NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life
Get here NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life.
More Detail
Latest News
Finished viewing? Save it for later —
Download NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life (PDF · 9 pages)Downloaded 206 times
About NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life is available here for free download. Published by NCERT for Class 9, this solution can be viewed online or downloaded as a PDF (9 pages). Candidates preparing for Class 9 can use NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life to understand the exam pattern, the type of questions asked, and the overall difficulty level.
Frequently Asked Questions
How can I download NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life?
Open this page and click the Download button to save NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life as a PDF. It is completely free on AglaSem Docs.
Is NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life free to download?
Yes. NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life can be viewed online and downloaded as a PDF free of cost on AglaSem Docs.
How many pages does NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life have?
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life contains 9 pages, which you can read online or download together as a single PDF.
Where can I find more Class 9 study material?
You can find more Class 9 question papers, sample papers, syllabus, and answer keys on AglaSem Docs.
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life – Text
Read the full text of this solution below — useful to quickly search, copy and reference the content online without downloading the PDF.
📄 View text version (9 pages)
Page 1
NCERT
SOLUTIONS
CLASS - 9th
aglase .co
SOLUTIONS
CLASS - 9th
aglase .co
Page 2
Book : Science Ncert Solutions | Chapter-5 Science
Class : 9th
Subject : SCIENCE
Chapter : 5
Chapter Name : THE FUNDAMENTAL UNIT OF LIFE
Q1 Who discovered cells, and how?
Answer. Cells were discovered in 1665 by an English Botanist, Robert Hooke. He used a primitive
microscope to observe cells in a cork slice.
Page : 59 , Block Name : Questions
Q2 Why is the cell called the structural and functional unit of life?
Answer. Cells constitute various components of plants and animals. A cell is the smallest unit of
life and is capable of all living functions. Cells are the building blocks of life. This is the reason
why cells are referred to as the basic structural and functional units of life. All cells vary in their
shape, size, and activity they perform. In fact, the shape and size of the cell is related to the
speci c functions they perform.
Page : 59 , Block Name : Questions
Q1 How do substances like CO and water move in and out of the cell? Discuss
2
Answer. The cell membrane is selectively permeable and regulates the movement of substances in
and out of the cell. Movement of CO : 2
CO is produced during cellular respiration. Therefore, it is present in high concentrations inside
2
the cell. This C02 must be excreted out of the cell. In the cell's external environment, the
concentration of CO is low as compared to that inside the cell. Therefore, according to the
2
principle of diffusion,CO moves from a region of higher concentration (inside the cell) towards a
2
region of lower concentration (outside the cell). Similarly, O enters the cell by the process of
2
diffusion when the concentration of O inside the cell is low as compared to its surroundings.
2
Movement of water:
Water moves from a region of high concentration to a region of low concentration through the
plasma membrane. The plasma membrane acts as a semi-permeable membrane, and this
movement of water is known as osmosis. However, the movement of water across the plasma
membrane of the cell is affected by the amo Copy sh.
Page : 59 , Block Name : Questions
Page 1 of 8 Aglasem Schools
Class : 9th
Subject : SCIENCE
Chapter : 5
Chapter Name : THE FUNDAMENTAL UNIT OF LIFE
Q1 Who discovered cells, and how?
Answer. Cells were discovered in 1665 by an English Botanist, Robert Hooke. He used a primitive
microscope to observe cells in a cork slice.
Page : 59 , Block Name : Questions
Q2 Why is the cell called the structural and functional unit of life?
Answer. Cells constitute various components of plants and animals. A cell is the smallest unit of
life and is capable of all living functions. Cells are the building blocks of life. This is the reason
why cells are referred to as the basic structural and functional units of life. All cells vary in their
shape, size, and activity they perform. In fact, the shape and size of the cell is related to the
speci c functions they perform.
Page : 59 , Block Name : Questions
Q1 How do substances like CO and water move in and out of the cell? Discuss
2
Answer. The cell membrane is selectively permeable and regulates the movement of substances in
and out of the cell. Movement of CO : 2
CO is produced during cellular respiration. Therefore, it is present in high concentrations inside
2
the cell. This C02 must be excreted out of the cell. In the cell's external environment, the
concentration of CO is low as compared to that inside the cell. Therefore, according to the
2
principle of diffusion,CO moves from a region of higher concentration (inside the cell) towards a
2
region of lower concentration (outside the cell). Similarly, O enters the cell by the process of
2
diffusion when the concentration of O inside the cell is low as compared to its surroundings.
2
Movement of water:
Water moves from a region of high concentration to a region of low concentration through the
plasma membrane. The plasma membrane acts as a semi-permeable membrane, and this
movement of water is known as osmosis. However, the movement of water across the plasma
membrane of the cell is affected by the amo Copy sh.
Page : 59 , Block Name : Questions
Page 1 of 8 Aglasem Schools
Page 3
Book : Science Ncert Solutions | Chapter-5 Science
Q2 Why is the plasma membrane called a selectively permeable membrane?
Answer. The cell membrane or the plasma membrane is known as a selectively permeable
membrane because it regulates the movement of substances in and out of the cell. This means that
the plasma membrane allows the entry of only some substances and prevents the movement of
some other materials.
Page : 59 , Block Name : Questions
Q1 Fill in the gaps in the following table illustrating differences between prokaryotic and
eukaryotic cells.
Answer.
Page : 63 , Block Name : Questions
Q1 Can you name the two organelles we have studied that contain their own genetic material?
Answer. Mitochondria and plastids are the two organelles that contain their own genetic material.
Page 2 of 8 Aglasem Schools
Q2 Why is the plasma membrane called a selectively permeable membrane?
Answer. The cell membrane or the plasma membrane is known as a selectively permeable
membrane because it regulates the movement of substances in and out of the cell. This means that
the plasma membrane allows the entry of only some substances and prevents the movement of
some other materials.
Page : 59 , Block Name : Questions
Q1 Fill in the gaps in the following table illustrating differences between prokaryotic and
eukaryotic cells.
Answer.
Page : 63 , Block Name : Questions
Q1 Can you name the two organelles we have studied that contain their own genetic material?
Answer. Mitochondria and plastids are the two organelles that contain their own genetic material.
Page 2 of 8 Aglasem Schools
Page 4
Book : Science Ncert Solutions | Chapter-5 Science
Both these organelles have their own DNA and ribosomes.
Page : 65 , Block Name : Questions
Q2 If the organisation of a cell is destroyed due to some physical or chemical in uence, what will
happen?
Answer. Cell is the smallest unit of life, which is capable of all living functions. If the organisation
of a cell is destroyed due to some physical or chemical in uence, then the ability of the cell to
perform all living functions such as respiration, nutrition, excretion, etc. would be affected.
Page : 65 , Block Name : Questions
Q3 Why are lysosomes known as suicide bags?
Answer. Lysosomes are membrane-bound vesicular structures that contain powerful digestive
enzymes. These enzymes are capable of breaking down any foreign food particle or microbes
entering the cell. Sometimes, lysosomes can cause self-destruction of a cell by releasing these
digestive enzymes within the cells. Hence, they are also known as 'suicidal bags'.
Page : 65 , Block Name : Questions
Q4 Where are proteins synthesised inside the cell?
Answer. Ribosomes are the site for protein synthesis. Ribosomes are very small structures found
either in a free state, suspended in the cytoplasm, or attached to the surface of the endoplasmic
reticulum. They are composed of ribonucleic acids and proteins.
Page : 65 , Block Name : Questions
Q1 Make a comparison and write down ways in which plant cells are different from animal cells.
Answer.
Page 3 of 8 Aglasem Schools
Both these organelles have their own DNA and ribosomes.
Page : 65 , Block Name : Questions
Q2 If the organisation of a cell is destroyed due to some physical or chemical in uence, what will
happen?
Answer. Cell is the smallest unit of life, which is capable of all living functions. If the organisation
of a cell is destroyed due to some physical or chemical in uence, then the ability of the cell to
perform all living functions such as respiration, nutrition, excretion, etc. would be affected.
Page : 65 , Block Name : Questions
Q3 Why are lysosomes known as suicide bags?
Answer. Lysosomes are membrane-bound vesicular structures that contain powerful digestive
enzymes. These enzymes are capable of breaking down any foreign food particle or microbes
entering the cell. Sometimes, lysosomes can cause self-destruction of a cell by releasing these
digestive enzymes within the cells. Hence, they are also known as 'suicidal bags'.
Page : 65 , Block Name : Questions
Q4 Where are proteins synthesised inside the cell?
Answer. Ribosomes are the site for protein synthesis. Ribosomes are very small structures found
either in a free state, suspended in the cytoplasm, or attached to the surface of the endoplasmic
reticulum. They are composed of ribonucleic acids and proteins.
Page : 65 , Block Name : Questions
Q1 Make a comparison and write down ways in which plant cells are different from animal cells.
Answer.
Page 3 of 8 Aglasem Schools
Page 5
Book : Science Ncert Solutions | Chapter-5 Science
Q2 How is a prokaryotic cell different from a eukaryotic cell?
Answer.
Page 4 of 8 Aglasem Schools
Q2 How is a prokaryotic cell different from a eukaryotic cell?
Answer.
Page 4 of 8 Aglasem Schools
Page 6
Book : Science Ncert Solutions | Chapter-5 Science
Q3 What would happen if the plasma membrane ruptures or breaks down?
Answer. If the plasma membrane of a cell is ruptured, then the cell will die. The plasma membrane
regulates the movement of substances in and out of the cell by diffusion or osmosis. Thus, if the
plasma membrane is ruptured, then the cell might leak out its contents.
Q4 What would happen to the life of a cell if there was no Golgi apparatus?
Answer. If there was no Golgi apparatus in the cell, then most activities performed by the Golgi
apparatus will not take place.
(i) Membranes of the Golgi apparatus are often connected to ER membranes. It collects simpler
molecules and combines them to make more complex molecules. These are then packaged in small
vesicles and are either stored in the cell or sent out as per the requirement. Thus, if the Golgi
apparatus is absent in the cell, then the above process of storage, modi cation, and packaging of
products will not be possible.
(ii) The formation of complex sugars from simple sugars will not be possible as this takes place
with the help of enzymes present in Golgi bodies.
Page 5 of 8 Aglasem Schools
Q3 What would happen if the plasma membrane ruptures or breaks down?
Answer. If the plasma membrane of a cell is ruptured, then the cell will die. The plasma membrane
regulates the movement of substances in and out of the cell by diffusion or osmosis. Thus, if the
plasma membrane is ruptured, then the cell might leak out its contents.
Q4 What would happen to the life of a cell if there was no Golgi apparatus?
Answer. If there was no Golgi apparatus in the cell, then most activities performed by the Golgi
apparatus will not take place.
(i) Membranes of the Golgi apparatus are often connected to ER membranes. It collects simpler
molecules and combines them to make more complex molecules. These are then packaged in small
vesicles and are either stored in the cell or sent out as per the requirement. Thus, if the Golgi
apparatus is absent in the cell, then the above process of storage, modi cation, and packaging of
products will not be possible.
(ii) The formation of complex sugars from simple sugars will not be possible as this takes place
with the help of enzymes present in Golgi bodies.
Page 5 of 8 Aglasem Schools
Page 7
Book : Science Ncert Solutions | Chapter-5 Science
(iii) The Golgi apparatus is involved in the formation of lysosomes or peroxisomes. Thus, if the
Golgi body is absent in a cell, the synthesis of lysosomes or peroxisomes will not be possible in the
cell.
Q5 Which organelle is known as the powerhouse of the cell? Why?
Answer. Mitochondria are known as the powerhouse of cells. Mitochondria create energy for the
cell, and this process of creating energy for the cell is known as cellular respiration. Most chemical
reactions involved in cellular respiration occur in the mitochondria. The energy required for
various chemical activities needed for life is released by the mitochondria in the form of ATP
(Adenosine triphosphate) molecules. For this reason, mitochondria are known as the powerhouse
of cells.
Q6 Where do the lipids and proteins constituting the cell membrane get synthesised?
Answer. Lipids and proteins constituting the cell membrane are synthesized in the endoplasmic
reticulum. SER (Smooth endoplasmic reticulum) helps in the manufacturing of lipids. RER (Rough
endoplasmic reticulum) has particles attached to its surface, called ribosomes. These ribosomes
are the site for protein synthesis.
Q7 How does an Amoeba obtain its food?
Answer. Amoeba obtains its food through the process of endocytosis. The exibility of the cell
membrane enables the cell to engulf the solid particles of food and other materials from its
external environment.
Q8 What is osmosis?
Answer. The movement of water molecules from a region of high concentration to a region of low
concentration through a selectively permeable membrane is called osmosis. It is a special case of
diffusion, where the medium is water. For example, if the medium surrounding the cell has a
higher water concentration than the cell i.e., if the solution is a dilute solution, then the cell will
Page 6 of 8 Aglasem Schools
(iii) The Golgi apparatus is involved in the formation of lysosomes or peroxisomes. Thus, if the
Golgi body is absent in a cell, the synthesis of lysosomes or peroxisomes will not be possible in the
cell.
Q5 Which organelle is known as the powerhouse of the cell? Why?
Answer. Mitochondria are known as the powerhouse of cells. Mitochondria create energy for the
cell, and this process of creating energy for the cell is known as cellular respiration. Most chemical
reactions involved in cellular respiration occur in the mitochondria. The energy required for
various chemical activities needed for life is released by the mitochondria in the form of ATP
(Adenosine triphosphate) molecules. For this reason, mitochondria are known as the powerhouse
of cells.
Q6 Where do the lipids and proteins constituting the cell membrane get synthesised?
Answer. Lipids and proteins constituting the cell membrane are synthesized in the endoplasmic
reticulum. SER (Smooth endoplasmic reticulum) helps in the manufacturing of lipids. RER (Rough
endoplasmic reticulum) has particles attached to its surface, called ribosomes. These ribosomes
are the site for protein synthesis.
Q7 How does an Amoeba obtain its food?
Answer. Amoeba obtains its food through the process of endocytosis. The exibility of the cell
membrane enables the cell to engulf the solid particles of food and other materials from its
external environment.
Q8 What is osmosis?
Answer. The movement of water molecules from a region of high concentration to a region of low
concentration through a selectively permeable membrane is called osmosis. It is a special case of
diffusion, where the medium is water. For example, if the medium surrounding the cell has a
higher water concentration than the cell i.e., if the solution is a dilute solution, then the cell will
Page 6 of 8 Aglasem Schools
Page 8
Book : Science Ncert Solutions | Chapter-5 Science
gain water by osmosis.
Q9 Carry out the following osmosis experiment:
Take four peeled potato halves and scoos each one out to make potato cups. One of these potato
cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) Keep cup A empty
(b) Put one teaspoon sugar in cup B
(c) Put one teaspoon salt in cup C
(d) Put one teaspoon sugar in the boiled potato cup D. Keep these for two hours. Then observe the
four potato cups and answer the following:
(i) Explain why water gathers in the hollowed portion of B and C.
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
Answer. Experimental set up
(i) Water gathers in the hollowed portions of set-up B and C because water enters the potato as a
result of osmosis. Since the medium surrounding the cell has a higher water concentration than
the cell, the water moves inside by osmosis. Hence, water gathers in the hollowed portions of the
potato cup.
(ii) Potato A in the experiment acts as a control set-up. No water gathers in the hollowed portions
of potato A.
(iii) Water does not gather in the hollowed portions of potato A because potato cup A is empty. It is
a control set-up in the experiment. Water is not able to enter potato D because the potato used
here is boiled. Boiling denatures the proteins present in the cell membrane and thus, disrupts the
cell membrane. For osmosis, a semi-permeable membrane is required, which is disrupted in this
case. Therefore, osmosis will not occur. Hence, water does not enter the boiled potato cup.
Q10 Which type of cell division is required for growth and repair of body and which type is
involved in formation of gametes?
Answer. Mitosis cell device is required for growth and repaired for growth and development and
meiosis cell division is used in the formation of gametes. In gametes formation the process is use
which is called as reductional division which helps to balance the number of chromosome in
Page 7 of 8 Aglasem Schools
gain water by osmosis.
Q9 Carry out the following osmosis experiment:
Take four peeled potato halves and scoos each one out to make potato cups. One of these potato
cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) Keep cup A empty
(b) Put one teaspoon sugar in cup B
(c) Put one teaspoon salt in cup C
(d) Put one teaspoon sugar in the boiled potato cup D. Keep these for two hours. Then observe the
four potato cups and answer the following:
(i) Explain why water gathers in the hollowed portion of B and C.
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
Answer. Experimental set up
(i) Water gathers in the hollowed portions of set-up B and C because water enters the potato as a
result of osmosis. Since the medium surrounding the cell has a higher water concentration than
the cell, the water moves inside by osmosis. Hence, water gathers in the hollowed portions of the
potato cup.
(ii) Potato A in the experiment acts as a control set-up. No water gathers in the hollowed portions
of potato A.
(iii) Water does not gather in the hollowed portions of potato A because potato cup A is empty. It is
a control set-up in the experiment. Water is not able to enter potato D because the potato used
here is boiled. Boiling denatures the proteins present in the cell membrane and thus, disrupts the
cell membrane. For osmosis, a semi-permeable membrane is required, which is disrupted in this
case. Therefore, osmosis will not occur. Hence, water does not enter the boiled potato cup.
Q10 Which type of cell division is required for growth and repair of body and which type is
involved in formation of gametes?
Answer. Mitosis cell device is required for growth and repaired for growth and development and
meiosis cell division is used in the formation of gametes. In gametes formation the process is use
which is called as reductional division which helps to balance the number of chromosome in
Page 7 of 8 Aglasem Schools
Page 9
Book : Science Ncert Solutions | Chapter-5 Science
parents and progeny.
Page 8 of 8 Aglasem Schools
parents and progeny.
Page 8 of 8 Aglasem Schools
Document Details
| Board / Org | NCERT |
| Exam | Class 9 |
| Type | Solution |
| Pages | 9 |
| Updated | 30 Apr 2026 |