Unique features of the living organisms


Last Updated : 29-03-2024 10:04:41
Share this :

All living organisms grow

  • Increase in mass and increase in number of individuals are twin characteristics of growth.
  • A multicellular organism grows by cell division. In plants, this growth by cell division occurs continuously throughout their life span. In animals, this growth is seen only up to a certain age.
  • However, cell division occurs in certain tissues to replace lost cells.
  • Unicellular organisms also grow by cell division. One can easily observe this in in vitro cultures by simply counting the number of cells under the microscope.
  • In majority of higher animals and plants, growth and reproduction are mutually exclusive events.
  • One must remember that increase in body mass is considered as growth.
  • Non-living objects also grow if we take increase in body mass as a criterion for growth. Mountains, boulders and sand mounds do grow. However, this kind of growth exhibited by non-living objects is by accumulation of material on the surface.
  • In living organisms, growth is from inside. Growth, therefore, cannot be taken as a defining property of living organisms.
  • Conditions under which it can be observed in all living organisms have to be explained and then we understand that it is a characteristic of living systems. A dead organism does not grow.

Reproduction

  • is a characteristic of living organisms. In multicellular organisms, reproduction refers to the production of progeny possessing features more or less similar to those of parents.
  • Invariably and implicitly we refer to sexual reproduction.
  • Organisms reproduce by asexual means also. Fungi multiply and spread easily due to the millions of asexual spores they produce. In lower organisms like yeast and hydra, we observe budding. In Planaria (flat worms), we observe true regeneration, i.e., a fragmented organism regenerates the lost part of its body and becomes, a new organism. The fungi, the filamentous algae, the protonema of mosses, all easily multiply by fragmentation.
  • When it comes to unicellular organisms like bacteria, unicellular algae or Amoeba, reproduction is synonymous with growth, i.e., increase in number of cells. We have already defined growth as equivalent to increase in cell number or mass. Hence, we notice that in single-celled organisms, we are not very clear about the usage of these two terms – growth and reproduction.
  • Further, there are many organisms which do not reproduce (mules, sterile worker bees, infertile human couples, etc). Hence, reproduction also cannot be an all-inclusive defining characteristic of living organisms. Of course, no non-living object is capable of reproducing or replicating by itself.

Metabolism

  • All living organisms are made of chemicals. These chemicals, small and big, belonging to various classes, sizes, functions, etc., are constantly being made and changed into some other biomolecules. These conversions are chemical reactions or metabolic reactions.
  • There are thousands of metabolic reactions occurring simultaneously inside all living organisms, be they unicellular or multicellular.
  • All plants, animals, fungi and microbes exhibit metabolism.
  • The sum total of all the chemical reactions occurring in our body is metabolism.
  • No non-living object exhibits metabolism.
  • Metabolic reactions can be demonstrated outside the body in cell-free systems. An isolated metabolic reaction(s) outside the body of an organism, performed in a test tube is neither living nor non-living. Hence, while metabolism is a defining feature of all living organisms without exception, isolated metabolic reactions in vitro are not living things but surely living reactions. Hence, cellular organisation of the body is the defining feature of life forms.

Consciousness

  • Perhaps, the most obvious and technically complicated feature of all living organisms is this ability to sense their surroundings or environment and respond to these environmental stimuli which could be physical, chemical or biological.
  • We sense our environment through our sense organs.
  • Plants respond to external factors like light, water, temperature, other organisms, pollutants, etc.
  • All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental cues.
  • Photoperiod affects reproduction in seasonal breeders, both plants and animals.
  • All organisms handle chemicals entering their bodies. All organisms therefore, are ‘aware’ of their surroundings.
  • Human being is the only organism who is aware of himself, i.e., has self-consciousness. Consciousness therefore, becomes the defining property of living organisms.
  • When it comes to human beings, it is all the more difficult to define the living state. We observe patients lying in coma in hospitals virtually supported by machines which replace heart and lungs. The patient is otherwise brain-dead. The patient has no self-consciousness. Are such patients who never come back to normal life, living or non-living?
  • All living phenomena are due to underlying interactions. Properties of tissues are not present in the constituent cells but arise as a result of interactions among the constituent cells.
  • Similarly, properties of cellular organelles are not present in the molecular constituents of the organelle but arise as a result of interactions among the molecular components comprising the organelle. These interactions result in emergent properties at a higher level of organisation. This phenomenon is true in the hierarchy of organisational complexity at all levels.
  • Therefore, we can say that living organisms are self-replicating, evolving and self-regulating interactive systems capable of responding to external stimuli.
  • Biology is the story of life on earth. Biology is the story of evolution of living organisms on earth. All living organisms – present, past and future, are linked to one another by the sharing of the common genetic material, but to varying degrees.

Leave a Reply

Your email address will not be published. Required fields are marked *

Online Test Series for Students

Each Test

Rs. 100
Solve Online Test At Moreques Authorized Exam Center

Each Test

Rs. 50
Solve Online Test on Own PC/Laptop/Mobile

UPSC Exams | Union Public Services Commission Examinations


Last Updated : 29-03-2024 10:04:41
Share this :

Civil Services Examination (IAS,IPS,IFS,IRS)

UPSC Civil Services Pre Examination 2016 Notification

last date to apply : 27 May 2016

Preliminary Exam : 07 Aug 2016

UPSC Civil Services Preliminary Exam

UPSC Civil Services Mains Exam

General Studies GS 1 Study Material

General Studies GS 2 Study Material

General Studies GS 3 Study Material

General Studies GS 4 Study Material

Optional Subject

History

UPSC Mains History Optional Paper 1 Syllabus

UPSC Mains History optional Paper 2 Syllabus

Optional Subject :

History

UPSC Previous Year Question Papers Download FREE for Prelims and Mains Exam

Indian Forest Service examination

Engineering Services Examination

Combined Defence Services Examination

National Defence Academy Examination And Naval Academy Examination

Combined Medical Services Examination

Special Class Railway Apprentice

Indian Economic Service/Indian Statistical Service Examination

Combined Geoscientist and Geologist Examination

Central Armed Police Forces(Assistant Commandant) Examination

State PSC Exams | State Public Services Commission Examinations


Last Updated : 29-03-2024 10:04:41
Share this :

  1. Andhra Pradesh Public Service Commission ( APSPSC )

    Group I

    Syllabus

    Study Notes

    Group II

    Syllabus

    Study Notes

    Group III

    Syllabus

    Study Notes

    Group IV

    Syllabus

    Study Notes

  2. Arunachal Pradesh Public Service Commission ( APPSC )

    District Statistics Officer/ Research Officer

    Steno Grade III

    Finance & Accounts Officer / Treasury Officer (FAO/TO)

  3. Assam Public Service Commission ( APSC )
  4. Bihar Public Service Commission ( BPSC )
  5. Chhattisgarh Public Service Commission ( CGPSC )
  6. Goa Public Service Commission ( GoaPSC )
  7. Gujarat Public Service Commission ( GPSC )
  8. Haryana Public Service Commission ( HPSC )
  9. Himachal Pradesh Public Service Commission ( HPPSC )
  10. Jammu & Kashmir Public Service Commission ( JKPSC )
  11. Jharkhand Public Service Commission ( JPSC )
  12. Karnataka Public Service Commission ( KPSC )
  13. Kerala Public Service Commission ( KeralaPSC )
  14. Madhya Pradesh Public Service Commission ( MPPSC )
  15. Maharashtra Public Service Commission ( MPSC )

    State Services Examination


    PSI/ STI/Assistant

  16. Manipur Public Service Commission ( ManipurPSC )
  17. Meghalaya Public Service Commission ( MeghalayaPSC )
  18. Mizoram Public Service Commission ( MizoramPSC )
  19. Nagaland Public Service Commission ( NPSC )
  20. Odisha Public Service Commission ( OPSC )
  21. Punjab Public Service Commission ( PPSC )
  22. Rajasthan Public Service Commission ( RPSC )
  23. Sikkim Public Service Commission ( SPSC )
  24. Tamil Nadu Public Service Commission ( TNPSC )
  25. Telangana state Public Service Commission ( TSPSC )
  26. Tripura Public Service Commission ( TPSC )
  27. Uttar Pradesh Public Service Commission ( UPPSC )
  28. Uttarakhand Public Service Commission ( UKPSC )
  29. West Bengal Public Service Commission ( WBPSC )

IBPS | Banking & Insurance Exam | Banking & Insurance Examinations


Last Updated : 29-03-2024 10:04:41
Share this :

Reserves Bank of India ( RBI )

Grade A & B Exams

State Bank of India ( SBI )

Probationary Officer ( PO) Exam

Junior Associate Exam

Nationalised Banks Probationary Officers

IBPS PO Exam

Bank Clerk

Bank Clerical Exams

National Bank for Agricultural & Rural Development ( NABARD )

Assistant Development Officer Grade A exam

Development Officer Grade B exam

LIC & GIC

LIC Assistant/ Steno/Typist Exam

LIC Development Officer Exam

LIC Officers Exam

GIC Assistant Exam

GIC Officers Exam

Institute Login




Register Your Institute

MoreQues for Institutes | Features

MoreQues

Create Course

MoreQues

Add students

MoreQues

Create New Tests

MoreQues

Solving Tests

MoreQues

Test Result

MoreQues

Test Rank

MoreQues

Payments Details

MoreQues

Time Table

MoreQues

Attendance

MoreQues

And Much More

Pricing

Sign Up FREE

Rs. 0
with Ads

Remove Ads

Rs. 4,000
Per Year

Remove Ads + Notification

Rs 6,000
Per Year

Customize Portal

Rs 10,000
Starting from Rs 10,000

Don't have Computer System for Online Test?

No Problem. We also provide Computer System for online test at our Test Centres. Please get in touch with us for more information. Write us at [email protected] or call us at +91-8390111719

MoreQues | How To Use it

Exam Center Login




Register as Exam Center

MoreQues for Internate Cafe | Become Authorized Exam Center

MoreQues

Add student

MoreQues

Assign Test

MoreQues

Manage Payment

Registration

Rs. 1000
Become Authorized Exam Center

Earnning

Rs. 50
for Each Test Solved at Centre

Find Coaching Classes in your City


keyboard_arrow_up