Question 2
Explain the structure and functions of various types of epithelial tissue.
On the basis of shape of the cells, epithelial tissues are classified into three types :
- Squamous epithelium — The cells of squamous epithelium are flat, hexagonal or irregular in shape. These cells line the inner walls of the blood vessels, lungs, heart and oesophagus. They also form the epidermis of the skin, where they provide protection and prevent the entry of germs.
Below diagram shows the structure of Squamous epithelium:
- Columnar epithelium — The length of the cells of Columnar epithelium appears much more than their width. The cells are placed side by sides like columns. The nucleus is present towards the base of the cell. They are present in the linings of the stomach, intestines and pharynx. They are specialized to absorb nutrients.
Below diagram shows the structure of Columnar epithelium:
- Cuboidal epithelium — The cells of Cuboidal epithelium have almost equal height and width. The nucleus is centrally located. They are found in thyroid gland, kidney tubules, salivary gland, pancreas and liver. They are specialized to secrete enzymes and hormones and remove waste (as in kidneys).
Below diagram shows the structure of Cuboidal epithelium:
Chapter 4: Tissue — ICSE Class VII Biology Notes
Complete ICSE Class VII Biology notes on Tissue covering meristematic and permanent plant tissues (parenchyma, collenchyma, sclerenchyma, xylem, phloem) and four animal tissue types with examples and diagrams.
Key Concepts and Topics
Topics covered: Meristematic tissue, Permanent tissue, Animal tissues, Xylem, Phloem
Weightage: Approximately 8 marks in the exam
Important Points to Remember
- Tissue: group of similar cells performing specific function
- Meristematic tissue: actively dividing cells at growth points
- Simple permanent: parenchyma (storage), collenchyma (flexibility), sclerenchyma (strength)
- Complex permanent: xylem (water up) and phloem (food both ways)
- Four animal tissues: epithelial, connective, muscular, nervous
- Three muscle types: skeletal, smooth, cardiac
- Blood is a connective tissue with liquid matrix
Frequently Asked Questions
Q: What is a tissue?
A: A tissue is a group of similar cells that perform a specific function together.
Q: What is the difference between xylem and phloem?
A: Xylem transports water upward and is made of dead cells. Phloem transports food in both directions and is made of living cells.
Q: Why is blood called a connective tissue?
A: Because it connects all body parts by transporting nutrients, oxygen, and waste, even though its matrix (plasma) is liquid.
Exam Preparation Tips
- Focus on understanding concepts rather than rote memorization
- Practice drawing and labelling diagrams regularly
- Use comparison tables for topics that require differentiation
- Solve previous year questions and practice papers
- Review the chapter notes provided by Bright Tutorials for comprehensive coverage
For complete chapter notes, practice questions, and test papers, contact Bright Tutorials at 9403781999.