Directions: In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
(c) If assertion is true but reason is false.
(d) If assertion is false but reason is true.
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Assertion : Genetic variation shown by the plant Rauwolfia vomitoria growing in different Himalayan ranges is very important economically.
Reason: The amount and variety of alkaloids present in this plant, change both between the Rauwolfia species and between the different strains of $R$. vomitoria.
(a) Rauwolfia vomitoria is a medicinal plant used in modern medicines because of the presence of certain alkaloids in its plant parts. This plant reveals genetic variation in different Himalayan ranges in terms of the potency and concentration of an active chemical. The amount and variety of these chemicals change both between the Rauwolfia species and between the different strains of R. vomitoria. Because of the increasing demand and decreasing natural resources, there is an attempt to develop new strains suitable for agricultural production.
Assertion : The species diversity present in a given community or habitat is referred to as alpha diversity.
Reason : Alpha diversity is usually expressed by species richness and species evenness in that community or habitat.
(a) Alpha diversity (within community diversity) is species diversity in a given community or habitat, a-diversity is dependent upon species richness and species evenness/ equitability. There is a lot of competition, adjustments and interrelationships amongst members of the same community. The number of species per unit area is called species richness. Number of individuals of different species represent species evenness or species equitability.
Assertion : Tropical regions have got a long evolutionary time for species diversification as compared to temperate regions.
Reason : Temperate regions have undergone frequent glaciations in the past whereas tropical regions have remained relatively undisturbed for millions of years.
(a) Speciation is a function of time. Temperate regions have undergone frequent glaciations in the past, due to which many species had been killed. However, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification.
Assertion : If the species-area relationships are analysed among very large areas like the entire continent, the value of Z, i.e., slope of line lies in the range of 0.1 to 0.2 .
Reason : The value of Z, i.e., slope of line of species area relationships lies in the range of 0.1 to 0.2 when analysis is done among small areas.
(d) Alexander von Humboldt observed that within a region, species richness (number of species per unit area) increases with increasing explored area, but only upto a limit. The relationship between species richness and area turned out to be rectangular hyperbola for a wide variety of texa such as birds, bats, freshwater fish or flowering plants. On a logarithmic scale, the relationship is a straight line.
\(
\log S=\log C+Z \log A
\)
Here \(S\) is species richness, \(Z\) is slope of line or regression coefficient, C is \(Y\) intercept while \(A\) is area.
The value of Z, i.e., slope of line (regression coefficient) of species-area relationships is similar and lies in the range of 0.1 to 0.2 when analysis is done among small areas. However, if the species area relationship is for very large areas like entire continent, the slope of the line is much steep with value of \(\)Z\(\) in the range of 0.6 to 1.2 , e.g., frugivorous birds and mammals of tropical forests of different continents with a steeper line of 1.15 . Thus larger the explored area, more is steepness of the slope of line.
Assertion : Species with low genetic variability are generally at greater risk of extinction than the species with more genetic variability.
Reason : Species with low genetic variability are more vulnerable to diseases, predators or other environmental challenges.
(a) Species with low genetic variability are generally at significantly greater risk of extinction than the species with more genetic variability, simply because they have a more limited arsenal with which to respond to the varieties of environmental change. Species with extremely low genetic variability are particularly vulnerable towards a new disease, predator or other environmental challenges, e.g., lack of genetic variability in the African cheetah (Acinonys jubatus) has been considered to be a significant factor contributing towards decline of cheetah population.
Assertion : Threatened species are those living species which have been greatly reduced in their number and are liable to become extinct if the causative factors continue.
Reason : IUCN is an international organisation which maintains the IUCN red list of threatened species, to assess the conservation status of different species.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion
Assertion: Critically endangered category Includes the species which have sufficient population at present but is undergoing depletion due to some factors.
Reason : Vulnerable species is not critically endangered but is facing a high risk of extinction in the wild in the medium term future.
(d) Critically endangered is the highest risk category assigned by the IUCN red list for wild species. Critically endangered species are those that are facing a very high risk of extinction in the wild and can become extinct any moment in the immediate future. ‘Vulnerable’ species are those whose population is sufficient at present but is undergoing depletion due to some factors so that it is facing the risk of becoming extinct in medium term future. In other words, a taxon is vulnerable when it is not critically endangered or endangered but is facing a high risk of extinction in the wild in the medium-term future.
Assertion: Over-exploitation of a species reduces the size of its population eventually leading to its extinction.
Reason : Steller’s sea cow is a large, herbivorous, terrestrial mammal which is on the verge of extinction due to over exploitation.
(c) Over exploitation or over-harvesting of a plant or an animal species reduces the size of its population leading to its extinction. Over-exploitation is one of the major causes threatening global biodiversity. Steller’s sea cow (Hydrodamalis gigas) was a large, herbivorous, marine mammal (largest member of the order- Sirenia) which had been discovered in 1741 and became extinct by 1768 . It is one of the few megafaunal mammal species to have died out during the historical period. It was over harvested for food, for skin, for its valuable subcutaneous fat, etc.
Assertion : The Nile perch introduced into lake Victoria in East Africa led to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake.
Reason: When alien species are introduced deliberately for economic or other uses, they often become invasive and cause extinction of indigenous species.
(a) If both assertion and reason are true and reason is the correct explanation of assertion
Assertion : Broadly utilitarian arguments say that we should conserve biodiversity because biodiversity plays a major role in many ecosystem senvices that nature provides.
Reason : Exploration of molecular, genetic and species level diversity to obtain the products of economic importance is included under broadly utilitarian category.
(c) We should conserve biodiversity for three reasons that have been included under three categories-narrowly utilitarian, broadly utilitarian and ethical. The broadly utilitarian arguments for conserving biodiversity say that biodiversity plays a major role in many ecosystem services that nature provides, e.g., replenishing \(O_2\) of atmosphere by plants, nutrient cycling, aesthetic value, etc. Bioprospecting [i.e., exploring molecular, genetic and species level diversity for products of economic importance) is included under narrowly utilitarian category, which is concerned with the countless direct economic benefits obtained from nature.
Assertion : Biodiversity hotspots are the regions which possess low levels of species richness, high degree of endemism and no loss to habitats.
Reason : Total number of biodiversity hotspots in the world is 34 with three of these hotspots found in India.
(d) Biodiversity hotspots are the regions characterised by very high levels of species richness, high degree of endemism and are also the regions of accelerated habitat loss. Initially 25 biodiversity hotspots were identified but subsequently nine more have been added to the list, bringing the total number of biodiversity hotspots in the world to 34 . Three of these hotspots, i.e., Western Ghats – Sri Lanka, Indo-Burma and Himalayas – cover our country’s exceptionally high biodiversity regions.
Assertion: Jim Corbett National Park is the first National Park of India and is famous for tigers.
Reason : Though the main focus is protection of wildlife, the reserve management has also encouraged ecotourism in this national park.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion
Assertion : In a wildlife sanctuary, collection of timber, harvesting of minor forest products and private ownership rights are allowed.
Reason : A sanctuary is a protected area meant for the conservation of both flora and fauna where cultivation of land is permitted.
(c) A wildlife sanctuary is a protected area which is eant for the conservation of only fauna. Human activities like harvesting of timber, collection of minor forest products and private ownership rights are allowed as long as they do not interfere with the well-being of animals.
Assertion: One of the most important traditional uses of sacred groves was that they acted as a repository for various ayurvedic medicines.
Reason: In modern times, sacred groves have become biodiversity rich areas, as they provide refuge to various plant and animal species of conservation significance.
(b) Step-by-Step Solution:
1. Understanding the Assertion: The assertion states that sacred groves served as repositories for various Ayurvedic medicines. This is true because sacred groves were traditionally protected areas where numerous medicinal plants thrived, which were essential for Ayurvedic practices.
2. Understanding the Reason: The reason provided states that in modern times, sacred groves have become biodiversity-rich areas that provide refuge for various plant and animal species of conservation significance. This is also true as sacred groves are recognized today for their ecological importance and role in conserving biodiversity.
3. Analyzing the Relationship: While both the assertion and reason are true, we need to determine if the reason correctly explains the assertion. The assertion focuses on the traditional use of sacred groves for Ayurvedic medicines, while the reason discusses their modern role in biodiversity conservation.
4. Conclusion: Since the reason does not directly explain why sacred groves acted as repositories for Ayurvedic medicines in the past, we conclude that both statements are true, but the reason is not the correct explanation of the assertion.
5. Final Answer: Therefore, the correct option is B: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
Assertion : Offite collections can be used to restock depleted populations, reintroduce species in the wild and restore degraded habitats.
Reason: In situ conservation refers to the conservation of endangered species in their natural habitats.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion
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