This page features NEET Questions from the topic Living World What is living Quiz 2/9 from the lesson The living world.


1. Growth as a Biological Process: Its Limitations as a Defining Feature of Life

In animals, growth is typically restricted to the early stages of life. Once adulthood is reached, most animal cells lose the capacity to divide, and overall body size does not increase further. However, limited cell division continues throughout life in specific tissues to replace injured, worn-out or dead cells. This includes processes such as skin regeneration, blood cell formation in the bone marrow and repair of damaged tissues. These cellular activities maintain the organism but do not contribute to overall body growth after maturity.

Unicellular organisms, on the other hand, “grow” by cell division, since the single cell itself represents the entire organism. Their growth is directly linked to reproduction, as each division results in the formation of two new individuals. This process can be easily observed in laboratory cultures by counting cell numbers under a microscope at regular intervals. The increase in number of cells in such populations reflects both growth and reproduction simultaneously, a unique feature of unicellular life.

In most higher plants and animals, however, growth and reproduction are distinct events, occurring independently of one another. Growth does not always imply reproductive ability, and reproduction can occur without significant increases in body mass. This distinction is crucial for understanding why growth alone cannot be considered a defining property of life.

Another important point is that increase in body mass is often used as a general indicator of growth. While this works well for living organisms, the same criterion can be misleading because non-living objects also grow in mass. For example, mountains, boulders and sand dunes increase in size over time. However, this type of growth occurs through accumulation of material on the outside surface—through sedimentation, deposition or layering. This is fundamentally different from the growth seen in living organisms.

Living organisms exhibit growth from within, driven by metabolic and developmental processes such as cell division and biosynthesis. Cells enlarge, divide and differentiate to form tissues and organs. This internally organised growth requires energy, genetic regulation and coordinated physiological activity—all exclusive to living systems. In contrast, non-living growth lacks internal regulation, organisation or metabolism.

Because non-living objects can also increase in mass, growth cannot be considered a defining property of life by itself. To use growth in defining life, one must qualify it with the condition that true biological growth arises from internal physiological processes. When understood in that context, growth becomes a reliable characteristic of living organisms. Importantly, a dead organism does not grow, even though its mass may change due to decomposition. This emphasizes that growth is intricately tied to living metabolic activity.

Overall, while growth is a universal characteristic observed in all living organisms under appropriate conditions, it must be carefully defined to avoid confusion with superficial growth seen in non-living matter.

2. Important Points

Animal growth is limited to early life; later cell division mainly supports repair.
Unicellular organisms grow by cell division, linking growth with reproduction.
In higher organisms, growth and reproduction are separate processes.
Non-living objects can increase in mass, but only through external accumulation.
True biological growth occurs internally through cell division and metabolism.
Growth alone cannot define life; it must be understood in the context of living systems.
Dead organisms do not grow, indicating the dependence of growth on metabolism.

3. Sample Questions

Growth in animals continues only through repair and replacement after maturity.
Unicellular organisms show growth by dividing into more individuals.
Non-living objects grow by external accumulation, not internal processes.
True biological growth must involve internally regulated cell division.
Growth cannot be accepted as a defining feature of life without specific conditions.

These sample questions give you a taste of the clarity expected in NEET. The full quiz contains 50 true/false items covering every micro-concept from the introduction.


4. Additional Scientific & Competitive-Exam Relevant Information

Growth in living organisms is tightly regulated by genetic and hormonal mechanisms. In animals, hormones such as growth hormone (GH), thyroid hormones and insulin-like growth factors (IGFs) regulate developmental growth and tissue regeneration. In plants, growth is controlled by plant hormones like auxins, gibberellins, cytokinins and ethylene. Their coordinated action ensures continuous growth in meristematic regions while maintaining structural integrity.

Cell growth also depends on metabolic pathways, particularly ATP production and biomolecule synthesis. Modern cell biology research explains how cyclins and cyclin-dependent kinases regulate cell cycle progression, ensuring controlled cell division. This distinguishes living growth from uncontrolled or passive accumulation seen in non-living systems.


5. Competitive exams such as NEET often test:

distinctions between growth in plants vs. animals
growth in unicellular organisms
why growth is not a defining feature of life
examples of non-living growth vs. biological growth
These distinctions are essential for correctly interpreting NCERT concepts.

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This page features NEET Questions from the topic Living World What is living Quiz 2/9 from the lesson The living world.
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