Chapter 5: The Fundamental Unit of Life
Learning Notes (Set 2) for Class 9 Science

Question 1: Who formulated the Cell Theory?

Answer: The Cell Theory was presented by Matthias Schleiden and Theodor Schwann.

Question 2: What is the main function of the nucleus?

Answer: The nucleus acts as the control center of the cell and plays a crucial role in cell reproduction.

Question 3: What is the key difference between a prokaryotic and a eukaryotic cell?

Answer: A prokaryotic cell lacks a well-defined nuclear membrane, whereas a eukaryotic cell has one.

You are on Chapter 5: The Fundamental Unit of Life (Learning Notes for Class 9 Science) Set 2

Question 4: What is the primary role of vacuoles in plant cells?

Answer: Vacuoles store sap and provide turgidity and rigidity to the plant cell.

Question 5: Which organelle is known as the "powerhouse of the cell" and why?

Answer: Mitochondria are called the powerhouse of the cell because they produce energy in the form of ATP.

Question 6: What is the main function of ribosomes?

Answer: Ribosomes are the sites for protein synthesis within the cell.

Question 7: What is plasmolysis?

Answer: Plasmolysis is the shrinking of the cell contents from the cell wall when a living plant cell loses water through osmosis.

Question 8: How does an amoeba acquire its food?

Answer: An amoeba acquires its food through a process called endocytosis, in which the cell membrane engulfs the food particle.

You are on Chapter 5: The Fundamental Unit of Life (Learning Notes for Class 9 Science) Set 2

Question 9: What is the difference between Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER)?

Answer: RER appears rough because of the presence of ribosomes on its surface, while SER does not have ribosomes.

Question 10: What is the significance of the cell wall in plant cells?

Answer: The cell wall provides structural support and protects the plant cell from bursting by withstanding the pressure from a hypotonic medium.