Living World What is living Quiz 6 NEET Questions

This page features NEET Questions from the topic Living World What is living Quiz 6/9 from the lesson The living world.



1. Consciousness and Environmental Responsiveness: A Defining Property of Life

One of the most striking and biologically intricate characteristics of living organisms is their ability to sense their surroundings and respond appropriately. This capability—called irritability or responsiveness—is universal across life forms, from the simplest prokaryotes to the most complex multicellular eukaryotes. Environmental stimuli may be physical (light, temperature, gravity), chemical (nutrients, toxins, pheromones) or biological (other organisms, predators, competitors). The capacity to detect and react to such stimuli ensures survival, adaptation and evolutionary success.

In humans and other higher animals, sensing the environment occurs through specialised sense organs linked to the nervous system. These organs detect changes with exceptional precision: eyes detect light, ears sense sound and pressure, skin detects touch and temperature, and the olfactory system responds to chemical cues. Signals are processed by the brain, which coordinates appropriate responses. This highly organised system allows humans to interact effectively with their surroundings.

Plants, although lacking a nervous system, are equally capable of responding to environmental factors. They react to light through phototropism, gravity through gravitropism, water through hydrotropism and touch through thigmotropism. Plants also respond to temperature changes, pollutants and interactions with other organisms, including herbivores and pathogens. These responses occur through hormonal regulation, electrical signalling, gene expression changes and movement of ions across membranes.

Thus, the ability to sense, respond and, in the case of humans, possess self-consciousness stands as one of the deepest and most essential characteristics of life.

2. Important Points

All living organisms sense and respond to environmental stimuli.
Stimuli may be physical, chemical or biological.
Humans use specialised sense organs; plants use tropic responses and hormones.
Even prokaryotes show responsiveness, e.g., bacterial chemotaxis.
Photoperiod influences reproduction in plants and seasonal animals.
All organisms exhibit environmental awareness.
Human beings uniquely possess self-consciousness.
Consciousness is considered a defining property of living organisms.

3. Sample Questions

All living organisms can sense and respond to physical, chemical or biological stimuli.
Plants show environmental responsiveness through tropisms and hormonal changes.
Photoperiodism influences reproduction in seasonal breeders.

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

Modern studies in neurobiology, plant signalling and microbial behaviour provide strong evidence that responsiveness is a fundamental feature of life. Research published in journals such as Nature Neuroscience, Cell Reports and Plant Physiology shows how electrical signals, hormones and receptor-mediated pathways allow organisms to detect and react to stimuli. Bacterial chemotaxis pathways involving proteins like CheA and CheY have been mapped in detail using molecular genetics.

Plant responses to light involve photoreceptors such as phytochromes and cryptochromes, which regulate growth, flowering and circadian rhythms. Studies in behavioural ecology highlight how animals respond to environmental cues for survival, migration and reproduction.

5. Competitive exams often test:

concepts of consciousness and responsiveness
differences in environmental sensing across plants, animals and microbes
examples of stimuli and responses
photoperiodism and its effects
why consciousness is a defining property of life

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This page features NEET Questions from the topic Living World Diversity in the Living World Quiz 3 from the lesson The living world.
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