UPSC Biology Diseases Nutrition, Health and Diseases

Nutrition, Health and Diseases

Category : UPSC








Nutrition is the process of intake and utilisation of nutrients/ food, by an organisms to get energy which is further used in various life processes. The substance that is needed to keep them living is called nutrient.


Nutrients are organic and inorganic substances which the organism obtains from its surroundings and uses it as a source of energy or for biosynthesis of its body constituents.


Organic nutrients - Carbohydrates, Proteins, Fats Inorganic nutrients - Water, Carbon dioxide, Minerals (Iron, copper, zinc, etc.)



Various organisms live in different environmental conditions and they have different methods of obtaining nutrients from the environment. The method of obtaining food by the organism is called mode of nutrition. Depending on the mode of nutrition, all organisms can be classified into two major groups - Autotrophic and Heterotrophic.



Nutrition in Plants



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\[\downarrow \]                                                                                                             \[\downarrow \]




Organisms which can make their own organic food from inorganic raw materials (carbon dioxide and water) and remain independent of obtaining external source of organic compound are called Autotrophs. All green plants are autotrophs.

Plants are generally autotrophic but there some plants which are unable to manufacture their food, due to lack of chlorophyll like parasitic plants saprophytic and insectivorous plants or symbionts

  • In addition to carbon, hydrogen and oxygen plants require a variety of mineral elements for their survival. Absorption of minerals and their utilization by plant is called mineral nutrition.
  • The technique of growing plants in a nutrient solution is known as hydroponics or soilless growth, this was discovered by juliusvon sachs.
  • Aeroprics is a system of growing plants with their roots bathed in nutrient mist (a cloud of moisture in air). The rooted plants are placed.


Role of Micro and Macro Elements and Their Deficiency Symptoms



S. no.

Name of element (location)


Deficiency symptoms


Nitrogen \[(N{{O}_{2}}^{-},N{{O}_{3}}^{-}or\,\,N{{H}_{4}}^{+})\]

Major constituent of proteins, nucleic acids, vitamins and minerals.

Chlorosis of leaves, stunting of plants, dormancy of lateral buds, inhibition of cell division etc.


Phosphorous \[({{H}_{2}}P{{O}_{4}}^{-},or\,\,HP{{O}_{4}}^{2-})\]

Constituent of cell membrane, nucleic acids, nucleotides and some proteins.

Delay in seed germination, reduced growth, purple or red spots on leaves etc.


Potassium \[({{K}^{+}})\]

Determine cation- anion balance in cell. Involved in protein synthesis, closing & opening of stomata.

Scorched leaf tips, shorter intemodes, chlorosis in interveinal, loss of apical dominance, loss of cambial activity.


Calcium \[(C{{a}^{2+}})\]

Activate certain enzymes and regulates metabolic activities. Used in synthesis of cell wall (middle

Stunted growth, necrosis (death of tissue) of meristematic regions, chlorosis along the margins of young leaves, wither tip disease, premature flower abscission, blossoms end rots of tomato.  


Magnesium (divalent \[M{{g}^{2+}}\])

Activate enzymes in respiration, photo -synthesis, DNA and RNA synthesis.

Chlorosis between leaf veins, necrosis on older leaves. Premature leaf abscission, reduced growth.


Sulphur \[(S{{O}_{4}}^{2-})\]

Constituent of amino acids like cystine and methionine and Main constituent of several coenzymes, vitamins (thymine, Co-A and ferredoxin, biotin)

Chlorosis of younger leaves, stunted growth, anthocyanin accumulation, leaf curl, less juice content in citrus, yellow disease of tea, marsh spots (peas)c.


Iron \[(F{{e}^{3+}})\]

Constituent of ferredoxin and cytochromes. Involves in electron transfer. Activates catalase and Helps in formation of chlorophyll.

Chlorosis-initiates in intravenous regions and then in the complete leaf, growth reduced, inhibition of chloroplast formation.




Green plants are autotrophic in the sense that they synthesize their own organic food from inorganic raw materials. This is done by the process of photosynthesis.

\[_{carbon\,\,dioxide}^{6C{{O}_{2}}}+_{water}^{12{{H}_{2}}O}\xrightarrow[Chlorophyll]{Light}_{Glu\cos e}^{{{C}_{6}}{{H}_{12}}{{O}_{6}}}+_{water}^{6{{H}_{2}}O}+_{oxygen}^{6{{O}_{2}}}\]



  • In higher plants photosynthesis occurs particularly in specialized cells called mesophyll cells of leaves. These cells contain chloroplast, which is the actual sites for photosynthesis. It fixes \[C{{O}_{2}}\] into carbohydrates.
  • Chloroplasts are double membrane bound organelle. The space limited by the inner membrane of the chloroplast is called the
  • A number of organised flattened membranous sacs (called the thylakoids) are present in the stroma. Thylakoids are arranged in stacks like the piles of coins called


Photosynthetic Pigments

  • Pigments are the organic molecules that absorb light of specific wavelengths in the visible region due to presence of conjugated double bonds in their structures.
  • Chlorophyll-a

Chlorophyll b

Chlorophyll c

Carotenes - \[{{C}_{40}}{{H}_{56}}\] and Xanthophylls - \[{{C}_{40}}{{H}_{56}}{{O}_{2}}\].

  • Chla and carotenes are universal pigment, which are found in all \[{{O}_{2}}\] liberating cells. Chlorophylls are soluble only in organic solvents like ketones, ethers etc.
  • Carotenoids absorb light energy and transfer it to Chla and thus act as accessory pigments.



  • Photosynthesis is an oxidation reduction process in which water is oxidised to release \[{{O}_{2}}\]and \[C{{O}_{2}}\] is reduced to form starch and sugars.
  • These are of two types

(i) light Reaction

(ii) Dark Reaction


Light reaction

It occurs in grana fraction of chloroplast and in this reaction are included those activities, which are dependent on light. Assimilatory powers (ATP and\[NADP{{H}_{2}}\]) are mainly produced in this light reaction.


Non Cyclic Photophosphorylation

  • In light reaction, the formation of ATP from ADP in presence of light called non-cyclic photophosphorylation. The system is dominant in green plants. It involves both PS-I and PS-II.
  • Flow of electrons is unidirectional. Here \[{{H}_{2}}O\] is utilized and \[{{O}_{2}}\] evolution occurs. In this chain, high energy electrons released from ‘P-680’ do not return to ‘P-680’ but pass through pheophytin, plastoquinone, cytochrome \[{{b}_{6}}-f\]complex plastocyanin (Cu containing pigment) and then enter P-700. Because in this process high energy electrons released from ‘P-680’ do not return to ‘P-680’ and ATP (1 molecule) is formed, this is called Noncyclic photophosphorylation. ATP is synthesized at only one step.
  • This non-cyclic photophosphorylation is also known as Z-scheme (because of shape of path of electron-flow) and this was given by Hill and Bendall (I960).



Cyclic Photophosphorylation

In this light reaction of photosynthesis, the formation of ATP from ADP and\[{{H}_{3}}P{{O}_{4}}\]in the presence of light & chlorophyll a during the cyclic transfer of electrons is called cyclic photophosphorylation. The system is found dominantly in bacteria. It involves only PS I. Flow of electron is cyclic. If NADP is not available then this process will occur. When the photons activate PS I, a pair of electrons are raised to a higher energy level. They are captured by primary acceptor which passes them on to ferredoxin, plastoquinone, cytochrome complex, plastocyanin and finally back to reaction centre of PS I i.e., \[{{P}_{700}}\]. At each step of electron transfer, the electrons lose potential energy. Their trip down hill is caused by the transport chain to pump H4' across the thylakoid membrane.


Dark Reaction

Dark reaction is a thermochemical reaction. It takes place in the stroma of the chloroplast.

It is also called \[C{{O}_{2}}\]fixation or carbon assimilation.

The dark reaction involves thermochemical reduction of \[C{{O}_{2}}\]to form carbohydrates. This was first established by Blackmail (1905), hence it is also called Blackmail reaction.

There are two main pathways for the biosynthetic or dark phase - Calvin cycle (\[{{C}_{3}}\]) and \[{{C}_{4}}\] (dicarboxylic acid) cycle.


Calvin Cycle-(\[{{C}_{3}}\] Cycle)

Carbon assimilation in \[{{C}_{3}}\] plants were explained by Melvin Calvin

\[l\]This is known as \[{{C}_{3}}\] cycle because \[C{{O}_{2}}\]reduction is cyclic process and first stable product in this cycle is a 3-C compound (i.e., 3-Phosphoglyceric acid or -PGA. Calvin cycle occurs in all photosynthetic plants whether they have \[{{C}_{3}}\] or \[{{C}_{4}}\] pathway.


\[{{C}_{4}}\] Cycle

  • \[{{C}_{4}}\]acid (dicarboxylic acid) is formed due to carboxylation. It was shown by Kortschak et al in sugarcane. Kortschak and Hart supplied \[C{{O}_{2}}\] to the leaves of sugarcane, they found that the first stable product is a four carbon (\[{{C}_{4}}\]) compound oxaloacetic acid instead of 3-carbon atom compound. The detailed study of this cycle was introduced by D. Hatch and C.R. Slack (1966). So it is called as “Hatch and Slack cycle”. The stable product in \[{{C}_{4}}\]plant is a dicarboxylic substance. Hence, it is called dicarboxylic acid cycle or DCA-cycle.
  • \[{{C}_{4}}\]plants are true xerophytic plants. They are adapted for hot and dry climate. The important \[{{C}_{4}}\] plants are sugarcane, maize, sorghum, Cyperus rotundus, Digitaria brownii, Amaranthus, etc.
  • These plants have “Kranz” (German term meaning halo or wreath) type of leaf anatomy. The vascular bundles in \[{{C}_{4}}\] leaves are surrounded by a layer of bundle sheath cells that contain large number of chloroplasts.


Table Difference between \[{{C}_{3}}\] and \[{{C}_{4}}\] Plants






Photosynthesis occurs in mesophyll cells.

Photosynthesis occurs in mesophyll and bundle sheath cells.


Kranz anatomy is absent.

Kranz anatomy is present.


RuBP is the primary carbon dioxide acceptor.

PEP is the primary carbon dioxide acceptor.


3-phosphoglyceric acid (3-PGA), a 3C-compound is the first stable product.

Oxaloacetic acid, a 4C-compound is the first stable product of photosynthesis.


Chloroplast are of only one type, i.e., granal.

Chloroplasts are dimorphic, i.e., granal in the mesophyll cells and agranal in the bundle sheath cells.




It is a biochemical process in which animals derives nutrients in the form of organic and inorganic substances for the proper maintenance and for all metabolic and catabolic activities occurs in the body.



Nutrition is divided into three types:



  • Holozoic nutrition:- This literally means feeding like an animal. Holozoic nutrition is a mode of heterotrophic nutrition in which an organism takes the complex organic food material into its body by the process of ingestion, which is then digested, absorbed and assimilated in the body cells of the organism.
  • Holozoic nutrition is of three types:

(i) Herbivores, (ii) Carnivores, (iii) Omnivores


  • It is a type of nutrition in which, animals derives nutrients from dead and decayed animals.

Ex-insects in drainage, on pickles, etc.



  • Organism derives its food from the host cell ex- plasmodium (causes malaria in man), etc.
  • Parasitic nutrition is of two types:

Macronutrients can be Summarized in the Flow Chart give Below:




Vitamins are organic compounds essential in trace amounts to the health of animals. Vitamins can be water soluble or fat soluble.

Fat Soluble Vitamins: These vitamins are stored in the liver in fat droplets.





Deficiency symptoms

Vitamin A (Retinol)

Carrot, tomato, papaya, mango, milk, eggs, cod-liver oil

Essential role for vision, growth, differentiation of epithelial tissue.

Night blindness, xerophthalmia poor growth, rough and dry skin.

Vitamin D It exists in two Forms \[{{D}_{2}}\] (Ergocalciferol) and\[{{D}_{3}}\] (cholecalciferol).

Cod liver oil. Skin can synthesize Vitamin D in the presence of sunlight.

It promotes growth of bones and teeth

Rickets in children and osteomalacia in adult.

Vitamin E (Tocopherol)

Wheat germ, green leafy vegetables. Fats of vegetable origin

Acts as good antioxidant, essential for normal functioning of reproductive organs

Reproductive failure, muscular dystrophy increased haemolysis leading to macrocytic anaemia

Vitamin K There are three deri vatives of vitamin K.

Leafy vegetables, wheat germ, Vitamin K is synthesized by bacteria of large intestine.

I helps in blood clotting, prevention of excessive bleeding.

Faculty blood clotting.

Water soluble Vitamins

Water soluble vitamins travel freely through the body, and excess amounts usually are excreted by the kidneys. The body needs water soluble vitamins in frequent small doses. Important water soluble vitamins are summorized below in the table.

B- Complex Vitamin \[{{B}_{1}}\] (Thiamine)

Whole gain wheat germ, legumes, nuts, fish.

It acts as thiamine pyrophosphate (TPP) in TCA cycle (Kerbs Cycle)

Beri beri disease (B1) deficiency in alcoholics causes Wernicke?s syndrome and Korsakoff?s syndrome

Vitamin \[{{B}_{1}}\] (Riboflavin)

Milk, chees, meats, eggs, legumes, wheat germ mushrooms, green leafy

It helps in RBCs production. It acts as FMN and FAD. FMN acts in ETC. however FAD acts in


Vitamin C (Ascorbic acid)

Cirtrus fruits amla, guava, tomato.

Essential for the formation of RBCs and the production of antibodies.

Its deficiency causes Scurvy





Anything that disturbs the proper functioning of cells, tissues and organs will result in the lack of proper activity of the body or unhealthy body. Thus, health is considered to be the state of perfect functioning of body and mind, unhindered by diseases. A good health is a healthy body with a healthy mind and healthy attitude.

Health is a state of complete physical, mental and social well-being, and not merely an absence of disease or infirmity (W.H O -1948). Any change from the normal state that causes discomfort or disability or impairs the health is called as disease.



Communicable Disease

  • Depending upon the type of causative agent communicable disease are the following types - bacterial, viral, rickettsial, spirochaetal, protozoan, fungal and helminthes etc.


Table: Bacterial Diseases in Human

S. No.



Main Symptoms


Cholera (Haiza)

Comma shaped -Vibrio comma (V. cholerae)

Severe diarrhoea and vomiting



Diplococcus or Streptococcus pneumoniae

Sudden chill, chest pain, difficulty in breathing



Rod like motile Salmonella typhi

Constant fever .



Mycobacterium tuberculosis (rod shaped)..

Cough, bloody sputum, chest pain, loss of weight



Viral Diseases

  • Viral diseases are transmitted by contact fomite and droplet method. Types of viral disease are-influenza, small pox, etc.


Table: Viral Diseases in Humans

S. No.



Main Symptoms


Influenza (Flu)

Myxovirus Influenzae

Nasal discharge, sneezing, coughing, fever, body ache


Chicken pox

Varicella zoster (DNA vims)

Skin sores that open & emit fluid


Poliomyelitis (polio) (Highly infectious disease of infants and children?s)

Polio virus

Inflammation of nervous system, muscle shrinkage, limb paralysis



Arbo virus (RNA)

Mild conjunctivitis, high fever, backache, nausea vomiting etc.


Hepatitis (Epidemic jaundice)

Infections & serum hepatitis viruses (A, B, C, D & E)

Jaundice due to damaged liver cells


- Hepatitis A (also called catarrhal jaundice)

A virus

Hepatic anorexia resulting in liver damage


- Hepatitis B

B virus

Swelling of liver cells


Protozoan disease




Causative agent




Plasmodium (female anopheles as vector)

It results in anaemia, toxaenia and splenomegaly. Antimalarial drugs are quinine, chloroquine etc. Dalaprim drug kills the parasitic stages present in both liver cells and RBC?s of blood.



Entamoeba histolytica

It is characterized by abdominal pain alternating diarrhoea and constipation etc. Entamoeba secretes cytolysin that erodes the mucous membrane of intestine.


Table: Sexually Transmitted Diseases (STD) in Human


S. No.


Causative organism




Retrovirus - HIV

Enlarged lymph nodes, long fever, weight loss - Nil


Genital Herpes

Herpes simplex virus

Painful ulcer on genitals - Nil


Genital warts

Human papilloma virus (HPVs)

Tumor of the vulva, vagina, anus and penis - Nil



Treponema pallidum

Cancer and skin eruption - Benzene and Penicillin


Non-Communicable Diseases

The main non-communicable diseases are diabetes, inflammatory diseases of joints such as arthritis, gout, cardiovascular diseases and cancer.


Diabetes Mellitus

Diabetes is characterized by chronic hyper glycemia which is excessive concentration of glucose in the blood. It primarily a result of relative or complete lack of insulin secretion by the \[\beta \]cells of islets of Langerhans in pancreas.



Arthritis is any inflammatory condition of the joints characterized by pain and swelling.







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\[\downarrow \]                                                           \[\downarrow \]                                                            \[\downarrow \]


Rheumatoid arthritis



It is characterized by inflammation of the synovial membrane. It is kind of rheumatoid arthritis that occurs in younger people is Still?s disease, and usually starts in the small joints in the hand and progress to other body joints.

It is a common disease among the elderly persons resulting from erosion of articular cartilage. In osteoarthritis, the secretion of lubricating synovial fluid between the bones at the joint stops.

Gout results from accumulation of uric acid crystals in the synovial joints. It is a disease associated with an inborn error of uric acid metabolism that increases production or interferes with the excretion of uric acid.


Cardiovascular Diseases

  • Cardiovascular diseases refer to a number of diseases associated with the blood vascular system.
  • Some major cardiovascular diseases are rheumatic heart disease, hypertensive heart disease and coronary heart disease.



Cancer is an abnormal and uncontrolled division of cells, known as cancer cells that invade and destroy the surrounding tissues. Neoplasm (called tumor) is a new abnormal tissue which is capable of continued growth. Tumors may be benign and malignant.





Benign tumor is a large localized mass of abnormal tissue enclosed in connective tissue which does not invade adjacent tissue.

Malignant tumor is not encapsulated and is capable of invading adjacent tissues and distant sites.



Symptoms of Cancer

  • Thickening or lump in the breast or any other part of the body.
  • Changes in bowel or bladder habits.
  • Indigestion of difficulty in swallowing.
  • Unexplained changes in weight.


Causes of Cancer

  • Chemical or physical agents that can cause cancer are known as

Depending on their mode action, carcinogens fall into the following main categories:

(i) Agents that can cause alterations in the genetic material (DNA), resulting in oncogenic transformation.

(ii) Agents that promote the proliferation of cells, which have already undergone genetic alterations responsible for oncogenic transformation. These agents are called tumour promoter, e.g. some growth factors and hormone.

(iii) Cancer causing DNA and RNA viruses (tumour viruses) have been shown to be associated with oncogenic transformation.



  • Surgery: By removing the entire cancerous tissue and infected lymph nodes.
  • Radiation: Cobalt therapy (Co-60), X-rays radiations are given. These radiations destroy the rapidly dividing cells.
    • Chemotherapy: Anti-cancerous drugs
  • like: Vincristine and Vinblastine obtained from Catharanthus roseus (vinca rosea)
  • Most of cancer are treated by combination therapy of surgery, radiation and anti-cancerous drug.


  • AIDS (Acquired Immune Deficiency Syndrome) is a chronic life threatening disorder which damages the human body’s immune system. It is caused by HIV (human immune-deficiency virus) which belong to retrovirus (group of RNA virus) The HIV can only survive in body fluids like blood, semen, vaginal secretion etc.
  • HIV is transmitted through body fluids by- Sexual contact (most common mode of transmission) (Probability < 1 %), blood contact (100%), and By mother to child by placenta (33%), By mother milk
  • HIV is not transmitted through - ordinary contact (hugging, dancing, talking, touching etc.) with someone who has HIV or AIDS; sweat, tears or saliva etc. The major cell affected by HIV is the helper-T-lymphocyte.



  • Screening test is Enzyme Linked Immune sorbent assay (E.L.I.S.A.).
  • Confirmatory tests: Western blot test Detects antibodies (proteins) in patient’s serum.



  • Drugs used are -

- AZT (Azidothymidine) or Zidowdine

- DDI (Dideoxyinosine)

- Foscamet

These drugs inhibit the enzyme of HIV

  • Highly active antiretroviral therapy (HAART) is a combination of three or more antiretroviral agents (called triple therapy or HAART), which has been highly effective in reducing the number of HIV particles in the blood stream and as a result increase the CD4 count.



  • System which protect the body from disease is called immune system.
  • The immune system consisting several organs as well as WBC in blood and lymph has the job of fighting off invading pathogens and preventing growth and spread of cancers.
  • Lymphoid organs are those organs where origin and maturation and proliferation of lymphocyte occur.
    • The primary lymphoid organs are bone marrow and
  • Bone marrow manufactures the billions of WBC needed by the body every day. Some newly produced WBC remain in the bone marrow to mature and specialize and while others travel to the thymus to mature.


Acquired Immunity

  • It is the resistance that an individual acquires during life. This is generated in response to an exposure to the micro-organism in question. This type of immunity is founds only in vertebrates. It is also called adaptive or specific immunity. This immunity is acquired after birth by experience and recognises and selectively eliminate the pathogen.



Aquired immunity



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\[\downarrow \]                                                                                                             \[\downarrow \]


Active acquired immunity

Passive aquired immunity

Resistance developed by an individual as a result of an antigenic stimulus.

It is received passively by host without participation or contribution from host s immune system. Immunological memory is absent here and the readymade antibodies are given in immuno suppressive individual.


Antibodies: These are complex glycoproteins made up of polypeptide chains.


S. No.

Group of Antibodies

Main Characters and occurrence




The primary antibodies present in colostrum, present in saliva, mucus and other secretions.

Protection of mucous membranes and outer surface of body and protection from inhaled ingested pathogens.



Present in trace amount on the surface of lymphocytes in blood.

Activation of B-lymphocytes and development and maturation of immune reactions.



Present in very small quantities, show specific linkage with mast cells and basophils.

Stimulation of mast cells. Related to allergic reactions and protection from parasites.



Most abundantly found antibodies, main immunoglobulin of blood and interstitial fluid which has capacity to pass through placenta.

Stimulate the complementary system, provide immune power to human embryo and specific linkage with phagocytic cells for phagocytosis.



Oldest and first antibody generated in response to antigens, present in blood plasma (80% ) and interstitial fluids and largest sized immunoglobulin with pentameric form, M.W.

First line of defense against bacteria, perfection of agglutination, related to complement system.



Table: Some Important Vaccines


S. No.

Name of Vaccine

Used for treatment of





Cholera vaccine



Oral Polio Vaccine (OPV)

Polio, 1st dose given when child is 3 months old. Booster dose is given after 1 year


Tetanus toxoid (TT)






Other Topics

Notes - Nutrition, Health and Diseases

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