Characteristics of Life

  • Biology (Greek: bios = life; logos = study). The study of living beings, that is, all plants and animals including human being. Hence biology is a scientific study of the life. Nowadays the term “life science” is used instead of biology.

Characteristics of Life:

  • Biology examines the structure, function, growth, origin, evolution, and distribution of living things. It classifies and describes organisms, their functions, how species come into existence, and the interactions they have with each other and with the natural environment.
  • Four principles form the foundation of modern biology: cell theory, evolution, genetics, and homeostasis.

Made of Cells:

  • Every living organism is made of structures called cells. Organisms that are very different such as ferns, fish, and elephants all look similar at the cellular level. A cell is the basic unit of structure.
  • Organisms are organized at the microscopic level from atoms up to cells. Atoms are arranged into molecules, then into macromolecules, which make up organelles, which work together to form cells. Beyond this, cells are organized in higher levels to form multicellular organisms. Cells together form tissues, which make up organs, which are part of organ systems, which work together to form an entire organism. Beyond this level, organisms form populations which make up parts of an ecosystem. Different ecosystems collectively form biosphere.


  • Metabolism is essentially a collection of chemical reactions occurring within the body (or cell). In body two activities are continuously taking place anabolic activities (making up) and catabolic activities (breaking up).
  • During anabolic activities, food material is digested, absorbed and assimilated in the body. In catabolic activities, the stored substances are broken down by hydrolysis or oxidation to produce energy in the form of ATP which is required for doing regular activities by the body.
  • Anabolic activities and catabolic activities are collectively called metabolic activities and the process is called metabolism.
  • Metabolism includes processes such as protein synthesis, chemical digestion, cell division, or energy transformation.

Growth and Change:

  • All living organisms have the ability to grow and change. A seed under the right conditions will sprout and form a seedling that will grow into a larger plant.  Even the smallest bacteria must grow by binary fission. The growth is also required for the persistence of the species. The growth of plant takes place throughout the life and at a specific portion of the body but the growth in the animal is time bound and overall.

Growth of Sunflower from Seed to Flower



  • All living organisms must have the ability to reproduce. Living things make more organisms like themselves. If a species does not reproduce the next generation, the species will go extinct. Reproduction is the process of producing the next generation.
  • Reproduction may be a sexual or an asexual process.
  • Sexual reproduction involves two parents and the fusion of gametes, haploid sex cells from each parent. Sexual reproduction produces offspring that are genetically unique and increases genetic variation within a species.
  • Asexual reproduction involves only one parent. It occurs without a fusion of gametes and produces offspring that are all genetically identical to the parent. Genetic variation is not possible in asexual reproduction.

Maintain Homeostasis:

  • Living organisms keep their internal environments within a certain range (they maintain a stable internal condition), despite changes in their external environment. This process is called homeostasis and is an important characteristic of all living organisms.
  • By this process, the body temperature, sugar level in the body is maintained at constant level.
  • It is vital characteristics of life. If it is disturbed, it will result into diseases and if not controlled can threten the life of the organism.

Responding to the Environment:

  • All living organisms respond to their environment.Living things know what is going on around them and respond to changes in the environment.  When touch me not plant is touched its leaves close. The Venus fly trap traps insects.
  • The stem of plant moves in the direction of light and above the ground. (positively phototropic and negatively geotropic. The Root grows towards the soil and away from light (positively geotropic and negatively phototropic)

Behaviour of Touch Me Not Plant (Mimosa Pudica)

Behaviour of Venus Fly Trap


  • Heredity means that our genetic information can be passed from one generation to another. This way characteristics are transferred from one generation to the other.


  • An adaptation refers to the process of becoming adjusted to an en ronment. Adaptations may include structural, physiological, or behavioral traits that improve an organism’s likelihood of survival.

Importance of Study of Biology:

Biology and Nature:

  • The world of plants and animals is so large that we can marvel at the variety of the plants and animals. By studying biology we can study similarities and differences in the species.
  • Gardens and zoological parks offer nice places for human entertainment. Plants are grown for decorating homes and the flowers are used variously.
  • rearing of animals and keeping pets give us happiness and it is useful in curing many diseases particularly psychosomatic diseases.
  • By the study of biology, the species of a variety of animals and plants can be preserved.

Biology and Health:

  • Basic knowledge of human anatomy and physiology can be acquired by studying morphology and physiology, some other easily available and easily controllable animals.
  • Biology helps us in understanding causes and symptoms of diseases.
  • A number of diseases are caused by microbes. Some of these diseases like cholera, plague, malaria etc., become epidemic killing hundreds and thousands of people. The study of biology helps us in finding out the causative organisms of a large number of diseases, the means of their spread and also the methods of treatment and eradication of such diseases.
  • Surgery involves the removal or replacement of defective or damaged part or organ of the body. It is possible due to the study of biology.
  • Medicines are mainly obtained from plants. Therefore, it is essential to have knowledge and plants. Antibiotics are obtained from fungi and microorganisms.  Veterinary Science helps in treating the disease of domesticated and pet animals.

Biology and Food:

  • Man uses vegetables, fruits, plant origin substances, fish, chicken, pig, goat, prawns, crabs etc. as a food. Man utilizes milk from cow and buffalo. From milk butter, cheese, ghee etc produced. Hen’s eggs are widely used as food.
  • With the knowledge of biology, it is possible to increase the number of the animals or plants uses as food and improve their variety and quality.
  • Hybrid cattle can give more milk with better fat content. For these reasons animal husbandry and veterinary science, poultry keeping etc., are important branches of biology.
  • Using biology the animals and plants can be safeguarded against many diseases. By knowing the causes, the diseases can be prevented and cured.

Biology and Horticulture:

  • The branch of biology, botany helps us in the development of numerous new varieties of ornamental and decorating plants. Flowers with new colour combinations, new varieties of different leaf shapes etc., are developed by hybridization.
  • A number of seedless crops of guava, banana, grapes, papaya, have also been developed.

Biology and Agriculture:

  • A rapid increase in human population has increased demand on food supply. This has led to increasing the yield of food grains by adopting measures like
    • Developing and raising high-yielding and disease resistant varieties and making their seeds available to the farmers.
    • By reducing the period of the cycle of development, many crops can be taken in a year.
    • Controlling the growth and kill the pests, insects, and weeds, using insecticides, pesticides, fungicides, and weedicides.
    • Understanding causes of different diseases to the plants and takes preventing action to avoid them or take curative action if plants are affected by the diseases.
    • Preservation of food such as pasteurization, drying freezing radiating etc. c an be done to increase its shelf life.

Biology and Animal Husbandry:

  • We get leather from the hide of mammals, silk from silk moth, fur and wool from sheep’s and lambs, fat and liver oil from fishes, honey and wax from honey bee, lack from lack insect and pearls from pearl oysters and corals, leathers, shells horns etc..
  • High production of these substances can be obtained by animal husbandry, piggery, poultry keeping, pisciculture, sericulture, lack culture, apiculture.  Productivity can be increased by the proper knowledge of habit, habitat and life cycle of the animals.

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