These DAV Class 6 Science Notes and DAV Class 6 Science Chapter 7 Notes – The World of Living act as excellent revision resources, particularly in preparation for board exams.
The World of Living Class 6 DAV Notes
→ Characteristics of Living Things
- Living beings are made up of cells
- Living things grow
- Living things need food
- Living things respire
- Living things move
- Living things respond to stimuli
- All living things reproduce
- Living things have a definite life span
- Living things excrete
→ Cell: Cell is the basic unit of life. It is a structural and functional unit of life.
→ Unicellular Organisms: An organism which is composed of a single cell is called unicellular organism.
→ Multicellular Organisms: An organism which is composed of more than one cell is called multicellular organism.
→ Nutrition: The process by which a living being takes and utilizes food is called nutrition. Green plants prepare their own food and hence they are called autotrophs. All other living beings directly or indirectly depend on green plants and hence they are called heterotrophs. Photosynthesis: The process by which green plants prepare their food is called photosynthesis. During photosynthesis, the green plant takes carbon dioxide from air and water from soil and with the help of chlorophyll convert solar energy into chemical energy, i.e. food.
→ Respiration: A living being breaks down the food to release energy so that this energy can be utilised for various functions. This process is called respiration.
→ Reproduction: A living being produces its own kind and the process is called reproduction. Reproduction is the way by which a living being maintains its race on the earth.
→ Excretion: As a result of various biological activities, many wastes are created in the body of a living being. The removal of such waste is called excretion.
→ Classification of Living Beings: All living beings can be broadly classified into plants and animals. Classification is necessary for proper study of living beings.
Classification Of Plants
1. Classification on the basis of their height, size and shape: On this basis, plants can be classified into three types, viz. herb, shrub and tree.
→ Herb: Herbs are very small plants. They are a few inches to about 3 feet in height. The stem of herbs is soft and green. Examples: grasses, some vegetables, etc.
→ Shrub: Shrubs are medium sized plants. They can be from 3 feet to 7 feet high. The stem of herb is thin but hard and woody. Examples: Rose, China Rose, bougainvillea, etc.
→ Tree: Trees are big sized plants. They can be up to about 100 metre high. The stem of tree is strong and woody. Examples: mango, litchi, peepal, banyan, etc.
2. Classification on the basis of their life span: On this basis, plants can be classified into three types, viz. annuals, biennials and perennials.
→ Annuals: Such plants survive for only one season. Examples: seasonal flowering plants, vegetables, crops, etc.
→ Biennials: Such plants live for two seasons. They show full vegetative growth in the first year and bear flowers and fruits in the second year. Examples: Carrot, radish, turnip, potato, etc.
→ Perennials: Such plants live for many years. They produce flowers and fruits for many times in their life span. Examples: Mango, guava, neem, etc.
3. Classification on the basis of their flowers: On this basis, plants can be classified into two groups, viz. flowering plants and non-flowering plants.
→ Flowering Plants: Such plants bear flowers and fruits. Examples: mango, litchi, banana, etc.
→ Non-flowering Plants: Such plants do not bear flowers and fruits. Examples: moss, fern, algae, pine, etc.
4. Classification on the basis of their habitat: The place where an organism lives is called its habitat. On this basis, plants can be classified into three groups, viz. mesophytes, xerophytes and hydrophytes.
→ Mesophytes: Plants which grow on land and need moderate amount of water for their survival are called mesophytes. The roots in such plants are of medium size. The leaves are normal in such plants. Examples: mango, guava, apple, etc.
→ Xerophytes: Plants which grow in deserts and can survive on minimum amount of water are called xerophytes. Roots of such plants are very long so that they go deep in the ground. The leaves in such plants are spiny so that they can prevent loss of water. Examples: cactus, acacia, etc.
→ Hydrophytes: Plants which live in water and need maximum amount of water for survival are called hydrophytes. Roots in such plants are either very small or altogether absent. Leaves in such plants are coated with thin film of wax to protect from water. Examples: Water lily, lotus, hyacinth, etc.
5. Classification on the basis of nutrition: On this basis, plants can be classified into two groups, viz. autotrophs and heterotrophs.
→ Autotrophs: Plants which produce their own food are called autotrophs. All green plants come under this category.
→ Heterotrophs: Plants which take food from other plants or animals are called heterotrophs. Heterotrophic plants can be further divided into two groups, viz. saprophytes and parasites.
→ Saprophytes: Plants which feed on dead and decaying bodies are called saprophytes. Examples: mushroom and other fungi.
→ Parasites: Plants which feed on living bodies are called parasites. Examples: Amarabel and orchids.
→ Classification Of Animals
1. Classification on the basis of backbone: On this basis, animals can be divided into two groups, viz. vertebrates and invertebrates.
→ Vertebrates: Animals which have a well developed bony skeleton are called vertebrates. Backbone is present in such animals. Examples: man, fish, horse, lion, frog, lizard, etc.
→ Invertebrates: Animals which have a soft body and which don’t have bony skeleton are called invertebrates. Backbone is absent in such animals. Examples: earthworm, cockroach, snail, octopus, starfish, etc.
2. Classification on the basis of food habits: On this basis, animals can be classified into following groups:
Herbivores: Animals which eat green plants are called herbivores, e.g. cow.
Carnivores: Animals which eat the flesh of other animals are called carnivores, e.g. lion.
Omnivores: Animals which eat both plants and flesh are called omnivores, e.g. man.
Frugivores: Animals which eat only fruits are called frugivores, e.g. parrot.
Insectivores: Animals which eat only insects are called insectivores, e.g. lizards.
Saprophytes: Animals which feed on dead and decaying bodies are called saprophytes, e.g. some types of bacteria.
Parasites: Animals which obtain food from living bodies are called parasites, e.g. leech, roundworm, lice, etc.
3. Classification on the basis of reproduction: On this basis, animals can be divided into following groups:
→ Reproduction by dividing the body: Amoeba and hydra are examples of animals which reproduce by dividing their body.
→ Egg laying animals: Animals which lay eggs are called oviparous or egg-laying animals. Examples: hen, turtle, crocodile, etc.
→ Viviparous Animals: Animals which give birth to young ones are called viviparous animals. Examples: Man, elephant, horse, etc.
4. Classification on the basis of body covering: Animals can also be divided on the basis of their body covering. Animals; like fish and snakes have scales over their body. The skin of frog is slimy. The body of a bird is covered with feathers.
Importance of Plants
- During photosynthesis, plants produce oxygen and thus plants maintain a balance between carbon dioxide and oxygen in the atmosphere.
- Plants are the most important source of food for us.
- Many industrial products; like rubber and paper; are obtained from plants.
- We get building material; like timber from plants.
- Many medicinal plants; like belladonna, clove oil, quinine and isabgol are obtained from plants.
→ Importance of Animals
- Some animals are used for transportation and for farm-related work.
- Animal excreta is used as manure.
- Silk is obtained from silk moth and wool is obtained from sheep.
- Milk, honey, egg and meat are important foods which are obtained from animals.
→ Metabolism: Various biological activities in a living being is called metabolism.
→ Nutrition: The process by which a living being takes and utilizes food is called nutrition.
→ Autotrophic Nutrition: The mode of nutrition in which a living being prepares its own food is called autotrophic nutrition.
→ Heterotrophic Nutrition: The mode of nutrition in which a living being takes food from other organisms is called heterotrophic nutrition.
→ Saprophytes: Oranisms which feed on dead and decaying bodies are called saprophytes.
→ Parasites: Organisms which feed on living bodies are called parasites.
→ Herbs: Small plants with soft and green stem.
→ Shrubs: Small plants with woody and thin steam.
→ Trees: Big plants with woody and strong stem.
→ Mesophytes: Plants which need moderate amount of water.
→ Xerophytes: Plants which need minimum amount of water.
→ Hydrophytes: Plants which need large amount of water.
→ Vertebrates: Animals which have bony skeleton and backbone.
→ Invertebrates: Animals which do not have bony skeleton and backbone.