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class 4th science chapter 1 characteristics and life process organisms

Characteristics And Life Processes Of Organisms

Characteristics And Life Processes Of Organisms

Animals and plants are two distinctive groups of living things. Both express the attributes of living things in their specific ways with different body parts. In this chapter, we will study various characteristics and the diversity found among both the groups of living organisms.

1.1- Characteristics of major groups of living things

Living things a great diversity ranging from tiny microorganisms to giant blue whale. Living organisms are present everywhere on the earth. Some are even found in the coldest regions (polar region) and hot water springs. All living organism share some common characteristics such as, all living organisms need food, they grow, breath, reproduce, excrete and have ability to sense their environment. However different groups of living organisms express all these life characteristics in their own way.

Here is given a brief comparison of characteristics of two major groups of living organisms i.e. plants and animals.

Table 1.1 Comparison Of Plants And Animals

Plants are green in colour and can prepare their own food.Animals cannot prepare their own food
Plants cannot move Animals have the ability to move.
All the process takes place through stomataAnimals take in oxygen which is released from plants and release carbon dioxide into the atmosphere.
Baby plants grow and develop into trees and larger plants. Baby Grow and become adults
Plants reproduce through seeds. Some plants produce through spores and some develop from buds. Some animals reproduce through eggs and some give birth to their babies.

1.2 Classification of animals

Animals have a wide variety on earth. They are classified in two major groups on the basis of presence or absence of backbone in their bodies. There are two groups of animals

1:- Vertebrates

2:- Invertebrates

1. Vertebrates

Vertebrates are the animals which possess a backbone or vertebral coloumn and internal skeleton i.e. endoskeleton in the body. These organs are usually made of bones.

Vertebrates are the most complex and advance forms of organisms on the earth. Their organs are well developed. Group of organs work together and form organ system. Animals in this group are fish, frogs, crocodile, rabbits, camel, cow and human, etc.

Fig:- 1.1 Human skeleton

Fig:- 1.1 Human skeleton

2. Invertebrates

Invertebrates are the animals which do not have bones nor vertebral column. However some of them have exoskeleton but it is not made up of bones. They have soft bodies because these animals do not have bones inside their bodies. Examples of invertebrates are molluscs, sponges, jelly fish, anemones, worms, insects (e.g. butter fly), starfish, etc. Here is a brief comparison between vertebrates and invertebrates.

Table 1.2 Comparison Of Invertebrates and Vertebrates

They are the animals without backbone. they have vartebral.
They lack well developed body organisation or system. Vertebrates have well developed organs systems which, nervous system digestive systems,etc
Invertebrates possess skeleton outside their body i.e. exoskeleton. For example snails, insects, etc. Vertebrates have internal body skeleton i.e endoskeleton.
Generally they are smaller in size but some4. invertebrates attain gigantic size. For example: Some of the squids have gigantic size i.e., colossal squid. It reaches the length of 46 feet.Vertebrates are relatively larger in size.
Majority of them have compound eyes. None of the vertebrates have compound eyes. They have a single lense in each eye. None of the vertebrates have compound eyes. They have a single lense in each eye.
Maximum 95% of animals are invertebratesOnly 5% of animals are vertebrates.

1.3 Classification of plants

Plants are living organisms with a wide variety of sizes, shapes and colours. Plants need air, water, nutrients and sunlight for their growth and survival. Plants are found almost everywhere. Based on the presence or absence of flowers, plants are divided into two major groups i.e. flowering plants and non-flowering plants.

Flowering plants

Flowering plants produce flowers at their adult stages. These flowers develop into fruit which produce seeds. Seed germinate into the new plant. Mango, banana, rose, sunflower, papaya, hibiscus, etc. are example flowering plants.

Fig 1.2 (a) Flowering plants

Fig 1.2 (a) Flowering plants

Non-flowering plants

The plants do not carry that flowers at any stage of their life. They produce spores. These spores are used for reproduction. Algae, fern, some how misfit as they donot produce spores, conifers and mosses are non-flowering plants.

Table 1.3 Comparison Between Flowering And non-flowering                                                                  
Flowering plantsNon-Flowering plants
They produce flowers.They produce spores and do not produce flowers.
All flowering plants produce seeds. Their seeds are inside a protective shell called seed coat. Some non-flowering plants produce seed but their seeds are naked i.e. have no cover.
Flowering plants have great diversity of features including true roots, leaves and stem. Non-flowering plants show less diversity of features Most of the non- flowering plants do not have roots, leaves and stem.

1.4 Diversity in life

Biodiversity refers to the variety of living species on Earth.The planet Earth is a home of millions of plants and animals. There are 2 million species of plants, animals, fungi and micro organisms. Each plant and animal has its own sets of unique features. In the picture given below, there are 37 species of cats. Even a single cat species may has distinctive characters. 

Just like cat and jasmine other organisms have great variations with in the members of their families. Such a large number of living organisms make this world biologically diverse.

Biodiversity is essential for the sustenance of life on the earth. The reason is that every species performs a specific role in its ecosystem. It consumes and stores energy. Many other organisms depend upon it for food, shelter, etc. The extinction of a species disturbs the whole food chain.

Many plants and animals become a reservoir of raw materials for industry (medicines, cosmetics, perfumery, resins, chemicals, fibres, etc.) food, such as fisheries, forests, livestock, etc. Hence, biodiversity supports ourindustry and the economy.

1.4.1 Ways to protect biodiversity

We should be very concerned for the safety of our environment as it supports biodiversity. Unfortunately, human activities are destroying biodivetrsity, leading to the extinction of species. We can protect biodiversity by our actions. Some of the ways to protect biodiversity are given below:

Protect the natural habitats.

Habitats support organisms to survive. These can be protected by:

  • Planting more trees and prevent deforestation.
  • Implementation of law and order in this regard by the government
  • Stop polluting the living places of animals. i.e. not dumping garbage into the water and around trees.

Preserve water resources

Do not pollute water bodies such as rivers, lakes, oceans, ponds, etc. Polluted water bodies put aquatic life  in danger.

Avoid illegal hunting

Hunting of animals reduces their population which affects the overall biodiversity. Government should take measures to stop illegal hunting of Wild animals etc.

Spread awareness

Increase awareness about biodiversity and the need to protect it. Support the conservation organizations such as the World Wildlife Fund (WWF) and others working for this noble cause.

Preserve endangered animals

Endangered animals may be bred in the captive breeding centers to save their race. Besides these measures, each little attempt will contribute to protect biodiversity such as avoid littering, cut plants for the sake of construction, etc.

1.5 Function of major structures of animals

Animals has to perform various functions which are performed with the help of various organs. Some of them are external and many are internal. The internal organs have been discussed below.

1:- Teeth

Teeth are hard bony structures in the mouth cavity. Most of the vertebrates have teeth.

Humans have a variety of teeth, i.e. flat, conical, pointed, etc. They help them in tearing, chewing and grinding food. Four types of teeth are found in animals, such as incisors, canines, molars. These teeth are shaped according to their eating habits.

Fig 1.3 Dentation pattern in humans

Fig 1.3 Dentation pattern in humans

2. Bones

All vertebrates have a network of bones. It is called a skeleton. It shapes up and provides a framework for the attachment of muscles. You can identify organisms by observing their skeletons.Bones Project various soft organs inside such as rib cage and skull.Bones Store minerals and bone marrow product blood cells.

Fig 1.4 :-Human skeleton and fish skeleton

Fig 1.4:-Human skeleton and fish skeleton

3. Lungs

Lungs are the organs of breathing Lungs take in air (oxygen) and exhale carbon dioxide through the mouth or nose.

Humans have well-developed pair of lungs. These lungs are divided into tiny air sacs (alveoli) for efficient gaseous exchange where lungs transfer inhaled oxygen to the blood.

Fig 1.5 Human lungs

Fig 1.5 Human lungs

4. Heart

The verb of heart is to pump blood in the animal body. Pumped blood delivers nutrients and oxygen to the tissues and carries carbon dioxide to the lungs. Heart is divided into chambers. Upper chambers are called atria, whereas lower chambers are known as ventricles

Fig 1.6 Heart

Fig 1.6 Heart

5. Stomach

Stomach is a muscular organ in humans and many other animals. It is responsible for further breakdown of food after chewing. In stomach, digestion of food occurs through gastric juices (enzymes and hydrochloric acid). The food is passed to intestine for further assimilation.

FiG 1.7 Stomach

FiG 1.7 Stomach

6. Muscle

Muscles are elongated fibres of the body which contract and relax to cause movement. Muscles are attached to bones and work together to develop an activity.

Fig 1.8 Muscles in a human

Fig 1.8 Muscles in a human

7 Brain

The brain works like a computer. It is protected by the skull.The some parts are common in vertebrates brain.

Fig 1.9 Human Brain

Fig 1.9 Human Brain

  • Forebrain (Cerebrum)
  • Midbrain
  • Hindbrain (Cerebellum)
  • Medulla


Controls attention and language, regulates fear and pleasure responses

2. Forebrain.

(Cerebrum) controls emotions, speech and muscular actions.

3. Midbrain 

Controls consciousness and response to different stimuli.

4. Medulla 

Controls heartbeat, blood pressure, breathing, etc.

1.6 Parts of plants and their functions

Plants consist of many parts. These are:

1 Roots         2 Stream       3 Leaves

4 Flowers      5 Fruit           6 Seeds

1.6.1 Functions of parts of plants

Each part of the plant performs some specific functions.


Roots grow below the surface/ground. They anchor the Fi plant into the soil. Roots absorb nutrients and water from the soil and transport it to the stem and leaves. In some of the plants also store food and become fleshy such as carrot, turnip, radish, etc.

Roots are divided into branches. Maximum branching of roots can increase water absorption and nutrients.


The stem is the aerial part, i.e. grows above the ground. Stem gives support to leaves, flowers and fruit. Stem favours two types of transportation:

  1. Transport roots to leaves and other parts of water.
  2.    Leaves, roots and other parts of the food transportation


Leaves are also aerial parts. They prepare food through photosynthesis. They are green in colour due to chlorophyll which helps the plants in photosynthesis. There are small veins in the leaves which distribute water and nutrients throughout the leaves. Leaves also help in releasing out extra water from the plant through transpiration.


A flower is the coloured, beautiful and bright part of a plant. It consists of four basic parts, i.e. sepals, petals, stamens and carpal. Sepals protect flowers. Petals are coloured, therefore, they attract insects and birds for pollen and seed dispersal. Stamen and carpel are reproductive parts of flower and produces seeds.


Seed is a hard part of a plant. Most of the seeds are enclosed in fruits. Seeds wait for suitable conditions to germinate and new plants. Seeds can survive for a long period even if detached from the plant.

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