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1800-102-2727Of all the planets present in the universe, what makes Earth different from all other planets is the presence of life. From there emerges the question - ‘What is life?’
Life can be defined as a unique and complex interaction of different molecules that results in growth, reproduction, development, responsiveness and adaptation.
Millions of things that are present on our planet can be divided into two types on the basis of the presence of life as follows:
Out of all the characteristics of a living being, there are certain features which make a living being different from a non-living thing. These features are called defining characteristics of living beings. Let’s take a deep dive into the defining characteristics of living things.
All living beings as well as non-living things have definite shape and size. Living things can undergo changes in their shape and size and hence are called morphous. Non-living things do not have this ability and hence are called amorphous.
Growth is defined as the irreversible increase in mass, size, dry weight and number of an individual. In other words, the twin characteristics of growth include increase in mass and increase in number of individuals.
Development is the term used to refer to the sum total of all the changes in an individual that occurs in their lifetime.
Growth occurs in the following two ways:
It is defined as the ability of a cell to divide and form new cells.
It is defined as the ability of a cell to grow in size (enlarge or elongate).
On the basis of time period taken for growth, it is of two types as follows:
Growth that occurs only up to a certain period of life after which only repair and regeneration of cells occur, is termed as definite growth. It occurs in animals.
Growth that continues throughout life is termed as indefinite growth. It is found in trees due to the presence of meristematic zones that retain the ability to undergo cell divisions.
Growth producing substances are of two types as follows:
Substances present in the cytoplasm and nucleus which are a part of the protoplasm of a cell and contribute to growth are known as Protoplasmic substances.
The nonliving part of the cell, like the cell wall that contributes to the growth of the cell, are known as Apoplasmic substances.
Growth is of two types as follows:
It is defined as the growth that happens from inside the individual’s body. Examples include the growth in humans.
It is defined as the growth that happens due to deposits outside the body. Examples include the growth of sand dunes, mountains, boulders, glaciers etc.
Since growth can be seen in both living as well as non-living things, it cannot be the defining property of living beings.
The production of new living beings or offspring from an existing organism is known as reproduction. Though it is a feature of living beings, it is not essential for the survival of individuals. Reproduction is synonymous with growth in unicellular organisms like bacteria, unicellular algae, Amoeba, etc.
Reproduction is of two types as follows:
Reproduction that involves fusion of gametes of opposite sexes in order to produce a new living organism is known as sexual reproduction. Examples include reproduction in animals like human beings, polar bears etc.
Reproduction that involves only a single parent to form a new living organism is known as asexual reproduction. Offsprings formed by this mode of reproduction are known as clones as they are identical to their parents. Examples include Binary fission in bacteria.
Common Examples of Asexual Reproduction
Few more examples of asexual reproduction are mentioned below:
Organism |
Reproduction |
Fungi |
Spore production |
Lower organisms like yeast and Hydra |
Budding |
Planaria (flatworms) |
True regeneration |
Fungi, the filamentous algae, protonema of mosses |
Fragmentation |
Unfortunately, all living organisms do not have the ability to reproduce. Examples include infertile couples, mules, sterile worker bees etc. Hence, reproduction cannot be the defining characteristic of living organisms.
Structural and functional deterioration of an organism that results in death is known as ageing. is Structural and functional deterioration is seen in living and nonliving things. For example, any engine will stop performing properly after some time due to wear and tear.
1. In an organism, growth is halted after a certain period in life. This type of growth is termed as __________.
a. Intrinsic growth
b. Definite growth
c. Indefinite growth
d. Extrinsic growth
Solution: Growth that occurs only up to a certain period of life after which only repair and regeneration of cells occur, is termed as definite growth. It occurs in animals. Hence the correct option is b.
2. Progeny of a prokaryotic organism is identical to the parent morphologically as well as genetically. Identify the type of reproduction by the parent organism.
a. Sexual reproduction
b. Binary fission
c. Vegetative propagation
d. None of the above.
Solution: Since the organism is a prokaryote producing progeny which is morphologically and genetically identical, the type of reproduction is called asexual reproduction. Reproduction that involves only a single parent to form a new living organism is known as asexual reproduction. Offsprings formed by this mode of reproduction are known as clones as they are identical to their parents. For example: Binary fission in bacteria. Hence the correct option is b.
3. Humans have the ability to change in shape and size. What is the term used to define this characteristic?
a. Morphous
b. Amorphous
c. Regeneration
d. Intussusception
Solution: All living beings as well as non-living things have definite shape and size. Living things can undergo changes in their shape and size and hence are called morphous. Non-living things do not have this ability and hence are called amorphous. Humans are living beings and hence, are morphous. So, the correct option is a.
4. Find the correct statement.
a. Hills and mountains do not show growth and these are non living things.
b. Definite growth is observed in both plants and animals.
c. Young ones produced by sexual reproduction are genetically different from parent organism.
d. Cytoplasm, nucleus and other protoplasmic content contribute to apoplasmic growth of cells.
Solution: Sexual reproduction is a type of reproduction that involves fusion of gametes of opposite sexes in order to produce a new living organism. For example: Reproduction in animals. Young ones produced by sexual reproduction are genetically different from parent organism.
Hence, the correct option is c.
Question 1. What is the difference between growth and development?
Solution: Growth is defined as the irreversible increase in mass, size, dry weight and number of an individual. In other words, the twin characteristics of growth include increase in mass and increase in number of individuals.
Development is the term used to refer to the sum total of all the changes in an individual that occurs in their lifetime.
Question 2. What is reproduction? What are different types of reproduction?
Solution: The production of new living beings from an existing organism is known as reproduction. There are two types of reproduction as follows:
Question 3. What are growth producing substrates?
Solution: Growth producing substances: Substrates that contribute in growth of an organism are growth producing substrates: These are of two types as follows:
Question 4. Write down the difference between extrinsic and intrinsic growth?
Solution: Intrinsic growth or intussusception is defined as the growth that happens from inside the individual’s body. For example, growth in humans.
Extrinsic growth or accretion is defined as the growth that happens due to deposits outside the body. For example, the growth of sand dunes, mountains, boulders, glaciers etc.