Mention the differences between pili and fimbriae.

Pili

Fimbriae

1. These are elongate tubular structures.

2. They are present mainly in Gram -ve bacteria.

3. They are involved in mating process and form conjugation tube.

4. These are not responsible in connecting cells.

1. These are small bristle like fibres.

2. They are present both in Gram +ve and Gram -ve bacteria.

3. They have no role in mating.

4. These are responsible for connecting cells.

 
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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.

 

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What is the function of contractile vacuole in amoeba?


Excretion.
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Distinguish between cilia and flagella.

Cilia

Flagella

1. They are 2-10nm in length.

2. They are hair-like.

3. Their number per cell is relatively large.

4. They usually cover the entire exposed surface of the cell.

5. They beat in co-ordinated manner.

6. They exhibit sweeping or rowing motion.

7. The ciliary locomotion is fast.

1. They reach a length upto 150nm.

2. They are whip like.

3. Their number per cell is relatively small, usually 1-4.

4. They are present at one end only.

5. They beat independently.

6. They show undulating motion.

7. The flagellar locomotion is slow.

 
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Who concluded 'Cells are the ultimate units forming the structure of all plant tissues'?


Mathias Schleiden.

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