# The Fundamental Unit of Life- NCERT Solutions of Chapter 5 (Science) for Class 9

## NCERT Solutions for Class 9 Science Chapter 5 - The Fundamental Unit of Life

Chapter 5 Science Class 9 is a fundamental chapter in Biology that describes the types and significant characteristics of a cell, the unit of life. The chapter also covers important topics about the structure of a cell, plasma membrane, nucleus, DNA, and chromatin material which plays a major role in the functioning of the cell of any living organism. The NCERT Solution for Class 9 Chapter 5 provides detailed answers to help students understand the topics covered in the chapter. The answers in the NCERT Solutions Class 9 Chapter 5 are explained with diagrams that provide a comprehensive understanding of the chapter. Maths Students who are looking for better solutions ,They can download Class 9 Maths NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations.

### NCERT Class 9 Science Chapter 5 explains the following topics in detail.

1.1  What are living organisms made up of?

1.2  What are these structures?

1.3  What is the cell made up of? What is the structural organisation of a cell?

• Plasma membrane or cell membrane

• Cell wall

• Nucleus

• Cytoplast

• Mitochondria

• Endoplasmic reticulum

• Plasmids

• Vacuoles

### A Glance About The Topic

1. Every living organism in the world is made up of cells. The shape and organs in the cell may differ from plants and animals.

2. Organisms are majorly classified into two types based on the count of cells, they are unicellular and multicellular organisms.

3. In 1665, Robert hook was the first person to discover the cell

4. A cell has certain components to perform specific tasks inside the cell, they are called organelles

5. The organelles of a cell are protected by a membrane called a cell wall. Cell walls also takes responsibility for cell respiration.

6. Mitochondria is a powerhouse of the cell

7. Cytoplasm is the fluid content present inside the cell

8. This chapter explains all the organelles which are present inside the cell and functions of each organelle in detail.

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## Access NCERT Solutions for Class 9 Science Chapter 5 - The Fundamental Unit of Life

1. Who discovered cells and how?

Ans: The dead cells were first discovered by Robert Hooke in 1665. He observed in cork cells that the cells are like honeycomb structures with the help of a basic microscope while the living cells were first discovered by Antoine van Leuwenhoek after the discovery of the electron microscope.

2. Why is the cell called the structural and functional unit of life?

Ans: Cell is the basic unit of life and is present in all living organisms. Each living cell performs its specific functions that are the characteristics of all living forms. The cell consists of various cell organelles which help the cell to live and perform all its functions. The various cell organelles perform their special function that includes making new material in the cell, removal of the waste material from the cell and so on. Thus, cells are called basic structural and functional units of life as they perform all these functions.

3. How do substances like $\mathbf{CO_2}$ and water move in and out of the cell? Discuss.

Ans: By the process of diffusion the substances like carbon dioxide and water move in and out of a cell from the region of high concentration to the region of low concentration. When the concentration of carbon dioxide and water is higher outside the cell than carbon dioxide and water moves inside the cell and when the concentration of carbon dioxide and water is lower outside the cell and is higher inside the cell then they move out of the cell.

4. Why is the plasma membrane called a selectively permeable membrane?

Ans: The plasma membrane or the cell membrane is known as a selectively permeable or semipermeable membrane because it is responsible for the regulation of the various substances in and out of the cell. This results in the entry of certain substances and inhibits the entry of other substances through the plasma membrane.

5. Fill in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.

 Prokaryotic Cell Eukaryotic Cell 1. Size: generally small $(1- 10^\mu)$ m $1^\mu$ m = $10^{-6}$ m. 1. Size: generally large ($5-{100}^\mu$ m). 2. Nuclear region: _____________________________ and is known as ________. 2. Nuclear region: well-defined and surrounded by a nuclear membrane 3. Chromosome: single 3. More than one chromosome 4. Membrane-bound cell organelles areabsent 4. ________________________________

Ans:

 Prokaryotic Cell Eukaryotic Cell 1. Size: generally small $(1- 10^\mu)$ m $1^\mu$ m = $10^{-6}$ m. 1. Size: generally large ($5-{100}^\mu$ m). 2. Nuclear region is poorly defined because of the absence of a nuclear membrane and is known as a nucleoid. 2. Nuclear region: well-defined andsurrounded by a nuclear membrane 3. Chromosome: single 3. More than one chromosome 4. Membrane-bound cell organelles are absent. 4. Membrane-bound cell organelles such as mitochondria, plastids, etc., are present

6. Can you name the two organelles we have studied that contain their own genetic material?

Ans: The two organelles we have studied that contain their own genetic material are mitochondria and plastids. Mitochondria help in respiration in the cell while plastids are responsible for the process of photosynthesis in leaves.

7. If the organization of a cell is destroyed due to some physical or chemical influence, what will happen?

Ans: If the organization of a cell is destroyed due to some physical or chemical influence then the cell will not be able to perform many basic functions like photosynthesis, respiration, nutrition, etc., and may also result in the stopping of all life activities in the cell. Due to the cell damage, the lysosome bursts, and their enzymes digest such cells.

8. Why are lysosomes known as suicide bags?

Ans: Lysosomes are the cell organelles that are vesicular structures and contain the digestive enzymes. The function of these enzymes inside the lysosomes is to break down any foreign body that enters the cell. Sometimes, the lysosome may also act suicidal by releasing the digestive enzymes inside the cell and leads to self-destruction. Thus lysosomes are known as suicidal bags.

9. Where are proteins synthesized inside the cell?

Ans: Proteins are the building blocks of the body that are made up of various amino acids. They are synthesized inside the ribosomes that are the small structures present in the cytoplasm or might be attached to the surface of the endoplasmic reticulum. The endoplasmic reticulum is called the rough endoplasmic reticulum due to the presence of ribosomes on its surface.

10. Make a comparison and write down ways in which plant cells are different from animal cells.

Ans: The difference between the plant cells and the animal cells are:

 Animal Cell Plant Cell Animal cells are found to be smaller when compared to the plant cells. Plants cells are found to be larger in size. The cell wall is absent. The cell wall is present. Plastids are absent except Euglena. They consist of plastids to perform photosynthesis. Vacuoles are much smaller in size than plant cells and are several in numbers. One central large vacuole is present.

11. How is a prokaryotic cell different from a eukaryotic cell?

Ans: The difference between a prokaryotic cell and a eukaryotic cell are:

 Prokaryotic Cell Eukaryotic Cell They are unicellular, made up of single cells. They are multicellular, made up of several cells. They are smaller in size. They are larger in size. The cell does not contain a true nucleus or nuclear membrane. The nucleus is prominent and bounded by a nuclear membrane that is present in the cell. A single chromosome is present. More than one chromosome is present. They lack nucleolus. They consist of a proper nucleolus. Cell organelles are not membrane-bound and are absent. Membrane-bound cell organelles are present. By mitosis, only the cell division occurs. By mitosis and meiosis, the cell division occurs. Examples - bacteria and blue-green algae. Example - fungi, plants, and animal cells.

12. What would happen if the plasma membrane ruptures or breaks down?

Ans: The function of the plasma membrane is to act as a semipermeable membrane and regulate the entry and exit of the various substances in and out of the cell by the process of diffusion or osmosis and if the plasma breaks or ruptures then the contents of the cell might leak. This will result in the cells getting less nutrition than required.

13. What would happen to the life of a cell if there was no Golgi apparatus?

Ans: The function of the Golgi apparatus is packaging and transferring substances from one part of the cell to another. If the Golgi apparatus is absent in a cell then packaging of the proteins or the arrangement of the structural protein will not take place inside a cell. Proteins are essential for cells to perform various metabolic functions and if the proteins fail to reach the cell then this metabolism in the cell will not take place and eventually this will cause the cell to die.

14. Which organelle is known as the powerhouse of the cell? Why?

Ans: Mitochondria are known as the powerhouse of the cell as they produce the energy which is required by the cell to perform various functions. The energy which is released by the mitochondria is in the form of ATP molecules and is required for various chemical activities needed for. The energy stored in ATP is used by the body to make new chemical compounds and to perform mechanical work. Thus, mitochondria are known as the powerhouse of cells.

15. Where do the lipids and proteins constituting the cell membrane get synthesized?

Ans: Lipids and proteins are the essential part of the plasma membrane which is synthesized through the endoplasmic reticulum. The endoplasmic reticulum is found to be of two types based on the substances they synthesize. The smooth endoplasmic reticulum is responsible for the synthesis of lipids while the rough endoplasmic reticulum is responsible for the synthesis of proteins.

16. How does an Amoeba obtain its food?

Ans: Amoeba contains pseudopodia which are responsible for engulfing as well as removing food. The process by which amoeba acquires their food is called endocytosis. The plasma membrane of the amoeba is quite flexible thus enabling the cell to engulf the food particles and other materials from its external environment and also excrete the waste outside through the process called exocytosis.

17. What is osmosis?

Ans: The process of movement of water molecules from a region of high water concentration to a region of low water concentration through a selectively permeable membrane is called osmosis. This process continues until the solute concentration reaches equilibrium. The movement of water takes place across a concentration gradient to maintain equity on both sides of the cell.

18. Carry out the following osmosis experiment:

Take four peeled potato halves and scoop 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,

1. Keep cup A empty

2. Put one teaspoon sugar in cup B

3. Put one teaspoon salt in cup C

4. Put one teaspoon of sugar in the boiled potato cup D.

Keep these for two hours. Then observe the four potato cups and Solution 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.

Ans: The Solutions Are as Follows:

(i) The concentration of water that surrounds the potato is found to be more than inside which results in the flow of water inside the potato by the process of osmosis. Thus, the water gathers in the hollowed portions of setup B and C.

(ii) Potato A in this experiment is necessary since it is kept as a control set-up that helps in comparing the changes that have taken place in the other two setups of the experiment. By this, we can easily detect the changes in the different setups.

(iii) Since there is no change in the concentration of water in cup A so the water will not gather in the hollowed-out portions while in the case of cup D, due to boiling plasmolysis has taken place which leads to the absence of osmosis thus here also the water will not gather in the hollowed-out portions.

### NCERT Solutions For Class 9 Science Chapter 5 The Fundamental Unit of Life - Free PDF Download

Reliable NCERT Solutions for the Fundamental Unit of Life Class 9 PDF is available on Vedantu. Students can download this PDF of NCERT Solutions for free of cost. These NCERT Solutions are prepared by the subject-matter experts at Vedantu who offer detailed explanation and analysis of every topic and exercises which are framed strictly adhering to the updated CBSE syllabus. Hence by following the NCERT Solution for Class 9 Chapter 5, students will be able to learn and understand the crucial concepts covered in the chapter.

### Fundamental Unit of Life Class 9 NCERT Solutions

Listed below are some examples of NCERT Solution of Class 9th Science Chapter 5 which helps students to learn and get greater insights into the concepts.

### NCERT Solution of Class 9th Science Chapter 5: Solution 1 &2

The first two answers in this PDF will help students to get a detailed understanding of basic concepts like how the cell was developed by Robert Hooke. Furthermore, it also elaborately briefs on why is the cell called the functional and structural unit of life. By learning these two answers students will be able to easily answer the MCQ questions.

Class 9 Fundamental Unit of Life: Solution 3 & 4.

NCERT Class 9 fundamental unit of answer 3 describes the scientific process of diffusion and osmosis that helps substances like carbon dioxide and water to move in and out of the cell, respectively. In this solution, both the processes are discussed in detail so that students can grasp the concepts better.

Similarly, NCERT Solution for Class 9 Chapter 5  solution 4 discusses the plasma membrane and the reason as to why it is selectively permeable. It helps to understand the basics of the chapter in greater depth.

### NCERT Solution Class 9 Science Chapter 5: Solution 5

Ch 5 science class 9 Chapter 5 solution number 5 explains the difference between Prokaryotic cell and Eukaryotic cell. Each difference is elaborated in a pointwise manner with respect to size, the position of nucleus, number of chromosomes, and membrane. By going through this solution, a student can distinctly understand the structural and functional differences between the two types of cells.

### Marks Weightage of Chapter 5 Science Class 9

Chapter 5 is covered in “Organization in the living world” which is unit 2 of the Class 9 Science syllabus. This unit comprises a considerable weightage of 26 marks out of 80.

In this regard, students should minutely focus on studying the intricacies of this chapter so that they can attempt all short and long answer questions properly during their exams.

### Benefits of NCERT Solution for Class 9 Chapter 5 PDF

There are several ways in which the PDF of Class 9 Fundamental Unit of Life NCERT Solutions are beneficial.

• Detailed solution for long answer type questions

• Elaborate examples and relevant diagrams

• Solved exercises to learn MCQs better

• Curated by expert science teachers

• Updated to the latest CBSE syllabus

All these factors ensure that students can adequately understand each topic in detail and therefore have a better learning experience.

The NCERT Solutions of Chapter 5 for Class 9 Science are well-curated with all the important questions from the point of view of the CBSE exam. The students are required to understand the type of questions being asked in the CBSE exam, for which they have to priorly study from these NCERT solutions.

## FAQs on The Fundamental Unit of Life- NCERT Solutions of Chapter 5 (Science) for Class 9

1. What is meant by Osmosis and Diffusion as per the NCERT Solutions?

Osmosis is a process through which water moves in and out of the cell membrane. The movement is always from a region of higher concentration to lower concentration of water through a selectively permeable membrane until it reaches an equilibrium.

In a similar manner, diffusion refers to the process by which Carbon Dioxide moves in and out of the cell membrane. The cellular wall contains a high level of CO2, whereas the CO2 concentration outside is significantly low. This causes the CO2 to move from a region of higher concentration to that of low concentration to maintain a level of equilibrium.

2. What are the important topics in the Fundamental Unit of Life as per the NCERT Solutions?

The important topics that students must learn in the chapter fundamental unit of life are – Discovery of the cell, Unicellular organism, Multi-cellular organism, characteristics of the cell, structural organization of cell-like plasma membrane, nucleus, and cytoplasm, DNA, Chromatin material, Chromosomes, and proteins.

Apart from this, students must also focus on topics like Mitochondria, Plastids, lysosomes, chloroplast, leucoplast, vacuoles, Golgi apparatus, Ribosomes, Endoplasmic reticulum, and Cell organelles. Students should focus on learning the topics extensively. Diagrams of every structure and its parts should be learned in detail to answer MCQ, long answer and questions based on diagrams.

3. What is the difference between Prokaryotic and Eukaryotic cells as per the NCERT Solutions?

There are four main differences between Prokaryotic and Eukaryotic cells, which are largely related to their structures and size.

The prokaryotic cells are smaller in size, whereas the Eukaryotic cells are generally larger. The nuclear region of the prokaryotic cell is known as nucleoid and lacks a nuclear membrane. In comparison, the Eukaryotic cell has a well defined nuclear membrane. The prokaryotic cell consists of a single chromosome, while the Eukaryotic cell has multiple chromosomes. In a prokaryotic cell, the membrane-bound cell organelles are absent, whereas in the eukaryotic cell the membrane-bound cell organelles are present.

4. How many questions are present under each exercise of the NCERT Solutions for Class 9 Science Chapter 5?

There are about 4 to 7 questions under each exercise in the NCERT solutions for Class 9 Science Chapter 5. All the questions have detailed solutions under them. Examples from within the textbook are also answered. Wherever necessary, the answers are explained in-depth with the help of tables and diagrams as well. All answers designed by experts are given in a simpler way to assure the students understand the concept easily. You can refer to Vedantu’s NCERT solutions for Class 9 Science Chapter 5 if you are looking for high-quality solutions.

5. How are the NCERT Solutions for Class 9 Science Chapter 5 designed in Vedantu?

All answers from the NCERT book are answered by Vedantu. Vedantu makes learning and memorising answers easier by making the answers interactive with the help of tables and diagrams. The diagrams are also labeled to help the students memorise easily. All questions are answered with the help of professionals. You can download these solutions free of cost. You can download them, save them on your computer and refer to them anytime while preparing for exams.

6. Why is the cell the basic unit of life according as per the NCERT Solutions?

A cell is the basic unit of life as it is the unit that forms anything in our body. They form the tissues that further form the organs and different systems in our body. Tissues help in the functioning of these systems and processes like digestion, respiration, etc. in our bodies. This is why cells are referred to as the structural and fundamental units of life.

7. Who discovered the cell and how, according to as per the NCERT Solutions?

Robert Hooke, in 1665, discovered the cell. He was examining a thin slice of cork through a microscope when he observed its honeycomb-like structure. It seemed to comprise mini compartment-like structures. These structures were then called cells. To study more and learn through diagrams students can refer to vedantu website or the app.

8. Can NCERT Solutions help you in the overall preparation for Class 9 Science Chapter 5 for the exam?

Yes, NCERT Solutions of Class 9 Science Chapter 5 introduces students to important topics and foundations that the students must know and have a strong base in for higher classes. The students should thoroughly revise what is taught in school and make regular notes. Note-writing will help them understand and memorise the chapter. Attempt and practice all the questions in the NCERT textbook and also attempt the extra questions in the NCERT Solutions PDF available online on the Vedantu website. The PDF will also help you revise quicker.