Question

Fill in the blanks.
A. Cells were first observed by _____________ in 1665.
B. Cells have three main parts ______, _____ and ______.

Answer 1

Hint: The multicellular organisms are made up of a large number of different cells. The cell is the smallest unit of any living organism. It is also called a basic or fundamental unit or building block of living beings. The cells are too small, which cannot be seen through naked eyes.

Complete answer: The cells can be seen with the help of a microscope. In 1665, Robert Hooke designed his own microscope with a high magnification power. He observed the slides of cork and found that there are small spaces in hexagonal design. These are looking similar to the small rooms in which monks live (cellula). So, the term cell for these structures was coined by Robert Hooke, and he published a book Micrographia. What Robert Hooke actually observed through his microscope was the cell wall present in dead cells of cork. The prokaryotic as well as the eukaryotic cell is surrounded by a thin plasma membrane. Inside the plasma membrane, it contains protoplasm.
The protoplasm can be divided into two parts:
-Nucleus that is surrounded by dense cytoplasm.
- Cytoplasm

Thus, the correct answers will be -
A. Cells were first observed by Robert Hooke in 1665.
B. Cells have three main parts: plasma membrane, nucleus and cytoplasm.

Note: The plasma membrane acts as a physical barrier and it protects the cell contents from the external environment. The cytoplasm is a site where the majority of biochemical reaction takes place. The nucleus controls the overall functioning of cells and the transfer of genetic materials to offspring.