CBSE Class 12 Biology Exemplar Chapter 15: Biodiversity and Conservation NCERT Solutions

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CBSE Class 12 Biology Exemplar, Chapter 15, delves into the critical topics of Biodiversity and Conservation. This chapter explores the multifaceted factors that contribute to the Earth's rich biodiversity, alongside the significant causes leading to its loss. It highlights the impact of invasive alien species and identifies the unique characteristics of biodiversity hotspots, areas crucial for conservation efforts. Furthermore, the chapter examines examples of extinct species, providing insights into the historical loss of life. These NCERT Solutions offer clear, concise explanations designed to help students grasp complex ecological concepts. By providing step-by-step problem-solving and reinforcing key ideas, this resource serves as an essential study aid for students preparing for their board examinations, ensuring a thorough understanding of biodiversity's importance and conservation strategies.

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BoardCBSE
ClassClass 12
SubjectBiology Exemplar
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 15

Chapter summary

Chapter 15 of the CBSE Class 12 Biology Exemplar, 'Biodiversity and Conservation,' explores the vast array of life on Earth and the critical need to protect it. The NCERT Solutions for this chapter address key concepts including the geographical distribution of biodiversity, the primary drivers of biodiversity loss like habitat destruction and over-exploitation, and the impact of invasive alien species. It also clarifies the defining features of biodiversity hotspots and revisits examples of extinct species. These solutions are structured to provide a clear understanding of ecological principles and conservation strategies.

Learning outcomes

  • Understand the factors influencing global biodiversity distribution.
  • Identify the primary causes of biodiversity loss.
  • Recognize examples of invasive alien species and their impact.
  • Define and identify characteristics of biodiversity hotspots.
  • Recall examples of extinct species and their geographical origins.
  • Differentiate between native and alien species.

Topics covered

Paper topics

  • Biodiversity
  • Tropical Biodiversity
  • Causes of Biodiversity Loss
  • Habitat Destruction
  • Alien Species Invasion
  • Over-exploitation
  • Extinct Species
  • Biodiversity Hotspots
  • Endemic Species
  • Insectivorous Plants
  • Conservation

Important topics

  • Causes of Biodiversity Loss
  • Invasive Alien Species
  • Biodiversity Hotspots
  • Extinct Species Examples
  • Factors Affecting Biodiversity

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Questions and Solutions

Question 1

Which of the following countries has the highest biodiversity?

(a) Brazil

(b) South Africa

(c) Russia

(d) India

Solution: The highest biodiversity is generally found in tropical regions, roughly between 23.5°N and 23.5°S latitude. This is because these areas experience relatively stable and favorable climatic conditions, including consistent temperature and ample moisture, which support a vast array of flora and fauna. Among the options provided, Brazil is a tropical country known for its extensive rainforests, such as the Amazon, which harbor immense biodiversity. Therefore, Brazil has the highest biodiversity. Answer: (a) Brazil

Question 2

Which of the following is not a cause for loss of biodiversity?

(a) Destruction of habitat

(b) Invasion by alien species

(c) Keeping animals in zoological parks

(d) Over-exploitation of natural resources

Solution: The loss of biodiversity is a significant environmental concern driven by several factors. The primary causes include: 1. Destruction of habitat: This is the leading cause, where natural environments are altered or destroyed due to human activities like deforestation, urbanization, and agriculture, leaving species without homes and resources. 2. Invasion by alien species: When non-native species are introduced into an ecosystem, they can outcompete native species for resources, introduce diseases, or alter the habitat, leading to a decline in native biodiversity. 3. Over-exploitation of natural resources: Unsustainable harvesting of plants and animals, such as overfishing or poaching, can deplete populations to the point of extinction. 4. Co-extinction: When a species becomes extinct, any species that depended on it for survival also face extinction. Keeping animals in zoological parks, on the other hand, is a conservation strategy aimed at protecting endangered species and is not a cause of biodiversity loss. Answer: (c) Keeping animals in zoological parks

Question 3

Which of the following is not an invasive alien species in the Indian context?

(a) Lantana

(b) Cynodon

(c) Parthenium

(d) Eichhornia

Solution: Invasive alien species are non-native organisms that, when introduced into a new environment, cause ecological or economic harm. In the Indian context, several species have become invasive and pose a threat to native biodiversity. Lantana (Lantana camara) is a flowering shrub that aggressively colonizes disturbed areas, outcompeting native vegetation. Parthenium (Parthenium hysterophorus), also known as congress grass or carrot grass, is a notorious weed that invades agricultural lands and natural habitats, causing allergic reactions and reducing crop yields. Eichhornia (Eichhornia crassipes), or water hyacinth, is an aquatic plant that forms dense mats on water bodies, blocking sunlight, reducing dissolved oxygen, and hindering navigation. Cynodon (Cynodon dactylon), commonly known as doob grass or Bermuda grass, is a widespread grass that is native to many parts of the world, including India. While it can be considered a weed in certain agricultural contexts, it is not typically classified as an invasive alien species in the same category as the others, as it is often considered naturalized or native. Answer: (b) Cynodon

Question 4

Where among the following will you find pitcher plant?
  1. Rain forest of North-East India
  2. Sunderbans
  3. Thar desert
  4. Western ghats
Solution: The pitcher plant, scientifically known as *Nepenthes*, is a carnivorous plant that typically grows in nutrient-poor soils, particularly those deficient in nitrogen. To supplement their nutrient intake, these plants have evolved specialized structures, the 'pitchers', to trap and digest insects. The rainforests of North-East India provide the humid and acidic conditions often suitable for such plants. While the Sunderbans are known for their unique mangrove ecosystem and rich fauna, and the Western Ghats are a global biodiversity hotspot, the specific habitat requirements of the pitcher plant are best met in the rainforests of North-East India among the given options. Xerophytes, adapted to arid conditions, are characteristic of the Thar Desert. Answer: (a) Rain forest of North-East India

Question 5

Which one of the following is not a feature of biodiversity hotspots?
  1. Large number of species
  2. Abundance of endemic species
  3. Mostly located in the tropics
  4. Mostly located in the polar regions
Solution: Biodiversity hotspots are specific regions on Earth that are both rich in biodiversity and significantly threatened by human activities. Key characteristics of these hotspots include: 1. High species richness: They contain a large number of different species. 2. High endemism: A significant proportion of these species are endemic, meaning they are found nowhere else on Earth. 3. Geographical location: They are predominantly located in tropical and temperate regions, where conditions are often favorable for diverse life forms. Conversely, polar regions are characterized by extreme cold and harsh conditions, which limit the diversity of life and are not considered biodiversity hotspots. Answer: (d) Mostly located in the polar regions

Question 6

Match the following columns.

Column I | Column II

  1. Dodo
  2. Quagga
  3. Thylacine
  4. Stellar's sea cow

with

  1. Africa
  2. Russia
  3. Mauritius
  4. Australia

Choose the correct match from the following:

  1. i-a, ii-c, iii-b, iv-d
  2. i-d, ii-c, iii-a, iv-b
  3. i-c, ii-a, iii-b, iv-d
  4. i-c, ii-a, iii-d, iv-b
Solution: This question requires matching extinct species with their original geographical locations. Let's analyze each pair: 1. Dodo: This flightless bird was endemic to the island of Mauritius and became extinct in the late 17th century. So, Dodo matches with Mauritius (c). 2. Quagga: This was a subspecies of the plains zebra native to South Africa. It became extinct in the late 19th century. So, Quagga matches with Africa (a). 3. Thylacine: Also known as the Tasmanian tiger, this carnivorous marsupial was native to mainland Australia, Tasmania, and New Guinea. It is believed to have gone extinct in the 20th century. So, Thylacine matches with Australia (d). 4. Steller's sea cow: This marine mammal inhabited the Commander Islands in the Bering Sea, off the coast of Kamchatka Peninsula, Russia. It was hunted to extinction in the 18th century. So, Stellar's sea cow matches with Russia (b). Therefore, the correct matching is i-c, ii-a, iii-d, iv-b. Answer: (d) i-c, ii-a, iii-d, iv-b

Common mistakes

  • Confusing causes of biodiversity loss with conservation efforts.
  • Misidentifying invasive alien species.
  • Incorrectly associating biodiversity hotspots with polar regions.
  • Errors in matching extinct species with their native regions.

Revision tips

  • Focus on understanding the 'why' behind biodiversity distribution and loss.
  • Memorize key examples of invasive species and extinct animals.
  • Create flashcards for matching extinct species to their locations.
  • Review the characteristics of biodiversity hotspots thoroughly.
  • Practice identifying which actions contribute to or mitigate biodiversity loss.

Practice MCQs

Q1. Which of the following countries is known for having the highest biodiversity, largely due to its tropical latitude?

Q2. Which of the following activities is NOT considered a cause for the loss of biodiversity?

Q3. Which of the following is NOT an invasive alien species that poses a threat to native species in the Indian context?

Q4. The insectivorous pitcher plant (Nepenthes) is typically found in which type of environment?

Q5. Which characteristic is NOT typical of a biodiversity hotspot?

Q6. Match the extinct species with their region of origin: Dodo, Quagga, Thylacine, Stellar's sea cow.

Frequently asked questions

What is biodiversity and why is it important according to Chapter 15?

Biodiversity refers to the variety of life on Earth at all its levels, from genes to ecosystems. Chapter 15 highlights its importance by discussing factors that influence it and the consequences of its loss.

What are the main reasons for the loss of biodiversity discussed in these solutions?

The primary reasons for biodiversity loss covered are destruction of natural habitats, invasion by alien species, over-exploitation of natural resources, and co-extinction of species.

What defines a biodiversity hotspot?

A biodiversity hotspot is a region with a high concentration of species, many of which are endemic (found nowhere else), and which is under significant threat from human activities.

Can you give an example of an invasive alien species mentioned?

Yes, examples of invasive alien species in the Indian context provided in the solutions include Lantana, Parthenium (congress grass), and Eichhornia (water hyacinth).

How do these NCERT solutions help in preparing for exams?

These solutions provide clear, rewritten explanations for each question, helping students understand the concepts of biodiversity and conservation better, identify key examples, and practice problem-solving for their exams.

What is the significance of studying extinct species like Dodo or Thylacine?

Studying extinct species serves as a stark reminder of the irreversible consequences of biodiversity loss and emphasizes the importance of current conservation efforts to prevent further extinctions.

Important links

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