Lakhmir Singh Solutions for Class 9 Biology Chapter 3 Cell - The Fundamental Unit of Life - PDF

1. Distinguish between prokaryotic and eukaryotic cells.

Ans: The difference between prokaryotic and eukaryotic cells is as follows:

2. Write down the difference between organ and organelle.

Ans: The difference between organ and organelle is as follows:

3. Write down the difference between the nucleus and nucleoid.

Ans: The difference between a nucleus and a nucleoid is as follows:

4. Mention the difference between a light microscope and an electron microscope.

Ans: The difference between a light microscope and an electron microscope is as follows:

5. Give a brief description of the discovery of the cell.

Ans: The cell is the fundamental structural and operational unit of life. In 1665, British physicist Robert Hooke coined the term "cell". He was the first to use a microscope to study living things, and when he looked at a thin slice of cork, he noticed honeycomb-like structures. Robert Hooke referred to these as cells.

6. Describe the plasma membrane proteins.

Ans: The plasma membrane contains two types of protein molecules:

1. Intrinsic proteins: They cover the lipid bilayer completely.

2. Extrinsic proteins: These can be found on either the outer or inner surface of the lipid layer.

7. Enumerate functions of the plasma membrane.

Ans: Only specific molecules can pass through the plasma membrane, which serves as a barrier separating the cell organelles from the external environment. It makes signalling and communication between cells easier.

8. Give an example of diffusion across the plasma membrane.

Ans: Gaseous exchange occurs in unicellular organisms such as Amoeba via the diffusion process.

9. Set up an experiment to demonstrate diffusion and osmosis?

Ans: The experiment to demonstrate diffusion and osmosis is as follows: 

1. Place three raisins in a common balance and weigh them. Let W1 be this value.

2. For two hours, leave these raisins in a dish of water.

3. Remove the raisins from the water and use blotting paper to gently pat them dry.

4. Use the common balance to weigh the drenched, enlarged raisins once more. Let W2 be this value. The raisins (W2) that are soaked and swelled weigh more than the raisins (W1) (W1). This is a result of the raisins absorbing water by endosmosis.

10. Differentiate between diffusion and osmosis?

Ans: The difference between diffusion and osmosis is as follows:

11. Write a note on endocytosis.

Ans: The process of absorbing a particle or substance from the external environment is known as endocytosis. Phagocytosis, usually referred to as cellular eating, and pinocytosis also referred to as cellular drinking, are the two forms of endocytosis. Endocytosis comes in three different forms:

1. Phagocytosis 

2. Pinocytosis 

3. Endocytosis mediated by receptors.

12. What happens to eukaryotic cells in hypotonic, hypertonic, and isotonic solutions?

Ans: The following changes are seen when eukaryotic cells are put in the corresponding solutions:

• Hypotonic Solution: Water flows from a low-osmolar zone to a high-osmolar region. Since the extracellular fluid in this situation has a low osmolarity, water would rush into the cell. The cell would then enlarge before lysing or bursting.

• Hypertonic Solution: Since the cell's osmolarity is lower than that of the extracellular fluid in this situation, water will exit the cell. As a result, a process known as plasmolysis would cause the cell to shrink.

• Isotonic Solution: Both liquids have the same osmolarity. As a result, even when water diffuses in and out, the volume of the cell does not alter significantly.

13. Name the following:

(a) Smallest cell organelle.

Ans: Ribosomes is the smallest organelle.

(b) Largest cell organelle.

Ans: Plastids in plants and nuclei in an animal cell.

(c) ER studded with ribosomes.

Ans: Rough endoplasmic reticulum contains ribosomes attached to its surface.

(d) Functional segments of the DNA molecule.

Ans: Genes are the functional segments of DNA molecules.

14. Distinguish between the following:

(a) Chromoplast and Chloroplast

Ans: The difference between chromoplast and chloroplast is as follows:

(b) Ribosome and centrosome

Ans: The difference between ribosomes and centrosomes are as follows:

15. Write the main difference between plant and animal cells.

Ans: The difference between plant cells and animal cells is as follows:

16. What happens if the nucleus of a cell is removed? 

Ans: A cell will die if its nucleus is removed since it will be unable to perform its essential duties.

17. Explain why spinach looks green, papaya yellow, and the edible part of watermelon red?

Ans: Chlorophyll, a green pigment, gives spinach its green colour. Caricaxanthin is responsible for the yellow colour of papaya. Due to the presence of the red pigment lycopene, the edible portion of a watermelon is colored red.

18. Write down the main functions of:

(a) Endoplasmic reticulum

Ans: It has a significant impact on how proteins and lipids are made, processed, and transported. It creates lysosomes, secretory vesicles, the Golgi apparatus, the cell membrane, and plant cell vacuoles in addition to transmembrane proteins and lipids for its membrane and many other cell components.

(b) Lysosomes

Ans: Removal of dead cells. Digesting within cells

19. Name the following.

(a) The cell organelle which synthesises protein.

Ans: Ribosome synthesises protein. 

(b) The type of plastid which stores food.

Ans: Leucoplast is the type of plastid that stores food.

20. Lysosomes are known as suicide bags. Why?

Ans: Because they contain lytic enzymes capable of breaking down undesired materials and cells, lysosomes are also referred to as the "suicide bags" of the cell. The lytic enzymes contained in lysosomes leak out into the surrounding cell, rupturing the cell membrane or cell wall and resulting in cell death.

Importance of Lakhmir Singh Class 9 Biology Chapter 3 Cell the Fundamental Unit of Life

This chapter is crucial for developing a conceptual foundation related to cells, the fundamental unit of life. There are different types of cells we find in multicellular plants and animals.

This chapter will explain the different types of tissues in a higher-order plant. It will explain how a plant tissue is organised by multiple cells to perform a function. The tissues are classified into different types according to their origin, form, and functions.

If you observe a collenchyma tissue diagram Class 9, you will find out how this tissue differs from the rest of the classifications. This tissue is responsible for the formation of elongated cells. These cells are mostly found in the leaves and stems.

This chapter will explain where this type of tissue is located. You can easily find and write the location and function of the collenchyma tissue. Here, you will also learn where the other tissues are found and what their functions are.

Similarly, this chapter will also explain what types of tissues we can find in the human body. This chapter is important for the students to learn about the different organisations of tissues to form various organs.

Benefits of Lakhmir Singh Class 9 Biology Chapter 3 Solutions

• The subject experts have designed these solutions following the ICSE Class 9 syllabus and standards mandated by the education board. The answers will be relevant and accurate. You can follow these solutions to understand the basic concepts of this chapter.

• Find out what answers you can frame for the fundamental questions and compare yours with the solutions. In this way, you can quickly figure out where you need to study more in this chapter.

• Resolve doubts on your own by using these solutions. You will be able to answer how collenchyma tissue is characterised by the cell walls and features.

• These notes will also offer a simplified version of the entire chapter. It will help you to revise and recall the whole chapter in no time before an exam.

Download Lakhmir Singh Class 9 Biology Chapter 3 Solutions PDF

Get the free version of the Lakhmir Singh Class 9 Biology book PDF notes and solutions for this chapter and complete your study material. Check how the experts have framed the answers to all the exercise questions. Learn how to frame such answers to score more in the exams. These notes will not only save time but will also assist you in staying ahead of your peers.