Question

what is Cell Theory ? write in about 80 words.

Answer 1

Cell : The basic unit of life

What a cell is?
The basic structural and functional unit of life that is capable of doing all the functions necessary for being alive is callled as cell. A cell is capable of independent existence and performing all the functions that are essential for life. Anything or any organism that is less than a complete structure of cell doesn't ensure independent living. This is why viruses are considered connecting link between living and non living organisms. Viruses attack the host cells and use their cellular functions to divide. Hence, cell is known as the fundamental or basic unit of life.
Cell was discovered by Robert Hooke in 1665. Later, Anton Von Leeuwenhoek discovered and described living cells.

Cell theory : All living things are made up of cell

In 1838, a German botanist named Matthias Schleiden studied various a large number of plants and observed that all plants are composed of different kinds of cells. About the same time in 1839, a British Zoologist named Theodore Schwann observed different types of animal cells. Based on his observations, he proposed that animals and plants are composed of cells.
This led to the formation of cell theory. Cell theory was formulated by both Matthias Schleiden and Theodore Schwann. But, this theory still lacked something that was "how new cells are formed?" In 1855, Rudolf Virchow added that all cells arise from pre existing cells. He gave the statement "Omnis cellula-e cellula" i.e., new cells arise from pre existing cells. Therefore, the hypothesis of Mattias Schleiden and Theodore Shwann was given final shape of cell theory by Robert Virchow. Hence,the present form of cell theory is as follows :
(i) All living organisms are composed of cells and products of cell.
(ii) all new cells arise from pre existing cells.


Hope It Helps

Answer 2

Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells also contain the body’s hereditary material and can make copies of themselves.

Cells have many parts, each with a different function. Some of these parts, called organelles, are specialized structures that perform certain tasks within the cell. Human cells contain the following major parts.