Unit 2  Solution 

Introduction to the Detailed Structure of the Body Unit Solution


Q1. Define a cell. Describe the structure and functions of a cell in detail.(10 Marks)

Answer

Definition

A cell is the smallest structural and functional unit of the human body. All body tissues and organs are made up of cells.


Structure of a Cell

The cell consists of three main parts:

1. Cell Membrane

a.Thin, elastic outer covering of the cell

b.Also known as plasma membrane

Functions

a.Protects the cell

b.Maintains the shape of the cell

c.Controls entry and exit of substances (selectively permeable)


2. Cytoplasm

a.Semi-fluid substance present inside the cell membrane

b.Contains various cell organelles

Functions

a.Site of metabolic activities

b.Provides support to cell organelles


Cell Organelles and Their Functions

Mitochondria: Powerhouse of the cell; produces energy

Ribosomes: Protein synthesis

Endoplasmic reticulum: Transport of materials

Golgi apparatus: Packaging and secretion

Lysosomes: Digestion of waste materials (suicide bags)

Centrioles: Help in cell division


3. Nucleus

  • Control center of the cell

  • Contains genetic material (DNA)

Functions

  • Controls all cell activities

  • Responsible for cell division

  • Transmits hereditary characters


Functions of a Cell

  • Respiration: Produces energy required for cellular activities

  • Growth: Increases size and number of cells

  • Excretion: Removes waste products from the cell

  • Reproduction: Formation of new cells by cell division

  • Movement: Allows movement of substances within the cell and body

  • Repair: Helps in healing and replacement of damaged cells


Q2. Describe the cell, tissues, and body cavities with their functions and examples.

(10 Marks)

Introduction

The human body is composed of cells, tissues, and organs. Cells form tissues, tissues form organs, and organs are located within body cavities.


1. Cell

Definition

A cell is the smallest structural and functional unit of the human body.

Parts of a Cell

Cell membrane: Protects the cell and regulates entry and exit of substances

Cytoplasm: Contains cell organelles and performs metabolic activities

Nucleus: Controls cell activities and contains genetic material

Functions of a Cell

Respiration

Growth

Excretion

Reproduction

Movement

Repair


2. Tissues

Definition

A tissue is a group of similar cells performing a specific function.

Types of Tissues

Epithelial tissue: Protection, absorption, secretion

Connective tissue: Support and binding

Muscular tissue: Movement

Nervous tissue: Transmission of nerve impulses


3. Body Cavities

Definition

Body cavities are spaces within the body that protect and support internal organs.

Types of Body Cavities and Contents

Cranial cavity: Brain

Spinal cavity: Spinal cord

Thoracic cavity: Heart and lungs

Abdominal cavity: Stomach, liver, intestines

Pelvic cavity: Urinary bladder and reproductive organs

Conclusion

Cells, tissues, and body cavities together maintain the structure and proper functioning of the human body.


Q3. Explain in detail the structure of the cell, classification of tissues, and body cavities with their contents.(10 Marks)

1. Structure of a Cell

  • Cell membrane

  • Cytoplasm

  • Nucleus

Cell organelles such as mitochondria, ribosomes, Golgi apparatus, and lysosomes perform essential cellular functions.

2. Classification of Tissues

Epithelial Tissue

  • Covers body surfaces

  • Example: Skin

Connective Tissue

  • Provides support and protection

  • Example: Bone, blood

Muscular Tissue

  • Helps in movement

  • Types: Skeletal, smooth, cardiac

Nervous Tissue

  • Transmits nerve impulses

  • Found in brain and spinal cord

3. Body Cavities and Their Contents

Dorsal cavity: Brain and spinal cord

Thoracic cavity: Heart and lungs

Abdominal cavity: Digestive organs

Pelvic cavity: Excretory and reproductive organs

Conclusion

Knowledge of cells, tissues, and body cavities is essential to understand the structure and functioning of the human body.