Master DAV Class 6 Science Chapter 2: Food with comprehensive, top-scoring solutions from the official DAV textbook The Living World. Here you will find step-by-step verified answers to all questions in Something To Know (Sections A, B, C, D, E), structured food nutrient testing procedures, 3-column deficiency disease tables, Value-Based Questions, and authentic DAV Board Examination Questions (PYQs).
🍎 Chapter 2 Quick Revision & Key Concepts Summary:
- Food Functions: Supplies energy for metabolic activities, enables body tissue growth and repair, and builds immunity against infectious diseases.
- Major Nutrients: Carbohydrates & Fats (Energy-giving foods), Proteins (Body-building foods), and Vitamins & Minerals (Protective foods).
- Water & Roughage: Dietary fibres provide bulk to stool and prevent constipation; water transports nutrients and regulates body temperature.
- Nutrient Tests: Starch test (turns blue-black with Iodine), Protein test (turns yellow with concentrated Nitric Acid / violet with Copper Sulphate + Caustic Soda), Fat test (leaves translucent oily mark on dry paper).
- Deficiency Diseases: Kwashiorkor (Protein deficiency), Marasmus (Protein & calorie deficiency), Anaemia (Iron deficiency), Goitre (Iodine deficiency), Scurvy (Vitamin C deficiency), Rickets (Vitamin D & Calcium deficiency).
- Balanced Diet: A daily diet providing all essential nutrients in proper proportions, alongside sufficient roughage and water.
Something To Know — A. Fill in the blanks
1. Living organisms need food to grow and survive.
Exam Note: Nutrients in food fuel cellular respiration and provide substrates for cell multiplication and tissue repair.
2. Vitamins A, D, E and K are soluble in fat whereas Vitamin B and C are water soluble.
Exam Note: Water-soluble vitamins cannot be stored in large quantities in the human body and must be regularly replenished in the diet.
3. The deficiency of vitamin B, in the diet, causes a disease called Beri-Beri.
Exam Note: Specifically Vitamin B1 (Thiamine); leads to weakened muscles and peripheral nerve damage.
4. Vitamin K helps in clotting of blood.
Exam Note: Synthesizes prothrombin, a key coagulation protein that prevents fatal haemorrhage during injuries.
5. The dietary Fibres constitute roughage.
Exam Note: Insoluble plant cellulose adds bulk to digestive chyme and facilitates smooth bowel movement.
B. Write True or False for the following statements
1. Vitamins and minerals are bodybuilding foods.
Answer: False
Correction / Scientific Reason: Vitamins and minerals are protective foods that guard the body against infectious diseases. Proteins are bodybuilding foods.
2. Our skin makes Vitamin E in the presence of sunlight.
Answer: False
Correction / Scientific Reason: Our skin synthesizes Vitamin D (the ‘sunshine vitamin’) when exposed to morning solar ultraviolet rays, not Vitamin E.
3. Deficiency of phosphorous can lead to anaemia.
Answer: False
Correction / Scientific Reason: Anaemia is caused by deficiency of Iron (which forms haemoglobin). Deficiency of phosphorus weakens bones and teeth.
4. We should eat food that has all its essential components in the right proportions.
Answer: True
Scientific Reason: Consuming a balanced diet with proper nutrient proportions ensures healthy organ functioning and prevents nutritional deficiency disorders.
5. Kwashiorkor occurs due to the deficiency of fat in the diet.
Answer: False
Correction / Scientific Reason: Kwashiorkor is caused by severe deficiency of proteins in the diet of young children.
C. Tick the correct option
1. When a drop of iodine solution was put on the cut surface of a potato, it turned blue-black in colour. This indicates the presence of—
(a) fat
(b) protein
(c) starch
(d) vitamin
Answer: (c) starch
Explanation: Iodine chemically reacts with complex carbohydrate starch chains to form a distinctive deep blue-black charge-transfer complex.
2. The deficiency of Vitamin A, in the diet, causes a disease known as—
(a) scurvy
(b) night blindness
(c) rickets
(d) beriberi
Answer: (b) night blindness
Explanation: Vitamin A (retinol) is essential for synthesizing rhodopsin pigment in retinal rod cells, without which vision in dim light fails.
3. Iron is essential for—
(a) development of strong bones
(b) formation of haemoglobin
(c) developing healthy teeth
(d) healthy skin
Answer: (b) formation of haemoglobin
Explanation: Iron binds with globin protein to create haemoglobin inside red blood cells, which carries oxygen from lungs to all body cells.
4. A child, who has bow legs, is suffering from a deficiency disease, known as—
(a) rickets
(b) anaemia
(c) goitre
(d) scurvy
Answer: (a) rickets
Explanation: Deficiency of Vitamin D and calcium prevents bone calcification; child’s leg bones remain soft and bend outward under body weight into bow legs.
5. The deficiency of proteins, in the diet of children, can cause a disease known as—
(a) anaemia
(b) marasmus
(c) kwashiorkor
(d) goitre
Answer: (c) kwashiorkor
Explanation: Pure protein deficiency manifests as kwashiorkor (protruding pot-belly and swollen oedema limbs), whereas deficiency of both proteins and calories causes marasmus.
D. Answer the following questions in brief
1. Name the important sources of our food.
Answer: The two fundamental sources of our food are:
1. Plant Sources: Cereals (wheat, rice, maize), pulses, vegetables, fruits, oilseeds, sugar, and spices.
2. Animal Sources: Milk and dairy products (butter, cheese, curd), eggs, meat, fish, and honey.
2. State the importance of carbohydrates in our diet.
Answer: Carbohydrates (consisting of carbon, hydrogen, and oxygen) are the primary energy-giving nutrients in our diet. In food, they occur as sugars and starches. They are broken down into glucose during digestion, supplying instant energy to fuel muscular and cellular activities.
3. Name the vitamin whose deficiency causes the disease of—
(a) night blindness → Vitamin A
(b) beri-beri → Vitamin B (B1)
(c) scurvy → Vitamin C
(d) rickets → Vitamin D
4. Name any three of the minerals needed by our body.
Answer: Three essential minerals required by our body are:
1. Calcium (builds strong bones and teeth, assists blood clotting)
2. Iron (essential for haemoglobin synthesis to transport oxygen)
3. Iodine (required for normal functioning of the thyroid gland)
5. State the role of calcium in our body.
Answer: Calcium is vital for:
1. Building and maintaining rigid, strong bones and teeth.
2. Regulating normal muscle contraction and nerve impulses.
3. Assisting normal blood clotting to prevent excessive bleeding during cuts.
6. Write the full forms of the terms PEM and PCM.
Answer:
• PEM: Protein – Energy – Malnutrition
• PCM: Protein – Calorie – Malnutrition
Exam Note: PEM and PCM are widespread nutritional disorders occurring in young children due to severe lack of dietary proteins and caloric energy.
E. Answer the following questions in detail
1. Name two rich sources of each of the following:
(a) Carbohydrates: Rice, Wheat, Potatoes, Bananas
(b) Proteins: Soybean, Pulses (dal), Milk, Eggs, Fish
(c) Fats: Butter, Ghee, Mustard oil, Groundnuts
(d) Roughage: Green leafy vegetables, Whole grain salads, Apples, Guavas
(e) Vitamin A: Carrots, Papaya, Milk, Spinach
(f) Vitamin C: Amla (Indian gooseberry), Lemons, Oranges, Guavas
2. Describe one test each for detecting the presence of the following in food:
(a) Proteins
(b) Starch
(c) Fats
(a) Test for Proteins (Nitric Acid Test as per DAV Textbook):
- Materials Required: Mortar and pestle, test tube, dropper, concentrated nitric acid.
- Procedure: Crush some bean or gram seeds in a mortar. Add water to make a suspension. Take 2 ml of this suspension in a clean test tube. Carefully add a few drops of concentrated nitric acid.
- Observation: The suspension turns distinct yellow in colour, confirming the presence of proteins. (Alternatively, adding copper sulphate and caustic soda yields a violet colour).
(b) Test for Starch (Iodine Test):
- Materials Required: Dilute iodine solution, dropper, food sample (boiled potato slice or bread).
- Procedure: Place a small piece of food on a watch glass. Using a dropper, add 2 to 3 drops of dilute iodine solution.
- Observation: The food surface immediately turns blue-black in colour, proving the presence of starch.
(c) Test for Fats (Translucent Paper Spot Test):
- Materials Required: Food sample (groundnut, butter, or drop of oil), a sheet of clean white paper.
- Procedure: Wrap the food sample in a piece of clean dry paper and crush it gently without tearing the paper. Straighten the paper and hold it against a light source.
- Observation: An oily, translucent spot appears on the paper that allows light to pass partially, proving the presence of fats.
3. Why do we need proteins and how do they affect our health?
Answer: Proteins are known as the ‘building blocks of life’ because every living cell is composed of proteins. Their vital functions and health impacts include:
1. Tissue Growth & Development: Essential for building new cells and developing muscular tissues in growing children and teenagers.
2. Wear and Tear Repair: Repairs damaged tissues, heals wounds, and replaces dead skin and blood cells across all ages.
3. Enzyme and Hormone Synthesis: Produces vital digestive enzymes, haemoglobin, antibodies, and growth hormones.
Lack of protein in childhood leads to stunted skeletal growth, muscle wasting, and severe deficiency disorders like Kwashiorkor.
4. A mineral ‘X’ is essential for the formation of a component ‘Y’, in the blood of a person. The function of component ‘Y’ is to transport oxygen in the body. The deficiency of mineral ‘X’, in the diet of a person, causes a disease ‘Z’. Identify X, Y and Z. Also mention the symptoms of disease Z.
Answer:
• Mineral ‘X’: Iron
• Component ‘Y’: Haemoglobin
• Disease ‘Z’: Anaemia
Symptoms of Anaemia:
1. The person looks unusually pale, tired, and weak with persistent lethargy.
2. Loss of appetite and dizziness upon physical exertion.
3. Whitening or loss of pink colour in fingernails, gums, and tongue.
4. Shortness of breath and swelling of hands and feet.
5. Deficiency of iodine is more common in mountainous regions. Why?
Answer: Deficiency of iodine (causing Goitre) is significantly more common in mountainous and hilly regions because:
1. Frequent heavy rainfall, snowmelt, and swift river currents wash away the soluble iodine minerals from mountain topsoils (soil leaching).
2. Consequently, both local soil and river drinking water in hilly areas are severely deficient in iodine.
3. The crops and vegetables grown in this depleted soil also lack iodine, depriving the local inhabitants of essential dietary iodine.
6. What is a balanced diet? Why should we take a balanced diet?
Answer: A balanced diet is a daily meal that contains all essential nutrients (carbohydrates, fats, proteins, vitamins, and minerals) in the right proportions, along with an adequate quantity of roughage and water.
Why we should take a balanced diet:
1. Provides sufficient caloric energy for daily physical and mental work without causing obesity.
2. Facilitates continuous growth and cellular tissue repair.
3. Strengthens the immune system to guard against infectious diseases.
4. Completely prevents nutritional deficiency diseases like kwashiorkor, marasmus, scurvy, and anaemia.
Master Deficiency Diseases & Vitamin Summary Table
| Nutrient / Vitamin | Deficiency Disease | Prominent Symptoms | Rich Food Sources |
|---|---|---|---|
| Protein | Kwashiorkor | Protruding pot-belly, swollen legs and face, discoloured hair, stunted growth. | Milk, soybean, pulses, eggs, fish |
| Protein & Calories | Marasmus | Severe muscle wasting, ribs clearly visible, loose wrinkled skin, sunken eyes. | Cereals, pulses, milk, bananas |
| Vitamin A | Night Blindness | Inability to see in dim light/night; dry conjunctiva and corneal opacity. | Carrots, papaya, mango, spinach |
| Vitamin B (B1) | Beri-Beri | Weak muscles, extreme exhaustion, nerve inflammation, numbness in limbs. | Unpolished rice, yeast, nuts, peas |
| Vitamin C | Scurvy | Bleeding and spongy gums, loose teeth, delayed wound healing, joint pain. | Amla, lemon, orange, guava, tomato |
| Vitamin D / Calcium | Rickets | Soft, weak bones; outward bent bow legs; pigeon chest; knock knees. | Morning sunlight, milk, egg yolk |
| Iron | Anaemia | Pale skin, fatigue, shortness of breath, whitening of nails, loss of appetite. | Spinach, jaggery (gur), apples, liver |
| Iodine | Goitre | Abnormal swelling of the thyroid gland in the neck; mental retardation in infants. | Iodised salt, sea fish, seaweed |
Value-Based Questions (VBQ) & HOTS (Higher Order Thinking Skills)
💡 Value-Based Question (VBQ):
Question: Aarav noticed that his friend brought packaged chips and cola drinks in his lunchbox every day, complaining of tiredness during physical education class. Aarav shared his lunch of fresh vegetable roti and boiled sprouts, advising him to eat balanced home-cooked meals.
Values Displayed: Empathy, caring attitude towards peers, awareness of healthy dietary choices over nutrient-empty junk food.
🧠 Higher Order Thinking Skill (HOTS):
Question: A boy consumes 2 glasses of milk, 4 chapattis, rice, and butter daily, but completely avoids eating green vegetables and fresh fruits. Will he stay healthy in the long run? Justify.
Answer: No, he will not stay healthy. While his diet provides plenty of carbohydrates, fats, and calcium, it is severely lacking in Vitamin C and dietary roughage. Over time, he will likely suffer from bleeding gums (scurvy) and chronic severe constipation due to the absence of dietary fiber.
🎯 DAV Examination Corner: Authentic Board Exam Questions (PYQs 2022–23 & 2023–24)
Below are authentic questions directly retrieved from the DAV Public Schools Common Examination (Half-Yearly & Annual Board Papers) covering Chapter 2:
Q1. [DAV Half-Yearly Exam 2022–23 • 1 Mark VSA]
The disease that occurs in humans due to lack of vitamin C is —
(i) Night-blindness (ii) Scurvy (iii) Beri-beri (iv) None of these
Model Answer: (ii) Scurvy. Symptoms include spongy bleeding gums and loose teeth.
Q2. [DAV Half-Yearly Exam 2022–23 • 1 Mark VSA]
The chemical used to test the presence of protein is —
(i) Nitric acid (ii) Iodine (iii) Ethanol (iv) All of the above
Model Answer: (i) Nitric acid. In the DAV textbook procedure, concentrated nitric acid turns a protein suspension into a yellow colour.
Q3. [DAV Half-Yearly Exam 2023–24 • 4-Bit Case Study MCQ]
Case Paragraph: “Vitamins are organic compounds needed in small quantities. Each organism has different requirements. Humans synthesize Vitamin D under sunlight, but must obtain Vitamin C from food…”
(I) Which vitamin is called sunshine vitamin? → (c) Vitamin D
(II) Beriberi occurs due to lack of: → (a) Vitamin B
(III) Due to lack of Vitamin E humans suffer from: → (d) Sterility / reproductive disorders
(IV) Select the vitamin which gets destroyed by heating: → (b) Vitamin C
Q4. [DAV Half-Yearly Exam 2022–23 • 3 Marks SA-II]
Name two rich sources of: (a) Fats (b) Proteins (c) Vitamin C
Model Answer:
(a) Fats: Ghee, Butter, Groundnuts
(b) Proteins: Pulses (dal), Soybean, Milk
(c) Vitamin C: Amla, Lemons, Oranges
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