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SS1: BIOLOGY - 1ST TERM

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  1. Introduction to Biology | Week 1
    6 Topics
    |
    1 Quiz
  2. Recognizing Living Things | Week 2
    3 Topics
    |
    1 Quiz
  3. Organisation of Life | Week 3
    3 Topics
  4. Classification of Living Organisms | Week 4
    7 Topics
    |
    1 Quiz
  5. Kingdom Prokaryotae / Monera & Kingdom Protista | Week 5
    3 Topics
    |
    3 Quizzes
  6. Kingdom Fungi & Kingdom Plantae | Week 6
    9 Topics
    |
    2 Quizzes
  7. Kingdom Animalia I | Week 7
    6 Topics
    |
    1 Quiz
  8. Kingdom Animalia II | Week 8
    5 Topics
    |
    1 Quiz
  9. The Cell | Week 9
    3 Topics
    |
    1 Quiz
  10. The Cell Structure and Functions | Week 10
    4 Topics
    |
    1 Quiz
  11. The Cell and its Environment | Week 11
    4 Topics
    |
    1 Quiz
  12. Nutrition in Plants | Week 12
    4 Topics
    |
    1 Quiz



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Lesson 9, Topic 2
In Progress

Forms in Which Living Cells Exist

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Amoeba

Cells of living organisms exist in different forms and they are;

  • Unicellular/single and free living
  • As a colony
  • As a filament
  • As part of a living organism

1. Cells as Unicellular and Independent Organisms:

Unicellular organisms are organisms that have a single cell. These organisms are capable of living independently without depending on other cells e.g. Amoeba, Paramecium, and Euglena.

structure of amoeba
Structure of amoeba.
structure of paramecium
Structure of paramecium.

Each organism can carry out all life processes such as movement, growth, nutrition, reproduction, excretion, respiration, etc.

feeding in amoeba
Feeding in amoeba.
movement in paramecium
Movement in paramecium.

2. Cells as a Colony (e.g Volvox, Pandorina):

Volvox
Volvox.
Volvox
Volvox.

These cells which are massed together cannot be differentiated from each other. They are connected to one another by strands of cytoplasm, forming a hollow ball. In Volvox, each cell has two flagella that help the organism propel itself forward.

3. Cells as Filaments:

Strcture_of_Spirogyra
Structure of Spirogyra

These cells are joined end to end to form unbranched filaments. Each cell of the filament functions as an independent cell, though, these organisms are multicellular organisms. e.g Spirogyra, Oedogonium, Zygnema, Oscilateria etc.

4. Cells as a Part of a Multicellular Organism:

Human cells e1658683634943
Cells in the human body.

These cells are interdependent, communicate with each other and work together to maintain homeostasis. e.g. red blood cells, Epidermal cells, nerve cells, and sex cells.

Different types of cells have different roles. Some are specialized for moving, some for reproduction, some for the production of the necessary substances that the organism needs, etc. Regardless of the role, each cell participates in maintaining homeostasis.

Homeostasis is an organism’s process of maintaining a stable internal environment suitable for sustaining life.

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