Organism MCQs Quiz | Class 9
Practice this Class IX Science (Code 086) quiz from Unit II: Organization in the Living World. This test focuses on the topic ‘Organism MCQs Quiz | Class 9’, covering the definition of an organism and the idea of integration in living systems. Answer the questions below, submit your response, and download the PDF answer sheet for revision.
Overview of Organization in the Living World
In Class IX Science, Unit II, we explore how life is organized from the simplest units to complex organisms. An organism is defined as a living entity capable of independent existence. The fundamental unit of all organisms is the cell. Based on the number of cells, organisms are classified as unicellular (single-celled) or multicellular (many-celled).
Levels of Organization
Life follows a hierarchical structure where simpler components combine to form more complex systems. This integration allows for higher efficiency and division of labour.
- Cellular Level: The basic building block (e.g., Muscle cell).
- Tissue Level: Groups of similar cells performing a specific function (e.g., Muscle tissue).
- Organ Level: Different tissues working together (e.g., Heart).
- Organ System Level: Organs working together for a major physiological function (e.g., Circulatory system).
- Organism Level: All systems working in integration to sustain life (e.g., Human being).
Key Concept: Integration
Integration refers to the coordination between various parts of an organism to function as a unified whole. In multicellular organisms, different cells specialize in different functions (division of labour), but they must communicate and coordinate through systems like the nervous and endocrine systems to maintain homeostasis (internal balance).
| Feature | Unicellular Organism | Multicellular Organism |
|---|---|---|
| Cell Number | Single cell | Many cells |
| Function | One cell performs all life functions | Specialized cells perform specific functions |
| Lifespan | Generally short | Generally long |
| Examples | Amoeba, Paramecium | Plants, Animals, Humans |
Quick Revision Notes
- Definition: An organism is any contiguous living system.
- Hierarchy: Cell -> Tissue -> Organ -> Organ System -> Organism.
- Division of Labour: Allows multicellular organisms to be efficient.
- Homeostasis: The maintenance of a stable internal environment despite external changes.
Extra Practice Questions
- What is the smallest unit of life capable of replicating independently? (Answer: Cell)
- Name the process by which an organism maintains a stable internal environment. (Answer: Homeostasis)
- Are bacteria unicellular or multicellular? (Answer: Unicellular)
- Which level of organization is higher: Tissue or Organ? (Answer: Organ)
- What term describes the sum of all chemical reactions within an organism? (Answer: Metabolism)
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