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: In this article, you will study that most mature plant cells have a large central vacuole that helps to maintain the turgidity of the cell and stores important substances including wastes. The CBSE NCERT solutions for class 9 science chapter 5 The Fundamental Unit of Life contains questions and solutions of all the topics and exercises mentioned in the chapter. The NCERT solutions aim at helping you solve difficult questions. Through this chapter, you will also get to know that, Prokaryotic cells have no membrane-bound organelles, their chromosomes are composed of only nucleic acid, and they have only very small ribosomes as organelles. Cells in organisms divide for growth of body, for replacing dead cells, and for forming gametes for reproduction. If you have any problem in answering the questions or you are not getting the correct answers then don't worry, solutions for NCERT class 9 science chapter 5 The Fundamental Unit of Life is there for you to help. It will give you solutions to all the questions which are mentioned in the NCERT textbook.

Here are the important topics of NCERT solutions for class 9 science chapter 5 The fundamental unit of life mentioned below:

5.1 What Are Living Organisms Made up of?

5.2 What Is a Cell Made up Of? What Is the Structural Organisation of a Cell?

    5.2.1 Plasma Membrane or Cell Membrane

    5.2.2 Cell Wall

    5.2.3 Nucleus

    5.2.4 Cytoplasm

    5.2.5 Cell Organelles

    5.2.5 (i) Endoplasmic Reticulum (ER)

    5.2.5 (ii) Golgi Apparatus

    5.2.5 (iii) Lysosomes

    5.2.5 (iv) Mitochondria

    5.2.5 (v) Plastids

    5.2.5 (vi) Vacuoles

NCERT solutions for class 9 science chapter 5 the fundamental unit of life

Topic 5.1 What are Living Organisms made up 

Q. 1.  Who discovered cells, and how?

Answer:

Cells were discovered in 1665 by Robert Hooke. He was examining a thin slice of cork using a primitive microscope designed by himself. He saw that the structure of the cork at a microscopic level is similar to that of a honeycomb. It had several small chambers like those in a honeycomb.

These small chambers were termed as cells.

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

Answer:

The cell called the structural and functional unit of life as it is the smallest living unit which can carry out all the living processes essential for living.

Topic 5.2 What is a cell made up of? What is the structural organization of the cell?

Q. 1.   How do substances like CO_{2}  and water move in and out of the cell? Discuss

Answer:

CO2 and water move in and out of the cell through the cell membrane by the process of diffusion and osmosis respectively.


Q. 2.  Why is the plasma membrane called a selectively permeable membrane?

Answer:

The plasma membrane called a selectively permeable membrane because it relatively allows the movement of substances from the inside of the cell to the outside and vice-versa.

This selectivity depends on the requirements of the cell and the substances present in the surroundings of the cell.

Solutions for NCERT for class 9 chapter 5 The Fundamental Unit of Life

Topic 5.2.2 Cell Wall

Q. 1.   Fill in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.

              Solutions for NCERT for class 9 chapter 5 The Fundamental Unit of Life

Answer:

Prokaryotic Cell Eukaryotic Cell
1. Size generally small.

1. Size generally large.

2. Nuclear Region: Poorly defined because of the absence of cell membranes and is called the nucleoid.

2. Nuclear Region: Well defined and surrounded by a nuclear membrane.

3. Chromosome: single.

3. More than one chromosome.

4. Membrane-bound cells organelles present 4. Membrane-bound cell organelles absent.

CBSE NCERT solutions for class 9 science chapter 5 The fundamental unit of life

Topic 5.2 What is a cell made up of? What is the structural organization of the cell?

Q. 1.   Can you name the two organelles we have studied that contain their own genetic material?

Answer:

Two organelles which contain their own genetic material are 

1. Mitochondria

2. Plastids

Q. 2.   If the organisation of a cell is destroyed due to some physical or chemical influence, what will happen?

Answer:

If the organisation of a cell is destroyed due to some physical or chemical influence it will not be able to perform the life processes essential for living and therefore would be digested by lysozymes.

Q. 3.   Why are lysosomes known as suicide bags?

Answer:

When the cells are damaged to such an extent that they are incapable of performing certain functions which are essentials for survival, the organism tries to get rid of these cells.

For this function, the lysosomes which are membrane-bound organelles burst and release digestive enzymes called lysozymes which destruct the cell and lysosomes are therefore called suicide bags.

Q. 4.   Where are proteins synthesized inside the cell?

Answer:

Inside the cells, the proteins are synthesized at sites called ribosomes.

These are very small structures made up of ribonucleic acids and proteins.

NCERT solutions for class 9 science chapter 5 The fundamental unit of life - Solved Exercise Solutions

Q1.  Make a comparison and write down ways in which plant cells are different from animal cells.

Answer:

Plant Cells Animal Cells
1. Plant cells are generally bigger than animal cells. 1. Animal cells are relatively small.
2. Plant cells have a cell wall. 2. Animal cells do not have a cell wall.
3. The nucleus is not present in the centre of the cell. 3. The nucleus is there at the center of the cell.
4. The size of the vacuole is large. 4. The size of the vacuole is small.
5. A chloroplast is present. 5. A chloroplast is absent.

Q2.   How is a prokaryotic cell different from a eukaryotic cell?

Answer:

Prokaryotic Cell Eukaryotic Cell

1. A prokaryotic cell is quite small in size.

( 1 - 10 pm)

1. A eukaryotic cell is relatively larger.

(5-100 pm)

2. The nuclear region is poorly defined as the nuclear membrane is absent.

2. The nuclear membrane is present and the nuclear region is well defined.

3. Organelles are not membrane-bound. 3. Organelles are membrane-bound.
4. Only one chromosome is present.  4. More than one chromosome is present.

Q3.   What would happen if the plasma membrane ruptures or breaks down?

Answer:

If the plasma membrane ruptures the cell would eventually die because the movement of substances won't be regulated.

This will cause important substances to move out of the cell and harmful substances from the environment would enter the cell.

Q4.  What would happen to the life of a cell if there was no Golgi apparatus?

Answer:

Golgi apparatus stores and transports materials through vesicles.

In the absence of the Golgi apparatus, these functions would stop and this will cause the death of the cell.

Q5.   Which organelle is known as the powerhouse of the cell? Why?

Answer:

Mitochondria are known as the powerhouse of the cell as mitochondria releases energy in the form of ATP which is essential for performing all the functions of the cell.

Q6.   Where do the lipids and proteins constituting the cell membrane get synthesized?

Answer:

Lipids and proteins are synthesized in the endoplastic reticulum.

In the Rough Endoplastic Reticulum proteins are manufactured whereas the manufacturing of lipids take place in the Smooth Endoplastic Reticulum.

Q7.    How does an Amoeba obtain its food?

Answer:

Amoeba obtains its food by the virtue of the flexibility of its shape.

Amoeba entraps the food particle around its membrane and then engulfs it within the cytoplasm. This process is called endocytosis.

Q8.   What is osmosis?

Answer:

Osmosis is the movement of water from a region of low concentration of solute(high water concentration) to a region of high concentration of solute(low water concentration) through a semi-permeable membrane.

Q9. (i) Carry out the following osmosis experiment:

Take four peeled potato halves and scoos each one out to make potato cups. One of these potato cup 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.

Answer:

(i) Due to the presence of a solute (sugar in case of B and salt in case of C), there is a concentration difference of water in the potato cup and the trough due to which osmosis takes place where the cells of the potato act as the semi-permeable membrane.


Q9. (ii)   Carry out the following osmosis experiment:

Take four peeled potato halves and scoops 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:

(ii) Why is potato A necessary for this experiment?

Answer:

Potato A is absolutely necessary because it acts as the control for the experiment. Without A we will have no reference to compare the other cases with. We can see that since there is no solute in the hollow part of this potato no osmosis has taken place.

Q9.(iii)   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:

 (iii) Explain why water does not gather in the hollowed-out portions of A and D.

Answer:

Since there is no solute in the hollow part of potato A no osmosis has taken place and water does not gather in the hollowed part of A.

In the case of D even after the presence of solute osmosis does not take place. Boiling this potato has destroyed the cells and thus no semi-permeable membrane is there for osmosis to take place.

Q10.   Which type of cell division is required for growth and repair of the body and which type is involved in the formation of gametes?

Answer:

Mitosis is required for growth and repair of body and meiosis is involved in the formation of gametes.

NCERT Solutions for Class 9 Science- Chapter Wise

Chapter No.

Chapter Name

Chapter 1

CBSE NCERT solutions for class 9 science chapter 1 Matter in Our Surroundings

Chapter 2

NCERT solutions for class 9 science chapter 2 Is Matter Around Us Pure

Chapter 3

Free NCERT solutions for class 9 science chapter 3 Atoms and Molecules

Chapter 4

CBSE NCERT solutions for class 9 science chapter 4 Structure of The Atom

Chapter 5

Solutions for NCERT class 9 science chapter 5The Fundamental Unit of Life

Chapter 6

NCERT textbook solutions for class 9 science chapter 6 Tissues

Chapter 7

Free NCERT solutions for class 9 science chapter 7 Diversity in Living Organisms

Chapter 8

CBSE NCERT solutions for class 9 science chapter 8 Motion

Chapter 9

NCERT solutions for class 9 science chapter 9 Force and Laws of Motion

Chapter 10

NCERT textbook solutions for class 9 science chapter 10 Gravitation

Chapter 11

NCERT free solutions for class 9 science chapter 11 Work and Energy

Chapter 12

CBSE NCERT solutions for class 9 science chapter 12 Sound

Chapter 13

Solutions for NCERT class 9 science chapter 13 Why Do We Fall ill?

Chapter 14

NCERT solutions for class 9 science chapter 14 Natural Resources

Chapter 15

NCERT textbook solutions for class 9 science chapter 15 Improvement in Food Resources

NCERT Solutions for Class 9- Subjectwise 

NCERT Solutions for Class 9 Maths
NCERT Solutions for Class 9 Science

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