Unit Test (Solutions): Tissues

Time: 1 hour 
M.M. 30 
Attempt all questions. 
Question numbers 1 to 5 carry 1 mark each. 
Question numbers 6 to 8 carry 2 marks each. 
Question numbers 9 to 11 carry 3 marks each. 
Question numbers 12 & 13 carry 5 marks each

Q1. What is a tissue? (1 Mark)

Ans: A tissue is a group of similar cells that work together to perform a specific function.

Q2. Where is the apical meristem found? (1 Mark)

Ans: Apical meristem is found at the tips of roots and shoots in plants.

Q3. Which tissue forms the husk of a coconut? (1 Mark)

Ans: Sclerenchyma tissue forms the husk of a coconut.

Q4. Name the tissue responsible for movement in our body. (1 Mark)

Ans: Muscular tissue.

Q5. Which tissue forms the inner lining of our mouth? (1 Mark)

Ans: Squamous epithelial tissue forms the inner lining of our mouth.

Q6. Why do meristematic cells lack vacuoles? (2 Marks)

Ans: Meristematic cells are actively dividing, requiring dense cytoplasm and prominent nuclei for rapid growth. Vacuoles, used for storage or structure in mature cells, are absent to maximize space for division.

Q7. State two differences between simple and complex permanent tissues in plants. (2 Marks)

Ans:

• Simple tissues are made of only one type of cell, while complex tissues have more than one type.

• Simple tissues perform basic functions like storage and support; complex tissues conduct water and food (e.g., xylem and phloem).

Q8. Why does the epidermis of desert plants have a thick waxy coating? (2 Marks)

Ans: In desert plants, the epidermis has a thick waxy layer of cutin to reduce water loss by transpiration and help retain moisture in dry conditions.

Q9. Describe the structure and function of collenchyma tissue. (3 Marks)

Ans:

Structure: Collenchyma consists of living, elongated cells with unevenly thickened cell walls at the corners.
Function: It provides flexibility and mechanical support to plant parts, allowing bending without breaking.

Q10. Differentiate between parenchyma, collenchyma, and sclerenchyma based on their cell wall. (3 Marks)

Ans:
Parenchyma cells have thin and flexible cell walls made of cellulose. These are living cells with large intercellular spaces.
Collenchyma cells have unevenly thickened cell walls, especially at the corners, made of cellulose and pectin. These are also living cells that provide flexibility and support.
Sclerenchyma cells have uniformly thick and lignified (hard) cell walls. These cells are dead at maturity and provide mechanical strength to the plant.

Q11. Explain the role of xylem and its components. (3 Marks)

Ans:

Role of Xylem:
Xylem is a complex permanent tissue in plants that conducts water and minerals from roots to other parts and provides mechanical support.

Components of Xylem:

1. Tracheids: Long, dead cells with thick walls that conduct water.

2. Vessels: Tubular structures that form continuous pipelines for water transport.

3. Xylem Parenchyma: Living cells that store food and help in sideways conduction.

4. Xylem Fibres: Dead cells that provide mechanical strength to the plant.

Q12. Explain the structure and function of different types of epithelial tissues in animals. (5 Marks)

Ans: Epithelial tissues cover the body and internal organs, protecting them and allowing exchange. Types:

• Simple squamous: Flat cells; allow diffusion (e.g., alveoli).

• Cuboidal: Cube-shaped; for secretion and absorption (e.g., kidney tubules).

• Columnar: Tall cells; absorb and secrete (e.g., intestine).

• Ciliated columnar: Have cilia; move substances (e.g., respiratory tract).

• Glandular: Specialized for secretion (e.g., glands).

All epithelial tissues rest on a basement membrane and have closely packed cells with minimal spaces.

Q13. Differentiate between striated, smooth, and cardiac muscles based on structure, location, and control. (5 Marks)

Ans:

1. Striated (Skeletal) Muscle:
   • Structure: Long, cylindrical, unbranched, multinucleate, with light and dark bands (striations).
   • Location: Attached to bones in limbs.
   • Control: Voluntary, controlled by conscious will.
2. Smooth (Unstriated) Muscle:
   • Structure: Long, spindle-shaped, uninucleate, no striations.
   • Location: In walls of internal organs like the alimentary canal, blood vessels, and bronchi.
   • Control: Involuntary, not under conscious control.
3. Cardiac Muscle:
   • Structure: Cylindrical, branched, uninucleate, with faint striations.
   • Location: In the heart.
   • Control: Involuntary, contracts rhythmically throughout life.