Which of the options represents the correct statements?
Statement II is incorrect because the airplane represents the ecosystem and the rivets represent the species. Statements I and III are correct.
Question 26 of 100
📘 CLASS XII
Biodiversity And Conservation
Consider the following statements regarding the loss of biodiversity:
I. While there is no doubt about continuing species losses, new species are being rapidly added through natural speciation to balance Earth's biological wealth. II. The colonisation of tropical Pacific Islands by humans is said to have led to the extinction of more than 2,000 species of native birds. III. The biological wealth of our planet is declining rapidly, and the primary driver is clearly human activities.
Which of the statements given above are correct?
Statement I is incorrect because it is doubtful whether new species are being added through natural speciation rapidly enough to replace those being lost. Statements II and III are correct.
Question 27 of 100
📘 CLASS XII
Biodiversity And Conservation
Evaluate the following data points documented by the IUCN Red List (2004) regarding extinctions in the last 500 years:
I. It documents the extinction of exactly 784 species in the last 500 years. II. The list of extinct species includes 338 vertebrates, 359 invertebrates, and 87 plants. III. Invertebrates represent more than 80 per cent of these recorded extinctions.
Which of the statements given above are correct?
Statement III is incorrect because invertebrates account for 359 out of 784 extinct species (approximately 46%), not more than 80%. Statements I and II are correct.
Question 28 of 100
📘 CLASS XII
Biodiversity And Conservation
Pair the following recently extinct species with their respective geographical locations:
I. Dodo – Mauritius II. Quagga – Africa III. Thylacine – Australia IV. Steller's Sea Cow – Russia V. Three subspecies of tiger (Bali, Javan, Caspian)
Which of the pairings given above are correct?
All five pairings are correct. Dodo belonged to Mauritius, Quagga to Africa, Thylacine to Australia, Steller's Sea Cow to Russia, and Bali, Javan, and Caspian are the three recently extinct tiger subspecies.
Question 29 of 100
📘 CLASS XII
Biodiversity And Conservation
Consider the following statements about taxonomic patterns of extinction:
I. The last twenty years alone have witnessed the disappearance of 27 species. II. Extinctions across different taxonomic groups occur in a completely random pattern. III. Amphibians appear to be highly vulnerable to extinction compared to other taxonomic groups.
Which of the statements given above are correct?
Statement II is incorrect because extinctions are not random across taxonomic groups. Amphibians are among the most vulnerable groups. Statements I and III are correct.
Question 30 of 100
📘 CLASS XII
Biodiversity And Conservation
Read the following statements regarding species currently facing the threat of extinction worldwide:
I. More than 15,500 species worldwide are facing the threat of extinction. II. Presently, 12 per cent of all bird species and 23 per cent of all mammal species face the threat of extinction. III. Presently, 32 per cent of all amphibian species and 31 per cent of all gymnosperm species face the threat of extinction.
Which of the statements given above are correct?
All three statements are correct. More than 15,500 species are threatened globally, including about 12% of birds, 23% of mammals, 32% of amphibians, and 31% of gymnosperms.