INTRODUCTION

• 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.

• The basic mode of getting nutrition is food.

• Most of the food sources are carbon – based.

• Food is needed for the following :-
  For growth
  For repair of cells
  For energy

• Both oxidation and reduction process occurs during the process of break-down of food.

• In unicellular organisms, no specific organ is built to carry out the essential processes, rather all the processes such as taking in food, excreting out wastes, exchange of gases taking place through simple diffusion.

• Unlike unicellular organisms, in multicellular organisms special organs are designed to carry out specific functions.

NUTRITION

• Food is complex in nature, so it must be broken down into simpler forms for an easy absorption by the body cells for the repair, growth and utilizing energy purposes  is known as digestion.

• These complex processes are done with the help of bio – catalysts commonly known as enzymes.

• Autotropic nutrition
  Autotropic nutrition is exhibited by green plants, certain cyanobacteria, red & green algae.
  
  Plants make their own food in the form of sugar with the help of carbon dioxide and water vapor in the presence of sunlight and chlorophyll, releasing oxygen as its by product  under the name of the process – photosynthesis.
  
  In plants the carbohydrates are stored in the form of starch and in animals as glycogen.

• Equation of photosynthesis:
  

• Steps in photosynthesis :

Absorption of light energy by chlorophyll.

Conversion of light energy to chemical energy.

Splitting of water molecules into hydrogen and oxygen.

Reduction of carbon dioxide to carbohydrates.

• Plant cells contain organelle known as chloroplasts which contain chlorophyll ( green pigment ).

• The parasitic mode of nutrition includes :

• Ticks and lice

• Cuscuta (amar-bel)
• Leeches and tapeworms

Parasites are plants or animals that live on or in a host getting their nutrients  from that host.
There are two types of parasites- ectoparasites and endoparasites. Endoparasites live inside the host which include heartworm and flatworms. Ectoparasites live on the hosts which include lice and fleas.

• Stomata

These are tiny pores present on the surface of the leaves.

Massive amounts of gaseous exchange takes place through stomata.

But gaseous exchange can also takes place through surface of stems and roots too. Also , a large amount of water is lost through these pores in the form of water vapor under the process of transpiration.

These pores open and close on the availability of carbon dioxide and water required for photosynthesis.

A pair of guard cells (bean-shaped) covers the stomatal pore.

The guard cells swells up when water gets into it and shrinks when water is lost from it.

Figure showing : open stomata and closed stomata

• Heterotopic nutrition

Organism which depend upon other organisms, plants or animals etc for the requirement of food and survival are said to exhibit heterotrophic nutrition.

Some organisms break down the food outside the body and then absorb it, under such categories comes the fungi and its types like bread mould, yeast (unicellular fungi) and mushrooms.

• In unicellular organisms, like amoeba takes in food using temporary finger like projections of the cell surface which fuse over the food particle forming a food vacuole.

• Inside the vacuole complex substances are broken down into simpler ones and then diffuse into the cytoplasm.

• In paramecium, the food is taken into a specific spot called as gullet, here the food is moved to this spot by the movement of cilia ( small , slender and hair – like structures present on cell surface for locomotion purposes).

NUTRITION  IN  HUMAN  BEINGS 

• Alimentary canal starts from the mouth to the anus.

• At first the food is crushed in the mouth with the help of teeth and then it gets masticated and wetted with the saliva.

• Saliva secreted by the salivary glands and saliva contains an enzyme known as salivary amylase which breaks down the starch into simple sugar.

• The food is chewed with the help of teeth and mixed & rolled with the help of muscular tongue.
• The food is then passed to the stomach through food pipe/esophagus in the form of peristaltic movement (rhythmic contraction and relaxation of the esophagus).

• The muscular walls of the stomach helps in mixing the food with the digestive juices.
• Digestion in stomach is done with the help of gastric glands present in the walls of the stomach.
• Gastric glands releases the following :
  HCL
  A protein digesting enzyme known as pepsin
  Mucus

• The mucus protects the inner lining of the stomach walls from the excoriation of the hydrochloric acid.

• The hydrochloric acid creates an acidic medium which facilitates the action of enzyme  pepsin.

• From the stomach the food enters the small intestine.

• Small intestine is the longest part of the alimentary canal which is compactly fitted because of its extensive coiling.

• Maximum digestion and absorption takes place in the small intestine.

• Herbivores need a longer small intestine to allow to digest the cellulose since meat is easier to digest so carnivores like tigers have a shorter small intestine.
  
• Small intestine is the site of complete digestion of carbohydrate , proteins and fats.
  
• Small intestine receives the secretions from liver and pancreas too.
  
• The food coming from the stomach is acidic in nature and has to be made alkaline for pancreatic enzymes to act on it.

• Bile juice containing bile salts acts on fats which breaks down larger fat globules to smaller fat globules , and this process is known as emulsification of fat.

• Pancreas secrete pancreatic juice which contains enzymes such as:

⮚Trypsin ( for digesting proteins )

⮚Lipase ( for breaking down emulsified fats )

• The walls of the small intestine contains glands which secrete intestinal juice and these enzymes finally convert :

• Finally the digested food is taken up by the walls of small intestine.

• The inner – lining walls of the small intestine has numerous amount of finger-like projections known as villi.

• Villi are supplied with blood vessels and it actually increases the surface area for more and more absorption.

• The unabsorbed food is sent to the large intestine from which more and more water is reabsorbed.

• The rest of the material is removed away through the anal sphincter.

RESPIRATION IN HUMAN BEINGS 

Respiration in human beings

• The breakdown of food ( glucose ) in the presence or absence of oxygen to release energy is known as respiration.

• At first, the glucose is broken down into a 3-carbon compound known as pyruvate which takes place in the cytoplasm.

• Then if the organism or any living cell exhibits aerobic mode of respiration
  (ie. presence of oxygen) the pyruvate further gets reduced to
  carbon dioxide + water and this process taken place in the mitochondria.

• If the organism exhibit anaerobic mode of respiration ( ie. absence of oxygen ) the pyruvate further gets reduced to ethanol and carbon dioxide and in case of yeast cells this process is known as fermentation, and if this happens inside muscle cells products formed are ethanol and carbon dioxide.

• The energy released during cellular respiration is immediately used to synthesize a molecule called ATP which is used to fuel all other activities in the cell.

• We have seen that plants exchange gases through stomata.

• At night, when there is no photosynthesis occurring, CO₂ elimination is the major exchange activity going on. During the day, CO₂ generated during respiration is used up for photosynthesis, hence there is no CO₂ release. Instead, oxygen release is the major event at this time. Animals have evolved different organs for the uptake of oxygen from the environment and for getting rid of the carbon dioxide produced. Terrestrial animals can breathe the oxygen in the atmosphere, but animals that live in water need to use the oxygen dissolved in water.

• Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms.

• Fishes take in water through their mouths and force it pass the gills where the dissolved oxygen is taken up by blood.

• Respiratory pigment in human beings is Hemoglobin.

• Hemoglobin is present in the red blood corpuscles (RBC’s).

• Hemoglobin transports oxygen to various parts of the body.

• Conjunction of hemoglobin and oxygen is known as oxy – hemoglobin.

• Conjunction of hemoglobin and carbon dioxide is known as carbamino –  hemoglobin.

• Within the lungs the trachea breaks into smaller and smaller tubes of balloon-like  vascularized sac/bag known as alveoli.

• Air is inhaled into the alveoli from there oxygen is transported to the body cells on return the carbon dioxide released by the body cells is exchanged with the alveoli and then released out to the atmosphere by the process of exhalation.
  
  

INHALATION	EXHALATION
Ribs lifted	Ribs flatten
Chest cavity becomes larger	Chest cavity becomes smaller
Diaphragm flatten	Diaphragm returns to its dome-shaped.

TRANSPORTATION IN HUMAN BEINGS

• The two circulating fluid in our body:

⮚Blood

⮚Lymph

• BLOOD

⮚Blood is a fluid connective tissue.

⮚Fluid part of blood : Plasma

• Cellular elements of blood :
  RBC ( erythrocytes )

WBC ( leucocytes )

Platelets ( thrombocytes )

• Blood carries the following:

⮚ Plasma carries food , hormones , carbon dioxide and nitrogenous wastes.

⮚ RBC carries oxygen. Heart is the pumping organ in our body which has 4 distinct chambers

• Upper chambers of the heart known as atria.

• Lower chambers of the heart known as ventricles.

• Deoxygenated blood from the organ enters the right atria.

• From the right atria it goes into the right ventricle through tricuspid valve.

• From the right ventricle it goes to the lungs through pulmonary artery where the deoxygenated blood gets oxygenated.

• From the lungs the oxygenated blood goes to the left atria through the pulmonary vein.

• From the left atria it goes into the left ventricle through bicuspid valve also known as mitral valve.
• From the left ventricle it goes back to the destined organ as oxygenated blood through aorta.
• Tricuspid & bicuspid valve ensures the direction of blood flow in a particular direction and prevents its backflow.

Chambers of heart	Groups /animals
2	Fishes (Pisces)
3	Amphibians and reptilia
4	Birds (Aves) and mammals

• In human beings , the heart undergoes double circulation.

• Three kinds of blood vessels are :

⮚Arteries ( carry away blood from heart to other organs , thick walled, doesn’t have valves )

⮚Veins ( carry blood from other organs to the heart , thin walled , have valves  )

⮚Capillaries ( one-celled thick )

• Platelets are one of the cellular elements of the blood which helps in clotting of blood.
  
  
• Lymph
  
  ⮚Lymph also known as tissue fluid which is another kind of circulating fluid in our body.
  
  ⮚Sometimes through the pores present in the walls of the capillaries some amount of plasma, proteins, blood cells escape out into the intercellular space to form lymph/tissue fluid.
  
  ⮚It contains less protein than the blood.
  
  ⮚Lymph carries digested and absorbed fat from the intestine.
  
  ⮚It drains excess fluid from extra cellular space back into the blood.
  
  ⮚The process by which plants take in carbon dioxide and water in the presence of sunlight and chlorophyll to make food (glucose) is known as photosynthesis.

TRANSPORTATION IN PLANTS 

• The food manufactured needs to be transported throughout the plant body.

• The absorption of essential elements by the plants occurs through the soil with the help of roots.

• There are two kinds of conducting tissues in the plants :

⮚Xylem : transports water and minerals.

⮚Phloem : transports food ( in the form of sucrose or glucose )

•Vessels and tracheids are the main elements of xylem tissue which helps in transportation of water and minerals.

•At the roots the ions are taken up actively ( through active transport ).

•The process by which water is lost from the stomata in the form of water vapour from the aerial parts of the plant is known as transpiration.

•And this evaporation of water creates a suction pull or most commonly the transpirational pull to conduct water upwards till the top of the plants.

•Thus transpiration helps in the following :

⮚Absorption of water

⮚Conduction /upward movement of water and minerals.

⮚Helps in temperature regulation.

• During night, the root pressure is under operation.

• During daytime, the transpiration pull is the main driving force.

• Companion cells and sieve tubes are the main elements which help in conduction of food (glucose & sucrose).

• The transport of products of photosynthesis occurs from leaves to other parts through the process of translocation.

• Phloem transports : food and amino acids.

• Translocation occurs in both upward and downward direction but transpiration occurs only in upward direction.

EXCRETION IN PLANTS

• Plants have other mechanisms for the process of excretion .

• Even oxygen can be considered as a waste product during the process of photosynthesis.

• Plants excrete out excess water by the process of transpiration.

• The organelle in plants which stores the waste products – Vacuoles

• In old xylem, resins and gums gets accumulated as waste products.

• Plants also excrete out wastes  in the soil around them.

EXCRETION IN HUMAN BEINGS

• Unicellular organisms excrete out wastes through simple diffusion.

• In human beings the principle excretory organs include:

⮚Kidney (urine manufacturer)

⮚Ureter ( transports urine from kidneys to urinary bladder )

⮚Urinary bladder ( voluntarily stores the urine )

⮚Urethra ( releases the urine )

• Location of kidneys : these are paired organs present in the abdomen on either side of the backbone.

• The basic filtration unit are the kidneys.

• Two kinds of nitrogenous wastes :

⮚Urea

⮚Uric acid

• The unit of kidney is nephron.

• Each nephron has a cup like structure known as bowman’s capsule (it receives the filtrate) which receives a network/cluster of capillaries.

• Substances in the initial filtrate are : glucose , amino acids.

• Urinary bladder is muscular and controlled by the nervous system.