Science Exploration Notes Class 9 English Medium 2026-27

Science Exploration Chapter 2. Cell: The Building Block of Life

CBSE Notes New Syllabus: Class 9

Assignments - What Have You Learned?

Chapter 2. Cell: The Building Block of Life

This assignment is designed according to the latest CBSE competency-based pattern. It covers the complete chapter and helps students strengthen conceptual understanding, application skills and analytical thinking.

Chapter Assignment

1. One Word Answer

1. The basic structural and functional unit of life.
2. The scientist who first observed cork cells.
3. The instrument used to observe microscopic cells.
4. The living outer covering of the cell.
5. The rigid outer covering present in plant cells.
6. The jelly-like substance inside the cell.
7. The control centre of the cell.
8. The powerhouse of the cell.
9. The protein factory of the cell.
10. The hereditary material present in the nucleus.

2. Fill in the Blanks

1. Every living organism is made up of one or more __________.
2. The term "Cell" was given by __________.
3. The plasma membrane is __________ permeable.
4. Plant cells possess a __________.
5. Movement of water through a selectively permeable membrane is called __________.
6. ATP is mainly produced in the __________.
7. Ribosomes help in __________ synthesis.
8. Genes are present on __________.
9. The Golgi apparatus modifies and __________ proteins.
10. New cells arise from __________ cells.

3. True or False

1. All living organisms are made up of cells.
2. Animal cells possess a cell wall.
3. The nucleus controls all activities of the cell.
4. Diffusion and osmosis are the same process.
5. Mitochondria are called the powerhouse of the cell.
6. Ribosomes are membrane-bound organelles.
7. Chloroplasts are present in animal cells.
8. Lysosomes contain digestive enzymes.
9. DNA carries hereditary information.
10. Cell division helps in growth and repair.

4. Match the Following

5. Very Short Answer Questions

1. Define a cell.
2. Who discovered the cell?
3. What is a microscope?
4. What is the function of the plasma membrane?
5. What is osmosis?
6. Name any two membrane-bound organelles.
7. What is the function of the nucleus?
8. Why are mitochondria called the powerhouse of the cell?
9. What is a chromosome?
10. State one difference between plant and animal cells.

6. Short Answer Questions

1. Explain the importance of the discovery of the cell.
2. Describe the structure and functions of the plasma membrane.
3. Differentiate between diffusion and osmosis.
4. Explain the functions of the cell wall.
5. Compare prokaryotic and eukaryotic cells.
6. Describe the structure and functions of the nucleus.
7. Write the functions of mitochondria and ribosomes.
8. Explain the role of the Golgi apparatus and lysosomes.
9. Describe the different types of plastids.
10. Why is cell division important in living organisms?

7. Long Answer Questions

1. Explain the structure of a cell with the help of labelled components.
2. Describe the discovery of the cell and the development of microscopes.
3. Explain the structure and functions of different cell organelles.
4. Differentiate between plant cells and animal cells with suitable diagrams.
5. Compare prokaryotic and eukaryotic cells with examples.
6. Explain the structure and functions of the nucleus, chromosomes, DNA and genes.
7. Describe the movement of substances across the plasma membrane through diffusion and osmosis.
8. Explain Cell Theory and discuss its importance.
9. Describe how different cell organelles work together to keep the cell alive.
10. Explain the importance of cells in the organisation of living organisms.

8. Case Study Questions

Case Study – 1

A student observed onion peel under a microscope and noticed many rectangular structures with a distinct boundary and nucleus.

1. Which type of cell did the student observe?
2. Name the rigid outer covering present in these cells.
3. Why do these cells appear rectangular?
4. Which organelle controls all activities of the cell?

Case Study – 2

A potato strip placed in pure water became swollen, while another strip placed in concentrated salt solution became soft and shrank.

1. Which process is demonstrated in this activity?
2. Why did the potato strip swell in water?
3. Why did the strip shrink in salt solution?
4. Name the membrane involved in this process.

Case Study – 3

A scientist observed bacteria under a microscope and found that they lacked a membrane-bound nucleus.

1. Which type of cells are bacteria?
2. Why are they called prokaryotic cells?
3. Name one organism with eukaryotic cells.
4. State one major difference between the two cell types.

Case Study – 4

A muscle cell requires a large amount of energy to perform continuous work.

1. Which organelle supplies this energy?
2. What form of energy is produced?
3. Why are these organelles numerous in muscle cells?
4. What is the common name of this organelle?

Case Study – 5

A plant leaf appears green and prepares food in the presence of sunlight.

1. Which organelle performs this function?
2. Which pigment is responsible for the green colour?
3. Name the process involved.
4. Why is this organelle absent in animal cells?

9. Competency-Based Questions

1. Why are cells called the basic structural and functional units of life?
2. How did the invention of microscopes change the study of biology?
3. Why is the plasma membrane called selectively permeable?
4. Explain why osmosis is important for plant cells.
5. How does the cell wall protect plant cells?
6. Why do multicellular organisms require specialised cells?
7. How do mitochondria and ribosomes work together to keep a cell alive?
8. Why is the nucleus considered the control centre of the cell?
9. How do genes influence inherited characteristics?
10. Explain how different cell organelles coordinate to perform life processes.

10. HOTS Questions

1. What problems would living organisms face if cells had no plasma membrane?
2. Why are mitochondria more numerous in actively working cells than in inactive cells?
3. If plant cells did not have a cell wall, how would their structure and function change?
4. How would the absence of ribosomes affect the survival of a cell?
5. Why are lysosomes called the "suicidal bags" of the cell? Do you think this name is justified?
6. How does the structure of a cell support its function?
7. Can a multicellular organism survive if its cells stop dividing? Give reasons.
8. Why is the study of cells considered the foundation of modern biology?
9. How do specialised organelles make a eukaryotic cell more efficient than a prokaryotic cell?
10. Imagine a cell without a nucleus. Which important life processes would be affected? Explain.