Title Chapter 1 The Living World.pdf ✅

BIOLOGY Chapter 1: The Living World
(1) 01 THE LIVING WORLD THE LIVING WORLD What is Growth To differentiate whether an organism is living or not, various characteristics need to be checked in the case of living organisms. Growth: All living organisms can undergo the process of growth and development that results in an increase in the mass and number of cells. Multicellular organisms grow by cell division. The growth of plants and animals takes place with the help of cell division. In the case of plants, the cell division occurs throughout their life while in the case of animals the cell division occurs up to a certain age, and then the cells lose their capability to divide. It results in an increase in body mass and increases in the number of cells. Examples: Mountains, boulders, sand mounds, etc grow by the accumulation of the materials although they are non-living. So, growth cannot be taken as the factor which categorizes the organism as living. Metabolism: As the body and organs are the constituents of different chemicals, they perform various metabolic functions that result in the conversion of chemicals into other biomolecules. All plants, animals, and microbes exhibit metabolism. It is absent in the case of non-living organisms but may be introduced through the in-vitro method.
(2) 01 THE LIVING WORLD Sensitivity: The living organisms whether prokaryotes or eukaryotes respond according to their surroundings and the stimuli present around them, it may be physical, chemical, or biological. The living organisms are sensitive about their surroundings and are responsible in accordance with their stimuli. The stimuli can either be biological, physical, or chemical. Cellular Organization: It is the defining characteristic of living organisms since all living organisms are made up of cells that help in performing various cellular functions resulting in the growth and development, reproduction, metabolism, etc in the body. Since non-living organisms are not made up of cells so they do not have cellular organization. Movement: The lining organisms show movement and locomotion and more specifically plants move according to the movement of the sun. Example: The flame of a candle and a crystal do not show movement while if we take mango trees then we can see they undergo movement, growth, and development along with reproduction and results in the production of more trees through their seeds. Thus mango trees are said to be alive as they show movement while candles flame and crystal are not alive. Also, the organisms that are aware and are conscious of their surroundings will be living organisms. What is Living? We do know that all living organisms reproduce, grow and metabolize. But when we look at the microscopic realm, the actual definition of life is rather blurred. For instance, viruses are basically a nucleic acid that is protected by a protein coat. They exhibit no
(3) 01 THE LIVING WORLD typical characteristics of living organisms such as reproduction, until and unless it is inside a host. Another “organism” that borders between the living and non-living are Prions. These are essentially misfolded proteins can reproduce by making other healthy proteins to misfold. These entities are responsible for causing diseases such as Spongiform Encephalopathy, fatal familial insomnia, which are almost always fatal. In conclusion, the realm between the living and the non-living differs even now as the definition of “life” is ambiguous. Characteristics of Life Living organisms exhibit undisputable signs of life – such as growth, reproduction and metabolism. Higher organisms such as humans showcase consciousness – where we become aware of our surroundings. Similarly, consciousness may be observable in many lower forms of life such as bacteria and protozoa. When these organisms engulf food or react to their environment, it is done primarily to ensure survival.