Question

In view of the current status of our knowledge about the cell structure, which of the following statements about cell theory is/are correct?
(i) The cell theory does not hold good since all living organisms are not cellular in the organization.
(ii) The cell theory in its modified form means that all living objects are composed of cells capable of reproduction.
(iii) The cell theory in its modified form means that all living objects are composed of cells capable of reproduction.
(iv) The cell theory needed modification due to the discovery of subcellular structure such as chloroplast and mitochondria.

A. (i) and (ii)
B. (i), (ii), (iii)
C. Only (i)
D. (ii) and (iii)

Answer 1

Cell theory tells us that all living things are made up of a cell, which is the basic structural and functional unit of life and all organisms, it is also the basic unit of reproduction, all new cells come into existence form the pre-existing cell.

Complete answer:
Robert Hooke discovered the first time cell, and a number of theories put forward that gives an idea about cell and cell theory. All unicellular or multicellular organisms are made up of cells. The cell theory is formulated by german scientist Schwann, Matthias Schleiden proposed the spontaneous generation of a method for cell origin and Rudolph Virchow stated that Omnis cellula e cellula that means all existing cells have come from pre-existing cells.

The cell theory states that: All living organisms are made up of cells either unicellular or multicellular. Those organisms like a virus are not made up of cells. A cell arises from a pre-existing cell.

Apart from the theory of cell given by a German scientist, some other points are given in modern cell theory they are as follow:
• The activity of an organism depends upon the total activity of independent cells.
• Energy flow occurs within cells
• A cell contains genetic material in the nucleus as a chromosome which carries DNA segments or RNA.
• All cells are the same in chemical composition in similar species.

The modern version of cell theory includes ideas such as energy flow occurs within a cell, hereditary material passes from one cell to another cell and cells have the same basic chemical composition.

Hence, the correct answer is option (C).

Note: Cell is composed of many subcellular organelles which is necessary to carry out all metabolic activity for the survival of the cell and for producing new cells. Some other subcellular organelles are as follows:- nucleus, endoplasmic reticulum, mitochondria, centriole, Golgi body, ribosomes, vacuoles, chloroplast.