Biology · The Living World · NEET
Cellular organisation means every living organism is built from one or more cells. The cell is the basic unit of structure and function. A bacterium is one cell (unicellular); a human is trillions of cells (multicellular). Non-living things like rocks or water have no cells. So cellular organisation is a common feature of ALL living things, but NCERT does not call it the single 'defining' property, because we describe life by many features together.
They overlap but are not identical words. Self-replication means an organism can make copies of itself. Reproduction is the biological process of producing new individuals of the same kind. In unicellular organisms (like Amoeba, bacteria), one cell just divides into two — this single division IS both growth AND reproduction (they are synonymous). This exact point was tested in NEET 2016. In many-celled organisms, growth (more cells in the body) and reproduction (new offspring) are separate events.
Self-consciousness here means awareness — the ability to sense and respond to what is happening around and inside the body. NCERT states that living organisms are 'self-conscious'. All living things react to stimuli (light, heat, sound, chemicals, touch). NCERT calls this awareness of surroundings the property that could be seen as truly special to living things, but it still teaches metabolism as the technical defining property, because consciousness is hard to measure in simple organisms.
NCERT says metabolism is the only defining property. All living things carry out metabolism — the sum of all chemical reactions (building up and breaking down molecules) inside the body. Features like growth, reproduction and cellular organisation exist in living things but each has an exception (for example, mules do not reproduce, non-living crystals grow). Metabolism has NO exception in living things and never happens in truly non-living things, so it is the defining property. Consciousness is described as the 'defining property' in a philosophical sense, but for NEET, metabolism is the safe technical answer.
This is a classic confusion. Viruses can self-replicate (copy their genetic material), but ONLY inside a living host cell. On their own, outside a cell, they show no metabolism and cannot copy themselves. Because they lack cellular organisation and independent metabolism, viruses sit on the border between living and non-living. So self-replication alone does not make something fully 'living' — this is why it is not the single defining property.
Study the four statements (A–D) and select the two correct ones: A. Definition of biological species was given by Ernst Mayr. B. Photoperiod does not affect reproduction in plants. C. Binomial nomenclature system was given by R.H. Whittaker. D. In unicellular organisms, reproduction is synonymous with growth.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
No. Cellular organisation is a common feature of all living things, but NCERT names metabolism as the only defining property. Cellular organisation is a key structural feature, not the single defining test.
Not by itself. Viruses self-replicate only inside host cells and show no metabolism outside, so self-replication alone does not make a thing fully living. Metabolism plus cellular organisation are needed.
Yes. In organisms like bacteria and Amoeba, one cell divides into two. That single division is both growth and reproduction, so the two are synonymous. This was tested in NEET 2016.
Consciousness (awareness of surroundings) is described by NCERT as the property truly special to living beings in a broad sense, but it is hard to measure. Metabolism is the technical, exception-free defining property used for NEET answers.
NEET loves 'which is the defining property' and 'which statement is correct' traps in The Living World. Knowing that metabolism (not reproduction, growth, or cellular organisation) is the ONLY defining property, and that unicellular growth = reproduction, directly wins marks.
