Chapter 9 — The Living Organisms and their Surroundings

Living and non-living — how to tell: Around us there are many things: chairs, stones, toys, plants and animals. Some things are living and some are not. To decide whether something is living we look for certain activities. Living things perform a set of life processes — growth, movement, respiration, nutrition, excretion, reproduction and response to stimuli. These activities are not always obvious at once; observing over time helps.

Growth and reproduction: Growth is an increase in size or number of cells. A baby grows into a child and then an adult. Reproduction is making new individuals similar to parents. Plants make seeds and animals give birth or lay eggs. Even single-celled organisms divide to form new cells. Non-living things do not grow by themselves or produce offspring.

Nutrition and respiration: Living beings obtain and use food. Plants make food by photosynthesis; animals eat plants or other animals. Respiration is the process of releasing energy from food. This may be through breathing air (as in humans) or other methods in small organisms. Non-living things do not take food or respire.

Movement and response: Movement can be obvious, like walking, or slow and internal, like growth towards light. Plants bend toward light; animals move to get food or avoid danger. Response means reacting to changes in the surroundings. Touch, light, heat and sound are common stimuli. Excretion removes waste products produced in the body; for example, humans urinate and plants release oxygen and excess water.

Organisation of living things: Living things are organised — made of cells that form tissues, organs and systems in larger animals and plants. This internal organisation allows coordinated life functions. A simple class activity is to place a seed and a pebble in similar conditions and watch the seed sprout and grow while the pebble remains unchanged; record differences to reinforce the idea. Understanding these characteristics helps students recognise living organisms in different forms and prepares them for deeper biology topics.

Definition and basics: A habitat is the natural environment where an organism lives and obtains its needs — food, water, shelter and space. Every organism lives in a habitat suitable for its survival. Habitats can be large, such as forests, deserts and oceans, or small, such as a tree stump, a rock crevice or a puddle. Each habitat contains living and non-living elements that together support life.

Living and non-living components: The living components include plants, animals and microorganisms that interact in the habitat. The non-living components, called abiotic factors, include sunlight, temperature, soil, water and air. These abiotic factors determine what types of organisms can live in a habitat. For example, moisture and temperature influence which plants will grow in a place; sandy soil supports different plants than clay soil.

Microhabitats: Within larger habitats there are many microhabitats — small areas that provide specific conditions. Under a pile of leaves there is more moisture and less light, so worms, fungi and insects live there. The bark of a tree can be a microhabitat for lichens and insects. Recognising microhabitats helps students see how abundance of life is supported even in small spaces.

Adaptation to habitats: Organisms have features and behaviours that fit their habitat. Fish need water to breathe and move, so they have streamlined bodies and gills. Desert plants have thick stems to store water. Birds that live near water may develop webbed feet. By studying habitats and common residents, students learn why certain traits are useful in particular places.

Human effects and protection: Human activities change habitats, often reducing the space available for organisms. Polluted water, cleared forests and built-up areas reduce biodiversity. Protecting habitats — for example, conserving ponds, planting native trees, and avoiding dumping waste — helps preserve the plants and animals dependent on those environments. Field activities such as listing organisms in the school garden and noting where they live make the topic concrete and encourage stewardship.

Meaning of adaptation: Adaptation refers to the features or behaviours that enable organisms to survive in their habitats. These changes may be in the shape of body parts, internal processes or patterns of behaviour. Adaptations develop over many generations so the species becomes better suited to its environment.

Types of adaptations: Structural (physical) adaptations are visible body parts — thick fur for insulation, long necks to reach leaves, webbed feet for swimming, or spines in cacti to reduce water loss. Behavioural adaptations are actions that help survival — migrating to avoid cold, nocturnal activity to escape daytime heat, or building nests for young. Physiological adaptations are internal functions such as a camel’s ability to conserve water, or desert plants closing stomata to reduce transpiration.

Examples across habitats: In deserts, many plants have deep roots or store water in stems. Animals like camels store fat and can go long without water; some reptiles slow their metabolism. In aquatic environments, fish have gills to extract oxygen from water and fins for swimming. High mountain animals have thick fur and more red blood cells to carry oxygen at low pressure. Such comparisons explain how structure links to function.

Adaptation and survival: Adaptations help in finding food, avoiding predators and tolerating climate. For instance, camouflage helps prey hide; sharp beaks and talons help predators catch food. Students should connect each adaptation to its usefulness, not just list features. Activities like matching animals to habitats or making cards describing one structural and one behavioural adaptation reinforce understanding.

Observation activity: Choose five local animals or plants and note one structural and one behavioural adaptation for each. Discuss how a change in habitat (like less water or more pollution) would affect those adaptations. This links adaptation to real-life consequences and shows why protecting habitats matters.

Purpose of classification: There are thousands of different living organisms. Classification helps us arrange them into groups so we can study and remember them more easily. It is based on observable features such as body parts, shape, habitat and behaviour. Simple classification is suitable for Class 6: group plants as trees, shrubs and herbs; group animals as mammals, birds, reptiles, amphibians, fishes and insects.

Groups of plants: Trees are tall and have a single woody stem (e.g., mango). Shrubs are smaller with several woody stems (e.g., hibiscus). Herbs are soft-stemmed plants (e.g., coriander). Knowing these groups helps in identifying plants in our surroundings and understanding how they are used by humans for food, timber and medicine.

Groups of animals: Mammals usually have hair and produce milk for their young (cow, dog). Birds have feathers, wings and beaks; most can fly (sparrow, crow). Reptiles have dry scaly skin and usually lay eggs (snake, lizard). Amphibians live partly in water and partly on land and often have a life cycle with metamorphosis (frog). Fishes live in water and breathe through gills (rohu). Insects have six legs and three body parts (ant, butterfly).

Using simple identification keys: A key asks yes/no questions about observable features to place an organism in a group. For example: Does it have feathers? If yes, it is a bird; if no, go to next question. Creating a basic key for local organisms trains observation and logical thinking. Students can practise by collecting leaves, seeds and pictures of animals and grouping them based on two or three features.

Limitations and learning value: Simple classification is not the full scientific system but it helps beginners learn similarities and differences. Some organisms are hard to place because they share features of multiple groups. Discussing such exceptions enhances critical thinking and prepares students for deeper study in higher classes.

Basic parts and their roles: Most plants have roots, stems, leaves, flowers, fruits and seeds. Roots hold the plant in soil and absorb water and minerals. Stems support leaves and flowers and transport water and food between different parts of the plant. Leaves are the main sites of photosynthesis — they use sunlight, water and carbon dioxide to make food. Flowers are reproductive organs that help plants make seeds; fruits protect seeds and help in their dispersal.

How parts work together: Roots absorb water which moves up the stem to leaves; leaves make food and some food moves down to roots for storage. In storage organs like potatoes and carrots (modified stems and roots), plants keep food for future growth. Seeds contain an embryo and stored food to start a new plant. An understanding of these parts explains why cutting roots or leaves affects plant health.

Modified plant parts: Many plants have modified leaves, stems or roots to suit their environment. Examples: Tendrils in climbers are modified leaves that help the plant climb; bulbs (onion) store food; succulent stems in cacti store water; aerial roots in banyan help support heavy branches. These modifications show adaptation while keeping the basic functions.

Photosynthesis and transpiration: Photosynthesis occurs mainly in green leaves where chlorophyll captures sunlight to make glucose and oxygen from carbon dioxide and water. Transpiration is the loss of water vapour from leaves which creates a pull to draw more water up from roots; it also cools the plant. Both processes are vital to plant life and explain why light and water are essential.

Hands-on activities: Plant a bean seed and watch root and shoot development; dissect a flower to identify petals, sepals, stamens and pistil; observe a cross-section of a stem and leaf under magnifier. Record observations to link structure with function and reinforce learning through doing.

Body structures and role: Animals differ in body coverings, limbs and internal organs that suit their ways of life. Body coverings include fur, feathers, scales or skin. Limbs vary: legs for walking, wings for flying, fins for swimming. These structures are linked to habitat and habits. For example, birds have light bones and feathers to fly; fish have streamlined bodies and fins to swim efficiently.

Feeding and digestion: Animals have different feeding habits. Herbivores eat plants and usually have flat teeth for grinding, long digestive systems to process cell walls. Carnivores eat meat and have sharp teeth for tearing and shorter guts. Omnivores eat both and show mixed features. The mouth parts, teeth and digestive organs of animals reflect their diet and show how structure supports function.

Locomotion and survival strategies: Movement helps animals find food, mates and shelter and avoid predators. Crawling, hopping, running, swimming and flying are common modes. Behavioural strategies such as living in groups, camouflage, migration and hibernation help animals survive seasonal changes and threats. For instance, many birds migrate to warmer regions to find food in winter.

Habit and habitat link: Animals’ habits are suited to their habitats. Nocturnal animals are active at night to avoid daytime heat or predators; arboreal animals live in trees and have adaptations like gripping feet. Studying local animals — for example, sparrows, lizards and cows — helps students notice how body parts and habits match living conditions.

Classroom task: Make a table noting habitat, body covering, feeding habit and movement for three animals. Discuss how losing habitat or food would alter their life. This fosters understanding of interdependence and the consequences of environmental change.

Introduction to microbes: Microorganisms are tiny living organisms that cannot be seen with the naked eye. They include bacteria, fungi (moulds and yeasts), protozoa and some algae. Microbes live everywhere — in soil, water, air, on our skin and inside our bodies. They are usually seen with a microscope or by their effects, such as the growth of mould on bread.

Useful microbes: Many microorganisms help humans and the environment. Yeast is used to ferment dough to make bread and to ferment batters for idlis and dosa. Bacteria in soil fix nitrogen from air into forms plants can use, improving soil fertility. Microbes help decompose dead plants and animals, recycling nutrients back into the soil. They are also used in making medicines like antibiotics, and in industries for producing cheese, yogurt and other fermented foods.

Harmful microbes and disease: Some microbes cause diseases in humans, animals and plants. Pathogenic bacteria and viruses can cause fever, cough, diarrhoea and other illnesses. Fungi may cause skin infections or crop diseases. Good hygiene — washing hands, boiling water, cooking food properly and vaccination — reduces disease spread. In agriculture, crop rotation, clean seeds and timely treatment help control plant diseases caused by microbes.

Conditions for growth and simple experiments: Microbial growth depends on temperature, moisture and food. Bread left in a warm, moist place grows mould faster than bread kept dry and sealed. Simple class experiments, done safely with teacher supervision, can show where microbes grow. Always use gloves and avoid direct contact. Observing yoghurt bacteria under a microscope or watching yeast rise in dough are safe ways to learn their roles. Understanding microbes helps students appreciate both benefits and risks and fosters good hygiene habits.

Roles in obtaining food: In any habitat, organisms play different roles in how they get food. Producers (mainly green plants) make their own food by photosynthesis using sunlight, water and carbon dioxide. Consumers cannot make food and eat producers or other consumers. Decomposers break down dead plants and animals into simpler substances, returning nutrients to the soil.

Types of consumers: Primary consumers are herbivores that eat plants (e.g., grasshopper). Secondary consumers eat primary consumers (e.g., frog eats grasshopper). Tertiary consumers eat other carnivores (e.g., snake eats frog). Omnivores, such as humans or crows, eat both plant and animal foods. These feeding links form chains that show energy flow from the sun through plants to animals.

Importance of decomposers: Decomposers like bacteria and fungi perform a vital recycling job. They break complex organic matter into simpler chemicals that plants can use again. Without decomposers dead leaves and animals would accumulate and nutrients would be locked away, reducing soil fertility. Compost pits use decomposer action to transform kitchen waste into rich manure for gardens.

Energy flow and efficiency: Energy flows from producer to consumer with losses at each step due to heat and life processes. This is why food chains usually have only a few steps; there is not enough energy to support many large predators above. Simple classroom activities, such as making a chain in the school garden (grass → grasshopper → frog → snake), show how energy and matter move and why balance among organisms is important.

Human connection: Humans depend on producers directly (crops) or indirectly (animals that eat plants). Over-harvesting producers or removing decomposers by bad practices harms food availability. Teaching conservation of soil and water links directly to maintaining food chains and supporting life.

From chain to web: In nature, many food chains overlap to form complex food webs. A single organism may feed on several kinds of food and be eaten by several predators. A food web shows these multiple connections with arrows indicating the direction of energy flow. Food webs give a more accurate picture of feeding relationships in a community than a single chain.

Interdependence among organisms: Organisms depend on each other for food, shelter, pollination and seed dispersal. For example, bees pollinate flowers while collecting nectar; plants provide nectar for bees. Predators control herbivore numbers; if predators are removed, herbivores may increase and overgraze plants. Decomposers make nutrients available to plants which again support consumers. This network of needs creates interdependence at every level.

Stability and changes: Biodiversity and multiple connections make ecosystems stable. If one species declines, others may fill its role partly. But large changes such as removal of a keystone species, pollution, or habitat loss can break links and destabilise the community. For example, removing all frogs from a pond affects insects and fish numbers and can allow algae to grow unchecked due to fewer grazers.

Class activity and reasoning: Drawing a food web for a pond or garden helps students see many links. Ask students to mark what happens if a species is removed — which species gain and which lose? This exercise develops reasoning about cause and effect. Understanding webs encourages students to value each species and to support conservation efforts that protect entire communities, not only single animals or plants.

Defining an ecosystem: An ecosystem is a community of living organisms interacting with each other and with their non-living environment. It includes producers, consumers, decomposers, soil, water, air, sunlight and the physical features of an area. Interactions in an ecosystem determine how energy flows and how materials cycle.

Major ecosystem types: Terrestrial ecosystems include forests, grasslands and deserts. Aquatic ecosystems include freshwater systems (ponds, rivers) and marine systems (seas, oceans). Each ecosystem type has characteristic plants and animals adapted to local conditions. For example, mangroves live in coastal tidal zones and protect shorelines while providing habitat for many species. Grasslands support grasses and grazing animals; deserts support specialized drought-resistant plants and animals.

Smaller ecosystems and human-made ones: Small ecosystems such as a puddle, a tree or a compost pit also show interactions among organisms and environment. Human-made ecosystems like gardens, farms and parks can be managed to support biodiversity but may lack complexity of natural systems. Urban ecosystems depend on human inputs but still host many plants, birds and insects.

Energy flow and nutrient cycling: Solar energy is captured by producers and moves through consumers. Decomposers return nutrients to the soil, allowing growth to continue. Disruption of any link — for example, pollution killing decomposers — affects the whole ecosystem. Ecosystems provide services to humans: food, clean water, climate regulation and raw materials.

Conservation and management: Protecting ecosystems maintains biodiversity and human well-being. Activities such as planting native species, protecting wetlands and reducing pollution help ecosystems stay healthy. Students can study a local ecosystem to observe its parts and propose ways to protect and improve it, learning both science and citizenship.

Role of abiotic factors: Abiotic factors are the non-living physical and chemical parts of the environment such as sunlight, water, soil, temperature and air. They strongly influence which organisms can live in a place and how well they grow. Plants and animals show many features because they are adapted to the local abiotic conditions.

Light: Sunlight is the main source of energy for ecosystems. Plants use light for photosynthesis. Light intensity and day length also influence flowering and leaf growth. Some plants of shady places have larger leaves to capture more light, while desert plants have small or waxy leaves to avoid water loss under strong sunlight.

Water: Water availability shapes life. Aquatic organisms are adapted to live in water; terrestrial plants have roots to take up water. Water affects seed germination, plant turgor (firmness) and animal behaviour. Regions with more rainfall support lusher vegetation and different animal communities than dry areas.

Soil and temperature: Soil type determines nutrient availability and water retention. Sandy soil drains quickly; clay holds water. Plants adapted to certain soils will succeed in those soils. Temperature affects metabolic rates — cold-blooded animals depend on environmental temperature for activity. In cold weather some animals hibernate, while others migrate to avoid harsh conditions.

Human influence and experiments: Human actions often change abiotic factors by removing vegetation (which alters soil moisture) or polluting water. Simple class experiments include measuring soil moisture in shaded and sunny spots and observing plant differences. Recording temperature and plant responses across seasons helps students connect abiotic factors with living things and understand why protecting environmental conditions is essential.

Seasons affect living things: Seasonal changes bring variations in temperature, rainfall and daylight hours. These changes influence plant growth, flowering, fruiting and animal behaviour such as breeding, migration and hibernation. Observing seasons helps students link the timing of life events to environmental cues.

Life cycle concept: A life cycle describes the stages an organism goes through from birth to maturity and reproduction. Different organisms have different life cycles. For instance, butterflies undergo complete metamorphosis with four stages: egg, larva (caterpillar), pupa (chrysalis) and adult. Frogs develop from eggs to tadpoles (aquatic larvae) and then to adult frogs. Trees grow, flower and produce seeds that begin new individuals. Life cycles ensure continuation of species and often align with seasons for better survival.

Seasonal adaptations in plants and animals: Many plants flower in spring when conditions favour pollination and growth. Deciduous trees lose leaves in dry or cold seasons to conserve water and energy. Birds migrate to warmer places during winter to find food and breed in favourable seasons. Some mammals hibernate to survive winter when food is scarce. These seasonal patterns are adaptations that increase survival chances.

Practical observations and recording: Students can keep a seasonal diary to note events like flowering, leaf fall, bird visits and insect appearances. Such records over months show patterns and help link life-cycle stages to seasons. Garden activities like planting seasonal crops teach students how sowing and harvesting depend on weather and seasons.

Importance for humans: Farmers plan cropping according to seasons; understanding life cycles and seasonal behaviour helps manage agriculture, wildlife conservation and natural resource use. Learning these patterns builds respect for nature’s rhythms and the need to protect the timing and conditions many species depend upon.

Human activities and their effects: Humans change natural surroundings through agriculture, industry, urbanisation, deforestation and pollution. These actions can reduce the area of habitats, pollute air and water, and cause soil erosion. When habitats are destroyed, plants and animals lose homes and food sources which may lead to decline or extinction of species. Pollution affects health of humans and other organisms by contaminating water and food chains.

Specific consequences: Cutting trees removes shelter and food for many animals and changes local climate by reducing shade and moisture. Dumping waste into rivers harms aquatic life and can make water unsafe for human use. Overuse of pesticides harms not only pests but also beneficial insects like bees, reducing pollination for crops. Overfishing shrinks fish populations and affects people dependent on fishing for livelihood and food.

Conservation actions: Conservation includes protecting habitats, using resources wisely and reducing pollution. Simple actions include planting native trees, protecting water bodies from waste, using water carefully, and proper waste disposal and recycling. Protected areas like parks and sanctuaries safeguard species and allow ecosystems to recover. Community involvement, laws and education support conservation on larger scales.

Role of students and communities: Students can take practical steps: plant and care for trees; organise clean-up drives; compost kitchen waste to create organic manure; conserve water by fixing leaks; and spread awareness in the neighbourhood. Small actions at many places add up to large benefits. Projects such as a school pond clean-up or a tree-planting drive teach responsibility and show how collective effort protects living organisms and their habitats.