Question

Cell theory was propounded by
A. Schleiden and Schwann
B. Watson and Crick
C. Mendel and Morgan
D. Wallace and Darwin

Answer 1

Hint: All plants and animals are made up of cells. Robert Hooke coined the term cell in 1663. The cell is the basic unit of life. The cell theory was proposed by two scientists but later modified by a third one who added a third postulate to the cell theory.

Complete answer:
The cell theory states that -
A cell is the smallest unit of structure of all living beings.
The cell is the unit of function of all living organisms.
All cells arise from pre-existing cells.
Watson and Crick propounded the double-helical structure of deoxyribonucleic acid in the year 1953. They state that two strands of DNA are held together by hydrogen bonds between nitrogenous bases on opposite strands. The nitrogenous bases- Adenine and Thymine pair up together and a Cytosine with Guanine pair up together.
Therefore, option (b) is incorrect.
 Mendel and Morgan did high research on genetic studies. Gregor Johann Mendel is known as the father of genetics and H. Morgan is another person who had a tremendous contribution towards genetic studies through his experiment on Drosophila melanogaster.
Therefore, option (c) is also incorrect.
 Wallace and Darwin studied natural selection. Both the scientists co-developed the theory of natural selection and evolution. Wallace was inspired by Darwin and Booth were doing their research individually but coincidentally both published their research in the same year and thus both became pioneers of natural selection and evolution.
Therefore, option (d) is incorrect.
The cell theory was proposed by two scientists- Matthias Schleiden and Theodor Schwann. Earlier it was only limited to the cell being the structural and functional unit of all living beings but later Rudolf Virchow added on another point. This point stated that all cells arise from pre-existing cells and this theory opened new paths for all the scientists to work.
So, the correct answer is “Option A”.

Note:
-The older cell theory is the basis of the modern cell theory. There are certain postulates added to the cell theory.
-Cells are the components of each and every living thing.
-All the cells have the same chemical composition.
-The cell is the functional unit of living beings