Ncert-notes-class-9-science-chapter5 Class 9 Notes | EduRev

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Class 9 : Ncert-notes-class-9-science-chapter5 Class 9 Notes | EduRev

 Page 1


58 
 
Chapter 5: “The Fundamental Unit of Life” 
                         KEY  CONCEPTS  : [ *rating as per the significance of concept] 
CONCEPTS RATING 
Study of historical perceptive related to cell 
discovery  
***** 
Study of Microscope ** 
Study of Hypotonic/Isotonic/ 
Hypertonic solutions relation to osmosis. 
**** 
Cell wall *** 
Nucleus ***** 
Cytoplasm *** 
Cell organelles ***** 
1. All the living organisms are made up of fundamental unit of life called” cell”. 
2. The cell is a Latin word for “a little room”. 
3. The scientist Robert Hooke saw a little room in the cork (the bark of a tree) 
resembled the structure of a honeycomb. The use of the word “Cell” to describe 
these units is used till this day in Biology as” Cell Biology”. 
4. The Compound Microscope consist eye piece,objective lens and condenser to 
observe a cell after putting a drop of Safranin (for plant cell) and methylene blue (for 
animal cell). ( Please refer to Fig. 5.1: Compound Microscope NCERT Book Page-57)  
5. The scientist Leeuwenhoek saw free living cells in the pond water for the first time. ( 
father of microbiology) 
6. The scientist Robert Brown discovered the nucleus in the cell. 
7. The cell theory states that all the plants and animals are composed of cells, it was 
proposed by Schleiden and Schwann. 
8. The cell theory was further expanded by Virchow by suggesting that “all cells arise 
from the pre-existing cells”. 
9. The cells differ in size, shape, structure (Please refer to Fig. 5.2/5.3: Onion 
peel/Various cells in Human body, NCERT Book Page-57/58):Types of cells: Onion 
cells, Smooth muscle cell, Blood cells, Bone cell, Fat cell, Nerve cell, Ovum, Sperm 
etc. Each kind of cell performs specific function. 
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
Page 2


58 
 
Chapter 5: “The Fundamental Unit of Life” 
                         KEY  CONCEPTS  : [ *rating as per the significance of concept] 
CONCEPTS RATING 
Study of historical perceptive related to cell 
discovery  
***** 
Study of Microscope ** 
Study of Hypotonic/Isotonic/ 
Hypertonic solutions relation to osmosis. 
**** 
Cell wall *** 
Nucleus ***** 
Cytoplasm *** 
Cell organelles ***** 
1. All the living organisms are made up of fundamental unit of life called” cell”. 
2. The cell is a Latin word for “a little room”. 
3. The scientist Robert Hooke saw a little room in the cork (the bark of a tree) 
resembled the structure of a honeycomb. The use of the word “Cell” to describe 
these units is used till this day in Biology as” Cell Biology”. 
4. The Compound Microscope consist eye piece,objective lens and condenser to 
observe a cell after putting a drop of Safranin (for plant cell) and methylene blue (for 
animal cell). ( Please refer to Fig. 5.1: Compound Microscope NCERT Book Page-57)  
5. The scientist Leeuwenhoek saw free living cells in the pond water for the first time. ( 
father of microbiology) 
6. The scientist Robert Brown discovered the nucleus in the cell. 
7. The cell theory states that all the plants and animals are composed of cells, it was 
proposed by Schleiden and Schwann. 
8. The cell theory was further expanded by Virchow by suggesting that “all cells arise 
from the pre-existing cells”. 
9. The cells differ in size, shape, structure (Please refer to Fig. 5.2/5.3: Onion 
peel/Various cells in Human body, NCERT Book Page-57/58):Types of cells: Onion 
cells, Smooth muscle cell, Blood cells, Bone cell, Fat cell, Nerve cell, Ovum, Sperm 
etc. Each kind of cell performs specific function. 
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
59 
 
10. A single cell may constitute a whole organism as in Amoeba, Chlamydomonas, 
Paramecium and Bacteria; these are called as unicellular organisms. Whereas in 
multi-cellular organisms (Human beings) division of labor is seen. 
11. The feature in almost every cell is same: Plasma membrane, nucleus and 
cytoplasm. 
12. Plasma membrane: It is the outermost covering of the cell. 
                              - It is called as selective permeable membrane (because it prevents   
                                         movement of some materials).  
                             - It helps in diffusion and osmosis 
                             - Diffusion: movement of substance from high concentration to low                
                                        concentration.  
                                        Eg; exchange of carbon dioxide or oxygen with external environment. 
 
osmosis: it is the passage of water from the region of high water concentration to a region 
of low water concentration through a selective permeable membrane. 
                                   
a) The cell gains water, if the medium surrounding the cell has a higher water 
concentration (Hypotonic solution) than the cell. 
b) The cell maintains the same water concentration as the cell (Isotonic solution), 
water crosses the cell membrane in both directions.  
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
Page 3


58 
 
Chapter 5: “The Fundamental Unit of Life” 
                         KEY  CONCEPTS  : [ *rating as per the significance of concept] 
CONCEPTS RATING 
Study of historical perceptive related to cell 
discovery  
***** 
Study of Microscope ** 
Study of Hypotonic/Isotonic/ 
Hypertonic solutions relation to osmosis. 
**** 
Cell wall *** 
Nucleus ***** 
Cytoplasm *** 
Cell organelles ***** 
1. All the living organisms are made up of fundamental unit of life called” cell”. 
2. The cell is a Latin word for “a little room”. 
3. The scientist Robert Hooke saw a little room in the cork (the bark of a tree) 
resembled the structure of a honeycomb. The use of the word “Cell” to describe 
these units is used till this day in Biology as” Cell Biology”. 
4. The Compound Microscope consist eye piece,objective lens and condenser to 
observe a cell after putting a drop of Safranin (for plant cell) and methylene blue (for 
animal cell). ( Please refer to Fig. 5.1: Compound Microscope NCERT Book Page-57)  
5. The scientist Leeuwenhoek saw free living cells in the pond water for the first time. ( 
father of microbiology) 
6. The scientist Robert Brown discovered the nucleus in the cell. 
7. The cell theory states that all the plants and animals are composed of cells, it was 
proposed by Schleiden and Schwann. 
8. The cell theory was further expanded by Virchow by suggesting that “all cells arise 
from the pre-existing cells”. 
9. The cells differ in size, shape, structure (Please refer to Fig. 5.2/5.3: Onion 
peel/Various cells in Human body, NCERT Book Page-57/58):Types of cells: Onion 
cells, Smooth muscle cell, Blood cells, Bone cell, Fat cell, Nerve cell, Ovum, Sperm 
etc. Each kind of cell performs specific function. 
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
59 
 
10. A single cell may constitute a whole organism as in Amoeba, Chlamydomonas, 
Paramecium and Bacteria; these are called as unicellular organisms. Whereas in 
multi-cellular organisms (Human beings) division of labor is seen. 
11. The feature in almost every cell is same: Plasma membrane, nucleus and 
cytoplasm. 
12. Plasma membrane: It is the outermost covering of the cell. 
                              - It is called as selective permeable membrane (because it prevents   
                                         movement of some materials).  
                             - It helps in diffusion and osmosis 
                             - Diffusion: movement of substance from high concentration to low                
                                        concentration.  
                                        Eg; exchange of carbon dioxide or oxygen with external environment. 
 
osmosis: it is the passage of water from the region of high water concentration to a region 
of low water concentration through a selective permeable membrane. 
                                   
a) The cell gains water, if the medium surrounding the cell has a higher water 
concentration (Hypotonic solution) than the cell. 
b) The cell maintains the same water concentration as the cell (Isotonic solution), 
water crosses the cell membrane in both directions.  
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 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
60 
 
c)The cell loses water, if the medium has lower water concentration (Hypertonic 
solution) than the cell.   
Note - The cell drinking is endosmosis;  
-  omission of water is called ex-osmosis. 
 
13. The cell engulfs food is called endocytosis and ejects solid is called exocytosis. 
Amoeba acquires food through endocytosis and excretion of solid is called 
exocytosis.  
14. The cell wall is a rigid outer covering composed of cellulose. It provides structural 
strength to plant cells. When a living cell loses water, there is shrinkage of contents 
of a cell away from the cell wall. This phenomenon is called as plasmolysis. The cell 
walls permit the cells of plants, fungi and bacteria to withstand very dilute 
(Hypotonic) external media without bursting. 
15. The Nucleus: It is a dark colored, spherical or oval, dot-like structure near the center 
of a cell called Nucleus. The nucleus plays a central role in cellular activities/ 
reproduction. The chromatin material gets organized into chromosomes. The 
chromosomes contain information for inheritance of features from parents to next 
generations in the form of DNA( Deoxyribo Nucleic Acid ) and protein molecules. The 
functional segments of DNA are called genes. 
16. In some organisms like Bacteria nucleus is not covered by nuclear membrane. Hence 
it is called as prokaryote. (Pro= primitive; karyote = karyon = nucleus.) The organisms 
with cells having a nuclear membrane are called eukaryotes. 
17. Differences between prokaryotes and eukaryotes( Please refer to Fig. 5.4: 
Prokaryotic cell NCERT Book Page-62) 
Prokaryotes Eukaryotes 
Size: generally small (1-10 µm) Size: generally large. (5-500 µm) 
www.ncerthelp.com
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 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
Page 4


58 
 
Chapter 5: “The Fundamental Unit of Life” 
                         KEY  CONCEPTS  : [ *rating as per the significance of concept] 
CONCEPTS RATING 
Study of historical perceptive related to cell 
discovery  
***** 
Study of Microscope ** 
Study of Hypotonic/Isotonic/ 
Hypertonic solutions relation to osmosis. 
**** 
Cell wall *** 
Nucleus ***** 
Cytoplasm *** 
Cell organelles ***** 
1. All the living organisms are made up of fundamental unit of life called” cell”. 
2. The cell is a Latin word for “a little room”. 
3. The scientist Robert Hooke saw a little room in the cork (the bark of a tree) 
resembled the structure of a honeycomb. The use of the word “Cell” to describe 
these units is used till this day in Biology as” Cell Biology”. 
4. The Compound Microscope consist eye piece,objective lens and condenser to 
observe a cell after putting a drop of Safranin (for plant cell) and methylene blue (for 
animal cell). ( Please refer to Fig. 5.1: Compound Microscope NCERT Book Page-57)  
5. The scientist Leeuwenhoek saw free living cells in the pond water for the first time. ( 
father of microbiology) 
6. The scientist Robert Brown discovered the nucleus in the cell. 
7. The cell theory states that all the plants and animals are composed of cells, it was 
proposed by Schleiden and Schwann. 
8. The cell theory was further expanded by Virchow by suggesting that “all cells arise 
from the pre-existing cells”. 
9. The cells differ in size, shape, structure (Please refer to Fig. 5.2/5.3: Onion 
peel/Various cells in Human body, NCERT Book Page-57/58):Types of cells: Onion 
cells, Smooth muscle cell, Blood cells, Bone cell, Fat cell, Nerve cell, Ovum, Sperm 
etc. Each kind of cell performs specific function. 
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
59 
 
10. A single cell may constitute a whole organism as in Amoeba, Chlamydomonas, 
Paramecium and Bacteria; these are called as unicellular organisms. Whereas in 
multi-cellular organisms (Human beings) division of labor is seen. 
11. The feature in almost every cell is same: Plasma membrane, nucleus and 
cytoplasm. 
12. Plasma membrane: It is the outermost covering of the cell. 
                              - It is called as selective permeable membrane (because it prevents   
                                         movement of some materials).  
                             - It helps in diffusion and osmosis 
                             - Diffusion: movement of substance from high concentration to low                
                                        concentration.  
                                        Eg; exchange of carbon dioxide or oxygen with external environment. 
 
osmosis: it is the passage of water from the region of high water concentration to a region 
of low water concentration through a selective permeable membrane. 
                                   
a) The cell gains water, if the medium surrounding the cell has a higher water 
concentration (Hypotonic solution) than the cell. 
b) The cell maintains the same water concentration as the cell (Isotonic solution), 
water crosses the cell membrane in both directions.  
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
60 
 
c)The cell loses water, if the medium has lower water concentration (Hypertonic 
solution) than the cell.   
Note - The cell drinking is endosmosis;  
-  omission of water is called ex-osmosis. 
 
13. The cell engulfs food is called endocytosis and ejects solid is called exocytosis. 
Amoeba acquires food through endocytosis and excretion of solid is called 
exocytosis.  
14. The cell wall is a rigid outer covering composed of cellulose. It provides structural 
strength to plant cells. When a living cell loses water, there is shrinkage of contents 
of a cell away from the cell wall. This phenomenon is called as plasmolysis. The cell 
walls permit the cells of plants, fungi and bacteria to withstand very dilute 
(Hypotonic) external media without bursting. 
15. The Nucleus: It is a dark colored, spherical or oval, dot-like structure near the center 
of a cell called Nucleus. The nucleus plays a central role in cellular activities/ 
reproduction. The chromatin material gets organized into chromosomes. The 
chromosomes contain information for inheritance of features from parents to next 
generations in the form of DNA( Deoxyribo Nucleic Acid ) and protein molecules. The 
functional segments of DNA are called genes. 
16. In some organisms like Bacteria nucleus is not covered by nuclear membrane. Hence 
it is called as prokaryote. (Pro= primitive; karyote = karyon = nucleus.) The organisms 
with cells having a nuclear membrane are called eukaryotes. 
17. Differences between prokaryotes and eukaryotes( Please refer to Fig. 5.4: 
Prokaryotic cell NCERT Book Page-62) 
Prokaryotes Eukaryotes 
Size: generally small (1-10 µm) Size: generally large. (5-500 µm) 
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61 
 
Nuclear region: Not well defined 
and not surrounded by a nuclear 
membrane & known as nucleoids. 
Nuclear region: Well defined and 
surrounded by a nuclear membrane 
Chromosome: Single Chromosome: More than one 
chromosome 
Membrane-bound cell organelles 
absent 
Membrane-bound cell organelles 
present 
Eg- bacteria, blue green algae Eg fungi, plant cell and animal cell. 
18. Cell organelles: Every cell has fluid matrix (other than nucleus) is called cytoplasm. 
The nucleus and cytoplasm is together called as protoplasm. The protoplasm term 
was coined by Purkinje. It has important cell organelles: Endoplasmic Reticulum (ER), 
Golgi apparatus, Lysosomes, Mitochondria, Plastids, and vacuoles. 
19. Endoplasmic Reticulum (ER): It is a large network of membrane –bound tubules and 
vesicles.  
- There are two types of  Endoplasmic Reticulum  
- Rough Endoplasmic Reticulum (RER) (It looks rough because Ribosomes are 
attached to its surface. They are the sites of protein synthesis). 
-  Smooth Endoplasmic Reticulum (SER) (It looks smooth because Ribosomes 
are not attached to its surface. They are the sites of fat molecules synthesis).  
1. SER ; help in the functioning of enzymes and hormones to carryout 
biochemical activities.  
2. SER detoxifies many poisons and drugs from the cell. 
2. ER serves as channel for the transport of material between various regions of 
the cytoplasm and the nucleus. 
3. Proteins and fat molecules produced by ER helps in membrane biogenesis. 
20. Golgi apparatus: It was first described by a scientist Camillo Golgi. It is a system of 
membrane bound vesicles called cisterns. It functions include the storage, 
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
Page 5


58 
 
Chapter 5: “The Fundamental Unit of Life” 
                         KEY  CONCEPTS  : [ *rating as per the significance of concept] 
CONCEPTS RATING 
Study of historical perceptive related to cell 
discovery  
***** 
Study of Microscope ** 
Study of Hypotonic/Isotonic/ 
Hypertonic solutions relation to osmosis. 
**** 
Cell wall *** 
Nucleus ***** 
Cytoplasm *** 
Cell organelles ***** 
1. All the living organisms are made up of fundamental unit of life called” cell”. 
2. The cell is a Latin word for “a little room”. 
3. The scientist Robert Hooke saw a little room in the cork (the bark of a tree) 
resembled the structure of a honeycomb. The use of the word “Cell” to describe 
these units is used till this day in Biology as” Cell Biology”. 
4. The Compound Microscope consist eye piece,objective lens and condenser to 
observe a cell after putting a drop of Safranin (for plant cell) and methylene blue (for 
animal cell). ( Please refer to Fig. 5.1: Compound Microscope NCERT Book Page-57)  
5. The scientist Leeuwenhoek saw free living cells in the pond water for the first time. ( 
father of microbiology) 
6. The scientist Robert Brown discovered the nucleus in the cell. 
7. The cell theory states that all the plants and animals are composed of cells, it was 
proposed by Schleiden and Schwann. 
8. The cell theory was further expanded by Virchow by suggesting that “all cells arise 
from the pre-existing cells”. 
9. The cells differ in size, shape, structure (Please refer to Fig. 5.2/5.3: Onion 
peel/Various cells in Human body, NCERT Book Page-57/58):Types of cells: Onion 
cells, Smooth muscle cell, Blood cells, Bone cell, Fat cell, Nerve cell, Ovum, Sperm 
etc. Each kind of cell performs specific function. 
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
59 
 
10. A single cell may constitute a whole organism as in Amoeba, Chlamydomonas, 
Paramecium and Bacteria; these are called as unicellular organisms. Whereas in 
multi-cellular organisms (Human beings) division of labor is seen. 
11. The feature in almost every cell is same: Plasma membrane, nucleus and 
cytoplasm. 
12. Plasma membrane: It is the outermost covering of the cell. 
                              - It is called as selective permeable membrane (because it prevents   
                                         movement of some materials).  
                             - It helps in diffusion and osmosis 
                             - Diffusion: movement of substance from high concentration to low                
                                        concentration.  
                                        Eg; exchange of carbon dioxide or oxygen with external environment. 
 
osmosis: it is the passage of water from the region of high water concentration to a region 
of low water concentration through a selective permeable membrane. 
                                   
a) The cell gains water, if the medium surrounding the cell has a higher water 
concentration (Hypotonic solution) than the cell. 
b) The cell maintains the same water concentration as the cell (Isotonic solution), 
water crosses the cell membrane in both directions.  
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
60 
 
c)The cell loses water, if the medium has lower water concentration (Hypertonic 
solution) than the cell.   
Note - The cell drinking is endosmosis;  
-  omission of water is called ex-osmosis. 
 
13. The cell engulfs food is called endocytosis and ejects solid is called exocytosis. 
Amoeba acquires food through endocytosis and excretion of solid is called 
exocytosis.  
14. The cell wall is a rigid outer covering composed of cellulose. It provides structural 
strength to plant cells. When a living cell loses water, there is shrinkage of contents 
of a cell away from the cell wall. This phenomenon is called as plasmolysis. The cell 
walls permit the cells of plants, fungi and bacteria to withstand very dilute 
(Hypotonic) external media without bursting. 
15. The Nucleus: It is a dark colored, spherical or oval, dot-like structure near the center 
of a cell called Nucleus. The nucleus plays a central role in cellular activities/ 
reproduction. The chromatin material gets organized into chromosomes. The 
chromosomes contain information for inheritance of features from parents to next 
generations in the form of DNA( Deoxyribo Nucleic Acid ) and protein molecules. The 
functional segments of DNA are called genes. 
16. In some organisms like Bacteria nucleus is not covered by nuclear membrane. Hence 
it is called as prokaryote. (Pro= primitive; karyote = karyon = nucleus.) The organisms 
with cells having a nuclear membrane are called eukaryotes. 
17. Differences between prokaryotes and eukaryotes( Please refer to Fig. 5.4: 
Prokaryotic cell NCERT Book Page-62) 
Prokaryotes Eukaryotes 
Size: generally small (1-10 µm) Size: generally large. (5-500 µm) 
www.ncerthelp.com
Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips,
 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
61 
 
Nuclear region: Not well defined 
and not surrounded by a nuclear 
membrane & known as nucleoids. 
Nuclear region: Well defined and 
surrounded by a nuclear membrane 
Chromosome: Single Chromosome: More than one 
chromosome 
Membrane-bound cell organelles 
absent 
Membrane-bound cell organelles 
present 
Eg- bacteria, blue green algae Eg fungi, plant cell and animal cell. 
18. Cell organelles: Every cell has fluid matrix (other than nucleus) is called cytoplasm. 
The nucleus and cytoplasm is together called as protoplasm. The protoplasm term 
was coined by Purkinje. It has important cell organelles: Endoplasmic Reticulum (ER), 
Golgi apparatus, Lysosomes, Mitochondria, Plastids, and vacuoles. 
19. Endoplasmic Reticulum (ER): It is a large network of membrane –bound tubules and 
vesicles.  
- There are two types of  Endoplasmic Reticulum  
- Rough Endoplasmic Reticulum (RER) (It looks rough because Ribosomes are 
attached to its surface. They are the sites of protein synthesis). 
-  Smooth Endoplasmic Reticulum (SER) (It looks smooth because Ribosomes 
are not attached to its surface. They are the sites of fat molecules synthesis).  
1. SER ; help in the functioning of enzymes and hormones to carryout 
biochemical activities.  
2. SER detoxifies many poisons and drugs from the cell. 
2. ER serves as channel for the transport of material between various regions of 
the cytoplasm and the nucleus. 
3. Proteins and fat molecules produced by ER helps in membrane biogenesis. 
20. Golgi apparatus: It was first described by a scientist Camillo Golgi. It is a system of 
membrane bound vesicles called cisterns. It functions include the storage, 
www.ncerthelp.com
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 NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More... 
62 
 
modification and package of cell products. The complex sugars are made from simple 
sugars in the Golgi apparatus. It is also involved in the formation of lysosomes. 
21. Lysosomes: They contain membrane-bound sacs with powerful digestive enzymes 
(enzymes are made by RER) to digest the worn-out cell organelles. When the cell 
gets damaged, lysosomes may burst and the enzymes digest their own cell, hence 
called as “Suicidal bags of a cell”. It is a waste disposal system of the cell. 
22. Mitochondria: It is covered by a double membrane. Outer membrane is very porous 
and the inner membrane is deeply folded. These folds create a large surface area for 
ATP (Adenosine Triphosphate) molecule synthesis. ATP is the energy currency of a 
cell; hence the Mitochondria are called as Power House of a Cell. Mitochondria have 
their own DNA and Ribosomes; therefore they can make their own proteins. 
23. Plastids: They are present only in plant cells. They are two types.  
1. Chromoplasts (Colored Plastids: Chloroplasts – Green pigmented and 
useful in Photosynthesis and also contains various other pigments like 
yellow or orange) 
2.  Leucoplasts (White or colorless plastids; stores materials such as oils, 
proteins, fats etc. ) Plastids are also covered by a double membrane. 
The matrix is called Stroma, seat for enzymatic actions. Plastids have 
their own DNA and Ribosomes; therefore they can make their own 
proteins. 
24. Vacuoles: Storage sacs for solid or liquid contents. They are small in size in animals 
while plants have large, may occupy 50-90 % of the cell volume. Helps to provide 
turgidity and rigidity to the cell. Many substances like amino acids, sugars, organic 
acids and proteins are stored in vacuoles. In Amoeba food vacuole is specialized to 
play an important role. 
25. Cell: It is the fundamental structural unit of living organisms, helps in respiration, 
obtaining nutrition and clearing waste material or forming a new protein. 
Differences between Plant cell and Animal Cell  
(Please refer to Fig. 5.5 Animal cell & 5.6: Plant cell NCERT Book Page-63&64) 
 
 
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