Biology Nutrition
Biology Nutrition – RRB Science Study Material
Key Concepts & Formulas
| # | Concept | Quick Explanation |
|---|---|---|
| 1 | Nutrients | Chemical substances in food (carbohydrates, proteins, fats, vitamins, minerals, water) needed for energy, growth & repair. |
| 2 | Calorific Value | Energy released on complete oxidation: CHO = 4 kcal/g, Protein = 4 kcal/g, Fat = 9 kcal/g. |
| 3 | Balanced Diet | Daily intake of ≈ 55 % CHO, 25 % fat, 15 % protein plus vitamins–minerals for 2000 kcal (adult Indian). |
| 4 | Photosynthesis | 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂; occurs in chloroplast; light & dark reactions; produces 1 glucose + 686 kcal. |
| 5 | Enzymes of GIT | Salivary amylase (ptyalin) → maltose; Pepsin (stomach) → peptides; Trypsin (pancreas) → peptides; Lipase → fatty acids + glycerol. |
| 6 | Vitamins & Deficiency | A – night-blindness; B₁ – beri-beri; C – scurvy; D – rickets; K – delayed clotting. |
| 7 | BMI | Body-Mass Index = weight(kg) / height²(m); 18.5–24.9 normal, >30 obesity. |
10 Practice MCQs
Q1. Which nutrient gives the highest energy per gram?
Answer: D) Fat
Solution:
Calorific values: CHO 4, Protein 4, Fat 9 kcal/g → Fat highest.
Shortcut: Remember “9 for Fat, 4 for rest”.
Concept: Calorific values of macronutrients.
Q2. Night-blindness is caused by deficiency of which vitamin?
Answer: A) Vitamin A
Solution:
Vitamin A forms retinal for eye → deficiency → night-blindness.
Shortcut: “A for Apple & Eyes”.
Concept: Fat-soluble vitamins.
Q3. The enzyme present in human saliva is
Answer: B) Ptyalin
Solution:
Salivary amylase is also called ptyalin; starts starch digestion.
Concept: Digestive enzymes.
Q4. A 60 kg Indian coolie needs 2400 kcal/day. If his diet supplies 300 g carbohydrates, how much extra energy must come from fat?
Answer: C) 1200 kcal
Solution:
CHO energy = 300 g × 4 = 1200 kcal
Required = 2400 kcal
Remaining = 1200 kcal → must come from fat/protein.
Shortcut: ½ energy by CHO → rest by fat+protein.
Concept: Balanced diet calculations.
Q5. Photosynthesis converts solar energy into chemical energy at the rate of about
Answer: A) 686 kcal per mole of glucose
Solution:
1 mole glucose stores ≈ 686 kcal; this is standard textbook value.
Concept: Photosynthesis energy balance.
Q6. A train pantry car uses potatoes (20 % starch). 200 g potatoes yield how much energy?
Answer: B) 160 kcal
Solution:
Starch = 20 % of 200 g = 40 g; treat as CHO → 40 × 4 = 160 kcal.
Shortcut: 1 g CHO = 4 kcal.
Concept: Energy from food.
Q7. Which pair is NOT correctly matched?
Answer: C) Pepsin – Small intestine
Solution:
Pepsin acts in stomach, not SI; others correct.
Concept: Enzyme location.
Q8. BMI of an RPF constable is 28. His category is
Answer: C) Overweight
Solution:
BMI 25–29.9 = overweight; >30 = obese.
Concept: BMI classification.
Q9. A railway worker’s diet contains 50 g fat, 100 g protein, 400 g CHO. Percentage of total kcal from fat is
Answer: B) 29 %
Solution:
Fat = 50 × 9 = 450 kcal
Protein = 100 × 4 = 400 kcal
CHO = 400 × 4 = 1600 kcal
Total = 2450 kcal
% from fat = (450/2450) × 100 ≈ 18.4 % (nearest option 20 %).
Shortcut: Fat % ≈ (9×g fat)/(total kcal) × 100.
Concept: Macronutrient distribution.
Q10. During marathon duty, a runner stores 450 g glycogen. How many minutes can he run at 15 kcal/min if glycogen is sole fuel?
Answer: C) 120 min
Solution:
Glycogen energy = 450 g × 4 = 1800 kcal
Time = 1800 / 15 = 120 min.
Shortcut: 1 g glycogen ≈ 4 kcal → divide total kcal by rate.
Concept: Energy storage & expenditure.
5 Previous Year Questions
PYQ 1. The main site of photosynthesis in green plants is RRB NTPC 2021 CBT-1
Answer: C) Chloroplast
Solution:
Chloroplast contains chlorophyll where light reaction & Calvin cycle occur.
Exam Tip: “Chloroplast = Photosynthesis factory”.
PYQ 2. Deficiency of Vitamin D causes RRB Group D 2022
Answer: B) Rickets in children
Solution:
Vit-D regulates Ca-P metabolism; deficiency softens bones → rickets.
Exam Tip: “D for Dense bones”.
PYQ 3. Which enzyme is secreted by the stomach? RRB ALP 2018
Answer: A) Pepsin
Solution:
Gastric chief cells secrete pepsinogen → HCl converts to pepsin.
Exam Tip: “Pepsin starts protein digestion”.
PYQ 4. Calorific value of protein is RRB JE 2019
Answer: C) 4 kcal/g
Solution:
Same as carbohydrates; fat is 9 kcal/g.
Exam Tip: Remember 4-4-9 rule.
PYQ 5. Night-blindness is due to lack of RPF SI 2019
Answer: A) Vitamin A
Solution:
Retinal (from Vit-A) is part of rhodopsin in rods.
Exam Tip: Most repeated; mug-up Vit A–eyes link.
Speed Tricks & Shortcuts
| Situation | Shortcut | Example |
|---|---|---|
| Calorific value recall | “4-4-9” – CHO 4, Protein 4, Fat 9 kcal/g | 50 g butter → 50×9 = 450 kcal |
| Vitamin-deficiency match | “ABCDK” – A-eyes, B-beri, C-cut bleeding, D-deform bones, K-klotting | Scurvy → C |
| Photosynthesis equation | “6-6-1-6” – 6CO₂ + 6H₂O → 1C₆H₁₂O₆ + 6O₂ | Recall 6’s |
| BMI category | 18-25-30 rule – <18 thin, 25-30 over, >30 obese | 27 → overweight |
| Enzyme location | “SPEL” – Saliva-Ptyalin, stomach-Pepsin, intestine-Lipase | Order of action |
Common Mistakes to Avoid
| Mistake | Why Students Make It | Correct Approach |
|---|---|---|
| Confusing pepsin & trypsin sites | Similar names | Pepsin-STOMACH, Trypsin-SMALL intestine |
| Taking 1 kcal = 1000 J as 1 cal = 4.2 J | Unit mix-up | In biology, always use kcal (Calorie) values given |
| Forgetting water is a nutrient | Only solids considered | Water = essential nutrient; 2-3 L/day |
| Over-estimating protein energy | Assume 9 kcal/g | Protein = 4 kcal/g same as CHO |
| Skipping dark reaction details | Focus only on light | Remember Calvin cycle also inside chloroplast |
Quick Revision Flashcards
| Front | Back |
|---|---|
| Calorific value of fat | 9 kcal/g |
| Deficiency of Vit-C | Scurvy |
| Organ where bile stored | Gall bladder |
| Enzyme converting maltose → glucose | Maltase |
| Photosynthesis pigment | Chlorophyll-a |
| BMI formula | weight(kg)/height²(m) |
| Daily CHO % in balanced diet | ~55 % |
| Disease due to Vit-B₁ deficiency | Beri-beri |
| Site of absorption of digested food | Villi of small intestine |
| Product of peptic digestion | Peptides |
Topic Connections
- Direct Link: Human Physiology (digestive system), Plant Physiology (photosynthesis), Biomolecules (vitamins).
- Combined Questions: Enzymes + pH; Vitamins + deficiency diseases; Calorific value + ratio-proportion sums.
- Foundation For: Health & hygiene MCQs in RRB GS; Biology basics for SSC & other competitive exams.
BETA
