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Cell : The Unit of Life

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CBSE Gujarat Board Haryana Board

## Previous Year Papers

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Class 10 Class 12
Write the functions of nuclear envelope, nuclear matrix  and nucleolus.

The nuclear envelope performs the following functions :

1. It maintains the shape of the nucleus.

2. It keeps the nuclear contents in place and distinct from the cytoplasm.

3. It regulates the flow of materials into and out of the nucleus by active transport and outpocketing.

4. Its pores allow the exit of ribosomal subunits.

Functions of nuclear matrix :

1. It maintains the shape of the nucleus.

2. Chromatin fibres are anchored to nuclear matrix.

3. The machinery for various nuclear activities such as transcription and replication is associated with the matrix.

Functions of nucleolus :

1. It is the site for rRNA synthesis.

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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.
941 Views

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

Theodore Schwann
1046 Views

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

Mathias Schleiden.
1517 Views

State one difference between gram positive and gram negative bacteria.

Gram positive bacteria retains the gram stain whereas the Gram negative bacteria does not.
1562 Views

What is the function of contractile vacuole in amoeba?

Excretion.
1170 Views