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Cell : The Unit of Life

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Define the following :

1. Nucleoid

2. Eukaryotic cells

3. Cristae

4. Mitochondrial matrix.

1. Nucleoid. It is the open nuclear material of prokaryotes. It is an irregularly shaped region that contains the genetic material of the prokaryotic cell.

2. Eukaryotic cells. The cells in which the nuclear material is enclosed by a definite nuclear membrane are known as eukaryotic cells.

3. Cristae. The infoldings of the inner membrane of mitochondria which look like finger like projections are called cristae.

4. Mitochondrial matrix. It is ground substance present in the space enclosed by the inner mitochondrial membrane. It is also known as nucleoplasm.

What are receptor molecules ?

Receptor molecules are specific proteins in the cell's plasma membrane that receive chemical signals from outside the cell. When such chemical signals bind to a receptor, they cause some form of cellular response.

Who reported that the cell had an outer layer which is known as plasma membrane today?

Theodore Schwann

State one difference between gram positive and gram negative bacteria.

Gram positive bacteria retains the gram stain whereas the Gram negative bacteria does not.

Who concluded, “Cells are the ultimate units forming the structure of all plant tissues”?

Mathias Schleiden.

What is the function of contractile vacuole in amoeba?

Excretion.

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