Question 1

The two characteristics that together define growth in living organisms are:

Accepted Answer

Increase in mass and increase in number of individuals (cells). Growth is shown by an increase in body mass and an increase in the number of cells/individuals — these are the twin characteristics of growth.

Question 2

In living organisms, growth occurs:

Accepted Answer

From inside the body (intrinsically), by cell division. Living organisms grow from inside (intrinsic growth) through cell division, unlike non-living objects that grow by surface accumulation.

Question 3

A mountain or a boulder increasing in size due to accumulation of material on its surface is an example of:

Accepted Answer

Extrinsic (non-living) growth. Non-living objects grow by the accumulation of material on the outer surface — this extrinsic growth is different from the intrinsic growth of living organisms.

Question 4

Growth cannot be taken as a defining property of living organisms because:

Accepted Answer

Non-living objects also grow (by accumulation) and dead organisms do not grow. Since non-living things (e.g. crystals, boulders) can also grow and dead organisms cannot, growth is not a defining property of life.

Question 5

Which statement about growth in plants and animals is correct?

Accepted Answer

Plants grow throughout their life; most animals grow only up to a certain age. Plants continue to grow throughout their life span, whereas growth in most animals is limited to a certain age.

Question 6

In unicellular organisms, growth is best described as:

Accepted Answer

An increase in the number of cells (synonymous with reproduction). In single-celled organisms, growth (increase in cell number) and reproduction are synonymous — both mean an increase in the number of cells.

Question 7

Cell division occurring in the adult body of animals mainly serves to:

Accepted Answer

Replace and repair worn-out cells. In adults, cell division largely serves replacement and repair of damaged/old cells rather than an overall increase in body size.

Question 8

Budding is a form of asexual reproduction seen in:

Accepted Answer

Yeast and Hydra. Yeast and Hydra reproduce asexually by budding, where a new individual develops from an outgrowth (bud).

Question 9

True regeneration (a broken body fragment developing into a new organism) is characteristically seen in:

Accepted Answer

Planaria. Planaria (flatworm) shows true regeneration — fragments of the body can regenerate into complete new organisms.

Question 10

Reproduction cannot be considered an all-defining property of living organisms because:

Accepted Answer

Many living things (mules, sterile worker bees, infertile couples) do not reproduce. Organisms such as mules, sterile worker bees and infertile human couples are living yet do not reproduce, so reproduction is not a defining property of life.

Question 11

In organisms like bacteria, unicellular algae and Amoeba, reproduction is synonymous with:

Accepted Answer

Growth (increase in number of cells). In such single-celled organisms, an increase in number (reproduction) is the same event as growth.

Question 12

Metabolism is best defined as:

Accepted Answer

The sum total of all chemical reactions occurring in the body. Metabolism is the sum total of all the chemical reactions (thousands of them) taking place in an organism's body.

Question 13

Reactions that build up complex molecules from simpler ones are called _____ reactions, while those that break down molecules are _____ reactions.

Accepted Answer

Anabolic; catabolic. Anabolic reactions synthesise (build up) molecules; catabolic reactions break down molecules. Together they constitute metabolism.

Question 14

Which of the following is a defining feature of all living organisms without exception?

Accepted Answer

Metabolism. Metabolism (and cellular organisation) is exhibited by all living organisms without exception; growth and reproduction are not.

Question 15

Isolated metabolic reactions carried out in a test tube (cell-free system) are:

Accepted Answer

Living reactions, but not living things. Metabolic reactions performed in vitro (outside a cell) are living reactions, but such an isolated system is not "living" — cellular organisation is required.

Question 16

No _____ object exhibits metabolism.

Accepted Answer

Non-living. Metabolism is unique to living systems; no non-living object shows metabolism.

Question 17

The defining feature of all life forms, because every living organism is made up of one or more cells, is:

Accepted Answer

Cellular organisation of the body. Cellular organisation — being composed of cells — is a defining feature of all living organisms.

Question 18

The ability of an organism to sense its surroundings/environment and respond to external stimuli is called:

Accepted Answer

Consciousness. Consciousness — the capacity to sense the environment and respond to stimuli — is regarded as the defining property of living organisms.

Question 19

External stimuli to which living organisms respond include all of the following EXCEPT:

Accepted Answer

A crystal enlarging in a solution. Organisms respond to physical, chemical and biological stimuli — light, temperature, water, other organisms, pollutants, etc. A growing crystal is a non-living phenomenon, not a stimulus response.

Question 20

The only organism that is aware of itself, i.e. shows self-consciousness, is:

Accepted Answer

Human being. Among all organisms, human beings are the only ones who are self-conscious (aware of themselves).

What is Living? — NEET Biology MCQs with Solutions

Questions with solutions