Tag: cell-the basic unit of life

Pasteur work on fermentation and germ theory of biology. Schleiden and Schwann are the co-founders of cell theory. Robert Brown was a Botanist and he discovered the nucleus. Rudolf Virchow was a German Physician, Biologist, Pathologist as well as a writer. The phrase 'Omnis cellula e cellula' is coined by Virchow which means all cells come from a cell, all cells born from a previous cell. So the answer is 'Virchow'.

Cell principle states that the cell is a fundamental unit of life and has all structural and functional properties of an organism. Also according to this principle cells are made from pre-existing cells and all organisms are made up of cells. Bacteria, algae and fungi obey the cell principle rules whereas viruses are under debate of being living or dead. They have many features of life but according to cell theory, they are not alive. Viruses lack cellular structure (cell wall, cytoplasm, ribosomes etc.) but do have genetic material in the form of RNA and they can only multiply when inside a host cell. Outside a host, they are unable to survive. Since a virus is not a cell, cell principle is not applicable to them. 

• A cell is a unit mass of protoplasm which is surrounded by protective and semi-permeable plasma membrane which separates the cell contents from the environment. 
• It is the basic unit of life and carries out the different functions of life. The body of all organisms is made up of cells so it is the structural unit of life. 
• Also, all the physiological, biochemical and genetic functions of the body are carried out by cells so it is called a functional unit of life. So, the correct answer is option D.

Micrographia is a book written by Robert Hooke when he discovered the cells in 1665. His all observation about the discovery of cells is detailed in this book. Hans and Zacharias designed the first compound microscope and by using this microscope Robert Hooke studied insects, sand, bird feathers, snowflakes and plants. He also observed a piece of cork which made him discover a framework of cells with empty spaces within it. its visual similarity with honeycomb cells made him name those units as the cell. He recorded all such observation through different lenses in the book Micrographia which is the first scientific bestseller.  

In 1838, Matthias Schleiden who was a German Botanist while studying a large number of plants he made an observation that plants also composed of different kinds of cells. These cells were arranged into tissues. Whereas Schwann was studying animal cells and reported the existence of cell membrane that surrounds cytoplasm. Together Schleiden and Schwann proposed cell theory based on their observation plants and animal cells. So Schleiden applied cell theory specifically to plans and Schwann to animals.  

Schleiden and Schwann proposed a cell theory according to which all cells are formed from preexisting cells. After the discovery of protoplasm by Corti, Dujardin observed a living juice inside the cells and named it as sarcode. Purkinje coined the term protoplasm while observing sap of plant cells. Max Schultze established similarity between protoplasm and sarcode that leads him to propose a theory which is called as the protoplasmic theory by Hertwig. This theory states that protoplasm is the physical basis of life. So answer B is correct.

The organismal theory teaches that the organism (even a multicellular organism) is the basic unit of life. It was proposed by Sachs. Thus the correct option is B.

a) Mutation theory is proposed by Hugo de Vries.