Living and Non-living

Overview

Living and Non-living is a foundational topic in science that forms the basis for understanding biology and ecology. For CG TET Paper II, this topic tests your ability to distinguish between living organisms and non-living matter, identify the essential characteristics of life, and understand how scientists classify the diversity of living things.

This topic connects directly to other Paper II science areas—human body systems, plant life, and ecosystems all build upon the fundamental understanding of what makes something "alive." Questions typically focus on the seven characteristics of living things, the five-kingdom classification system, and the hierarchical levels of biological classification. Mastering this topic gives you a framework for approaching nearly all biology-related questions in the exam.

Students must be able to recall the defining features of life, differentiate between living and non-living with borderline cases (like viruses), and explain the logic behind biological classification from kingdom to species.

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Key Concepts

• **Living things** are entities that exhibit all life processes—nutrition, respiration, growth, excretion, reproduction, response to stimuli, and movement. Non-living things lack these processes or show only some passively.

• **The seven characteristics of life** (MRS GREN or similar mnemonics) provide a checklist: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition. An organism must display all seven to be considered truly living.

• **Growth in living things** is intrinsic (from inside, by cell division) and irreversible, while non-living things may increase in size externally (like a crystal or snowball) but not through internal biological processes.

• **Viruses are borderline cases**—they show characteristics of life only inside a host cell. Outside, they behave like non-living particles. They are often called "connecting link" between living and non-living.

• **Classification** is the systematic arrangement of organisms into groups based on similarities and differences. It helps in easy identification, study, and understanding evolutionary relationships.

• **Taxonomy** is the science of classification. Carolus Linnaeus is the "Father of Taxonomy" and introduced binomial nomenclature—two-part scientific names (Genus + species).

• **Five-Kingdom Classification** (by R.H. Whittaker, 1969) divides all organisms into Monera, Protista, Fungi, Plantae, and Animalia based on cell structure, mode of nutrition, and body organisation.

• **Hierarchy of classification** from broadest to most specific: Kingdom → Phylum (Division for plants) → Class → Order → Family → Genus → Species.

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Formulas / Key Facts

| Characteristic | Living Things | Non-living Things | |----------------|---------------|-------------------| | Nutrition | Obtain and use food | Do not need food | | Respiration | Exchange gases for energy | No respiration | | Growth | Internal, by cell division | External or no growth | | Excretion | Remove metabolic waste | No waste production | | Reproduction | Produce offspring | Cannot reproduce | | Sensitivity | Respond to stimuli | No response | | Movement | Self-generated movement | Move only by external force |

**Five Kingdoms at a glance:**

| Kingdom | Cell Type | Cell Wall | Nutrition | Examples | |---------|-----------|-----------|-----------|----------| | Monera | Prokaryotic | Present (non-cellulose) | Autotrophic/Heterotrophic | Bacteria, Blue-green algae | | Protista | Eukaryotic | Present/Absent | Autotrophic/Heterotrophic | Amoeba, Paramecium, Euglena | | Fungi | Eukaryotic | Present (chitin) | Heterotrophic (saprophytic) | Mushroom, Yeast, Mould | | Plantae | Eukaryotic | Present (cellulose) | Autotrophic | Mango tree, Fern, Moss | | Animalia | Eukaryotic | Absent | Heterotrophic | Human, Fish, Insects |

**Binomial Nomenclature Rules:**

• Written in Latin or Latinised form
• Genus name starts with capital letter; species name in lowercase
• Printed in italics; handwritten with underline
• Example: *Homo sapiens* (humans), *Mangifera indica* (mango)

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Worked Examples

**Example 1:** A student argues that a car is living because it moves and needs fuel. Is this correct?

**Solution:**

• Movement: Car moves, but only by external force (engine powered by human control)
• Nutrition: Fuel is not nutrition—no metabolic conversion inside
• Respiration: No gas exchange for energy release in cells
• Growth: Car does not grow internally
• Reproduction: Car cannot produce another car
• Sensitivity: No biological response to stimuli
• Excretion: No removal of metabolic waste

**Conclusion:** A car shows only superficial similarities. It lacks all seven life characteristics, so it is non-living.

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**Example 2:** Classify the following into the correct kingdom: (a) Mushroom (b) Amoeba (c) Cyanobacteria (d) Rose plant

**Solution:**

• (a) Mushroom → **Fungi** (eukaryotic, chitin cell wall, saprophytic nutrition)
• (b) Amoeba → **Protista** (eukaryotic, unicellular, heterotrophic)
• (c) Cyanobacteria → **Monera** (prokaryotic, also called blue-green algae)
• (d) Rose plant → **Plantae** (eukaryotic, cellulose cell wall, autotrophic)

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**Example 3:** Write the scientific name of humans following binomial nomenclature rules.

**Solution:**

• Genus: Homo (capital H)
• Species: sapiens (lowercase s)
• Written as: *Homo sapiens* (italicised or underlined)

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Common Mistakes

• **Confusing growth with increase in size** → Students mark crystals or mountains as living because they "grow." Correct understanding: Living growth is internal, through cell division; non-living increase is external accumulation.

• **Treating viruses as fully living** → Viruses reproduce only inside host cells and lack cellular structure. They are not placed in any kingdom and are considered at the boundary of living and non-living.

• **Mixing up Monera and Protista** → Both can be unicellular, but Monera are prokaryotic (no true nucleus), while Protista are eukaryotic (true nucleus present).

• **Writing scientific names incorrectly** → Common errors include capitalising species name or not italicising. Remember: *Genus species* format with only genus capitalised.

• **Forgetting that Fungi are not plants** → Fungi lack chlorophyll and are heterotrophic. They belong to a separate kingdom despite having cell walls.

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Quick Reference

• **MRS GREN** = Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition — the seven life processes.

• **Viruses** = Non-cellular, reproduce only in host, neither fully living nor non-living.

• **Linnaeus** = Father of Taxonomy; introduced binomial nomenclature.

• **Five Kingdoms** = Monera, Protista, Fungi, Plantae, Animalia (Whittaker, 1969).

• **Classification hierarchy** = King Philip Came Over For Good Soup (Kingdom, Phylum, Class, Order, Family, Genus, Species).

• **Prokaryotic** = No true nucleus (Monera); **Eukaryotic** = True nucleus (all other kingdoms).