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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
Name two cell-organelles that are double membrane bound. What are the characteristics of these two organelles ? State their function and draw labelled diagrams of both.

Chloroplasts and mitochondria are organelles which have double membrane .

Mitochondria - is called the power house of the cell as it produces cellular energy in the form of ATP. It is bounded by two membrane, the inner membrane forms inner foldings called cristae. The matrix has a single circular DNA molecule.

Chloroplasts - are also double membrane bound organelles which help to trap the solar energy and produce food. The stroma contains many flattened disc like structures called thylakoids which are arranged in stacks to gorm grana. The chloroplasts consists of the pigment chlorophyll that helps to convert sun's energy to chemical energy.

Functions of :

Mitochondria - It produces the cellular energy in the form of ATP.

Chloroplasts - trap the energy of the sun and produce food.

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

Theodore Schwann

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.

State one difference between gram positive and gram negative bacteria.

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

What is the function of contractile vacuole in amoeba?

Excretion.

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

Mathias Schleiden.

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