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100 questions in this collection · Page 5 of 10
Question 41 of 100
📘 CLASS XII
Biodiversity And Conservation
Study the following statements regarding invasive plant species in India:
I. Carrot Grass (Parthenium), Lantana, and Water Hyacinth (Eichhornia) are invasive weed species that cause environmental damage and threaten native species. II. Eichhornia (Water Hyacinth) is an indigenous species that has successfully prevented alien species from invading Indian wetlands. III. These weeds pose a significant threat because they are highly nutritious and over-consumed by native herbivores.
Which of the statements given above is/are correct?
Statement I is correct. Parthenium, Lantana, and Water Hyacinth are invasive alien weeds. Statement II is incorrect because Eichhornia itself is an invasive exotic species. Statement III is incorrect because their threat arises from aggressive invasion rather than being over-consumed by herbivores.
Question 42 of 100
📘 CLASS XII
Biodiversity And Conservation
Evaluate the following statements regarding biological invasions in aquatic ecosystems:
I. The African Catfish Clarias gariepinus was introduced illegally for aquaculture purposes. II. This introduction is posing a threat to the indigenous catfishes in Indian rivers. III. Clarias gariepinus is a native Indian river catfish threatened by the illegal introduction of African Nile Perch.
Which of the statements given above are correct?
Statement III is incorrect because Clarias gariepinus is the African Catfish introduced into India and is itself the invasive species threatening native catfishes. Statements I and II are correct.
Question 43 of 100
📘 CLASS XII
Biodiversity And Conservation
With reference to co-extinctions, consider the following statements:
I. When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct. II. When a host fish species becomes extinct, its unique assemblage of parasites meets the same fate. III. Coevolved plant-pollinator mutualisms represent situations where the extinction of one partner has no effect on the other.
Which of the statements given above are correct?
Statements I and II are correct. Statement III is incorrect because in obligate plant-pollinator relationships, extinction of one partner generally results in extinction of the other.
Question 44 of 100
📘 CLASS XII
Biodiversity And Conservation
Read the following statements regarding habitat degradation and historical extinctions:
I. Besides total habitat loss, degradation of habitats by pollution also threatens the survival of many species. II. Marine fish populations are currently under-harvested, meaning commercial fishing has no impact on their populations. III. The extinction of the Passenger Pigeon in the last 500 years is a classic example of co-extinction driven by the loss of its host tree.
Which of the statements given above is/are correct?
Statement I is correct. Statement II is incorrect because many marine fish populations are overharvested. Statement III is incorrect because the Passenger Pigeon became extinct due to human over-exploitation, not co-extinction.
Question 45 of 100
📘 CLASS XII
Biodiversity And Conservation
Consider the following statements summarizing extinction patterns and future projections:
I. If the present trends of biodiversity loss continue, nearly half of all species on Earth might be wiped out within the next 100 years. II. The pre-human extinction rates were much faster than the rates of extinction witnessed today. III. Human activities are the primary driving force behind the accelerated rates of species extinctions.
Which of the statements given above are correct?
Statement II is incorrect because present extinction rates are estimated to be 100 to 1,000 times higher than pre-human rates. Statements I and III are correct.
Question 46 of 100
📘 CLASS XII
Biodiversity And Conservation
Consider the following statements regarding the "narrowly utilitarian" arguments for conserving biodiversity:
I. Humans derive direct economic benefits such as food, firewood, and fibre from nature. II. Industrial products like tannins, lubricants, dyes, resins, and perfumes are obtained from nature. III. This argument includes critical ecosystem services like pollination and oxygen production which are of indirect economic value.
Which of the statements given above are correct?
Statements I and II represent direct economic benefits and are classified under the narrowly utilitarian argument. Statement III is incorrect because pollination and oxygen production are ecosystem services that belong to the broadly utilitarian category dealing with indirect economic benefits.
Question 47 of 100
📘 CLASS XII
Biodiversity And Conservation
Study the statements regarding the medicinal importance of plants to human health:
I. More than 25 per cent of the drugs currently sold in the market worldwide are derived from plants. II. Exactly 10,000 species of plants contribute to the traditional medicines used by native peoples around the world. III. We have completely explored and catalogued all the medicinally useful plants in the tropical rain forests.
Which of the statements given above is/are correct?
Statement I is correct. Statement II is incorrect because about 25,000 plant species contribute to traditional medicines worldwide. Statement III is incorrect because many medicinally useful tropical rainforest plants are still undiscovered.
Question 48 of 100
📘 CLASS XII
Biodiversity And Conservation
With reference to bioprospecting, evaluate the following statements:
I. Bioprospecting refers to the exploration of molecular, genetic, and species-level diversity for products of economic importance. II. Nations endowed with rich biodiversity can expect to reap enormous benefits from bioprospecting. III. Bioprospecting is a key component of the broadly utilitarian argument for conservation since it relies on intangible aesthetic services.
Which of the statements given above are correct?
Statements I and II are correct. Statement III is incorrect because bioprospecting belongs to the narrowly utilitarian argument as it focuses on products of direct economic importance.
Question 49 of 100
📘 CLASS XII
Biodiversity And Conservation
Consider the following statements regarding the oxygen-producing service of the Amazon forest:
I. The fast-dwindling Amazon forest is estimated to produce, through photosynthesis, 20 per cent of the total oxygen in the Earth's atmosphere. II. Putting a precise economic value on nature's oxygen production is simple because hospitals spend a standardized, low amount on oxygen cylinders. III. This oxygen-generating role is a prime example of the narrowly utilitarian argument for conservation.
Which of the statements given above is/are correct?
Statement I is correct. Statement II is incorrect because assigning an exact economic value to global oxygen production is highly complex. Statement III is incorrect because oxygen production is a broadly utilitarian ecosystem service.
Question 50 of 100
📘 CLASS XII
Biodiversity And Conservation
Read the following statements about pollination as an ecosystem service:
I. Pollination is a crucial service that ecosystems provide, without which plants cannot produce fruits or seeds. II. Major natural pollinators include bees, bumblebees, birds, and bats. III. Accomplishing pollination artificially without the help of natural pollinators would be incredibly cheap and easily manageable.
Which of the statements given above are correct?
Statements I and II are correct. Statement III is incorrect because replacing natural pollination artificially would be extremely expensive and practically impossible on a global scale.