Revision Notes — Diversity in Living World
Overview
The living world around us is full of a variety of organisms — from tiny microorganisms that cannot be seen with the naked eye to large trees and animals. This variety is called biological diversity or biodiversity. In this chapter we learn how scientists group living organisms into different categories using observable features so that studying them becomes easier and meaningful.
1. What is Diversity?
Diversity means a lot of different kinds. In biology, it refers to many different forms of life — plants, animals, fungi and microorganisms. Diversity is important because different organisms perform different roles in nature. For example, plants produce oxygen and food, while decomposers like fungi and some bacteria help return nutrients to the soil.
2. Characteristics of Living Organisms
All living organisms share some common features. These help us tell living things apart from non-living matter:
- Growth: Living organisms grow — they increase in size or number of cells.
- Movement: Organisms may move from place to place (animals) or show internal movement (plants move parts like leaves toward light).
- Respiration: They use oxygen and release energy from food (or for some, use other processes).
- Sensitivity: Ability to respond to stimuli — e.g., plants bending to light, animals sensing danger.
- Reproduction: Making new organisms — can be sexual or asexual.
- Nutrition: Obtaining and using food — plants make food by photosynthesis, animals eat plants or other animals.
- Excretion: Getting rid of waste products of metabolism.
3. Major Groups of Living Organisms
To study and understand living organisms we group them into broad categories. At Class 6 level we use simple, practical groups:
Plants
- Plants are producers — they make their own food by photosynthesis.
- Common types: trees (tall, woody), shrubs (medium woody plants), herbs (soft, green stems), climbers (use support to climb), creepers (spread across ground).
- Parts: root, stem, leaves, flowers, fruit, seeds — practice sketching a labelled plant diagram.
Animals
- Animals are consumers — they eat plants or other animals.
- Types: birds, mammals, reptiles, amphibians, fishes, insects and many invertebrates. At this stage focus on simple differences like presence of backbone ( vertebrates ) or not ( invertebrates ).
Fungi
- Fungi (e.g., mushroom, bread mould, yeast) are mostly decomposers — they feed on dead and decaying matter and help recycle nutrients.
- They do not perform photosynthesis and often grow in moist, shaded places.
Microorganisms
- Very small organisms like bacteria, protozoa, some fungi and algae that can only be seen with a microscope.
- Many are helpful (help in digestion, fermentation, making medicines), and some can cause diseases (so wash hands and keep food clean!).
4. Why Classify Living Organisms?
Classification helps us arrange organisms into groups so they are easier to study and remember. It is based on similarities and differences in characteristics like body structure, method of nutrition, movement, and habitat. Simple classification at this level groups organisms by how they look and live — e.g., animals that fly, animals that live in water, plants that are trees vs herbs.
5. Simple Ways to Classify — Practical Tips
When you look at any organism, ask these simple questions:
- Does it make its own food? (If yes → plant)
- Does it have a backbone? (If yes → vertebrate animal)
- Does it grow in soil or on other things? (Might be fungus)
- Can you see it without a microscope? (If not → microorganism)
Create a small chart of 10 organisms from your surroundings (e.g., mango tree, dog, mushroom, housefly, yeast in bread) and classify them — this is a great exercise for exams.
6. Habitat and Adaptations
A habitat is the natural place where an organism lives — e.g., pond, soil, tree canopy, human home. Adaptations are special features that help an organism survive in its habitat — thick fur in cold places, webbed feet for swimming, long roots to reach water, etc. Understanding a few examples of adaptation helps answer many exam questions.
7. Importance of Biodiversity
Biodiversity provides food, medicines, clothing materials, shelter and helps keep the environment balanced. Each organism, however small, has a role — plants provide oxygen, decomposers clean up waste, and predators help control population of other species.
8. Simple Practical Activities (Exam & Classwork Friendly)
- Make a small classification chart of 15 living things from your school ground — group them into plants, animals, fungi, microorganisms (if any observed under teacher's microscope).
- Sketch and label a plant and an animal. Write one sentence about where each lives and one adaptation.
- Observe bread mould on a stale bread piece (under teacher supervision) to learn about fungi — draw what you see.
- Create flashcards: term on one side (e.g., "Decomposer") and definition + example on the other.
9. Quick Revision Checklist (Before Tests)
- Can you name five types of plants and five types of animals with examples?
- Explain in simple words: habitat, adaptation, classification, microorganism.
- Know characteristics common to all living organisms (growth, reproduction, etc.).
- Be ready to classify and give reasons for your grouping (e.g., why a mushroom is not a plant).
- Practice one short diagram (labelled plant) and one short answer (50–70 words).
10. Model Short Answer (Example)
Q: Why are fungi not placed in the plant kingdom?
A: Fungi do not prepare their own food by photosynthesis because they lack chlorophyll. They obtain their food from dead or decaying matter (they are decomposers). Their cell structure and mode of nutrition differ from plants, so they are placed in a separate group called fungi.
Exam Tips & Final Advice
- Write clear short answers — begin with definition, add one-two features and an example.
- Use labeled diagrams where possible; diagrams fetch marks quickly.
- During revision, practice classifying common organisms from your locality — practical examples make answers stronger.
- Revise glossary terms and key differences (plant vs fungus, unicellular vs multicellular).
This study module follows NCERT's intent for Class 6 Science Chapter 2 and is structured to support CBSE-style assessments. Use the activities and the revision checklist to prepare for periodic tests and annual examinations.