Class 12 Biology Chapter 13 Biodiversity And Conservation

Key Concept:Tropical Biodiversity

b) More solar energy
[Solution Description] One of the key factors contributing to higher biodiversity in the tropics is more solar energy, which enhances primary productivity leading to greater species richness.

Key Concept:Historical Extinctions

c) Five
[Solution Description] Before the current Sixth Mass Extinction, there were five major mass extinction events known from the geological record. These events drastically reduced biodiversity on Earth at various points in history.

Key Concept:Intrinsic vs. Utilitarian

b) It represents the inherent worth of a species, without considering its utility.
[Solution Description] The intrinsic value of a species refers to its inherent worth, independent of any economic or utilitarian benefits. This concept is based on the philosophical belief that every species has value in and of itself, regardless of its usefulness to humans.

Key Concept:Ecosystem Functions

d) Coral reefs
[Solution Description] The function that maintains the oxygen balance and supports marine life involves photosynthesis, where plants and certain algae produce oxygen as a byproduct. Coral reefs house numerous algae (zooxanthellae) which perform photosynthesis, making them critical to this function.

Key Concept:Speciation Factors

c) Longer evolutionary time
[Solution Description] Tropical areas experience more stable climates over long periods, which allows species to evolve and adapt without drastic environmental changes disrupting the process. This stability provides an opportunity for natural selection to act over extended timescales, facilitating diversification.

Key Concept:Conservation Challenges

b) Limited conservation resources
[Solution Description] Countries often face limited financial resources, which make it challenging to allocate sufficient funds for conserving all aspects of their biological wealth. The prioritization of certain species or ecosystems becomes necessary due to budget constraints.

Key Concept: Biodiversity Hotspots

b) To focus on conservation efforts

[Solution Description] Biodiversity hotspots are regions with significant levels of biodiversity that are under threat from human activities. The primary purpose of identifying these areas is to prioritize them for conservation efforts due to their high species richness and the immediate risk of habitat degradation or loss.

Key Concept:Basic Definition

b) Decline of native species
[Solution Description] Invasive alien species often outcompete native species for resources, leading to their decline or extinction.

Key Concept:Fact Identification

d) Tropical rainforests
[Solution Description] According to the syllabus, tropical rainforests are significantly affected by habitat loss due to their dense biodiversity and large area requirements for species.

Key Concept:Role of Hotspots, Cultural Impact

c) By establishing sacred groves that serve as biodiversity reserves.
[Solution Description] Cultural traditions in the Indo-Burma region often include practices like maintaining sacred groves which are patches of forest preserved for religious or cultural reasons. These groves act as refuges for various plant and animal species, thereby promoting biodiversity through habitat protection without direct scientific intervention. Such culturally driven conservation methods complement formal conservation efforts by preserving genetic reservoirs.

Key Concept:Predictive Analysis, Real-World Application

c) Enhancing international cooperation and policy-making for habitat protection.
[Solution Description] A comprehensive approach involving habitat preservation, stringent enforcement of anti-poaching laws, and public education on sustainable practices would likely be most effective. These efforts must be combined to address the root causes of biodiversity decline effectively and sustainably.

Key Concept:Process Understanding

c) Embryo transfer
[Solution Description] In vitro fertilization (IVF) involves several steps including the collection of eggs and sperm, fertilization outside the body, and the transfer of embryos to a surrogate mother. A critical step is embryo transfer because it ensures that the fertilized egg is placed into a suitable environment for development into a viable offspring.

Key Concept:Mega Diversity Countries

c) Diverse ecosystems
[Solution Description] India is recognized as one of the 12 mega diversity countries due to its high species richness and genetic diversity, which includes nearly 45,000 plant species and twice that number in animal species. It is not only the quantity but also the wide variety of ecosystems present in India that contribute significantly to its biodiversity. Therefore, the presence of diverse ecosystems across different geographic regions in India plays an important role in making it a mega diversity country.

Key Concept:Initiative Identification

b) Sustainable utilization of biodiversity benefits
[Solution Description] The Convention on Biological Diversity in 1992 emphasized initiatives focused on the conservation of biodiversity and sustainable utilization of its benefits. It highlighted sustainable development as a core approach to conserving biological resources while maintaining ecological balance.

Key Concept:Comparative Analysis

c) Biosphere reserves often integrate human communities focusing on sustainable development, whereas national parks have stricter limitations on human activity.
[Solution Description] Biosphere reserves are larger areas that include multiple ecosystems for conservation, research, and sustainable use, whereas national parks focus particularly on protecting wildlife and their habitats with a higher level of restriction. Given this differentiation, the statement that biosphere reserves support a broader scope including human settlements and sustainable development is correct.

Key Concept:Agreements and Protocols

c) Agenda 21
[Solution Description] The Earth Summit resulted in several critical agreements focused on sustainable development, including Agenda 21, which is a comprehensive plan designed to be implemented at local, national, and global levels to foster sustainable growth and protect the environment.

Key Concept: Latitudinal Gradients, Ecosystem Stability

c) Equatorial regions experience high species diversity which enhances ecosystem resilience.

[Solution Description] Latitudinal gradients refer to the increase in biodiversity from the poles towards the equator. As species diversity increases with latitude, ecosystems tend to exhibit greater resilience and stability due to a higher variety of interactions among different species. This is because diverse communities can better withstand environmental changes and disturbances.

Key Concept:Critical Rivets

c) Loss of key species is equivalent to losing structural integrity in an airplane.
[Solution Description] The rivet popper hypothesis suggests that key species are analogous to critical rivets on an airplane’s wings. Their removal can severely affect ecosystem function or stability, similar to how losing a rivet from a wing could compromise flight safety.

Key Concept:Comparison with In Situ

c) Ex situ conservation involves human intervention
[Solution Description] Ex situ conservation involves human intervention to remove species from their natural habitats and conserve them elsewhere, unlike in situ conservation, which takes place within their natural environments.

Key Concept: Intermediate Analogy

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

[Solution Description] According to the ‘rivet popper hypothesis’, each species plays a critical role in maintaining an ecosystem’s stability, similar to how each rivet supports an airplane’s structure. If critical species, also known as keystone species, are lost, it can lead to significant consequences. Both assertion and reason highlight the importance of every species; however, the reason focuses on the impact of losing key species specifically. Therefore, while both statements are true, the reason does not directly explain the assertion regarding the general concept of ecosystem stability involving all species.

Key Concept:Historical Context

c) It adopted the Convention on Biological Diversity, setting concrete goals for conserving biodiversity globally.
[Solution Description] The Earth Summit, held in 1992, led to the adoption of the Convention on Biological Diversity, which established international commitments to conserve biological diversity, promote sustainable development, and ensure fair distribution of benefits from genetic resources.

Key Concept:Application of Formula

c) 57
[Solution Description] To find $C$, we start with the equation:
$$
\log S = \log C + Z \log A
$$
Substituting values, we have:
$$
\log 150 = \log C + 0.3 \times \log 25
$$
Calculating the logarithms,
$$
\log 25 = 1.39794
$$
$$
\log 150 = 2.17609
$$
Now substitute these into the equation:
$$
2.17609 = \log C + 0.3 \times 1.39794
$$
Simplifying,
$$
2.17609 = \log C + 0.419382
$$
Solving for $\log C$:
$$
\log C = 2.17609 – 0.419382 = 1.756708
$$
Hence,
$$
C = 10^{1.756708} \approx 57
$$
The Y-intercept $C$ is approximately 57.

Key Concept:Consequences of Overexploitation

c) Reduction in fish stock diversity
[Solution Description] Overexploitation in marine ecosystems often leads to a reduction in biodiversity, destabilizing these systems. This typically manifests as reduced population sizes and even extinction of key species that play crucial roles in maintaining ecological balance.

Key Concept:Basic Benefits

a) Food
[Solution Description] Direct economic benefits from biodiversity include food, firewood, fibre, construction materials, industrial products, and medicinal products.

Key Concept:Cryopreservation

c) It allows for long-term storage without genetic degradation.
[Solution Description] Cryopreservation involves freezing biological samples at very low temperatures, allowing for long-term storage without degradation, which helps preserve the genetic material of rare or endangered plants effectively for future use.

Key Concept: Conceptual Understanding

c) By enhancing adaptability and recovery

[Solution Description] Species diversity contributes to ecosystem resilience by providing a variety of responses to environmental changes, thereby stabilizing ecosystem processes despite disturbances. Diverse communities are more likely to contain species that can thrive and maintain ecosystem functions when conditions change.

Speciation Factors

d) Fungi have more species than all vertebrate species combined
[Solution Description] Based on the syllabus, fungi have more species than all vertebrate species combined. Thus, d) is the correct option.

Key Concept:Service Impact

b) Decreased fruit production
[Solution Description]
Bees are crucial for the pollination process which leads to fruit and seed production. Without bees, many crops would face decreased yields due to lack of effective pollination.
This could lead to decreased fruit production directly affecting agriculture economics and food supply.

Key Concept:Historical Extinctions

c) Co-extinctions
[Solution Description] Co-extinctions occur when the survival of one species is intricately linked with that of another. If one becomes extinct, its dependent species may also face extinction.

Key Concept:Species Distribution

c) Species diversity decreases from the equator towards the poles.

[Solution Description] Species diversity is known to be higher in tropical regions and tends to decrease as one moves away from the equator towards the poles. This pattern is due to several factors, including climate stability and energy availability in the tropics.

Key Concept: Hypothetical Scenario

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

[Solution Description] According to the ‘rivet popper hypothesis’, each species in an ecosystem is akin to a rivet in an airplane; losing a few may not cause immediate damage, but losing too many can lead to catastrophic failure. Therefore, the loss of a key species can lead to significant instability because every species contributes uniquely to the ecosystem’s structure and functioning.

Key Concept:Ecosystem Stability

d) It suggests that each species plays a critical role in maintaining ecosystem function, and losing too many can destabilize it.
[Solution Description] According to the ‘rivet popper hypothesis’, the loss of a few species may not immediately disturb an ecosystem, but continuous losses could jeopardize its stability, much like rivets holding together an airplane wing.

Key Concept:Global Initiatives

b) Earth Summit
[Solution Description] The Earth Summit, held in Rio de Janeiro in 1992, led to the Convention on Biological Diversity (CBD), which emphasizes the conservation of biodiversity, sustainable use of its components, and fair sharing of benefits arising from genetic resources.

Species-Area Relationship

d) It increases
[Solution Description] As per the species-area relationship, species richness increases with an increase in area. This means that larger areas tend to have more species.

Key Concept:Example Recognition

b) Host fish and its parasites
[Solution Description] An example of co-extinction is the extinction of host fish leading to the extinction of its parasites because the parasites depend entirely on their host for survival.

Key Concept:Policy Implications

c) Sustainable utilization of biodiversity benefits
[Solution Description] The World Summit on Sustainable Development highlighted several policy implications to address biodiversity issues. Among them, the emphasis was on the sustainable utilization of biodiversity benefits. This approach advocates for using biodiversity resources responsibly to ensure long-term ecological balance and availability.