Digestive System and Nutrition: Vitamins, Minerals, Balanced Diet
Every bite of food we eat has to be broken down before the body can use it. The digestive system does this job – it turns rice into glucose, dal into amino acids and ghee into fatty acids, and then sends them into the blood. Nutrition is the science of what these foods contain and how much of each we need. Carbohydrates and fats give energy, proteins build the body, vitamins and minerals keep it working properly, and water and fibre keep everything moving smoothly.
Digestion and Nutrition is a favourite area for General Science questions in SSC CGL, CHSL, MTS, GD, RRB NTPC, Group D, WBCS, WBPSC, Police and Banking exams. Questions come on digestive enzymes, types of carbohydrates, essential amino acids, calorie values, vitamins and minerals with their deficiency diseases, protein-energy malnutrition, BMI and balanced diet, along with government nutrition schemes. This guide explains each topic in simple language with diagrams, easy tables, memory tricks and 20 MCQs with answers.
➤ Nutrients: Carbohydrates, proteins, fats (macronutrients) · Vitamins, minerals (micronutrients) · Water and dietary fibre
➤ Energy per gram: Carbohydrate ≈ 4 kcal · Protein ≈ 4 kcal · Fat ≈ 9 kcal
➤ Digestion begins: Starch in the mouth · Protein in the stomach · Fat in the small intestine
➤ Most digestion and absorption: Small intestine (villi) · Water absorption: Large intestine
➤ Fat-soluble vitamins: A, D, E, K · Water-soluble: B-complex and C
➤ Protein deficiency: Kwashiorkor · Protein + calorie deficiency: Marasmus
➤ BMI: Weight (kg) ÷ Height² (m²) · Normal range 18.5–24.9 (WHO)
What is Nutrition?
Nutrition is the process of taking in food and using it for energy, growth, repair and protection from disease. The substances in food that do these jobs are called nutrients. Nutrients needed in large amounts (grams per day) are called macronutrients, and those needed in very small amounts (milligrams or micrograms) are called micronutrients. Humans cannot make their own food like green plants, so we depend on plants and animals – this is called heterotrophic nutrition, and because we eat both plant and animal food, humans are omnivores.
Figure 1: Classification of nutrients in our food
The Digestive System – How Food is Broken Down
The digestive system has two parts: the alimentary canal (a muscular tube about 8–9 metres long from the mouth to the anus) and the digestive glands (salivary glands, liver and pancreas) that pour juices into it. Food is moved forward by rhythmic waves of muscle contraction called peristalsis. Digestion has five steps: ingestion (taking food in), digestion (breaking it down), absorption (taking it into blood), assimilation (using it in cells) and egestion (removing waste).
| Organ | What happens here | Key exam fact |
|---|---|---|
| Mouth (buccal cavity) | Teeth chew food; tongue mixes it with saliva | Saliva contains salivary amylase (ptyalin) – starch digestion starts here |
| Pharynx and oesophagus | Swallowed food moves down by peristalsis | Epiglottis stops food entering the windpipe; no digestion in the oesophagus |
| Stomach | Churns food with gastric juice for a few hours | HCl makes it strongly acidic (pH about 1.5–3.5) and kills germs; pepsin digests protein; mucus protects the stomach wall |
| Small intestine (duodenum, jejunum, ileum) | Bile and pancreatic juice enter the duodenum; digestion is completed | Longest part of the canal (about 6–7 m); villi absorb digested food |
| Liver | Makes bile; stores glycogen; makes urea; removes toxins | Largest gland of the body; bile has no enzyme |
| Gall bladder | Stores and concentrates bile | Gall stones can block bile flow |
| Pancreas | Releases pancreatic juice with trypsin, amylase and lipase | Both exocrine (juice) and endocrine (insulin, glucagon) gland |
| Large intestine (caecum, colon, rectum) | Absorbs water and salts; forms faeces | About 1.5 m long; the appendix attached to the caecum is a vestigial organ |
| Anus | Removes undigested waste (egestion) | Controlled by a ring of muscle (sphincter) |
Where Each Nutrient is Digested
Each major nutrient is broken down by specific enzymes at specific places. Figure 2 shows the three pathways side by side – a very common source of exam questions.
Figure 2: Step-by-step digestion of carbohydrates, proteins and fats, and where the end products are absorbed
Digestive Enzymes at a Glance
| Gland / Juice | Enzyme | Acts on | Product |
|---|---|---|---|
| Salivary glands – saliva | Salivary amylase (ptyalin) | Starch | Maltose |
| Stomach – gastric juice | Pepsin | Proteins | Peptides |
| Stomach (infants) | Rennin | Milk protein (casein) | Curdled milk |
| Pancreas – pancreatic juice | Trypsin | Proteins, peptides | Smaller peptides |
| Pancreas – pancreatic juice | Pancreatic amylase | Starch | Maltose |
| Pancreas – pancreatic juice | Lipase | Emulsified fats | Fatty acids + glycerol |
| Small intestine – intestinal juice | Maltase, sucrase, lactase | Maltose, sucrose, lactose | Glucose, fructose, galactose |
| Small intestine – intestinal juice | Peptidases (erepsin) | Peptides | Amino acids |
| Liver – bile | No enzyme (bile salts) | Fats | Emulsified fat droplets |
Exam point: People who lack enough lactase cannot digest milk sugar properly – this is called lactose intolerance. Humans cannot digest cellulose because we do not make the enzyme cellulase; cows and goats can, with the help of bacteria in their rumen.
Carbohydrates – The Main Energy Source
Carbohydrates are made of carbon, hydrogen and oxygen. They are the cheapest and main source of energy, and in an Indian diet they come mostly from rice, wheat, millets, potatoes and sugar. Glucose is the fuel that every cell, especially the brain, uses. Extra glucose is stored as glycogen in the liver and muscles, and the rest is turned into fat.
| Type | Meaning | Examples and sources |
|---|---|---|
| Monosaccharides (simple sugars) | Single sugar unit; cannot be broken further | Glucose (grape sugar, blood sugar), Fructose (fruit sugar – sweetest natural sugar), Galactose |
| Disaccharides | Two sugar units joined | Sucrose (cane sugar = glucose + fructose), Lactose (milk sugar = glucose + galactose), Maltose (malt sugar = glucose + glucose) |
| Polysaccharides (complex) | Many sugar units; not sweet | Starch (plants' stored food), Glycogen ("animal starch"), Cellulose (plant cell wall – dietary fibre), Chitin (insect shells) |
Dietary fibre (roughage): Mostly cellulose from whole grains, fruits, vegetables and salads. It gives no energy because we cannot digest it, but it adds bulk to food, helps bowel movement and prevents constipation. Iodine solution turns starch blue-black – this is the common test for starch.
Proteins – The Body-Building Food
Proteins are made of long chains of smaller units called amino acids. They contain nitrogen in addition to carbon, hydrogen and oxygen. Proteins build and repair muscles, skin, hair and blood; they make enzymes, hormones like insulin, and antibodies that fight disease. That is why growing children, pregnant women and people recovering from illness need more protein.
About 20 amino acids are found in human proteins. Our body can make some of them (non-essential amino acids), but 9 essential amino acids must come from food. Animal proteins (milk, egg, fish, meat) contain all the essential amino acids and are called complete proteins. Most plant proteins lack one or more, but eating cereals and pulses together – like rice with dal or roti with rajma – makes the mixture complete.
| Rich sources of protein | Protein facts for exams |
|---|---|
| Pulses (dal), soyabean, groundnut, milk, paneer, curd, eggs, fish, meat | Soyabean is among the richest plant sources of protein |
| Hair and nails | Made of the protein keratin |
| Blood | Haemoglobin is an iron-containing protein |
| Bones and skin | Collagen – the most abundant protein in the body |
| Milk | Main protein is casein |
Fats (Lipids) – The Concentrated Energy Store
Fats give the most energy – about 9 kcal per gram, more than double that of carbohydrates or proteins. They are stored under the skin and around organs, where they keep the body warm and protect organs from shock. Fats are also needed to absorb vitamins A, D, E and K. Fats are made of fatty acids and glycerol.
| Type of fat | Nature | Sources | Effect on health |
|---|---|---|---|
| Saturated fat | Solid at room temperature | Ghee, butter, coconut oil, red meat | Too much raises bad cholesterol (LDL) |
| Unsaturated fat | Liquid at room temperature | Mustard, groundnut, sunflower and olive oils, nuts | Better for the heart |
| Omega-3 fatty acids | Essential polyunsaturated fat | Fish (including hilsa and rohu), flaxseed, walnuts | Good for heart and brain |
| Trans fat | Made when oils are partially hydrogenated | Vanaspati, repeatedly fried snacks, bakery items | Most harmful – raises heart disease risk |
Exam point: Vanaspati ghee is made by hydrogenation of vegetable oil using nickel as a catalyst. FSSAI has limited industrially produced trans fat in oils and foods to not more than 2%. Cholesterol is a fat-like substance made in the liver; animal foods contain it but plant foods do not.
Energy Values of Food
The energy in food is measured in kilocalories (kcal) or kilojoules (kJ). 1 kcal = 4.184 kJ. Figure 3 compares the energy given by one gram of each macronutrient.
Figure 3: Energy released by one gram of each macronutrient – fat gives more than twice as much
Example: A snack has 20 g carbohydrate, 5 g protein and 10 g fat. Energy = (20 × 4) + (5 × 4) + (10 × 9) = 80 + 20 + 90 = 190 kcal.
Vitamins – Small Amounts, Big Jobs
Vitamins are organic compounds needed in very small amounts for normal growth and good health. They do not give energy but help enzymes work. The term "vitamine" was coined by the Polish biochemist Casimir Funk in 1912. Vitamins A, D, E and K are fat-soluble and can be stored in the liver and fat. Vitamins B-complex and C are water-soluble – extra amounts leave the body in urine, so they must be eaten regularly. Vitamin C is easily destroyed by heat and long cooking.
| Vitamin | Chemical name | Main function | Deficiency disease | Sources |
|---|---|---|---|---|
| A | Retinol | Healthy eyes and skin | Night blindness, xerophthalmia | Carrot, papaya, mango, green leafy vegetables, milk, fish liver oil |
| B1 | Thiamine | Releases energy from carbohydrates; nerves | Beriberi | Whole grains, unpolished rice, pulses |
| B2 | Riboflavin | Energy release, skin | Cracks at mouth corners (cheilosis), sore tongue | Milk, eggs, green vegetables |
| B3 | Niacin | Energy release | Pellagra (3 Ds: dermatitis, diarrhoea, dementia) | Groundnut, meat, fish |
| B5 | Pantothenic acid | Energy metabolism | Burning feet syndrome | Most foods |
| B6 | Pyridoxine | Protein metabolism | Anaemia, skin and nerve problems | Cereals, meat, bananas |
| B7 | Biotin | Fat and sugar metabolism | Hair loss, skin rash | Egg yolk, nuts |
| B9 | Folic acid | Making new cells and DNA | Megaloblastic anaemia; neural tube defects in babies | Green leafy vegetables, pulses |
| B12 | Cyanocobalamin (contains cobalt) | RBC formation, nerves | Pernicious anaemia | Only animal foods – milk, eggs, meat, fish |
| C | Ascorbic acid | Healthy gums, wound healing, iron absorption, immunity | Scurvy (bleeding gums) | Amla (richest), guava, lemon, orange, tomato |
| D | Calciferol | Absorption of calcium for bones and teeth | Rickets (children), osteomalacia (adults) | Sunlight on skin, milk, egg yolk, fish |
| E | Tocopherol | Antioxidant; protects cells; fertility | Reproductive problems, weak muscles | Vegetable oils, nuts, wheat germ |
| K | Phylloquinone | Blood clotting | Excessive bleeding | Green leafy vegetables; also made by gut bacteria |
Exam point: Vitamin D is called the "sunshine vitamin" because skin makes it in sunlight, and it acts like a hormone. Vitamin B12 is the only vitamin with a metal (cobalt). Vitamin C is the vitamin most easily lost in cooking. Excess of fat-soluble vitamins, especially A and D, can be toxic.
Minerals – For Bones, Blood and Balance
Minerals are inorganic elements that the body cannot make. Macrominerals are needed in larger amounts (more than about 100 mg a day), and trace minerals (microminerals) in very small amounts.
| Mineral | Main function | Deficiency / excess | Sources |
|---|---|---|---|
| Calcium (Ca) | Bones, teeth, blood clotting, muscle contraction | Rickets, osteoporosis (weak bones) | Milk, curd, cheese, ragi, green vegetables |
| Phosphorus (P) | Bones, teeth, ATP and DNA | Weak bones | Milk, meat, cereals |
| Sodium (Na) and Potassium (K) | Water balance, nerve and muscle function | Low: muscle cramps; Excess sodium: high blood pressure | Common salt; bananas and potatoes (potassium) |
| Magnesium (Mg) | Enzymes, muscles and nerves | Muscle weakness | Green vegetables (Mg is at the centre of chlorophyll), nuts |
| Iron (Fe) | Part of haemoglobin, which carries oxygen | Anaemia (tiredness, pale skin) | Green leafy vegetables, jaggery, dates, liver, meat |
| Iodine (I) | Making thyroxine (thyroid hormone) | Goitre; cretinism in children | Iodised salt, sea food |
| Zinc (Zn) | Growth, immunity, wound healing | Stunted growth, poor immunity | Pulses, nuts, meat |
| Fluorine (F) | Strong tooth enamel | Less: tooth decay; Excess: fluorosis (mottled teeth, bone damage) | Drinking water, tea |
| Cobalt (Co) | Part of vitamin B12 | Anaemia | Animal foods |
Exam point: Iron deficiency anaemia is the most common nutritional problem in India, especially among women and children. Vitamin C helps the body absorb iron, while tea taken with meals reduces iron absorption. Excess arsenic in groundwater, found in several districts of West Bengal, causes arsenicosis.
Water – The Forgotten Nutrient
About 60–70% of the adult human body is water. Water carries nutrients and wastes, helps digestion, controls body temperature through sweat, and keeps joints lubricated. Loss of water and salts due to diarrhoea causes dehydration, which can be dangerous for children. Oral Rehydration Solution (ORS) – a mixture of salt, sugar and water – is the simple, life-saving treatment.
Malnutrition and Deficiency Diseases
Malnutrition means "bad nutrition". It includes undernutrition (too little food or nutrients) and overnutrition (too much food leading to obesity). Hidden hunger is the deficiency of micronutrients like iron, iodine, vitamin A and zinc even when a person eats enough calories.
| Condition | Cause | Signs |
|---|---|---|
| Kwashiorkor | Lack of protein (calories may be enough) | Swollen belly and legs (oedema), thin hair, skin patches; usually in children aged 1–5 years |
| Marasmus | Lack of both protein and calories | Extremely thin child, "skin and bones", no swelling; usually in infants |
| Stunting | Long-term undernutrition | Low height for age |
| Wasting | Recent severe undernutrition or illness | Low weight for height |
| Underweight | Combination of the above | Low weight for age |
| Obesity | Too many calories, too little activity | Excess body fat; risk of diabetes, heart disease, high BP |
Body Mass Index (BMI)
BMI is a simple way to check whether a person's weight is healthy for their height.
BMI = Weight (kg) ÷ [Height (m)]²
Example: A person weighs 64 kg and is 1.6 m tall. BMI = 64 ÷ (1.6 × 1.6) = 64 ÷ 2.56 = 25.
| BMI (WHO classification) | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal |
| 25 – 29.9 | Overweight |
| 30 and above | Obese |
So the person in the example falls just into the overweight range. For Asian populations, including Indians, health experts often use lower cut-offs (overweight from 23) because Indians tend to carry more body fat at the same BMI.
Balanced Diet – The Right Food in the Right Amount
A balanced diet contains all the nutrients – carbohydrates, proteins, fats, vitamins, minerals, water and fibre – in the right proportion to meet the body's needs. Needs depend on age, sex, body weight, physical activity and conditions like pregnancy. A labourer needs more calories than an office worker, and a growing teenager needs more protein and calcium than an older adult.
In India, the National Institute of Nutrition (NIN), Hyderabad, a unit of ICMR, issues the Dietary Guidelines for Indians. Its revised guidelines released in 2024 contain 17 guidelines. They stress eating a variety of foods, filling a large part of the plate with vegetables and fruits, choosing whole grains and millets, getting protein from pulses, milk, eggs, fish or meat, limiting salt, sugar and oil, avoiding ultra-processed foods, and drinking enough safe water. Figure 4 shows a simple balanced plate based on this idea.
Figure 4: A simple balanced plate – half vegetables and fruits, the rest shared between cereals, protein foods and milk
Food Groups and What They Give
| Food group | Examples | Main nutrients | Role |
|---|---|---|---|
| Cereals and millets | Rice, wheat, ragi, jowar, bajra | Carbohydrates, some protein, B vitamins, fibre | Energy-giving |
| Pulses, eggs, fish, meat | Dal, chana, rajma, soyabean, egg, fish, chicken | Protein, iron, B vitamins | Body-building |
| Milk and milk products | Milk, curd, paneer | Protein, calcium, vitamin B2 | Body-building |
| Vegetables and fruits | Spinach, carrot, pumpkin, guava, banana, amla | Vitamins, minerals, fibre | Protective |
| Fats, oils, nuts and sugar | Mustard oil, ghee, groundnut, jaggery | Fats, energy | Energy-giving (use in small amounts) |
Millets – the "Nutri-cereals": Millets like ragi (finger millet), jowar and bajra are rich in fibre, iron and calcium. Ragi is especially rich in calcium. At India's proposal, the United Nations declared 2023 the International Year of Millets, and the Government of India calls millets "Shree Anna".
Government Nutrition Programmes in India
| Programme | Started | Key points |
|---|---|---|
| Integrated Child Development Services (ICDS) | 2 October 1975 | Supplementary nutrition, health check-ups and pre-school education through Anganwadi centres |
| Mid-Day Meal / PM POSHAN | National scheme 1995; renamed PM POSHAN in 2021 | Hot cooked meal for children in government and aided schools |
| POSHAN Abhiyaan (National Nutrition Mission) | 8 March 2018, launched from Jhunjhunu, Rajasthan | Reduce stunting, undernutrition, anaemia and low birth weight; September is observed as Rashtriya Poshan Maah |
| Anaemia Mukt Bharat | 2018 | Iron and folic acid supplements, deworming and testing |
| National Iodine Deficiency Disorders Control Programme | Began as the Goitre Control Programme in 1962 | Universal use of iodised salt |
| Eat Right India (FSSAI) | 2018 | Safe, healthy and sustainable food; campaigns against trans fat and excess salt and sugar |
West Bengal Connection – Food, Nutrition and History
The traditional Bengali meal of rice and fish – "maachh-bhaat" – is a good example of a cereal paired with high-quality protein. River and pond fish such as rohu, katla and hilsa provide protein and healthy omega-3 fats, while greens (shaak) and seasonal vegetables add vitamins and minerals. The tragic Bengal Famine of 1943, in which around three million people died, remains one of the darkest chapters of food insecurity in Indian history and is often asked in WBCS and history-linked science questions. Economist Amartya Sen, born in Santiniketan, showed through his study of this famine that famines can happen even when food is available if people lose the means to buy it; he received the Nobel Prize in Economics in 1998.
For more practice with science questions, try our CSIR NAL MTS Mock Test. You can also read about India's natural grassland and scrubland ecosystems, the VAIBHAV Fellowship for Indian-origin scientists, and the new ISRO Space Gallery at Darbhanga. All our biology notes are in the Science section.
Quick Revision Box – Easy Tricks to Memorise
Trick 1 – "4-4-9"
Carbohydrate 4, Protein 4, Fat 9 kcal per gram. "Fat is Fine-9."
Trick 2 – Where digestion starts: "Mouth–Stomach–Small"
Carbohydrate starts in the Mouth, Protein in the Stomach, Fat in the Small intestine.
Trick 3 – Fat-soluble vitamins "DEAK"
D, E, A, K dissolve in fat; B and C dissolve in water.
Trick 4 – "Night, Beri, Scurvy, Rickets, Bleed" in A-B-C-D-K order
Vitamin A – Night blindness, B1 – Beriberi, C – Scurvy, D – Rickets, K – Bleeding (no clotting).
Trick 5 – Pellagra's 3 Ds
Niacin (B3) deficiency causes Dermatitis, Diarrhoea and Dementia.
Trick 6 – "Cobalt is Twelve's metal"
Vitamin B12 contains cobalt and is found only in animal foods.
Trick 7 – Sugars: "Fruit – Milk – Cane – Malt"
Fructose = fruit sugar, Lactose = milk sugar, Sucrose = cane sugar, Maltose = malt sugar.
Trick 8 – "Kwashiorkor = Kwash-Protein, Marasmus = Most Missing"
Kwashiorkor – only protein missing (swollen belly). Marasmus – both protein and calories missing (very thin).
Trick 9 – Mineral pairs "Iron-Anaemia, Iodine-Goitre, Calcium-Bones"
Also: Fluoride less = tooth decay, Fluoride excess = fluorosis.
Trick 10 – BMI "W over H square"
BMI = kg ÷ m². Normal 18.5–24.9; 25+ overweight; 30+ obese.
Trick 11 – "Bile has No Bite"
Bile has no enzyme; it only emulsifies fat. It is made in the liver and stored in the gall bladder.
Trick 12 – Amla for C
Amla is the richest common source of vitamin C; vitamin C helps iron absorption.
Trick 13 – Nutrition calendar
ICDS 1975 (2 October), POSHAN Abhiyaan 2018 (8 March), Poshan Maah = September, Year of Millets = 2023.
20 MCQs on Digestive System and Nutrition
Q1. Digestion of starch begins in the:
(a) Stomach
(b) Mouth
(c) Small intestine
(d) Large intestine
Answer: (b) – Salivary amylase (ptyalin) in saliva starts breaking starch into maltose in the mouth.
Q2. Which enzyme starts the digestion of proteins in the stomach?
(a) Trypsin
(b) Lipase
(c) Pepsin
(d) Amylase
Answer: (c) – Pepsin works in the acidic stomach; trypsin from the pancreas continues protein digestion in the intestine.
Q3. Bile helps in the digestion of fats by:
(a) Emulsifying them
(b) Converting them into glucose
(c) Acting as an enzyme
(d) Making the medium acidic
Answer: (a) – Bile salts break fat into tiny droplets; bile itself has no enzyme and makes the medium alkaline.
Q4. One gram of fat gives about how much energy?
(a) 4 kcal
(b) 6 kcal
(c) 2 kcal
(d) 9 kcal
Answer: (d) – Fats give about 9 kcal per gram, while carbohydrates and proteins give about 4 kcal per gram.
Q5. Fructose is commonly known as:
(a) Fruit sugar
(b) Milk sugar
(c) Cane sugar
(d) Malt sugar
Answer: (a) – Fructose is fruit sugar and the sweetest natural sugar; lactose is milk sugar and sucrose is cane sugar.
Q6. Glycogen is stored mainly in the:
(a) Kidneys and lungs
(b) Liver and muscles
(c) Brain and heart
(d) Pancreas and spleen
Answer: (b) – Extra glucose is stored as glycogen ("animal starch") in the liver and muscles.
Q7. Humans cannot digest cellulose because they lack:
(a) Amylase
(b) Pepsin
(c) Cellulase
(d) Lipase
Answer: (c) – Without cellulase, cellulose passes through as dietary fibre, which still helps bowel movement.
Q8. How many amino acids are essential for adult humans and must come from food?
(a) 20
(b) 12
(c) 5
(d) 9
Answer: (d) – About 20 amino acids are found in proteins; 9 of them cannot be made by the body.
Q9. Kwashiorkor is caused by the deficiency of:
(a) Protein
(b) Carbohydrates
(c) Vitamin A
(d) Iron
Answer: (a) – Kwashiorkor is protein deficiency with swelling; marasmus is a deficiency of both protein and calories.
Q10. Which vitamin is called the "sunshine vitamin"?
(a) Vitamin A
(b) Vitamin D
(c) Vitamin C
(d) Vitamin K
Answer: (b) – The skin makes vitamin D in sunlight; its deficiency causes rickets in children.
Q11. Which vitamin contains cobalt?
(a) Vitamin B1
(b) Vitamin E
(c) Vitamin B12
(d) Vitamin C
Answer: (c) – Vitamin B12 (cyanocobalamin) contains cobalt; its deficiency causes pernicious anaemia.
Q12. Pellagra is caused by deficiency of:
(a) Thiamine
(b) Riboflavin
(c) Folic acid
(d) Niacin
Answer: (d) – Niacin (B3) deficiency causes pellagra; thiamine (B1) deficiency causes beriberi.
Q13. The richest common source of vitamin C is:
(a) Amla
(b) Carrot
(c) Milk
(d) Rice
Answer: (a) – Amla (Indian gooseberry) is very rich in vitamin C, whose deficiency causes scurvy.
Q14. Goitre is caused by deficiency of:
(a) Iron
(b) Iodine
(c) Calcium
(d) Zinc
Answer: (b) – Iodine is needed to make thyroxine; its lack enlarges the thyroid gland.
Q15. Excess fluoride in drinking water causes:
(a) Anaemia
(b) Goitre
(c) Fluorosis
(d) Scurvy
Answer: (c) – Too much fluoride causes fluorosis (mottled teeth, bone damage); too little causes tooth decay.
Q16. A person weighs 81 kg and is 1.8 m tall. What is his BMI?
(a) 45
(b) 22
(c) 30
(d) 25
Answer: (d) – BMI = 81 ÷ (1.8 × 1.8) = 81 ÷ 3.24 = 25.
Q17. Most of the absorption of digested food takes place in the:
(a) Small intestine
(b) Stomach
(c) Large intestine
(d) Oesophagus
Answer: (a) – Finger-like villi in the small intestine absorb digested food; the large intestine mainly absorbs water.
Q18. Vanaspati ghee is made from vegetable oil by the process of:
(a) Oxidation
(b) Hydrogenation
(c) Fermentation
(d) Distillation
Answer: (b) – Hydrogen is added using a nickel catalyst; partial hydrogenation creates harmful trans fats.
Q19. POSHAN Abhiyaan was launched in 2018 from which state?
(a) Gujarat
(b) Uttar Pradesh
(c) Rajasthan
(d) West Bengal
Answer: (c) – It was launched on 8 March 2018 from Jhunjhunu, Rajasthan.
Q20. The United Nations declared which year as the International Year of Millets?
(a) 2021
(b) 2022
(c) 2024
(d) 2023
Answer: (d) – 2023 was the International Year of Millets, declared at India's proposal.
Want more practice? Try our Daily GK Quiz and Mock Tests.
Conclusion
Good health depends on both a working digestive system and the right food. The mouth, stomach and small intestine break carbohydrates, proteins and fats into glucose, amino acids and fatty acids, and the villi absorb them into the body. Vitamins and minerals, though needed in tiny amounts, protect us from diseases like scurvy, rickets, anaemia and goitre. For exams, remember the enzymes and where they act, the 4-4-9 energy rule, types of sugars, the vitamin and mineral tables, kwashiorkor versus marasmus, the BMI formula and the major nutrition schemes. Revise the tricks above and practise the MCQs regularly.
Reference: NCERT Science Class VI–X (Components of Food; Nutrition in Animals; Life Processes); NCERT Biology Class XI; ICMR–NIN Dietary Guidelines for Indians (2024); Ministry of Women and Child Development.
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Pradip Chakraborty is the founder and editor of CrackGK. Every article is checked against official and trusted sources such as PIB, NCERT and government websites before publishing. Spotted a mistake? Let us know.