LIFE PROCESS • The basic functions performed by living organisms to maintain their life on this earth are called life processes. • The basic life processes common to all the living organisms are • Nutrition and Respiration • Transport and Excretion • Control and Coordination • Growth • Movement and Reproduction
NUTRITION • Nutrient – It is a substance which an organism obtains from its surroundings and uses it either as an energy source or for biosynthesis of body constituents. • Example- Proteins, Carbohydrate,Fats etc. • Nutrition – It is a process of intake of nutrients as well as utilisation of nutrients by an organism.
MODE OF NUTRITION • Mode of nutrition means method of procuring food or obtaining food by an organism. Depending on the mode of obtaining food, all organisms can be classified into two groups, • Autotrophic • Heterotrophic
AUTOTROPHIC MODE OF NUTRITION • Auto means self and troph means to nutrition, thus autrotrophic means self nutrition. • It can be defined as a type of nutrition in which organisms synthesise its own food ( Organic material) from the simple inorganic materials like carbon dioxide and water. • Exa: – Green plants, autotrophic bacteria
HETEROTROPHIC MODE OF NUTRITION • The word hetero means other and troph means nutrition, which means nutrition obtained from others. • Heterotrophic nutrition can be defined as a mode of nutrition in which an organism cannot make its own food from simple inorganic materials like carbon dioxide and water, and depends on other organisms for its food. • Example- All animals, bacteria and fungi.
Heterotrophic nutrition is of three types which are as follows :-- • Saprophytic Nutrition • Parasitic Nutrition • Holozoic Nutrition
SAPROPHYTIC NUTRITION • The word sapro means rotten. • Saprophytic mode of nutrition is a nutrition in which an organism obtains its food from dead and decaying organic matter. • Example- Fungi and bacteria • Such organisms are called saprophytes.
PARASITIC NUTRITION • The word para means others. • The parasitic nutrition is a nutrition in which an organism derives its food from the body of another living organism(called its host). • The organism which obtains food is called parasite and the organism from whose body food is obtained is called host. • Example of parasite – Plasmodium, Cuscuta, roundworm
HOLOZOIC NUTRITION • Holozoic nutrition means feeding on solid food. • The holozoic nutrition is a nutrition in which an organism takes the complex organic food materials into its body by the process of ingestion, which is subsequently digested and obsorbed. • Example – Amoeba, frog, human beings.
NUTRITION IN PLANTS • PHOTOSYNTHESIS – The process by which green plants make their own food ( like glucose) from carbon dioxide and water by using sunlight energy in the presence of chlorophyll, is called photosynthesis. • Oxygen gas is released during this process. • The overall equation of photosynthesis is represented as follows Sunlight • 6CO2 + 12 H2O C6H12O6 + 6H2O + 6O2 chlorophyll
STRUCUTE OF CHLOROPLAST • STRUCTURE :- In the chloroplast of higher plants, • Stacks of thylakoids(lamellar structures) are present which are called grana (sing.-granum). • Thylakoid is a flattened sac of membrane which contains chlorophyll molecules responsible for Photosynthesis. The Light dependent reaction (or light reaction) of photosynthesis occurs in the thylakoids.
A thylakoid of one granum is connected to other granum with the help of stroma lamellae (single thylakoid). • The chloroplast is filled with a liquid called stroma or matrix. The light independent reaction (or dark reaction) occurs in the stroma of the chloroplast. • A double membrane surrounds the entire chloroplast.
PORTION OF THE LEAF • LEAF SECTION
CHLOROPHYLL • Chlorophyll and carotenoid pigments are photoreceptor molecules which play a key role in photosynthesis. • The green colour of plant is due to the presence of chlorophyll. • Different types of chlorophyll are • Chlorophyll a, b, c, d, e and bacteriochlorophyll • Chlorophyll a and b are most common and are found in all plants. • Chlorophyll pigments are found inside chloroplasts.
PHOTOSYNTHESIS • PHOTOSYNTHESIS – The process by which green plants make their own food ( like glucose) from carbon dioxide and water by using sunlight energy in the presence of chlorophyll, is called photosynthesis. • Oxygen gas is released during this process. • The overall equation of photosynthesis is represented as follows Sunlight • 6CO2 + 12 H2O C6H12O6 + 6H2O + 6O2 chlorophyll
RAW MATERIALS FOR PHOTOSYNTHESIS • The raw materials for photosynthesis are • 1) Chlorophyll • 2) Sunlight • 3) Carbon dioxide • 4) Water
MECHANISM FOR PHOTOSYNTHESIS • The entire process of photosynthesis can be divided into two main stages. • 1) Light reaction – Light dependant • 2) Dark reaction – Light independent
LIGHT REACTION • When light strikes chlorophylls, photons are absorbed which excite electrons of chlorophylls to a higher energy level. The emitted electrons travel through the electron transport chain present in the chloroplast. The process requires a number of electron acceptors • In this process ATP is synthesized from ADP and inorganic phosphate. This ATP is used as a source of energy during dark reaction.
In light reaction photolysis of water takes place. • 2H2O 4H+ + O2 + 4e- • The hydrogen ions which is released during photolysis reduce the NADP molecule (Nicotianamide adenine diphosphate) into NADPH2 which is also used during the dark reaction. It is important to note that oxygen released during photosynthesis comes from water.
DARK REACTION • The NADPH2 molecule as well as ATP(assimilatory power) produced during the light reaction are utilized in the stroma of chloroplast for synthesis of carbohydrate from CO2. This is called carbon fixation • In this process CO2 enters into a series of reactions with Ribulose biphosphate ( five carbon sugar). At the end carbohydrate is synthesized and Ribulose biphosphate is regenerated. This is called Calvin-Benson cycle. After its discoverer Melvin Calvin & Ande Benson.
Ribulose biphosphate changes into a unstable 6 carbon compound which breaks into two molecules of 3-carbon compound called phospho-glyceric acid. • This compound is finally converted into 6-carboncompound called Glucose (Carbohydrate).
FACTORS NECESSARY FOR PHOTOSYNTHESIS • A number of factors affect the process of photosynthesis, as a result of which productivity is affected. These are • Carbon dioxide • Water • Chlorophyll • Light • Temperature
CARBON DIOXIDE (CO2) • Air contains 0.03% of CO2. It is released by respiration, combustion of fossil fuels and microbial decomposition. • During early morning hours and evening hours, CO2 released in respiration is sufficient for photosynthesis. At this stage, there is no exchange of gases between the plant and the environment. This is called compensation point.
An increase in the concentration of CO2 upto 0.1% increases the rate of photosynthesis. • Higher concentration of CO2 decreases the rate of photosynthesis.
WATER • Plants absorb water and mineral salts through root hair and pass it to the leaves through xylem. • If there is less availability of H2O, then stomata closes ( to reduce the water loss by transpiration) and there is decreased CO2 absorption and sunlight absorption. • Therefore the rate of photosynthesis decreases.
CHLOROPHYLL • Only cells having chlorophyll are photosynthetic. There is no proportionality between the rate of photosynthesis and amount of chlorophyll.
LIGHT • White light consists of all the seven colours. Highest rate of photosynthesis is seen in red light and minimum in green light. Chlorophyll can absorb violet, blue and red light rays. • The rate of photosynthesis increases at the lower intensity of light and decreases in the stronger intensity of light.
TEMPERATURE • Photosynthesis is an enzymatic process. The enzymes function within an optimum range of temperature. • Lower temperature has an inhibitory effect on the rate of photosynthesis because the enzymes are inactivated. • Increase in temperature increases the rate of photosynthesis but it ultimately inhibits photosynthesis.
CARBON DIOXIDE • The rate of photosynthesis increases with an increase in carbon dioxide concentration upto a certain level. • Beyond that, CO2 concentration has no effect on the rate of photosynthesis. On the contrary it decreases the rate.
NUTRITION IN AMOEBA • Amoeba is a unicellular animal which feeds on microscopic animals and plants that float in a water body. • The mode of nutrition in amoeba is holozoic. • The process of obtaining food in amoeba is termed as phagocytosis. • The various steps of nutrition are ingestion, digestion, assimilation and egestion.
Amoeba engulfs the food by forming pseudopodia. • When the food is completely encircled and the tips of encircling pseudopodia touch each other, the membrane at that point dissolves. • The food is encaptured into the cell like a bag called food vacuole. • Inside the food vacuole, the food gets digested by digestive enzymes.
The digested food diffuses into the cytoplasm and is utilised by the cell. This is termed as assimilation. • The undigested food remains in the food vacuole, and is thrown out of the body. • This process is called egestion.
NUTRITION IN GRASSHOPPER • Grasshopper is herbivorous which feeds mainly on leaves of plants. • The mouth parts in grasshoppers are adapted for biting and chewing.