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Ans 12. Robert  Hooke,  in  1665,  discovered  the  cell  under  his  own  constructed  microscope.  He  examined  a  thin  slice  of  cork  under  his  microscope.  He  saw  that  they  represented  structures  like  that  found  inside  a  honeycomb.  He  coined  them  as  cells,  which,  in  Latin,  means  a  'small  little  room'.

Ans 13. a) Contribution of Robert hooke:

The term cell was introduced by Robert Hooke in 1665, while examining a slice of cork through his microscope. Cork is obtained from the bark of a tree. Under a compound microscope, he observed many small compartments resembling a honeycomb. He termed these as cells.

b) Contributions of Leeuwenhoek:

Leeuwenhoek was the first person to observe single-celled animals (protozoa) with a microscope.

Leeuwenhoek was also the first person, using a microscope, to observe clearly and to describe red blood cells in humans and other animals, as well as sperm cells.

The existence of microscopic organisms was discovered by Antony van Leeuwenhoek.He reported his observations with accurate description and drawings. His best lenses were capable of magnification up to x270.

He was the first to observe and describe single celled organisms, which he originally referred to as animalcules, and which we now refer to as microorganisms.

c) Contribution to Robert Brown: 
Robert Brown was a botanist who discovered cell nucleus. Robert brown studied the epidermis of a collection of orchids with his microscope and found the spot in these cells that he named nucleus.

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