Organization of Life

Class: JSS2

Subject: Basic Biology

 

Objective:

By the end of the lesson, student should be able to;

1.      Know and memorize the levels of organization of life.

2.      Understand the complexity of organization in higher organisms.

3.      Know the advantages and disadvantages of complexity in higher organisms.

 

Day One:

 

Introduction

All living things are highly organized and this organization occurs in levels. The simplest structures are found at the lowest levels and they interact to build up more complex structures at the next level.

 

Day Two:

Levels of Organization of Life

There are four levels of organization of life in organism. These are;

1.      Cells (first level): Cell can be defined as the smallest unit of living organism. It is the first level of organization of life. All plants and animals are made up of cells.

2.      Tissues (second level): A tissue is a group of similar cells forming a layer in an organism which performs a particular function. E.g. Xylem, Epidermal, Bone, Muscle, etc.

3.      Organ (third level): It is a group of similar tissue forming a layer in an organism which performs specific functions. Organs in animals are; skin, brain, eyes, ears, stomach, heart, liver, etc.

4.      System (fourth level): It is a group of similar organs which work together to perform specific functions e.g. skeletal, reproductive and digestive system.

Organization of Life (Credit:pinterest.com)

 

Day Three:

Complexity of organization in higher organisms

This involves an increase in complexity from unicellular to multicellular organisms. Even though unicellular organisms can perform all life processes, they still lack vital tissues, organs or systems that is efficient and capable of ensuring their survival. As a result of this, higher organisms have advantages and some disadvantages in complexity over the unicellular organisms.

 

 

Day Four:

Advantages of complexity in higher organisms

 

1.      It leads to cellular differentiation: As a result of complexity, group of similar cells are differentiated to form tissues that carry out similar functions.

2.      It leads to internal structural specialization: Differentiation leads to internal structural specialization in which the group of similar cells or tissues become specialized to carry out one or more functions.

3.      Complexity leads to efficiency: Complexity makes higher organism to be efficient in carrying out life processes.

4.      Complexity leads to increase in size: Complexity leads to increase in size of organisms because there are spaces between cells for growth.

 

Disadvantages of complexity in higher organisms

1.      Inability of individual cells to exist on their own: In complexity, cells lose their independence and become increasingly dependent on one another activities.

2.      Difficulties in acquisition of oxygen and food materials: Increased size creates difficulties in acquisition of respiratory gas (oxygen), food materials and loss off waste products.

3.      It leads to slower rate of diffusion: Complexity leads to slower rate of diffusion of oxygen or respiratory gas to individual cells.

4.      Slower rate of expulsion of waste products: Complexity leads to slower rate of expulsion of waste products from cells.

5.      Difficulty in reproduction: Complexity also leads too difficulties in reproduction in higher organisms.

 

   Day Five:

 

 

Tests and Exercises

1.      Amoeba belongs to which organism? (a) Unicellular (b) Multicellular (c) Bicellular (d) Tri cellular.

2.      The levels of organization of life are (a) Cell, Nymph, System and Organs (b) Cell, Tissue, Organ and System (c) Cell, Tissue, Egg and System.

3.      An example of system is (a) Kidney (b) Digestive (c) Skin.

4.      ________ is a group of similar organs which work together to perform specific functions (a) System (b) Organic (c) Cell (d) None of the above.