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NCERT Solutions for Class 9th Science

 

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Chapter 5. The Fundamental Unit of Life

Additional -Questions

 

 

 

Nucleus – Nucleus is a largest cell organelle which consists inside the cell. Nuclei are found in all eukaryotic cells. It contains chromatin.

Cytoplasm –

Ribosomes : They are extremely small round bodies present either in free state in the cytoplasm.

Functions :

  1.  it is responsible for synthesis of proteins from amino-acid.
  2. They provide a surface for bio-chemical activities of the cell.                          

Q – Distinguish between plant and animal cell.

A –

Plant cell

Animal cell

  1. It has cell wall.
  2. Chloroplast is present.
  3. Vacuoles are large in size.
  4. The process of photosynthesis occurs in it.
  1. It has not cell wall.
  2. Chloroplast is not present.
  3. Vacuoles are mostly absent or present is very small size.
  4. The process of photosynthesis doesn’t occur in it.

 

Q – write the differences between prokaryotic cell and Eukaryotic cell.

prokaryotic cell

Eukaryotic cell

  1.  It is often small in size.
  2. Nucleus membrane is absent.
  3. It has one chromosome.
  4. There mostly cell organelles are absent. 

 

  1. Example. Yeast cell
  1. It is often large in size.
  2. Nucleus membrane is present.
  3.  It has more than one chromosomes.
  4. There mostly cell organelles are present.
  5. Example: All multicellular organism.

 

 

Q – How does an Amoeba obtain its food?

A – Amoeba obtains its food by the process of endocytosis, in which it take food from outside by the help of its body surface. It encloses the food by plasma membrane. It engulfs the food and digest it.

Q – Why is plasma membrane is called selectivity permeable membrane?

A – The plasma membrane allows or permits the entry and exit of some material in and out of the cell, therefore it is called a selectivity permeable membrane.

Q – What is Osmosis?

A – Water also obeys the law of diffusion. The movement of water molecules through such a selectively permeable membrane is called Osmosis.

 

 

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