Simplified Notes: Tissues

Class 9 Chapter 6 Tissues Science Notes | Quiztives | Explained Simply

1. Introduction: From a Single Brick to a Wall | Class 9 Chapter 6 Tissues

Welcome back, students! Remember how we learned that cells are like bricks? Well, if a cell is a single brick, a Tissue is a whole wall.

In complex living things (like humans or big trees), one cell can’t do everything. We have a system called “Division of Labor.” Just like a school has teachers, cleaners, and drivers doing different jobs, our body has groups of similar cells working together to do one specific job. This group is called a Tissue.

2. Are Plants and Animals Made of the Same Tissues? | Class 9 Chapter 6 Tissues

Think about it: Do plants run around? No, they stand still. Do animals stand in one spot forever? No, they move to find food.

• Plants: Since they don’t move, they need strong, supportive tissues to stand upright. Surprisingly, many of these tissues are actually dead because dead cells provide strength but don’t need food/maintenance!
• Animals: We move, so we need a lot of energy. Most of our tissues are living.

3. 🌱 Plant Tissues

Plant tissues are basically of two types: those that are growing (Meristematic) and those that have settled down (Permanent).

3.1 Meristematic Tissues (The Growth Engines)

Have you noticed how plants only grow from specific tips? That’s where the Meristematic tissue is. These cells are like energetic kids—they are constantly dividing to make the plant bigger.

Look at the diagram: Growth happens at the top (Apical), the sides (Lateral), and near the leaves (Intercalary).

• Apical Meristem: Sits at the tip of the stem and roots. It makes the plant taller.
• Lateral Meristem (Cambium): Sits on the sides. It makes the stem thicker (increases girth).
• Intercalary Meristem: Found near the nodes (where leaves attach). It helps branches and leaves grow.

3.2 Permanent Tissues (The Retired Cells)

When meristematic cells get old, they stop dividing and take up a permanent shape and function. We call this process Differentiation.

A. Simple Permanent Tissues (Made of one type of cell)

[Image of parenchyma collenchyma sclerenchyma diagram]

• Parenchyma (The Packer): These are simple living cells that fill up the soft parts of the plant. They mainly store food. If they have chlorophyll, we call them Chlorenchyma (for photosynthesis). If they have air gaps (like in lotus plants), we call them Aerenchyma so the plant floats.
• Collenchyma (The Bender): Have you seen how plants bend in the wind without snapping? That’s thanks to Collenchyma. It provides flexibility.
• Sclerenchyma (The Hardener): These are dead, rock-hard cells. They make the plant stiff. Think of the hard husk of a coconut—that is Sclerenchyma!

B. Complex Permanent Tissues (Made of different types of cells)

These are the transport systems of the plant. [Image of xylem and phloem structure]

• Xylem (Water Pipes): Carries water and minerals from the roots upwards. It is mostly made of dead cells (Tracheids and Vessels).
• Phloem (Food Trucks): Carries food made in the leaves to the rest of the plant. Unlike Xylem, Phloem is mostly living cells and can move materials in both directions.

4. 🐾 Animal Tissues

Animal bodies are complex. We have four main types of tissues to handle everything.

4.1 Epithelial Tissue (The Wrapper)

This is the covering tissue. It protects us. Your skin is epithelium. The lining of your mouth is epithelium. It covers the body and organs to keep them separate and safe.

4.2 Connective Tissue (The Glue)

As the name suggests, it connects things together. The cells here usually float in a jelly or fluid called a matrix.

• Blood: A fluid tissue! It transports oxygen and food.
• Bone: Hard and strong frame for the body.
• Ligament & Tendon: Ligament connects Bone-to-Bone (very elastic). Tendon connects Muscle-to-Bone (strong).
• Cartilage: Soft bone-like stuff. Touch your ear or nose tip—that flexible stuff is cartilage.
• Adipose: Fat tissue. It keeps us warm (insulation).

4.3 Muscular Tissue (The Movers)

These tissues consist of long cells that can contract (shorten) and relax (lengthen) to cause movement.

Notice the difference: Skeletal muscles have stripes, Smooth muscles are pointy, and Cardiac muscles are branched.

• Striated (Skeletal): These attach to bones. You control them (Voluntary). They have light and dark bands (stripes).
• Smooth: These are in your stomach and intestines. You can’t control them (Involuntary). They move food along.
• Cardiac: Found ONLY in the heart. They work non-stop to pump blood and never get tired.

4.4 Nervous Tissue (The Messengers)

This tissue makes up your Brain, Spinal Cord, and Nerves. The cells are called Neurons. They are like long wires that carry electrical signals instantly across the body. [Image of neuron structure labelled]

5. Let’s Practice! (Questions & Answers)

Part A: Multiple-Choice Questions (MCQs)

1. Which plant tissue is responsible for the increase in the girth (diameter) of a tree trunk?
   a) Apical meristem
   b) Intercalary meristem
   c) Lateral meristem
   d) Chlorenchyma
   Answer: c) Lateral meristem (Lateral means ‘side’, it helps the plant grow wider).
2. The flexibility in plants, which allows them to bend without breaking, is due to which tissue?
   a) Parenchyma
   b) Sclerenchyma
   c) Collenchyma
   d) Xylem
   Answer: c) Collenchyma (It provides mechanical support with flexibility).
3. Which type of animal tissue forms the inner lining of the mouth and skin?
   a) Connective tissue
   b) Muscular tissue
   c) Nervous tissue
   d) Epithelial tissue
   Answer: d) Epithelial tissue (It acts as the protective covering).
4. A tissue that connects muscle to bone in the human body is called:
   a) Ligament
   b) Tendon
   c) Cartilage
   d) Areolar tissue
   Answer: b) Tendon (Remember: Tendons tie muscle to bone).
5. Which type of muscle tissue is found only in the heart and is involuntary?
   a) Striated muscle
   b) Smooth muscle
   c) Cardiac muscle
   d) Skeletal muscle
   Answer: c) Cardiac muscle (Cardiac refers to the heart).

Part B: Short Answer Questions

6. What is differentiation in the context of plant tissues? Answer: Differentiation is the process where young, dividing meristematic cells stop dividing and take up a permanent shape, size, and function to become permanent tissues.
7. List the four components that make up xylem tissue. Answer: The four elements of xylem are:
   1. Tracheids
   2. Vessels
   3. Xylem Parenchyma
   4. Xylem Fibers
8. Why do meristematic cells lack vacuoles? Answer: Meristematic cells are very active and constantly dividing. Vacuoles are used for storage or rigidity, which these young cells don’t need yet. They need to be full of dense cytoplasm to divide quickly.
9. What is the main difference between bone and cartilage in terms of their matrix and flexibility? Answer:
   Bone: Has a hard matrix made of calcium and phosphorus. It is non-flexible.
   Cartilage: Has a solid but soft matrix made of proteins and sugars. It is flexible.
10. Name the tissue responsible for storing fat in our body and state one of its functions besides storage. Answer: The tissue is Adipose tissue. Besides storing fat, it acts as an insulator (keeping the body warm).

Part C: Long Answer Questions

11. Draw a labelled diagram of a neuron and describe the function of its main parts. Answer: (Draw a star-shaped head with a long tail)
    1. Dendrites: Short branches that pick up signals from other nerve cells.
    2. Cell Body (Cyton): The main part containing the nucleus and cytoplasm.
    3. Axon: The long tail that carries the electrical signal away from the cell body to the next neuron.
12. Differentiate between parenchyma, collenchyma, and sclerenchyma tissues. Answer:
    1. Parenchyma: Living cells with thin walls. Function: Stores food and fills space.
    2. Collenchyma: Living cells with thickened corners. Function: Provides flexibility and support.
    3. Sclerenchyma: Dead cells with very thick walls (lignin). Function: Provides hardness and strength.
13. Compare and contrast the three types of muscular tissues. Answer:
    1. Striated/Skeletal: Cylindrical shape, has stripes (striations), many nuclei. Voluntary (we control them). Found attached to bones.
    2. Smooth: Spindle-shaped (pointed ends), no stripes, single nucleus. Involuntary. Found in stomach/intestines.
    3. Cardiac: Cylindrical and branched, faint stripes, single nucleus. Involuntary. Found only in the heart.
14. What is complex permanent tissue in plants? Describe the structure and primary functions of the two types. Answer: Complex permanent tissues are made of more than one type of cell working together as a unit.
    1. Xylem: Mostly dead cells. It transports water and minerals vertically from roots to leaves.
    2. Phloem: Mostly living cells. It transports food prepared in leaves to all other parts of the plant in both directions.
15. You accidentally touch a hot object and immediately pull your hand away. Explain how nervous tissue and muscular tissue work together to make this rapid response possible. Answer:
    1. The Nervous tissue (in your skin) detects the heat.
    2. A signal is sent rapidly through neurons to the spinal cord/brain.
    3. The brain sends a command back via motor nerves to the muscles in your arm.
    4. The Muscular tissue receives the signal and contracts (shortens), pulling your hand away from the heat.

Read Also: Class 9 Chapter 5- The Fundamental Unit of Life

For more check official website of NCERT