Class 9 The Fundamental Unit of Life Important Questions : Solution

Notes Important Questions

The Fundamental Unit of Life Important Questions : Solution

1. Define nucleoid.
   Ans:- The nucleoid is an irregularly shaped region within the prokaryotic cell that contains all or most of the genetic material.
   
2. .
   1. Why mitochondria is called the powerhouse of the cell ?
   2. Why is the inner membrane of mitochondria deeply folded ?
      Ans:– 1. Mitochondria is known as the powerhouse of the cell as it is responsible for cellular respiration and the release of energy in the form of ATP i.e., Adenosine triphosphate.
      2. The inner membrane of mitochondria is deeply folded to increase the surface area for generating more ATP. 
      
3. Where is protein synthesized in a cell ? Explain.
   Ans:- Proteins are synthesised by ribosomes which are present on the membrane of RER (rough endoplasmic reticulum), plastids and miochondria.
   
4. Name the three solutions that can be used to stain the cell while observing it under the microscope ?
   Ans:- The three solutions that can be used to stain the cell while observing it under the microscope are safranin, methylene blue solution and iodine.
   
5. What would happen to the life of a cell if there was no golgi apparatus ?
   Ans:- Without  Golgi apparatus, there would be no lysosomes in a cell. Subsequently, the cell would not be able to digest or break down the materials left over from protein creation. This would create a lot of unwanted materials within the cell. If this happened, the cell wouldn’t be able to live for very long.
   
6. How do substances like CO₂ and water move in and out of the cell ? Explain.
   Ans:- The substances like CO2 move in and out of a cell by diffusion .
   Diffusion is the spontaneous movement of substances from the region of higher concentration to lower concentration.
   Water move in and out of a cell by osmosis .
   Osmosis is the spontaneous movement of water from the region of higher water concentration to lower water concentration through a semi permeable membrane.
   
   
7. What does it mean by endocytosis ? Name an organism that obtains its food by endocytosis.
   Ans:- The process by which the cells engulf in food & other materials due to the flexibility of the cell membrane is called endocytosis.
   Amoeba acquires its food through endocytosis.
   
8. Where proteins and lipids synthesized in a cell ? Write two functions of proteins and lipids.
   Ans:- Proteins are synthesised by ribosomes which are present on the membrane of RER (rough endoplasmic reticulum), plastids and miochondria and lipids are synthesized in SER (smooth endoplasmic reticulum).
   Two functions of proteins and lipids are:-
   (a) They help in building cell membrane.
   (b) Some proteins and lipids function as enzymes and hormones.
   
9. What does it mean by plasmolysis ?
   Ans:- When a plant cell loses water through osmosis there is shrinkage of contents of the cell away from the cell wall. This phenomenon is known as plasmolysis.
   
10. Why cell membrane is called selectively permeable membrane ?
    Ans:- Cell membrane controls the entry & exit of the materials in and out of the cell. So, cell membrane is called selectively permeable membrane.
    
11. Name the two cell organelles having their own ribosomes and DNA.
    Ans:- The two cell organelles having their own ribosomes and DNA are:-
    (a) Mitochondria
    (b) Plastids
    
12. a. Name the cell organelle that helps in formation of lysosomes.
    b. Why are lysosomes called suicide bags of a cell ?
    Ans:-(a) Golgi apparatus
    (b) Lysosomes are known as suicide bags of a cell because if the cell gets damaged, lysosomes may burst and the enzymes present in it will digest their own cell.
    
13. Write the differences between prokaryotic and eukaryotic cell.
    Ans:-

S. No.	Prokaryotic Cell	Eukaryotic Cell
1.	Nuclear membrane is absent.	Nuclear membrane is present.
2.	Its size is generally smaller.	Its size is generally larger.
3.	Single chromosome is present.	More than one chromosomes are present.
4.	Membrane bound cell organelles are absent.	Membrane bound cell organelles are present.
5.	Ex:- bacteria, cyanobacteria (blue green algae) etc.	Ex:- Fungi, plants, animals etc.