Class 6 Human Digestive System MCQ with Answers

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Practice Class 6 Human Digestive System MCQs with answers.
Learn the alimentary canal, digestion, absorption, enzymes, and nutrition - with instant answers and performance report.

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Quick Revision: Human Digestive System

Human Digestive system Diagram
  • Digestion: The process of breaking down complex food into simple, absorbable substances so the body can utilise them.
  • Alimentary Canal: The long tube from mouth to anus through which food passes. Parts: Mouth → Oesophagus → Stomach → Small Intestine → Large Intestine → Rectum → Anus.
  • Mouth: Teeth (chewing — mechanical digestion), Saliva (contains salivary amylase that breaks down starch into sugar — chemical digestion). Tongue helps mix and push food.
  • Oesophagus: Muscular tube that carries food from mouth to stomach. Uses rhythmic contractions called peristalsis.
  • Stomach: Muscular bag that churns food. Produces hydrochloric acid (kills germs, creates acidic medium for enzymes), pepsin (digests proteins), and mucus (protects stomach lining).
  • Small Intestine: Long coiled tube (about 7 m). Main site of digestion and absorption. Divided into Duodenum, Jejunum, and Ileum.
  • Liver: Largest gland in the body. Produces bile (stored in gall bladder) that breaks down fats into droplets (emulsification).
  • Pancreas: Produces pancreatic juice containing enzymes that digest carbohydrates, proteins, and fats.
  • Villi: Finger-like projections in the inner wall of the small intestine that increase surface area for maximum absorption of nutrients into the blood.
  • Large Intestine: Absorbs water and minerals from undigested food. Remaining waste forms faeces.
  • Rectum & Anus: Rectum stores faeces temporarily. Anus is the opening through which faeces (egestion) are expelled.
  • Nutrients — Carbohydrates: Provide energy (rice, wheat, bread, potatoes). Broken down into glucose.
  • Nutrients — Proteins: Body-building foods (pulses, eggs, meat, milk). Broken down into amino acids.
  • Nutrients — Fats: Provide energy and warmth (butter, oil, nuts). Broken down into fatty acids and glycerol.
  • Vitamins & Minerals: Protective foods needed in small amounts for proper body functioning (fruits, vegetables).
  • Roughage (Dietary Fibre): Indigestible plant material that helps in bowel movement and prevents constipation.
  • Water: Essential for digestion, absorption, and transport of nutrients. The body loses water through urine, sweat, and breath.
  • Balanced Diet: Food containing all nutrients (carbohydrates, proteins, fats, vitamins, minerals, roughage, water) in the right proportions.
  • Malnutrition: Deficiencies caused by lack of one or more nutrients over a long period (e.g., scurvy — vitamin C, rickets — vitamin D, anaemia — iron).

Human Digestive System Class 6 Questions and Answers (FAQ)

What is the human digestive system and how does it work for Class 6 students?
The human digestive system is a group of organs that work together to break down food into simpler substances that the body can absorb and use for energy, growth, and repair. It consists of the alimentary canal (a 9-meter long tube from mouth to anus) and associated glands (liver, pancreas, salivary glands). The process involves: ingestion (eating), digestion (breaking down food), absorption (nutrients entering the blood), assimilation (cells using nutrients), and egestion (removing waste). Key organs include the mouth, oesophagus, stomach, small intestine, and large intestine.
What are the main parts of the alimentary canal and their functions?
The alimentary canal has six main parts: (1) Mouth - teeth chew food and saliva begins starch digestion; (2) Oesophagus - muscular tube that pushes food to the stomach via peristalsis; (3) Stomach - J-shaped organ that churns food and secretes HCl, pepsin, and mucus for protein digestion; (4) Small Intestine - 6.25m long tube where most digestion and absorption occurs, with villi to increase surface area; (5) Large Intestine - 1.5m tube that absorbs water and salts, forming faeces; (6) Rectum and Anus - stores and expels waste.
What are the different types of teeth and their functions?
Humans have four types of teeth: (1) Incisors (8 total) - front teeth used for biting and cutting food; (2) Canines (4 total) - pointed teeth for tearing food; (3) Premolars (8 total) - flat teeth for crushing and grinding; (4) Molars (12 total, including 4 wisdom teeth) - larger flat teeth for grinding food. Children have 20 milk teeth which are gradually replaced by 32 permanent teeth in adults. The last four molars (wisdom teeth) appear between ages 18-25.
What is the role of enzymes in digestion for Class 6 Science?
Enzymes are biological catalysts (biocatalysts) that speed up the breakdown of complex food into simpler molecules. Key digestive enzymes include: (1) Salivary amylase - in mouth, breaks starch into maltose; (2) Pepsin - in stomach, breaks proteins into peptones; (3) Rennin - in children's stomach, curdles milk protein; (4) Trypsin - from pancreas, breaks proteins into smaller peptides; (5) Pancreatic amylase (amylopsin) - breaks starch into maltose; (6) Pancreatic lipase (steapsin) - breaks emulsified fats into fatty acids and glycerol. Each enzyme works on specific nutrients.
What is a balanced diet and why is it important for Class 6 students?
A balanced diet contains all essential nutrients (carbohydrates, proteins, fats, vitamins, minerals, roughage, and water) in the right proportions. It's important because: (1) Carbohydrates and fats provide energy for daily activities; (2) Proteins build and repair body tissues; (3) Vitamins and minerals protect against diseases and maintain health; (4) Roughage (dietary fibre) aids digestion and prevents constipation; (5) Water helps absorb nutrients and remove wastes. A balanced diet promotes proper growth, strong immunity, and prevents deficiency diseases like scurvy (Vitamin C), rickets (Vitamin D), and anaemia (Iron).

Chapter Summary: Human Digestive System

The human digestive system is responsible for breaking down food into simple substances that the body can absorb and use. The alimentary canal is a long tube starting at the mouth and ending at the anus. Digestion begins in the mouth where teeth chew food (mechanical digestion) and saliva breaks down starch (chemical digestion). Food passes through the oesophagus via peristalsis to the stomach, where hydrochloric acid, pepsin, and mucus digest proteins and kill germs. The small intestine is the main site of digestion and absorption — with help from bile (liver) and pancreatic juice (pancreas). Finger-like villi absorb nutrients into the bloodstream.

The large intestine absorbs water and minerals from undigested food, forming faeces that are stored in the rectum and expelled through the anus. A balanced diet must include carbohydrates (energy), proteins (growth), fats (energy/warmth), vitamins, minerals, roughage (fibre), and water. Deficiency of nutrients over time leads to malnutrition and deficiency diseases such as scurvy (vitamin C), rickets (vitamin D), and anaemia (iron). Proper nutrition is essential for growth, development, and overall health.

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