CBSE Class 6- Chapter 2: Diversity in the Living World- Study Notes (PDF)

Study Guide: Diversity in the Living World

Study Notes

This study note provides a comprehensive overview of the key concepts related to biodiversity, the classification of living organisms, and their relationship with their environment as presented in the Class 6 new NCERT science book (Curiosity).

1. Introduction to Biodiversity

Definition: Biodiversity refers to the variety of plants and animals found in a particular region.

Observation: The primary method for studying biodiversity is through direct observation, such as on a nature walk. This involves noticing the variety of plants (grasses, bushes, trees) and animals (birds, insects, mammals), as well as listening to sounds (like unique bird chirps) and observing different smells.

Interdependence: Plants and animals within an ecosystem are dependent on each other. For example, trees provide food and shelter for animals, and animals help in spreading plant seeds.

2. Grouping (Classification) of Living Organisms

Grouping, or classification, is the process of arranging organisms based on their similarities and differences, which makes them easier to study and understand.

2.1 Grouping Plants

Plants can be grouped based on a variety of features, including their stems, leaves, roots, and seeds.

A. Based on Height and Stem Type:

• Herbs: Typically small plants with soft, tender, and green stems. Example: Tomato.
• Shrubs: Medium-sized plants with hard, brown, woody stems that are not very thick. They often have many stems that start branching very close to the ground. Example: Rose.
• Trees: Tall plants with hard, thick, brown, and woody stems. Their branches typically start higher up on the stem, away from the ground. Example: Mango.
• Climbers & Creepers: Plants with weak stems. Climbers need support to climb and grow, while creepers spread along the ground.

B. Based on Leaf Venation:

• Venation: The pattern of veins on a leaf.
• Reticulate Venation: A net-like pattern of veins on both sides of a thick middle vein. Example: Hibiscus, Sadabahar (Periwinkle).
• Parallel Venation: Veins that run parallel to each other. Example: Banana, Grass, Lemongrass, Wheat.

C. Based on Root System:

• Taproot System: Consists of one main root (the taproot) with smaller side roots growing from it. Example: Mustard, Hibiscus, Sadabahar, Chickpea.
• Fibrous Root System: A bunch of similar-sized, thin roots that arise from the base of the stem. Example: Common grass, Lemongrass, Wheat.

D. Based on Seed Structure (Cotyledons):

Cotyledon: The part of a seed that can be split. Based on cotyledons, plants are grouped as:

• Dicotyledons (Dicots): Plants with seeds that have two cotyledons. Example: Chickpea.
• Monocotyledons (Monocots): Plants with seeds that have a single cotyledon. Example: Maize.

E. Correlation Between Plant Features:

There is a general correlation between leaf venation, root type, and cotyledon number:

• Dicots typically have reticulate venation and a taproot system.
• Monocots typically have parallel venation and a fibrous root system.

2.2 Grouping Animals

Animals can be grouped based on features such as their habitat, diet, movement, and physical characteristics.

• Based on Movement: Animals exhibit diverse movements like flying, running, crawling, walking, hopping, or jumping. They use different body parts for this, such as legs (goat, ant), wings (pigeon, housefly), or fins (fish).

• Based on Habitat: This is a primary way to group animals. (See Section 3).

3. Habitats and Adaptations

• Habitat: The specific place where a plant or animal lives. A habitat provides food, water, air, shelter, and other necessities for survival. Different types of plants and animals can share the same habitat.
  • Terrestrial Habitats: Land-based environments like forests, deserts, grasslands, and mountains.
  • Aquatic Habitats: Water-based environments like ponds, lakes, rivers, and oceans.
  • Amphibians: Animals, such as frogs, that can live both on land and in water.

• Adaptation: The special features that enable a plant or animal to survive in its particular habitat or region. Biodiversity varies from region to region due to diverse environmental conditions that require different adaptations.

Examples of Adaptations:

Organism	Habitat/Region	Adaptations
Cactus	Hot Desert	Thick, fleshy stems to store water.
Deodar Tree	Cold Mountains	Conical shape and sloping branches to let snow slide off easily.
Rhododendron	Windy Mountain Tops (Nilgiris)	Shorter height and smaller leaves to survive heavy winds.
Hot Desert Camel (Rajasthan)	Hot Desert	One hump for food storage, long legs with wide hooves to walk on sand, excretes little urine/sweat to conserve water.
Cold Desert Camel (Ladakh)	Cold Desert Mountains	Two humps for food storage, shorter legs for walking in mountains, long hair for warmth.
Fish	Aquatic	Streamlined body and fins for swimming in water.

4. Biodiversity Conservation

• Threats to Biodiversity: The primary threat is the damage and loss of natural habitats, often caused by human activities. This results in the loss of homes, food, and resources for plants and animals.

• Conservation Efforts in India:
  • Project Tiger (1973): Initiated to protect the declining population of the Bengal Tiger.
  • Cheetah Reintroduction Project (2022): Aimed at restoring the Cheetah population.
  • Great Indian Bustard Protection: Habitats declared as Protected Areas in Gujarat, Rajasthan, and Maharashtra.
  • Sacred Groves: Undisturbed patches of forest protected by local communities, serving as treasures of biodiversity.
  • Save Silent Valley Movement: A successful public movement that saved a moist evergreen forest in Kerala from a hydroelectric dam project.

• Key Figures:
  • Janaki Ammal (1897–1984): An Indian botanist who documented and preserved India’s plant biodiversity and was a key figure in the ‘Save Silent Valley’ movement.
  • Salim Ali (1896–1987): Known as the ‘Birdman of India’, he documented bird diversity, habitats, and travel routes, helping to establish bird sanctuaries like Keoladeo National Park.

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Short-Answer Quiz

Answer each question in 2-3 complete sentences.

1. What is biodiversity, and why is the interdependence of plants and animals important for it?

2. Describe the three main categories of plants (herbs, shrubs, and trees) based on their stem characteristics and height.

3. Explain the difference between reticulate and parallel venation in plant leaves, providing an example for each.

4. What is the general relationship between the number of cotyledons in a plant’s seed and its root system type?

5. Define “adaptation” and provide one example of an animal adaptation from the text.

6. How do the physical features of a deodar tree help it survive in its mountainous habitat?

7. What is the difference between a terrestrial and an aquatic habitat? Give an example of an animal for each.

8. According to the text, what is the main cause of biodiversity loss, and what are its consequences for plants and animals?

9. Who was Salim Ali, and what was his major contribution to the conservation of biodiversity in India?

10. What are sacred groves, and how do they contribute to the protection of biodiversity?

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Answer Key

1. Biodiversity is the variety of plants and animals found in a particular region. The interdependence of plants and animals is crucial because they rely on each other for survival; for instance, trees provide shelter and food, while animals help disperse seeds, maintaining the health of the ecosystem.

2. Herbs are small plants with soft, green stems. Shrubs are medium-sized with hard, woody stems that branch near the ground. Trees are tall plants with a thick, hard, woody main stem, and their branches start higher up.

3. Reticulate venation is a net-like pattern of veins, such as that found in a hibiscus leaf. Parallel venation consists of veins that run parallel to each other, as seen in a banana or grass leaf.

4. Generally, plants with two cotyledons (dicots) have a taproot system. Plants with a single cotyledon (monocots) typically possess a fibrous root system.

5. An adaptation is a special feature that enables a plant or animal to survive in its particular region. For example, the camel in a hot desert has long legs and wide hooves, which is an adaptation that helps it walk on sand without sinking.

6. Deodar trees are adapted to snowy mountains with their conical shape and sloping branches. These features allow heavy snow to slide off easily, preventing the branches from breaking under the weight.

7. A terrestrial habitat is a land-based environment, such as a forest where a goat lives. An aquatic habitat is a water-based environment, such as an ocean where a fish lives.

8. The main cause of biodiversity loss is the damage to natural habitats by human activities. The consequences are that plants and animals lose their homes, food sources, and other essential resources for survival.

9. Salim Ali, known as the ‘Birdman of India’, was a scientist who traveled across India to observe bird diversity. He documented their habitats and migration routes, which led to the conservation of important regions like Keoladeo National Park.

10. Sacred groves are undisturbed patches of forests that are protected by local communities. They contribute to biodiversity protection by providing a safe home for many kinds of plants and animals, as no one is allowed to harm wildlife or cut trees within them.

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Essay Questions

1. Discuss the different criteria used to group plants as detailed in the source text. Explain how features like stem type, leaf venation, root system, and seed structure are interconnected.

2. Using the specific examples of the hot desert camel, the cold desert camel, and the deodar tree, elaborate on the concept of adaptation. Explain how these specific features make each organism uniquely suited to its environment.

3. Describe the concept of a habitat and explain how damage to habitats leads to a loss of biodiversity. Reference the conservation projects mentioned in the text (e.g., Project Tiger, Save Silent Valley) as examples of efforts to counteract this loss.

4. Imagine you are leading the nature walk described at the beginning of the chapter. Outline your plan, including the instructions you would give to students, the specific observations you would guide them to make about plants and animals, and how you would use these observations to explain the concepts of diversity and grouping.

5. Compare and contrast terrestrial and aquatic habitats. Discuss the different types of movement and physical adaptations animals have developed to thrive in each of these environments, using examples like the goat and the fish. Include a brief explanation of amphibians and their unique place between these two habitats.

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Glossary of Key Terms

• Adaptation: The special features that enable plants and animals to survive in a particular region.
• Amphibians: Animals, such as frogs, that can live in water as well as on land.
• Aquatic Habitat: A habitat where plants and animals live in water (e.g., ponds, lakes, rivers, oceans).
• Biodiversity: The variety of plants and animals found in a particular region.
• Climbers: Plants with weak stems that need support to climb and grow.
• Cotyledon: A part of a seed; seeds can have one (monocot) or two (dicot).
• Creepers: Plants with weak stems that creep along the ground.
• Dicotyledons (Dicots): Plants that have seeds with two cotyledons.
• Fibrous Root: A root system that appears as a bunch of similar-sized thin roots arising from the base of the stem.
• Grouping: The method of arranging things into groups based on their common features.
• Habitat: The place where plants and animals live, which provides them with food, water, air, shelter, and other needs.
• Herbs: Small plants with soft and green stems.
• Monocotyledons (Monocots): Plants with seeds that have a single cotyledon.
• Parallel Venation: A pattern on a leaf where the veins run parallel to each other.
• Reticulate Venation: A net-like pattern of veins on a leaf.
• Sacred Groves: Undisturbed patches of forests protected by the local community.
• Shrubs: Medium-sized plants with hard but not very thick woody stems that branch near the ground.
• Taproot: A root system consisting of one main root and smaller side roots arising from it.
• Terrestrial Habitat: A habitat where plants and animals live on land (e.g., forests, deserts, mountains).
• Trees: Tall plants with hard, thick, brown, and woody stems.
• Venation: The pattern of veins on a leaf.