Class 9 Biology Cell The Fundamental Unit of Life Worksheet

All living things, from tiny bacteria to large animals like elephants, are made up of cells. The cell is the basic unit of life. Just like a house is made of bricks, the bodies of all living organisms are made of cells. Some organisms, like bacteria and amoeba, are made of a single cell, while others, like humans and trees, have millions or even trillions of cells.

The cell was first discovered by Robert Hooke in 1665 when he observed a thin slice of cork under a microscope. Later, scientists like Anton van Leeuwenhoek and Rudolf Virchow helped in understanding cells better. The cell theory, proposed by Schleiden and Schwann, states that:

1. All living things are made of cells.
2. The cell is the basic unit of life.
3. All cells arise from pre-existing cells.

Cells come in different shapes and sizes depending on their function. For example, nerve cells are long to help carry messages, while red blood cells are round and small to move easily in the blood. Cells also have different parts, each with a special role.

Main Parts of a Cell

1. Cell Membrane – A thin layer that surrounds the cell and controls what enters and exits.
2. Cytoplasm – A jelly-like substance inside the cell where different cell parts are found.
3. Nucleus – The control center of the cell that contains genetic material (DNA).
4. Organelles – Tiny structures inside the cell that perform specific functions, like mitochondria (the powerhouse of the cell), ribosomes (protein-making factories), and vacuoles (storage spaces).

There are two main types of cells:

• Prokaryotic cells (like bacteria) – simple cells without a nucleus.
• Eukaryotic cells (like plant and animal cells) – more advanced cells with a nucleus and many organelles.

Cells also differ in plants and animals. Plant cells have a cell wall, chloroplasts for photosynthesis, and large vacuoles, while animal cells do not.

This worksheet will help students understand the structure and function of cells. By answering questions and solving exercises, students will learn why cells are important and how they help living organisms grow, repair, and function. Cells are truly the building blocks of life!

Worksheet for Class 9 Biology Cell The Fundamental Unit of Life

1. Which is the biggest cell in the human body?
   a) Nerve cell
   b) Muscle cell
   c) Liver cell
   d) Kidney cell
2. What happens to a cell when placed in a hypertonic solution?
   a) It shrinks
   b) It swells up
   c) It remains the same size
   d) It undergoes plasmolysis
3. How does all life begin?
   a) As a single cell
   b) As a gene
   c) As a chromosome
   d) As an egg
4. Centrioles help in:
   a) DNA synthesis
   b) Respiration
   c) Cell division
   d) Reproduction
5. What is the main component of the plant cell wall?
   a) Cellulose
   b) Proteins
   c) Hemicellulose
   d) Phospholipids
6. What is chromatin made of?
   a) DNA and histone proteins
   b) RNA only
   c) DNA only
   d) RNA and histone proteins

True or False

7. The fluid part of the cell around the nucleus is called protoplasm. (T/F)
8. Genes are found inside chromosomes. (T/F)
9. Flower pigments like anthocyanins dissolve in cell sap. (T/F)
10. Mitochondria are called the “powerhouse of the cell” because they produce oxygen. (T/F)

Short Answer Questions

11. What is osmosis?
12. Explain the cell theory and name the scientists who proposed it.
13. Why is the cell called the basic unit of life?
14. How do substances like carbon dioxide and water move in and out of cells?
15. What are the differences between prokaryotic and eukaryotic cells?
16. How does an Amoeba get its food?
17. What are the different types of endoplasmic reticulum? What do they do?
18. Why is the plasma membrane called a selectively permeable membrane?
19. Which organelle is known as the powerhouse of the cell? Explain why.
20. Name two organelles that have their own DNA.
21. What is the function of lysosomes in a cell?
22. How does diffusion help in cellular processes?
23. Name the different levels of organization in living things.

Fill in the Blanks

24. __________ is the control center of the cell.
25. The jelly-like substance inside the cell is called __________.
26. The process by which water moves across a membrane is called __________.
27. __________ is the process by which cells take in food through engulfing, like in Amoeba.
28. The function of ribosomes is to __________.
29. Plant cells have an extra layer called the __________ that provides support and protection.
30. The two types of endoplasmic reticulum are __________ and __________.

Match the Following