Biodiversity and Conservation - Class 12 Biology - Chapter 13 - Notes, NCERT Solutions & Extra Questions
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Extra Questions - Biodiversity and Conservation | NCERT | Biology | Class 12
The skeleton of corals is formed of:
A) Silica
B) Calcium carbonate
C) Chitin
D) Spongin fibres
The correct answer is Option B: Calcium carbonate. Coral skeletons are primarily composed of calcium carbonate (CaCO3), which provides them with a sturdy and resilient structure, particularly suited to the marine environment.
Which one of the following is not a poisonous snake? (a) Cobra (b) Viper (c) Python (d) Krait
Python is the correct answer as it is not a poisonous snake. Unlike Cobra, Viper, and Krait, which are all highly venomous, Pythons are non-venomous and kill their prey through constriction, which involves wrapping their body around the prey and suffocating it.
Write a short note on sustainable management. Next, explain what biodiversity hotspots are. [5 MARKS]
Sustainability is defined as the capability of natural systems to maintain diversity, functionality, and generation of what is needed to keep the ecology balanced. It also takes into account that human civilization requires resources to uphold a modern lifestyle. Throughout history, there have been examples where civilizations have endangered their own survival chances by mismanaging and excessively exploiting their environment. It is crucial to emphasize how we can coexist peacefully with nature, ensuring its protection from harm. This involves integrating economic development, social development, and environmental protection.
Biodiversity hotspots are specific geographical areas around the globe known for their significant levels of biodiversity. These regions are predominantly located around 40 degrees north and south of the equator.
Which is not a taxonomical aid?
A) Zoological park
B) Botanical garden
C) Museum
D) Biodiversity hot-spot
Taxonomical aids are instrumental in helping us study the taxonomic hierarchy and understand the diversity of various plant and animal species. Common examples of taxonomical aids include:
Zoological parks: These are places where animals are kept in captivity, and they provide substantial information about various animal species.
Botanical gardens: These focus on the cultivation of a wide range of plants, serving as a repository for plant species and helping in the study of plant taxonomy.
Museums: They showcase preserved plants and animal specimens, which are crucial for studying and understanding the diversity and characteristics of different species.
However, biodiversity hot-spots, while significant for the conservation of flora and fauna, do not serve the same educational purpose in taxonomy. A biodiversity hotspot is defined as a biogeographic region with significant levels of biodiversity that is under threat from human interaction, hence focusing more on conservation rather than educational taxonomy.
Thus, the correct answer to the question "Which is not a taxonomical aid?" is: D) Biodiversity hot-spot.
What causes extinctions?
A. Habitat loss and fragmentation
B. Over-exploitation
C. Natural disasters
D. Background extinctions
The correct answers are:
A. Habitat loss and fragmentation
B. Over-exploitation
C. Natural disasters
D. Background extinctions
Extinctions can occur due to a variety of reasons. Natural disasters can lead to mass extinctions by drastically altering the environment in a short period. Apart from sudden catastrophic events, there is a natural rate at which species go extinct, known as background extinction. This process involves natural selection and evolution, where less adapted species gradually disappear, allowing the survival of the fittest.
In addition to natural factors, human activities contribute significantly to extinction. These anthropogenic factors include habitat loss and fragmentation, where natural habitats are degraded or divided, leading to the loss of biodiversity. Over-exploitation of species through hunting, fishing, and harvesting at rates that exceed their natural capacity to reproduce is another major cause. Other human-driven factors like the introduction of invasive species and co-extinctions also play crucial roles in the current extinction rates.
Q. With reference to the National Mission for Sustaining Himalayan Ecosystem, which of the following statements is/are incorrect? Select the correct answer using the codes given below:
A) 1 only
B) 2 only केवल 2
C) Both 1 and 2 1
D) Neither 1 nor 2
The correct answer is D. Neither 1 nor 2.
Explanation:
Statement 1 is correct: The National Mission for Sustaining the Himalayan Ecosystem was initiated in 2010 and formally approved in 2014. Its primary objectives are to assess the vulnerability of the Himalayan system and to develop and implement strategies for safeguarding the Himalayan ecosystem. This mission is implemented by the Department of Science and Technology.
Statement 2 is correct: The mission encompasses all eleven states including all the seven states of North East along with Sikkim, Himachal Pradesh, Uttarakhand, West Bengal, and the Union Territories of Jammu, Kashmir, and Ladakh.
Differentiate between a wildlife sanctuary and a biosphere reserve.
Wildlife Sanctuary vs. Biosphere Reserve
Aspect | Wildlife Sanctuary | Biosphere Reserve |
---|---|---|
Definition | A wildlife sanctuary is a protected area for animals where they can live in their natural habitat. | A biosphere reserve is a specially designated area that conserves biodiversity and the cultural aspects of a region. |
Prohibitions | In wildlife sanctuaries, activities such as hunting, poaching, grazing, and felling trees are strictly prohibited. | A biosphere reserve includes various types of protected areas such as sanctuaries, national parks, and includes special zones where certain activities are controlled. |
Includes | Primarily focused on protecting animal species. | Includes multiple features such as sanctuaries, national parks, lakes, mountains, and sometimes even cultural sites. |
Number in India (approximate) | There are approximately 440 wildlife sanctuaries in India. | There are 15 biosphere reserves in India. |
These designations are crucial for the conservation of environments and species, each serving specific ecological, cultural, and protective functions highlighted in their definitions and operational protocols.
The most studied and well-known mass extinction occurred:
A) 429 million years ago
B) 63 million years ago
C) 225 million years ago
D) 369 million years ago
The correct option is B) 63 million years ago.
In evolutionary history, five major mass extinctions have been documented. Of these, the most studied and well-known event occurred 63 million years ago. This particular mass extinction event is distinguished because it marks the disappearance of dinosaurs. It is not only the most recently studied of the large-scale extinctions but also notable for the significant impact it had on the course of life on Earth.
Which of the following is a factor causing loss of biodiversity?
A) Poaching
B) Climate Change
C) Global Warming
D) Pollution
All of the options given are factors that cause loss of biodiversity. Let's detail each one:
A) Poaching: Illegal hunting or capturing of wild animals, often leading to a decline in populations of endangered species.
B) Climate Change: Significant changes in temperature, weather patterns, and water availability can alter habitats and threaten species survival.
C) Global Warming: An increase in Earth's average surface temperature due to rising levels of greenhouse gases leads to habitat shifts and disruptions that many species cannot adapt to quickly enough.
D) Pollution: The introduction of contaminants into natural environments can poison wildlife and destruct habitats.
Summary
Factors causing loss in biodiversity include:
Climate Changes: Drastic shifts in climate can result in many species becoming endangered or extinct.
Poaching: The illegal hunting of rare animals significantly reduces their population numbers.
Pollution: Human-generated pollutants can lead to the death of various species through habitat destruction or direct poisoning.
Global Warming: The rising global temperatures can alter or completely obliterate habitats, leading to species extinction.
Consider the following statements about Javan Green Magpie:
It is listed as a critically endangered species by IUCN.
It is endemic to montane forests in Asia and Europe.
Which of the above statements are correct?
A) 1 only B) 2 only C) Both 1 and 2 D) Neither 1 nor 2
The correct option is A) 1 only.
Javan Green Magpie is correctly listed as Critically Endangered by the International Union for Conservation of Nature (IUCN).
This bird species is endemic exclusively to the montane forests on the Indonesian island of Java, not Asia and Europe as mentioned.
Additional Information About the Javan Green Magpie:
These birds have a unique characteristic of naturally dying themselves bright green. This is due to their diet of green insects, which contain a yellow pigment called lutein.
In captivity, their color can shift from green to bright blue if their diet does not include sufficient lutein.
For Biomagnification to occur, the pollutant must be:
Short-lived
Immobile
Soluble in water
Biologically active
Select the correct answer using the codes given:
A) Only 2 and 4
B) Only 2, 3 and 4
C) Only 4
D) All of the above
The correct answer is option C: Only 4.
For biomagnification to occur, the pollutant must primarily be biologically active. Let's consider each option:
Short-lived pollutants are broken down quickly and are unlikely to accumulate significantly within an organism or food chain.
Immobile pollutants are not effectively absorbed or incorporated by organisms, limiting their potential for biomagnification.
Water-soluble pollutants tend to be more easily excreted by organisms and do not accumulate significantly.
Biologically active pollutants can interact with biological systems, potentially disrupting normal processes and accumulating in tissue over time.
Thus, the characteristic critical for biomagnification is that the pollutant is biologically active, as this allows it to interact with and accumulate within biological systems.
Forests are biodiversity hot spots.
A) True
B) False
A) True
Forests are indeed biodiversity hot spots. This statement is true as forests support a high diversity of species, encompassing various plants, animals, and microorganisms, making them crucial for maintaining ecological balance.
What is the variety of plant and animal life in a particular habitat?
A. Biodiversity
B. Trophic level
C. Consumer
D. Ecosystem
The correct answer is A. Biodiversity.
Biodiversity refers to the variety of plant and animal life in a particular habitat or ecosystem. Comparatively, a trophic level represents the position that an organism occupies in the food chain, typically defined by how the organism gains energy. Consumers are organisms that obtain energy and nutrients by feeding on other organisms. Lastly, an ecosystem encompasses a biological community of interacting organisms and their physical environment.
State whether true or false: Regions with very low levels of ecological richness are termed 'Biodiversity Hotspots'.
A) True
B) False
The correct answer is B) False.
Biodiversity Hotspots are regions recognized for their high levels of species richness and diversity, particularly where species exhibit a high degree of endemism, meaning they are found nowhere else on Earth. These areas are often legally protected due to their ecological value and vulnerability. Contrary to the statement in the question, biodiversity hotspots do not represent areas with low ecological richness but are indeed areas of significant ecological importance, with 34 recognized hotspots globally.
Tourism is important. Select all the options that support this statement.
A) Tourism attracts only domestic travelers to places of interest and generates income.
B) Tourism brings a sense of preservation and conservation among the people of the nation.
C) Tourism is a tertiary occupation.
D) Tourism introduces a country's natural, social, and cultural environment to the world.
Correct options that affirm the importance of tourism are:
B) Tourism brings a sense of preservation and conservation among the people of the nation.
C) Tourism is a tertiary occupation.
D) Tourism introduces a country's natural, social, and cultural environment to the world.
Explanation:
Option B highlights the role of tourism in fostering a culture of preservation, as it increases awareness and the need to maintain the natural and historical heritage to attract tourists.
Option C recognizes tourism as part of the tertiary sector encompassing services, affirming its importance as a major economic activity which provides jobs and supports businesses.
Option D underscores how tourism acts as a global advertisement by showcasing a country's diversity and heritage to the world, thus boosting international recognition and pride.
Additional Context:
Tourism accounts for 7% of the world's exports in goods and services, reflecting its significance in global economic interactions. The sector's growth outpaces that of overall world trade, demonstrating its pivotal role in economic development by attracting both domestic and international tourists. This not only boosts local economies through consumption of goods and services, but also enhances the country's economic strength.
The Chipko Andolan is associated with: A) Tomatoes B) Turtles C) Trees D) Lions
The correct answer to the question "The Chipko Andolan is associated with" is:
C) Trees
Explanation:
The Chipko Andolan, also known as the Chipko Movement, was primarily associated with the conservation of trees. This environmental movement emerged in response to the extensive deforestation occurring in some regions of India, which was posing a significant ecological and economic impact on rural communities.
The Chipko Movement started in the early 1970s in the state of Uttarakhand, India, when a group of peasant women in the village of Mandal decided to hug the trees in their forest to prevent loggers from cutting them down. This act of embracing the trees to protect them was significant because it demonstrated a nonviolent form of protest.
This movement later spread to other parts of India and brought about a change in the government’s policies towards forest conservation. The Chipko Andolan highlighted the importance of trees for the ecosystem, including preventing soil erosion, supporting biodiverse habitats, and maintaining a stable climate.
In a broader context, Chipko Andolan has been a symbol of the fight against environmental destruction and a representation of grassroots advocacy for the sustainable management of natural resources.
Which pollutant is dangerous for Taj Mahal?
A) Sulphur dioxide (SO2)
B) Carbon dioxide (CO2)
C) Carbon monoxide (CO)
D) All of these
The primary pollutant that poses a significant threat to the Taj Mahal is Sulphur Dioxide (SO₂). Sulphur dioxide contributes to the phenomenon known as acid rain, which severely affects the marble of the Taj Mahal. When sulphur dioxide mixes with water vapor present in the atmosphere, it forms sulphuric acid. Falling as acid rain, it has a harmful effect on the white marble, leading to a gradual deterioration and discoloration of its once pristine appearance. Therefore, the answer to which pollutant is dangerous for the Taj Mahal is:
A) Sulphur dioxide (SO2).
Amrita Devi Bishnoi of Rajasthan is related with:
A. Plant conservation
B. Education
C. Sports
D. Politics
Amrita Devi Bishnoi of Rajasthan is widely recognized for her dedication to plant conservation. This association primarily comes from a significant event in 1731, where she sacrificed her life to protect Khejri trees in Jodhpur, Rajasthan. This act of bravery set a historical precedent and highlighted the deep connection she had with environmental conservation.
In honor of her sacrifice, the Government of India instituted the Amrita Devi Bishnoi National Award, which is given to individuals who excel in wildlife and plant conservation efforts. Notably, this award underlines her ceaseless dedication to the protection of plants, specifically highlighting the Khejri tree during her lifetime.
Given this information, Amrita Devi Bishnoi is indeed closely associated with plant conservation, making Option A the correct answer.
Rajasaurus is a fossil of:
A) Tree trunk
B) Invertebrate
C) Fish
D) Dinosaur.
The correct answer is D) Dinosaur.
Rajasaurus was a type of dinosaur known for its strong physical traits, such as robust teeth, which contributed to its role as a fierce predator during its time. The structure or 'frame work' of its body was significantly hard and durable, allowing it to survive over long periods and effectively compete against other predators.
Moreover, the extinction of dinosaurs, including species like Rajasaurus, occurred around the Cretaceous-Paleogene extinction event. This period marked significant changes on Earth and eventually led to the emergence of humans after the disappearance of the dinosaurs.
Therefore, the answer is D) Dinosaur, as Rajasaurus is a famous dinosaur fossil.
Tal Chhapar Wildlife Sanctuary is located at
A. Alwar
B. Jaipur
C. Churu
D. Kota
Tal Chhapar Wildlife Sanctuary is located in Churu district of Rajasthan. This location is specifically in the northeastern region of Rajasthan, within the Shekhawati region of India. Tal Chhapar Sanctuary serves as a habitat for a variety of wildlife, including but not limited to blackbucks and a diverse range of bird species. Thus, the correct answer to the question of where Tal Chhapar Wildlife Sanctuary is located is:
C. Churu
Which one of the following signifies ex situ conservation?
A. National parks and Biosphere reserves
B. Wild animals in their natural habitats
C. Inhabitants of natural ecosystems
D. Conservation methods practiced in Zoo and Botanical garden.
Ex situ conservation is defined as the preservation of components of biological diversity outside their natural habitats. This approach focuses on the protection of endangered or threatened species by relocating them to new locations such as zoos and botanical gardens, where they are cared for under human supervision. The aim is to increase their populations in a controlled environment.
Options provided are:
A. National parks and Biosphere reserves
B. Wild animals in their natural habitats
C. Inhabitants of natural ecosystems
D. Conservation methods practiced in Zoo and Botanical garden.
Among these, the first three options pertain to strategies and entities located within natural habitats, representing in situ conservation methods.
In contrast, Option D, "Conservation methods practiced in Zoo and Botanical garden," falls under ex situ conservation because it involves conservation efforts outside of the species' natural habitats, in controlled settings such as zoos and botanical gardens.
Thus, the correct answer is: D. Conservation methods practiced in Zoo and Botanical garden.
Which one of the following elements is essential for synthesis of Thyroxin Hormones? A. Zinc B. Iodine C. Boron D. Nitrogen
The correct element essential for the synthesis of Thyroxin Hormones is Iodine. Let's delve into why this is the case.
Thyroxin hormones, which include T3 (triiodothyronine) and T4 (thyroxine), are produced by the thyroid gland located in the neck. These hormones play a significant role in regulating the body's metabolic rate among other functions.
The central constituent of thyroxin hormones is Iodine. This means that iodine is a critical component in the formation of these hormones. Without sufficient iodine, the thyroid gland cannot synthesize T3 and T4 effectively, which can lead to various thyroid disorders.
Given the options:
A: Zinc
B: Iodine
C: Boron
D: Nitrogen
The correct answer is B: Iodine, as it is vital for the production of thyroxin hormones.
Scientist who proposed the five kingdom classification is:
A. Carolus Linnaeus B. Whittaker C. Robert Brown D. Hugo de Vries
The question is asking for the scientist who proposed the five kingdom classification. To provide an accurate answer:
Carolus Linnaeus was a pioneer in the field of taxonomy, but he primarily developed a binomial nomenclature system categorizing organisms into genus and species. This does not relate to the five kingdom classification.
Robert Brown discovered the cell nucleus, and thus his contribution is also majorly distinct from the domain of broader classification systems.
Hugo de Vries is best known for his theories on mutations and genetics, again not directly contributing to organismal classification into kingdoms.
The correct answer to the question, therefore, is: B. Whittaker
Robert Whittaker, in the year 1969, famously proposed a system classifying all known organisms into five kingdoms: Monera, Protista, Fungi, Plantae, and Animalia. This classification was based on characteristics such as cell structure, mode of nutrition, and reproductive strategies, providing a comprehensive framework to understand the biological world's vast diversity.
Conclusion:
The scientist responsible for the proposal of the five kingdom classification is Robert Whittaker, making option 'B. Whittaker' the correct choice.
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Name the three important components of biodiversity.
The three important components of biodiversity are:
Genetic diversity: This refers to the variation of genes within a species. A single species might show high genetic diversity across its range, such as the medicinal plant *Rauwolfia vomitoria* which shows variability in the potency and concentration of the chemical (reserpine) it produces in different Himalayan ranges.
Species diversity: This refers to the variety of species within a region. For example, the Western Ghats have higher amphibian species diversity compared to the Eastern Ghats.
Ecological diversity: This refers to the diversity of ecosystems within a certain area. For instance, India has a rich diversity of ecosystems including deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows.
How do ecologists estimate the total number of species present in the world?
Ecologists estimate the total number of species present in the world using a few different methods:
Published Records: They refer to the published records of species that have already been discovered and named. According to the IUCN (International Union for Conservation of Nature and Natural Resources, 2004), the total number of described plant and animal species is slightly more than 1.5 million.
Statistical Comparison: They use statistical comparisons between well-studied regions (usually temperate regions) and less-studied regions (usually tropical regions). By studying the species richness in exhaustively studied groups, such as certain insects, in temperate regions and then comparing it to the richness in the tropics, ecologists extrapolate the data to estimate the number of species in less-studied areas.
Extrapolation and Educated Guesses: They make educated guesses based on patterns and ratios observed from the study groups. This method takes into account the higher proportion of species believed to be present but yet undiscovered, particularly in tropical regions.
Moderate Estimates: Ecologists like Robert May provide conservative and scientifically sound estimates. Robert May's estimate places global species diversity at about 7 million species.
Give three hypotheses for explaining why tropics show greatest levels of species richness.
The tropics show the greatest levels of species richness, and ecologists and evolutionary biologists have proposed several hypotheses to explain this phenomenon:
Speciation Time Hypothesis: Speciation, the process through which new species arise, is generally a function of time. Tropics have remained relatively undisturbed for millions of years, unlike the temperate regions which have been subjected to frequent glaciations in the past. This long evolutionary time allowed for extensive species diversification.
Environmental Stability Hypothesis: Tropical environments are less seasonal, relatively more constant, and predictable compared to temperate ones. These constant environments promote *niche specialisation*, leading to greater species diversity.
Energy Productivity Hypothesis: There is more solar energy available in the tropics. This contributes to higher primary productivity, which in turn might support a greater variety of life forms, indirectly contributing to greater species diversity.
These hypotheses together highlight how the unique environmental conditions and historical factors of the tropics foster higher biodiversity.
What is the significance of the slope of regression in a species - area relationship?
In a species-area relationship, the slope of the regression line, denoted by $Z$, holds significant value. Here are the key points:
The relationship is described by the equation: $$ \log S = \log C + Z \log A $$ where $S$ is species richness, $A$ is the area, $Z$ is the slope of the line (regression coefficient), and $C$ is the Y-intercept.
The value of $Z$ generally falls between 0.1 and 0.2 when examining smaller areas or specific regions (e.g., plants in Britain, birds in California, or mollusks in New York State).
Steeper slopes indicate a stronger relationship between species richness and area in larger scales, such as entire continents. This means that a larger area correlates with a significantly higher number of species.
For very large areas (like entire continents), $Z$ values can range from 0.6 to 1.2. For example, for frugivorous (fruit-eating) birds and mammals in tropical forests, the slope can be as high as 1.15.
Significance of Steeper Slopes:
Higher Values of $Z$: These indicate a greater sensitivity of species richness to an increase in area. It means that the diversity of species increases more sharply with the exploration of larger areas.
Implication for Conservation: Recognizing that species richness increases with area can help conservationists prioritize larger contiguous areas for protection to maximize biodiversity conservation.
Example:
For frugivorous birds and mammals in the tropical forests of different continents, a steep slope ($Z$ value of around 1.15) implies that preserving larger areas is crucial for maintaining high species diversity.
In summary, the slope of the regression line ($Z$) in a species-area relationship helps quantify how much species richness increases with area and underscores the importance of protecting larger habitats to preserve biodiversity.
What are the major causes of species losses in a geographical region?
The major causes of species losses in a geographical region, often termed the "Evil Quartet," are:
Habitat Loss and Fragmentation:
The most important cause of species extinction.
Examples include the destruction of tropical rainforests, which were initially 14% of Earth's land surface but now cover only 6%.
Degradation by pollution and fragmentation into small habitats also impact species negatively.
Over-exploitation:
When human 'need' becomes 'greed', it leads to excessive use of natural resources.
Historical examples include the extinction of the Steller’s sea cow and passenger pigeon.
Alien Species Invasions:
Introduction of non-native species that become invasive, leading to the decline or extinction of native species.
Examples include the Nile perch in East Africa's Lake Victoria causing the extinction of native cichlid fish species.
Co-extinctions:
When a species goes extinct, other species that are dependent in an obligatory relationship with it also face extinction.
For example, the extinction of a host fish species leads to the extinction of its unique parasites.
How is biodiversity important for ecosystem functioning?
Biodiversity is crucial for the functioning of ecosystems in several ways:
Stability of Ecosystems: Ecosystems with higher species richness tend to be more stable. A stable ecosystem shows low variations in productivity over time and can recover quickly from disturbances, whether they are natural or human-induced.
Productivity: Greater species diversity can contribute to higher productivity. Different species often perform complementary roles, leading to more efficient utilization of resources in an ecosystem.
Resistance and Resilience: Ecosystems with high biodiversity are more resistant to invasions by alien species and more resilient to changes in the environment. This means they can better withstand disturbances such as droughts, fires, and pest invasions.
Ecosystem Services:
Pollination: Many plants depend on animals (such as bees, birds, and bats) for pollination, which is essential for the production of fruits and seeds.
Pest Control: A diverse array of predators and parasitoids can keep pest populations in check, reducing the need for chemical pesticides.
Nutrient Cycling: Different species contribute to the decomposition of organic matter and recycling of nutrients, which are essential for plant growth.
Water Regulation: Vegetation plays a role in regulating the water cycle, including water purification and flood prevention.
Ethical and Utilitarian Values: Beyond the direct benefits of biodiversity such as food, medicine, and industrial products, there is also an ethical responsibility to conserve the diversity of life forms that share our planet.
David Tilman's experiments empirically showed that plots with more species exhibited less variation in biomass year-to-year and higher productivity, highlighting the importance of species richness for ecosystem health and stability.
What are sacred groves? What is their role in conservation?
Sacred groves are tracts of forest that are protected due to religious or cultural beliefs. In many cultures, these areas are set aside and venerated, and the trees and wildlife within them are given total protection.
Role in Conservation
Biodiversity Hotspots: Sacred groves often contain a wide variety of species, many of which may be rare, endangered, or endemic to that region.
Protection: By safeguarding these areas from deforestation and over-exploitation, sacred groves help in preserving genetic diversity.
Refuges for Wildlife: These groves act as refuges for many species, providing habitat and shelter, contributing to the overall ecological balance.
Cultural Heritage: They maintain traditional ecological knowledge and practices, which can be essential for sustainable conservation efforts.
Examples in India:
Khasi and Jaintia Hills in Meghalaya
Aravalli Hills in Rajasthan
Western Ghat regions in Karnataka and Maharashtra
Chanda and Bastar areas in Madhya Pradesh
Sacred groves thus play a crucial role in both biodiversity conservation and the preservation of cultural heritage.
Among the ecosystem services are control of floods and soil erosion. How is this achieved by the biotic components of the ecosystem?
Flood control and soil erosion prevention are critical ecosystem services provided by the biotic components of ecosystems. These are primarily achieved through the interactions and activities of plants, animals, and microorganisms. Let's break this down:
Flood Control
Plant Roots
Absorption of Water: Plant roots absorb significant amounts of rainwater, reducing the volume of runoff and minimizing the risk of floods.
Increased Soil Permeability: Roots create channels in the soil, enhancing its ability to absorb and retain water.
Forest Canopy
Intercepting Rainfall: The canopy structure intercepts rain, reducing the amount and speed at which water hits the soil, thereby decreasing runoff and potential flooding.
Soil Erosion Prevention
Plant Roots
Soil Binding: Roots bind the soil particles together, making it more resistant to erosion by wind and water.
Soil Stabilization: Vegetation cover helps to stabilize the soil. Tree roots can reach deeper soil layers, providing additional stabilization.
Forest and Grassland Vegetation
Cover: Vegetation cover protects the soil surface from the direct impact of raindrops, which can cause soil particles to be dislodged and washed away.
Organic Matter: Decaying plant material adds organic matter to the soil, improving its structure and increasing its water retention capacity.
Role of Microorganisms and Animals
Decomposition and Soil Fertility
Microorganisms help decompose organic matter, enriching the soil with nutrients that promote healthy plant growth, which in turn contributes to erosion control.
Burrowing Animals
Animals like earthworms and other burrowers aerate the soil, improving its structure and water-holding capacity, which further aids in flood control and reducing soil erosion.
Significance of Biodiversity
Plant Diversity: Different plant species contribute differently to water absorption and soil stabilization. Plant diversity ensures that these functions are carried out effectively across various environmental conditions.
Microbial Diversity: Microbes play a crucial role in nutrient cycling and maintaining soil health, indirectly supporting plants in flood control and soil erosion prevention.
In summary, the biotic components of the ecosystem play a crucial role in maintaining and enhancing ecosystem services like flood control and soil erosion prevention through their interactions and contributions to soil health, water absorption, and vegetation cover.
The species diversity of plants ( 22 per cent) is much less than that of animals ( 72 per cent). What could be the explanations to how animals achieved greater diversification?
The greater species diversity of animals compared to plants can be explained by several factors:
Mobility: Animals, especially insects, can move around. This increases their ability to explore and exploit new niches, leading to more opportunities for speciation.
Behavioral complexity: Animals often have complex behaviors and social structures. These can lead to niche specialization and help reduce competition, allowing more species to coexist.
Rapid reproduction: Many animal species, particularly insects, have shorter generation times and can reproduce rapidly. This allows for faster evolution and more opportunities for diversification.
Ecological interactions: Predation, parasitism, and mutualisms create diverse interactions among animals, which can drive coevolution and lead to an increase in species diversity.
Habitat variety: Animals can inhabit a wider variety of ecosystems (land, water, air) and use different resources within those ecosystems, further promoting diversification.
Adaptive radiation: Animals often undergo adaptive radiation, where a single ancestral species rapidly diversifies into a variety of forms to exploit different ecological niches.
These factors collectively promote higher diversification rates in animals compared to plants.
Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?
Yes, there are situations where making a species extinct might be considered. One example would be the eradication of invasive species that cause significant harm to native ecosystems, agriculture, or human health.
Example: Eradication of Invasive Species
Species: Smallpox virus *(Variola major and Variola minor)*
Justification:
Public Health: Smallpox was responsible for millions of deaths and disfigurements throughout human history. Its eradication has saved countless lives and prevented severe illness.
Economic Benefits: The cost of vaccination campaigns, medical treatment, and lost productivity due to smallpox infections was immense. Eradicating smallpox led to substantial economic savings.
Biological Impact: Unlike other species, the smallpox virus had no beneficial role in the ecosystem. Its interaction with humans was purely detrimental.
The successful global eradication campaign led by the World Health Organization (WHO) culminated in the declaration of the eradication of smallpox in 1980.
Invasive Species Example:
Species: Cane toad *(Rhinella marina)* in Australia
Justification:
Environmental Impact: Cane toads are highly toxic and have led to the decline of many native predator species that ingest them. This has a cascading effect on the ecosystem.
Biodiversity Threat: They compete with and prey on native species, disrupting local biodiversity and leading to the decline of several endangered species.
Control Measures: Extensive efforts to control or eradicate cane toads can help restore balance to the ecosystems they have disrupted.
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Biodiversity and Conservation: Comprehensive Class 12 Notes
Introduction to Biodiversity and Conservation
Understanding Biodiversity
Biodiversity refers to the variety of life forms on Earth, which exist at multiple levels of biological organisation. It encompasses genetic diversity, species diversity, and ecological diversity, each contributing uniquely to the ecosystem.
- Genetic Diversity: Variations at the genetic level within species. For example, different strains of rice or mango varieties in India.
- Species Diversity: Variations among species in a particular habitat. For instance, the Western Ghats are known for their rich amphibian species.
- Ecological Diversity: Variations at the ecosystem level. India comprises diverse ecosystems like rainforests, deserts, and coral reefs.
Levels of Biodiversity
Genetic Diversity
- Definition: Diversity within the genetic makeup of organisms of the same species.
- Example: The medicinal plant Rauwolfia vomitoria has genetic diversity indicating different potencies and concentrations of the active chemical (reserpine).
Species Diversity
- Definition: Diversity among different species living in a particular area.
- Example: The Western Ghats exhibit higher amphibian species diversity compared to the Eastern Ghats.
Ecological Diversity
- Definition: Diversity at the ecosystem level covering various types of ecosystems.
- Example: India showcases ecosystems like mangroves, coral reefs, and alpine meadows.
Global and Indian Species Count
Global Species Count
- According to the International Union for Conservation of Nature (IUCN), over 1.5 million plant and animal species have been recorded globally. However, estimates suggest that there might be around 7 million species in total.
Indian Species Count
- India, which holds 2.4% of the world's land area, hosts 8.1% of global species diversity. It is home to approximately 45,000 plant species and about 90,000 animal species, making it a mega-diverse nation.
Patterns of Biodiversity
Latitudinal Gradients
- Biodiversity decreases from the equator towards the poles. Tropics are richer in species compared to temperate and polar regions.
- Example: Colombia has nearly 1,400 species of birds, while Greenland has only 56 species.
Species-Area Relationships
- Species richness increases with explored area but only up to a limit. This is represented mathematically as: [ \log S = \log C + Z \log A ] where ( S ) is the species richness, ( A ) is the area, ( Z ) is the slope, and ( C ) is the Y-intercept.
graph TD;
A[Area] -->|Increases| B[Species Richness];
B -->|Increases| C[Species Diversity];
Importance of Species Diversity to Ecosystems
Ecosystem Functionality
- Stability: Species-rich communities are more stable and resilient to disturbances. David Tilman's experiments show that ecosystems with higher species diversity have less year-to-year biomass variation and higher productivity.
Paul's Rivet Popper Hypothesis
- An airplane (ecosystem) has thousands of rivets (species). Removing too many rivets weakens the plane, just as losing species weakens ecosystems.
Loss of Biodiversity
Current Extinction Rates
- Human activities have accelerated species extinction rates by 100 to 1,000 times compared to pre-human times.
Major Threats
- Habitat Loss and Fragmentation: Major cause of species extinction. Tropical rainforests, like the Amazon, are shrinking rapidly.
- Over-exploitation: Human greed has caused the extinction of species like the Steller's sea cow and the passenger pigeon.
- Alien Species Invasions: Introduction of species like the Nile perch in Lake Victoria led to the extinction of native fish species.
- Co-extinctions: Species dependent on others for survival also go extinct, e.g., parasites of an extinct host fish.
Conserving Biodiversity
Why Conserve Biodiversity?
- Narrowly Utilitarian: Direct benefits like food, medicine, and industrial products.
- Broadly Utilitarian: Ecosystem services like oxygen production, pollination, and climate regulation.
- Ethical: Intrinsic value of all species and the moral duty to conserve them.
In Situ Conservation
- Protecting biodiversity within natural habitats. Identifies biodiversity hotspots with rich species and high endemism.
- Example: Western Ghats, Indo-Burma, and the Himalayas in India.
Ex Situ Conservation
- Conserving biodiversity off-site in controlled environments like zoos, botanical gardens, and seed banks.
- Techniques include in vitro fertilisation and cryopreservation.
India's Role in Biodiversity Conservation
Biodiversity Hotspots in India
- India has three biodiversity hotspots: Western Ghats, Indo-Burma, and the Himalayas.
Sacred Groves and Cultural Practices
- Sacred groves in regions like Meghalaya and Karnataka play a crucial role in conserving rare plants and animals.
Government and Legal Measures
- India has established 14 biosphere reserves, 90 national parks, and over 450 wildlife sanctuaries for in situ conservation.
International Efforts in Biodiversity Conservation
The Earth Summit and the Convention on Biological Diversity
- The 1992 Earth Summit in Rio de Janeiro emphasised global measures for conserving biodiversity.
World Summit on Sustainable Development
- At the 2002 summit in Johannesburg, 190 countries pledged to significantly reduce biodiversity loss by 2010.
Conclusion
Summary of Key Points
- Biodiversity includes genetic, species, and ecological diversity.
- India is a mega-diverse country contributing significantly to global biodiversity.
- Biodiversity conservation can be achieved through in situ and ex situ methods.
- International collaborations are crucial for effective biodiversity conservation.
The Future of Biodiversity Conservation
- Ongoing efforts and future initiatives are essential to protect biodiversity for ecosystem health and human well-being.
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Alpha, Beta & Gamma Diversity - Biodiversity and Conservation | Class 12 NCERT | Biology
Alpha (α) Diversity
Alpha Diversity, often referred to as 'local diversity', represents the species diversity within a particular area or ecosystem. Essentially, it measures the number of species (or biological diversity) in a single ecosystem or habitat. Alpha Diversity is of significant importance in ecology because it looks at the localised ecosystem and can provide helpful insights into the functionality of specific habitats. Its evaluation can be used to comprehend the effect of human activities on the level of biodiversity.
Beta (β) Diversity
Beta Diversity, or 'turnover diversity', reflects the change in species diversity between different ecosystems or habitats. Essentially, it exposes the extent to which species vary from one habitat to another, thereby measuring diversity between ecosystems. The central tenet of Beta Diversity is that different habitats, even within the same general area, can offer varying levels of biodiversity. For instance, a rainforest and a desert within the same geographical area would have a high Beta Diversity due to the considerably different species each habitat accommodates.
Gamma (γ) Diversity
Gamma Diversity, or 'regional diversity', pertains to the overall biodiversity over a large area, like an island or a continent, which contains multiple ecosystems. This form of diversity accounts for both the Alpha and Beta diversities of all habitats or ecosystems within the defined region. Gamma Diversity is key to understanding the bigger picture of biodiversity within a region. Measuring Gamma Diversity can provide us with the total number of species in a large area, contributing towards vital conservation and preservation efforts, as well as informing a region’s overall ecological health.
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