Diversity in the Living World
UNIT I
Diversity in the Living World
CHAPTER 1
The Living World
What is Living
Diversity in the living world
Taxonomic Categories
Taxonomical Aids
The living world is very wonderful. It contains wide range of life forms.
1.1 What is living – Living organisms are self-replicating, evolving and self-regulating interactive systems capable of responding to external stimuli.
Living organisms exhibit following distinctive characteristics.
All Living Organisms grow:
Twin characters of growth are increase in (a) mass and (b) number of individuals. Cell division leads to growth of an organism.
External Growth is shown in non-living bodies where the accumulation of material on the surface takes place thereby increasing the mass.
Internal Growth is a process in which the mass of living bodies grows by cell division.
Growth - by Cell Division
Animals – It is up to a certain age
Plants – Continues through out their life span
All Living Organisms Reproduce:
Organisms reproduce or replicate both by sexual and asexual means.
In unicellular organisms growth and reproduction are synonymous.
Organisms such as sterile working bees, mules are living but don’t reproduce. So it can’t be a defining factor for life.
No non-living organism is capable of reproducing itself.
Metabolism
All living organisms are made up of chemicals.
These chemicals are constantly being made and changed into other bio-molecules. These conversions are chemical reactions or metabolic reactions.
Thousands of metabolic reactions occur simultaneously in all the living organisms. The sum total of all the chemical reactions inside our body is metabolism.
Cellular organization of body is the defining feature of life forms.
Consciousness
The most obvious and technically complicated feature of all living organisms is their ability to sense their surroundings and environment and respond to these environmental stimuli
Diversity in the Living World
CHAPTER 1
The Living World
What is Living
Diversity in the living world
Taxonomic Categories
Taxonomical Aids
The living world is very wonderful. It contains wide range of life forms.
1.1 What is living – Living organisms are self-replicating, evolving and self-regulating interactive systems capable of responding to external stimuli.
Living organisms exhibit following distinctive characteristics.
All Living Organisms grow:
Twin characters of growth are increase in (a) mass and (b) number of individuals. Cell division leads to growth of an organism.
External Growth is shown in non-living bodies where the accumulation of material on the surface takes place thereby increasing the mass.
Internal Growth is a process in which the mass of living bodies grows by cell division.
Growth - by Cell Division
Animals – It is up to a certain age
Plants – Continues through out their life span
All Living Organisms Reproduce:
Organisms reproduce or replicate both by sexual and asexual means.
In unicellular organisms growth and reproduction are synonymous.
Organisms such as sterile working bees, mules are living but don’t reproduce. So it can’t be a defining factor for life.
No non-living organism is capable of reproducing itself.
Metabolism
All living organisms are made up of chemicals.
These chemicals are constantly being made and changed into other bio-molecules. These conversions are chemical reactions or metabolic reactions.
Thousands of metabolic reactions occur simultaneously in all the living organisms. The sum total of all the chemical reactions inside our body is metabolism.
Cellular organization of body is the defining feature of life forms.
Consciousness
The most obvious and technically complicated feature of all living organisms is their ability to sense their surroundings and environment and respond to these environmental stimuli