Question

Assertion: Rudolf virchow modified the hypothesis of cell theory given by Schleiden and Schwann.
Reason : Cell theory says that all cells arise from pre-existing cells.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect.

Answer 1

Hint: The classical cell theory which is universally accepted was given by Schleiden and Schwann. It states that a) all organisms are made up of cells and b) cells are a basic unit of life.

Complete Answer:
The cell theory proposed in 1838-39 by Schleiden and Schwann did not tell about how cells were formed. Rudolf Virchow gave omnis cellula e cellula in 1858. He stated that pre existing cells divide and form new cells by multiplication. This way a new shape was given to the cell theory by Virchow.

Let us analyse the options to find the correct answer.
Option B: Both the given assertion and reason statements are correct but the reason is not the correct explanation for assertion. Virchow gave a new aspect to the already existing cell theory but did not modify the hypothesis of cell theory given by Schleiden and Schwann. Hence, this is the correct option.

As per the cell theory,
- Every living organism present on earth is made up of cells.
- The cell is the basic unit of life.
- All cells arise from pre-existing cells.

Thus, the correct answer is option B) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

Additional information:
- The term cell was first coined by Robert Hooke while he was observing the cork cells under his lens.
- Advancements in microscopy and proposal of cell theory helped scientists to discover cellular components.

Note: The various functions of cells are as follows,
- They provide both support and structure to all organisms.
- They help in transportation of substances.
- They help in dividing cells via mitosis.
- They have a role in energy production and reproduction.