BIOLOGY
LIFE PROCESSES
1. Life processes are the basic processes in living organisms which are necessary for maintaining their life.
2. The basic life processes are – nutrition, respiration, transportation, and excretion.
3. Life processes require energy which is provided by nutrition.
A. Nutrition: It is the process of taking food by an organism and its utilization by the body for life processes.
I. Modes of Nutrition
(i) Autotrophic: It is a type of nutrition in which organisms can synthesize their own food.
E.g. Green Plants
(ii) Heterotrophic: It is a type of nutrition in which organisms do not possess the ability to synthesize their own
food. They depend on autotrophs for their food supply directly or indirectly.
Eg. Animals, Fungi
(iii) Types of heterotrophic nutrition:
There are three main types of heterotrophic nutrition. They are saprophytic, parasitic, and holozoic nutrition.
a) Saprophytic nutrition:
In this type of nutrition organisms secrete some digestive enzymes to digest the dead organic food and get
nourishment from organic remains like excreta, dead organisms, etc.
e.g. Fungi, yeast, and mushrooms
b) Parasitic nutrition:
In this type of nutrition, one organism resides on or inside the body of another organism and derives its food
without killing other organisms. Parasites are those organisms which obtain shelter & food from another
organism.
e.g. Cuscuta, orchids, ticks, lice, leeches, roundworms, tapeworms, plasmodium, etc.
c) Holozoic nutrition:
In this mode of nutrition, the organism involves the intake of solid pieces of food. This food is subsequently
digested and absorbed.
e.g. Amoeba, Paramecium, birds, fishes, humans, etc.
[1]
, It involves the following steps: ingestion, digestion, absorption, assimilation, and egestion.
II. Nutrition in Plants:
a) Photosynthesis: It is the process by which plants prepare food by using carbon dioxide and water in the presence
of sunlight and chlorophyll. The food prepared is carbohydrate which is stored in the form of starch. Oxygen is
released in this process.
b) Equation of photosynthesis:
c) Raw materials required in photosynthesis
1.Carbohydrate
2.Photosynthetic pigment
3.Sunlight
4.Water
d) Site of Photosynthesis: Photosynthesis occurs in the chloroplast or kitchen of the cell in green tissues inside and
young stem.
e) Mechanism of photosynthesis:
Photosynthesis takes place in three main steps.
i) Absorption of light energy by chlorophyll.
[2]
LIFE PROCESSES
1. Life processes are the basic processes in living organisms which are necessary for maintaining their life.
2. The basic life processes are – nutrition, respiration, transportation, and excretion.
3. Life processes require energy which is provided by nutrition.
A. Nutrition: It is the process of taking food by an organism and its utilization by the body for life processes.
I. Modes of Nutrition
(i) Autotrophic: It is a type of nutrition in which organisms can synthesize their own food.
E.g. Green Plants
(ii) Heterotrophic: It is a type of nutrition in which organisms do not possess the ability to synthesize their own
food. They depend on autotrophs for their food supply directly or indirectly.
Eg. Animals, Fungi
(iii) Types of heterotrophic nutrition:
There are three main types of heterotrophic nutrition. They are saprophytic, parasitic, and holozoic nutrition.
a) Saprophytic nutrition:
In this type of nutrition organisms secrete some digestive enzymes to digest the dead organic food and get
nourishment from organic remains like excreta, dead organisms, etc.
e.g. Fungi, yeast, and mushrooms
b) Parasitic nutrition:
In this type of nutrition, one organism resides on or inside the body of another organism and derives its food
without killing other organisms. Parasites are those organisms which obtain shelter & food from another
organism.
e.g. Cuscuta, orchids, ticks, lice, leeches, roundworms, tapeworms, plasmodium, etc.
c) Holozoic nutrition:
In this mode of nutrition, the organism involves the intake of solid pieces of food. This food is subsequently
digested and absorbed.
e.g. Amoeba, Paramecium, birds, fishes, humans, etc.
[1]
, It involves the following steps: ingestion, digestion, absorption, assimilation, and egestion.
II. Nutrition in Plants:
a) Photosynthesis: It is the process by which plants prepare food by using carbon dioxide and water in the presence
of sunlight and chlorophyll. The food prepared is carbohydrate which is stored in the form of starch. Oxygen is
released in this process.
b) Equation of photosynthesis:
c) Raw materials required in photosynthesis
1.Carbohydrate
2.Photosynthetic pigment
3.Sunlight
4.Water
d) Site of Photosynthesis: Photosynthesis occurs in the chloroplast or kitchen of the cell in green tissues inside and
young stem.
e) Mechanism of photosynthesis:
Photosynthesis takes place in three main steps.
i) Absorption of light energy by chlorophyll.
[2]
