[Biology] What is living?

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WHAT DO YOU MEAN BY LIVING?

  • The term living is derived from the word “lifende” meaning living or having life.
  • A living thing relates to any organism that exhibits the characteristic of life or being alive.
  • All living organisms grow. Increase in mass and increase in number.

CHARACTERISTICS OF LIVING THINGS

There are certain characteristics, on the basis of which an organism can be classified as living or nonliving.

These characteristics include:

  • Organization
  • Sensitivity
  • Reproduction
  • Growth
  • Metabolism
  • Evolution
  • Homeostasis

NCERT Chapter: The Living World Class 11 Notes - Leverage Edu

ORGANIZATION

  • Living things have different levels of complexity and organization which is not found in non-living objects.
  • At its most basic level, a living thing is composed of one or more cells. Cells are the basic structural and functional unit of a living organism.
  • The cells organizes into clusters called tissues, further tissues are grouped and forms organs. Organs form the organ system.

SENSITIVITY

  • Living organisms are sensitive in nature. They can detect and respond to various internal and external stimuli.

REPRODUCTION

  • All living things have the ability to divide and produce offspring by the process of reproduction. There are two types of reproduction, namely:
    • Asexual reproduction
    • Sexual reproduction
  • Reproduction refers to the progeny production where the characteristics will be more/less similar to the parents, though this only happens in Sexual reproduction.
  • But, in case of Fungi it multiplies and spreads with the help of spores. In Planaria (Flat worms) fragmented organism regenerates the lost part of body and forms a new organism. These are the happenings in case of asexual reproduction.

ASEXUAL REPROUCTION

  • Among plants and simple animals, reproduction involves only one parent, and the offspring are generally identical to the parent cell.
  • Example: Bacteria etc.

SEXUAL REPRODUCTION

  • More complex organisms involves two parents contribute to the formation of a new individual.
  • During this process, a new variety of traits can be produced.
  • Example: Flowering plants, Human beings etc.

GROWTH

  • Growth is the process which involves organisms to take in material from the environment and organize them into its own structures.

METABOLISM

  • All living organisms involve chemical processes that take place within their cells.
  • The chemical processes that occur within a living organism with the purpose of maintaining life are collectively known as metabolism. Nonliving things do not exhibit metabolism.
  • Metabolism can be appropriately divided into two types;
    • Catabolism: the molecules breakdown to attain energy. Energy gets released.
    • Anabolism: the synthesis of the biological compounds. Energy gets consumed.

EVOLUTION

  • Living organisms have the ability to adapt to their environment by the process of evolution.
  • During evolution the organisms in the population become more suitable to metabolize, respond, and reproduce in a specific environment.

HOMEOSTASIS

  • Homeostasis is a self-regulatory process through which living organisms maintain their internal environment from the harms and fluctuations of the external environment.
  • Example: Organisms living in cold areas, such as the polar bear, have body structures that help them tolerate low temperatures and conserve body heat.

CLASSIFICATION OF LIVING ORGANISMS

The basic classification of living organisms commences by dividing them into two major groups:

  • Plants
  • Animals

PLANTS

  • Plants are autotrophic, multi-cellular organisms that are capable of producing their own food by photosynthesis.

CLASSIFICATION OF PLANTS:

Plants are categorized into two basic types

  • Vascular plants
  • Non-Vascular Plants

VASCULAR PLANTS

  • Vascular plants consist of xylem and phloem tissues

The major types of vascular plants are: Ferns, Angiosperms, and Gymnosperms.

NON-VASCULAR PLANTS

  • Non-vascular plants lack xylem and phloem (the specialized vascular tissues).
  • They also lack true stem, leaves and roots.

The non vascular plants are: Mosses, Liverworts and Hornworts.

ANIMALS

  • Animals are heterotrophic organisms (hence they depend on others for food).

CLASSIFICATION OF ANIMALS

The animal kingdom has been divided into two major types:

  • Vertebrates
  • Invertebrates

VERTEBRATES

  • Vertebrates are the animals that consist of backbone in their body. They are also known as chordates.

These animals include: Fish, Amphibians, Reptiles, Birds and Mammals.

INVERTEBRATES

  • Invertebrates are animals that lack a backbone in their body and have soft bodies or a hard covering.

These include: Jellyfish, Worms, and Spiders

REFERENCES

  • Arihant’s handbook of biology. The living world. Page no: 1-6.
  • NCERT biology; textbook for class 11. The living world. Page no: 1-62.

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