Tag: microscope

The egg is the single- celled structure. The egg of an ostrich is the largest cell in the world and it measures up to 15 to 17 cm.

The cell is the structural unit of life and its size ranges from 0.5 micrometers to 100 micrometers. An egg of ostrich is a single-celled structure and is known as the largest cell. The size of each ostrich egg is 170 mm X 130 mm. Thus, the correct answer is option A.

The human egg (ovum) is the largest cell in the body and can be seen without the aid of a microscope. It is one millimeter in diameter. Whereas, a nerve cell is the longest cell in human body.

Phase contrast microscopy is particularly important in biology. It reveals many cellular structures that are not visible with a simpler bright field microscope. These structures were made visible to earlier microscopists by staining, but this required additional preparation and killed the cells. The phase contrast microscope made it possible for biologists to study living cells and how they proliferate through cell division. So, phase contrast microscope is best to study cell division in functional state compared to EM, SEM and simple microscope.

• The first person to see a living cell under the microscope was Antonie van Leeuwenhoek. 
• He called that cell as animalcule. He is commonly known as "the Father of Microbiology", and considered to be the first microbiologist. 

• The cell is the basic structural and functional unit of life. Schleiden proposed that new cells arise from within the old cells, especially from the nucleus. 
• This was corrected by Rudolf Virchow who proposed, "Theory of cell lineage" it states that all cells arise from pre-existing cells.

• Robert Hooke discovered cell in the year 1665. He observed cork cell in the bark of Spanish oak tree under a simple microscope and was able to see the empty structures surrounded by walls and named it a cell. 
• He elucidated his observation in a book called "Micrographia.

The well-known scientist Robert Brown discovered the nucleus in the year 1831. 

• Robert Hooke discovered cell in the year 1665. He observed cork cell in the bark of Spanish oak tree under a simple microscope and was able to see the empty structures surrounded by walls and named it a cell. 
• He elucidated his observation in a book called "Micrographia". He was unable to see the organelles inside the cell as cork cell which he observed was dead.

The invention of the microscope allowed the first view of cells. English physicist and microscopist Robert Hooke (1635–1702) first described cells in 1665. He made thin slices of cork and likened the boxy partitions he observed to the cells (small rooms) in a monastery. The open spaces Hooke observed were empty, but he and others suggested these spaces might be used for fluid transport in living plants. He did not propose, and gave no indication that he believed, that these structures represented the basic unit of living organisms.