UP Board (Eng. med.) Class 9 : Science : Chapter - TISSUES study notes

Class 9 Science : Chapter - Tissues

Introduction to Tissue

Definition: A tissue is a group of cells that work together to perform a specific function. In multicellular organisms, cells are organized into tissues, which further combine to form organs.

- Tissues are categorized into plant tissues and animal tissues.

Plant Tissues

Plant tissues are mainly categorized into Meristematic and Permanent tissues.

1. Meristematic Tissue :

Location: Found in the growing regions of the plant like tips of roots and shoots.

Characteristics :

•   Cells are small, cube-shaped, and have thin cell walls.
•   They divide actively to produce new cells.

Types :

•   Apical meristem : Located at the tips of roots and shoots, responsible for the lengthwise growth.
•   Lateral meristem : Found in the stems and roots, responsible for increasing the thickness of the plant.
•   Intercalary meristem : Located at the base of leaves or internodes, helps in regrowth.

2. Permanent Tissue :

Once cells of the meristematic tissue stop dividing, they differentiate and form permanent tissues.

Simple Permanent Tissue :

  1.  Parenchyma : Basic tissue, thin-walled, and involved in storage, photosynthesis, and buoyancy.

  2. Collenchyma : Provides mechanical support and flexibility. Cells have thickened corners.

  3. Sclerenchyma : Thick-walled, dead cells that provide structural support.

Complex Permanent Tissue :

  1. Xylem : Transports water and minerals.

                 Components: Tracheids, vessels, xylem parenchyma, and xylem fibers.

  2. Phloem : Transports food from leaves to other parts.

                  Components: Sieve tubes, companion cells, phloem parenchyma, and phloem fibers.

Animal Tissues

Animal tissues are categorized into - Epithelial, Connective, Muscular, and Nervous tissues .

1. Epithelial Tissue :

Functions : Protects body surfaces, secretes substances, and absorbs nutrients.

Types :

•   Squamous epithelium : Thin, flat cells found in the lining of the mouth.
•   Cuboidal epithelium : Cube-shaped cells, present in kidney tubules.
•   Columnar epithelium : Tall cells that help in absorption, found in the intestine.
•   Ciliated epithelium : Has cilia to move substances, found in respiratory tract.

2. Connective Tissue :

Functions : Supports, binds, and protects other tissues and organs.

Types :

•  Blood : A fluid connective tissue that circulates through the body.
•   Bone : A rigid tissue providing structure.
•   Adipose : Stores fat.
•   Cartilage : Flexible and smooth, found in joints.
•   Ligaments : Connect bones to bones.
•   Tendons : Connect muscles to bones.

3. Muscular Tissue :

Functions : Helps in movement.

Types :

•   Striated muscle : Voluntary muscles attached to the skeleton.
•   Smooth muscle : Involuntary muscles found in the digestive system.
•   Cardiac muscle : Found only in the heart, involuntary control.

4. Nervous Tissue :

Function : Transmits impulses across the body.

Components : Neurons (nerve cells) and supporting cells.

Exercise 

A. Multiple Choice Questions (MCQ):

1. Which of the following is not a function of Parenchyma?

   • a) Photosynthesis
   • b) Storage
   • c) Conduction of water
   • d) Transport of food
   • Answer: c) Conduction of water

2. Which tissue is responsible for the growth in the length of plants?

   • a) Xylem
   • b) Apical Meristem
   • c) Phloem
   • d) Lateral Meristem
   • Answer: b) Apical Meristem

3. Which of the following is a characteristic of cardiac muscles?

   • a) Voluntary control
   • b) Multinucleated
   • c) Found in the walls of blood vessels
   • d) Involuntary and branched
   • Answer: d) Involuntary and branched

4. Which connective tissue connects muscles to bones?

   • a) Ligaments
   • b) Tendons
   • c) Cartilage
   • d) Adipose
   • Answer: b) Tendons

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B. Fill in the Blanks (FIB):

1. The primary function of Xylem is to transport water and minerals.
2. Smooth muscles are found in the walls of hollow organs like the intestines.
3. Phloem tissue is responsible for the transportation of food in plants.
4. Cells of meristematic tissue actively divide to produce new cells.

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C. True or False:

1. All cells in a tissue perform the same function.
   False - Cells in a tissue work together, but may perform slightly different roles based on their location and structure.

2. Sclerenchyma provides mechanical support to plants.
   True - Sclerenchyma cells have thick walls, which provide rigidity and strength.

3. Cardiac muscles are voluntary muscles.
   False - Cardiac muscles are involuntary and function without conscious control.

4. Ligaments connect bone to bone.
   True - Ligaments are connective tissues that join bones.

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D. One Word Answers:

1. Which tissue transports water in plants?
   Xylem

2. Which tissue is responsible for food transport in plants?
   Phloem

3. What is the name of the basic packing tissue in plants?
   Parenchyma

4. Which tissue protects the body surfaces in animals?
   Epithelial tissues

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E. Very Short Questions and Answers :

1. What is a tissue?

 Ans -  A group of cells having a common origin and performing a similar function is called a tissue.

2. What is the function of meristematic tissue in plants?

 Ans - Meristematic tissue is responsible for the growth of plants in length and girth.

3. What are the characteristics of Parenchyma?

 Ans - Parenchyma cells are thin-walled, living cells that store food and sometimes perform photosynthesis.

4. Differentiate between Xylem and Phloem.

 Ans - Xylem transports water and minerals from roots to the rest of the plant, while Phloem transports food from leaves to other parts of the plant.

5. List any two types of animal connective tissue.

 Ans - Blood and Bone are examples of connective tissue.

6. Where is cardiac muscle found and what is its function?

 Ans - Cardiac muscle is found in the heart and it pumps blood throughout the body.

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F. Short Answer Questions:

1. What are the functions of Parenchyma?
   Answer: Parenchyma cells are responsible for storage of food, photosynthesis in some cases, and providing buoyancy to aquatic plants.

2. What are the types of meristematic tissue?
   Answer: The three types of meristematic tissue are Apical Meristem (growth in length), Lateral Meristem (growth in thickness), and Intercalary Meristem (growth at the base of leaves or internodes).

3. What is the role of xylem in plants?
   Answer: Xylem is responsible for transporting water and minerals from roots to all parts of the plant.

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G. Long Answer Questions:

1. Describe the structure and function of epithelial tissue in animals. Answer: Epithelial tissue consists of tightly packed cells that form a continuous layer. It covers the external surfaces of the body, lines the cavities, and forms glands. The primary functions include protection (skin), absorption (intestine), secretion (glands), and sensation. The types include squamous, cuboidal, columnar, and ciliated epithelium, each specialized for specific functions.

2. Differentiate between meristematic and permanent tissues in plants. Answer:

   • Meristematic Tissue: These are actively dividing tissues found in growing regions like the tips of roots and shoots. Cells are small, with thin walls and large nuclei.
   • Permanent Tissue: These are derived from meristematic tissue once they lose their ability to divide. They are specialized for specific functions, like support, transport, and storage. Permanent tissues can be further classified into simple (parenchyma, collenchyma, sclerenchyma) and complex (xylem, phloem).

NOTE : For more detailed questions and diagrams, you can refer to your textbook or book.