Life Processes in Animals Part 2: MCQs (Q26–Q50)

Part 2 — Alimentary Canal & Human Digestive System (Questions 26–50)

26. The alimentary canal begins at the _____ and ends at the _____.

A. Mouth; Anus
B. Stomach; Small intestine
C. Esophagus; Stomach
D. Nose; Mouth
Correct answer: A. Mouth; Anus

Explanations:
A) Alimentary canal is the continuous tube from mouth to anus — correct.
B) Stomach to small intestine is only part — incorrect.
C) Esophagus connects mouth to stomach but canal begins at mouth — incorrect.
D) Nose to mouth is unrelated — incorrect.

27. The narrow muscular tube connecting the mouth to the stomach is called:

A. Trachea
B. Oesophagus (esophagus)
C. Duodenum
D. Larynx
Correct answer: B. Oesophagus (esophagus)

Explanations:
A) Trachea connects larynx to lungs — incorrect.
B) Oesophagus carries food to stomach by peristalsis — correct.
C) Duodenum is first part of small intestine — incorrect.
D) Larynx is voice box — incorrect.

28. The stomach performs which of the following functions?

A. Stores food, mixes with gastric juice and begins protein digestion
B. Absorbs most nutrients
C. Emulsifies fats only
D. Filters blood
Correct answer: A. Stores food, mixes with gastric juice and begins protein digestion

Explanations:
A) Stomach stores and chemically digests proteins (pepsin + HCl) — correct.
B) Most absorption occurs in small intestine — incorrect.
C) Emulsification is bile’s role in small intestine — incorrect.
D) Filtering blood is kidney function — incorrect.

29. Gastric juice in the stomach contains:

A. Salivary amylase and bile
B. Hydrochloric acid and pepsinogen (which forms pepsin)
C. Insulin and glucagon
D. Trypsin and lipase only
Correct answer: B. Hydrochloric acid and pepsinogen (which forms pepsin)

Explanations:
A) Salivary amylase is in mouth; bile is from liver — incorrect.
B) Stomach secretes HCl and pepsinogen for protein digestion — correct.
C) Insulin and glucagon are pancreatic hormones — incorrect.
D) Trypsin/lipase are pancreatic enzymes in small intestine — incorrect.

30. Which part of small intestine receives bile and pancreatic juice?

A. Ileum
B. Jejunum
C. Duodenum
D. Colon
Correct answer: C. Duodenum

Explanations:
A) Ileum is lower part of small intestine mainly absorption — incorrect.
B) Jejunum absorbs nutrients — incorrect.
C) Duodenum is the first part where bile and pancreatic juice act — correct.
D) Colon = large intestine — incorrect.

31. Pancreatic juice helps digest:

A. Only carbohydrates
B. Proteins, fats and carbohydrates (enzymes like trypsin, lipase, amylase)
C. Only lipids
D. Only nucleic acids
Correct answer: B. Proteins, fats and carbohydrates (enzymes like trypsin, lipase, amylase)

Explanations:
A) Pancreatic amylase digests carbs but others digest proteins/fats too — incomplete/incorrect.
B) Pancreatic juice contains enzymes for proteins, lipids and carbohydrates — correct.
C) Lipase digests fats but not only — incorrect.
D) Nucleic acid digestion is by nucleases but not the sole function — incorrect.

32. Which organ absorbs water and forms faeces?

A. Stomach
B. Small intestine
C. Large intestine (colon)
D. Pancreas
Correct answer: C. Large intestine (colon)

Explanations:
A) Stomach digests proteins — incorrect.
B) Small intestine absorbs most nutrients, not mainly water — incorrect.
C) Large intestine absorbs water and compacts waste — correct.
D) Pancreas secretes digestive enzymes — incorrect.

33. The presence of villi in the small intestine:

A. Decreases surface area for absorption
B. Increases surface area for absorption
C. Has no effect on absorption
D. Aids only in mechanical digestion
Correct answer: B. Increases surface area for absorption

Explanations:
A) Villi increase, not decrease, surface area — incorrect.
B) Villi (and microvilli) greatly increase absorptive area — correct.
C) They significantly affect absorption — incorrect.
D) Villi are for absorption, not mechanical digestion — incorrect.

34. Teeth that mainly crush and grind food are:

A. Incisors
B. Canines
C. Premolars and Molars
D. Tongue
Correct answer: C. Premolars and Molars

Explanations:
A) Incisors cut food — incorrect.
B) Canines tear food — incorrect.
C) Premolars and molars grind and crush food — correct.
D) Tongue helps in taste and positioning food but not grinding — incorrect.

35. Which vitamin is produced by friendly bacteria in the large intestine?

A. Vitamin C
B. Vitamin K
C. Vitamin D
D. Vitamin B12
Correct answer: B. Vitamin K

Explanations:
A) Vitamin C mainly from fruits — incorrect.
B) Gut bacteria synthesize vitamin K (and some B vitamins) — correct.
C) Vitamin D formed in skin with sunlight — incorrect.
D) Some bacteria synthesize B vitamins, but classic board answer is K for large intestine — incorrect for this question.

36. The pancreatic duct opens into the:

A. Stomach
B. Duodenum
C. Large intestine
D. Mouth
Correct answer: B. Duodenum

Explanations:
A) Pancreatic duct does not open into stomach — incorrect.
B) It opens into the duodenum to deliver enzymes — correct.
C) Large intestine is downstream — incorrect.
D) Mouth is entry point, not pancreatic duct outlet — incorrect.

37. Over-eating and irregular diet can cause which digestive disorder commonly?

A. Asthma
B. Indigestion and acidity (gastric problems)
C. Fracture
D. Migraine
Correct answer: B. Indigestion and acidity (gastric problems)

Explanations:
A) Asthma is respiratory — incorrect.
B) Indigestion/acidity often result from poor diet habits — correct.
C) Fracture is bone injury — incorrect.
D) Migraine is neurological and not direct digestive disorder — incorrect.

38. Which of the following helps in mechanical digestion in the stomach?

A. Teeth
B. Tongue
C. Muscular churning movements of stomach walls
D. Bile emulsification only
Correct answer: C. Muscular churning movements of stomach walls

Explanations:
A) Teeth act in mouth for mechanical digestion — not in stomach — incorrect.
B) Tongue helps mix food in mouth — incorrect for stomach.
C) Stomach muscles churn food with gastric juice — correct.
D) Bile emulsifies fats (chemical/physical) in intestine, not mechanical churning in stomach — incorrect.

39. Which of these is NOT an accessory digestive organ?

A. Liver
B. Pancreas
C. Gall bladder
D. Small intestine
Correct answer: D. Small intestine

Explanations:
A) Liver is accessory (produces bile) — incorrect (it is accessory).
B) Pancreas is accessory (secretes enzymes) — incorrect.
C) Gall bladder stores bile — accessory — incorrect.
D) Small intestine is part of the alimentary canal (main organ) — correct as NOT accessory.

40. The term ‘egestion’ refers to:

A. Breakdown of food into molecules
B. Absorption of nutrients into blood
C. Removal of undigested food from the body
D. Secretion of digestive juices
Correct answer: C. Removal of undigested food from the body

Explanations:
A) Breakdown = digestion — incorrect.
B) Absorption is different process — incorrect.
C) Egestion = expulsion of faeces — correct.
D) Secretion is release of juices — incorrect.

41. Which of the following enzymes digests starch to maltose?

A. Lipase
B. Pepsin
C. Amylase
D. Trypsin
Correct answer: C. Amylase

Explanations:
A) Lipase digests fats — incorrect.
B) Pepsin digests proteins — incorrect.
C) Amylase (salivary and pancreatic) breaks down starch → maltose — correct.
D) Trypsin digests proteins in small intestine — incorrect.

42. The flap that prevents food from entering the windpipe during swallowing is called:

A. Epiglottis
B. Uvula
C. Glottis
D. Diaphragm
Correct answer: A. Epiglottis

Explanations:
A) Epiglottis covers the glottis to prevent choking — correct.
B) Uvula hangs at back of throat — not the flap preventing entry into windpipe — incorrect.
C) Glottis is opening of larynx — not the flap — incorrect.
D) Diaphragm is breathing muscle — incorrect.

43. Which organ produces digestive enzymes and hormones like insulin?

A. Liver
B. Pancreas
C. Gall bladder
D. Kidney
Correct answer: B. Pancreas

Explanations:
A) Liver produces bile and other metabolic products — incorrect.
B) Pancreas secretes digestive enzymes and hormones (insulin) — correct.
C) Gall bladder stores bile — incorrect.
D) Kidney filters blood — incorrect.

44. Which of the following statements is TRUE about digestion in the small intestine?

A. Only mechanical digestion occurs there.
B. Chemical digestion is completed and absorption begins there.
C. No absorption takes place there.
D. Food is stored there for long periods.
Correct answer: B. Chemical digestion is completed and absorption begins there.

Explanations:
A) Both chemical digestion and absorption happen — incorrect.
B) Enzymes complete digestion; villi absorb nutrients — correct.
C) Absorption is a key function there — incorrect.
D) It’s not mainly for storage — incorrect.

45. The primary function of the large intestine is to:

A. Digest proteins
B. Absorb nutrients like glucose
C. Absorb water and salts; form faeces
D. Secrete digestive enzymes
Correct answer: C. Absorb water and salts; form faeces

Explanations:
A) Proteins digested earlier in stomach/small intestine — incorrect.
B) Nutrient absorption mainly in small intestine — incorrect.
C) Large intestine reabsorbs water, salts and compacts waste — correct.
D) It does not secrete major digestive enzymes — incorrect.

46. The human digestive juice that has an alkaline pH and contains many enzymes is:

A. Gastric juice
B. Saliva
C. Pancreatic juice
D. Bile (acidic)
Correct answer: C. Pancreatic juice

Explanations:
A) Gastric juice is acidic due to HCl — incorrect.
B) Saliva is slightly alkaline but limited enzymes — incorrect.
C) Pancreatic juice is alkaline and contains multiple enzymes — correct.
D) Bile is alkaline but not enzyme-rich — incorrect.

47. The movement of food from the mouth to the stomach involves:

A. Ciliary action
B. Peristaltic wave of muscles in oesophagus
C. Gravity alone
D. Active secretion of bile
Correct answer: B. Peristaltic wave of muscles in oesophagus

Explanations:
A) Cilia move particles in respiratory tract, not oesophagus — incorrect.
B) Muscular contractions (peristalsis) push food down — correct.
C) Gravity helps but swallowing works even when upside down due to peristalsis — incorrect.
D) Bile secretion is unrelated — incorrect.

48. Which part of the human alimentary canal is the longest?

A. Stomach
B. Small intestine
C. Large intestine
D. Oesophagus
Correct answer: B. Small intestine

Explanations:
A) Stomach is shorter — incorrect.
B) Small intestine (several meters) is longest — correct.
C) Large intestine is shorter than small intestine — incorrect.
D) Oesophagus is short in length — incorrect.

49. Which of these processes takes place largely in the colon?

A. Protein digestion
B. Starch digestion
C. Water absorption from undigested food
D. Enzyme secretion for fat digestion
Correct answer: C. Water absorption from undigested food

Explanations:
A) Protein digestion occurs earlier — incorrect.
B) Starch digestion occurs in mouth and small intestine — incorrect.
C) Colon absorbs water and salts from undigested residue — correct.
D) Colon does not secrete major digestive enzymes — incorrect.

50. A balanced diet provides:

A. Only carbohydrates
B. All essential nutrients in correct proportions (carbohydrates, proteins, fats, vitamins, minerals, water, fiber)
C. Only proteins and fats
D. Only vitamins
Correct answer: B. All essential nutrients in correct proportions (carbohydrates, proteins, fats, vitamins, minerals, water, fiber)

Explanations:
A) Only carbs is incomplete — incorrect.
B) Balanced diet includes all nutrients in right amounts — correct.
C) Proteins and fats alone are insufficient — incorrect.
D) Vitamins alone are inadequate — incorrect. (more…)