SS1: BIOLOGY - 1ST TERM
Introduction to Biology | Week 16 Topics|1 Quiz
Recognizing Living Things | Week 23 Topics|1 Quiz
Organisation of Life | Week 33 Topics
Classification of Living Organisms | Week 47 Topics|1 Quiz
Kingdom Prokaryotae / Monera & Kingdom Protista | Week 53 Topics|3 Quizzes
Kingdom Fungi & Kingdom Plantae | Week 69 Topics|2 Quizzes
Kingdom Animalia I | Week 76 Topics|1 Quiz
Kingdom Animalia II | Week 85 Topics|1 Quiz
The Cell | Week 93 Topics|1 Quiz
The Cell Structure and Functions | Week 104 Topics|1 Quiz
The Cell and its Environment | Week 114 Topics|1 Quiz
Nutrition in Plants | Week 124 Topics|1 Quiz
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Forms in Which Living Cells Exist
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.
Each organism can carry out all life processes such as movement, growth, nutrition, reproduction, excretion, respiration, etc.
2. Cells as a Colony (e.g Volvox, Pandorina):
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:
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:
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.