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Cell : The Unit of Life

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Biology

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Biology

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12
Distinguish between prokaryotic and eukaryotic cells.

Prokaryotic cells

Eukaryotic cells

1. They have no nuclear membrane. Thus well defined nucleus is absent. They have nucleoid.

2. Nucleolus is absent.

3. They have one chromosome.

4. No histone protein around DNA.

5. Ribosomes are of 70S.

7. No streaming movement of cytoplasm.

8. E.R. is absent.

9. Mitochondria is absent.

10. Golgi apparatus is absent.

11. Lysosomes are absent.

12. Respiratory enzymes are attached at innerside of plasmalemma.

13. Mesosomes may be present.

 

1. They have well defined nucleus bounded by double nuclear membrane.

2. Nucleolus is present.

3. They have a number of chromosomes.

4. Histone protein is present around DNA.

5. Ribosomes are of 80S.

7. Cytoplasm exhibits streaming movements.

8. E.R. is present.

9. Mitochondria is present.

10. Golgi apparatus is present.

11. Lysosomes are present.

12. Respiratory enzymes are present in mitochondria.

13. Mesosomes are absent.

 


What is the function of contractile vacuole in amoeba?

Excretion.

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 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 

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

Mathias Schleiden.