The Fundamental Unit of Life Class 9 Science 20 Important Questions with answer

20 important questions with answers on the topic "The Fundamental Unit of Life" from Class 9 Science:

1. Question: What is the cell theory? Answer: The cell theory states that:

   • All living organisms are composed of one or more cells.
   • The cell is the basic unit of structure and function in all living organisms.
   • All cells arise from pre-existing cells.

2. Question: Who are the scientists credited with the development of the cell theory? Answer: Matthias Schleiden, Theodor Schwann, and Rudolf Virchow are credited with the development of the cell theory.

3. Question: What are prokaryotic cells? Give an example. Answer: Prokaryotic cells are cells that lack a well-defined nucleus and membrane-bound organelles. Example: Bacteria.

4. Question: What are eukaryotic cells? Give an example. Answer: Eukaryotic cells are cells that have a well-defined nucleus and membrane-bound organelles. Example: Animal cells and plant cells.

5. Question: What is the function of the plasma membrane? Answer: The plasma membrane regulates the entry and exit of substances in and out of the cell, thus maintaining the cell's internal environment.

6. Question: What is the difference between plant cells and animal cells? Answer: Plant cells have a cell wall, chloroplasts, and large central vacuole, whereas animal cells do not have these structures but have centrioles.

7. Question: What is the function of the nucleus in a cell? Answer: The nucleus acts as the control center of the cell, containing genetic material (DNA) and coordinating activities like growth, metabolism, and reproduction.

8. Question: What is cytoplasm? Answer: The cytoplasm is the jelly-like substance within the cell membrane that contains all organelles and cell parts.

9. Question: What are ribosomes and what is their function? Answer: Ribosomes are the sites of protein synthesis in the cell. They can be found floating in the cytoplasm or attached to the endoplasmic reticulum.

10. Question: Describe the structure and function of mitochondria. Answer: Mitochondria are double-membraned organelles known as the powerhouse of the cell. They generate energy in the form of ATP through cellular respiration.

11. Question: What is the endoplasmic reticulum and its types? Answer: The endoplasmic reticulum (ER) is a network of membranous tubules within the cytoplasm. There are two types: Rough ER (with ribosomes) involved in protein synthesis, and Smooth ER (without ribosomes) involved in lipid synthesis and detoxification.

12. Question: What is the function of the Golgi apparatus? Answer: The Golgi apparatus modifies, sorts, and packages proteins and lipids for storage or transport out of the cell.

13. Question: What are lysosomes and their function? Answer: Lysosomes are membrane-bound organelles containing digestive enzymes. They break down waste materials and cellular debris.

14. Question: What are vacuoles and their function? Answer: Vacuoles are storage sacs within the cell, larger in plant cells. They store nutrients, waste products, and help maintain turgor pressure in plant cells.

15. Question: What is the function of chloroplasts? Answer: Chloroplasts are the sites of photosynthesis in plant cells. They contain chlorophyll, which captures light energy to convert carbon dioxide and water into glucose and oxygen.

16. Question: Define cell wall and its function. Answer: The cell wall is a rigid layer outside the plasma membrane in plant cells, providing structural support and protection.

17. Question: What is the function of centrioles? Answer: Centrioles play a role in cell division by helping in the formation of the mitotic spindle.

18. Question: What are plastids and their types? Answer: Plastids are double-membrane organelles found in plant cells. Types include chloroplasts (photosynthesis), chromoplasts (pigment synthesis), and leucoplasts (storage).

19. Question: What is osmosis? Answer: Osmosis is the movement of water molecules through a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration.

20. Question: Define the term ‘cell’. Answer: A cell is the smallest structural and functional unit of an organism, which can exist independently or as part of a multicellular organism.

These questions cover fundamental concepts about cells, their structure, functions, and the differences between types of cells.