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Human digestive system is a… (Class 10 Science 2024, Q38)

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ScienceCBSE Class 10 · Board exam 2024, set 31/3/1 · 4 marks · Case-based

CBSE Class 10 Science 2024: question 38

Set in the CBSE Class 10 board exam of 2024, paper 31/3/1, section E, question 38, for 4 marks. Try it first; the hints and our step-by-step solution are below.

Q38 · 4 marks · Case-basedCompetency-basedLife Processes

Human digestive system is a tube running from mouth to anus. Its main function is to breakdown complex molecules present in the food which cannot be absorbed as such into smaller molecules. These molecules are absorbed across the walls of the tube and the absorbed food reaches each and every cell of the body where it is utilised for obtaining energy.

  1. (a)

    Name the glands present in the buccal cavity and write the components of food on which the secretion of these glands act upon.

    1 mark
  2. (b)

    Two organs have a sphincter muscle at their exit. Name them.

    1 mark
  3. (c)

    What will happen if : (i) mucus is not secreted by the gastric glands. (ii) Villi are absent in the small intestine.

    2 marks

  4. OR

    (c)

    "Bile juice does not contain any enzyme, yet it has important roles in digestion." Justify the statement.

    2 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/3/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Which juice in the mouth begins the digestion of starch?

Hint 2

Sphincters control exit points: one lets food out of an organ into the small intestine, the other controls removal of waste.

Hint 3

Think about what mucus protects, what villi increase, and how bile changes fats and the pH of food.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (a) Glands: The glands of the buccal cavity are the salivary glands.

    Food acted on: Saliva contains the enzyme salivary amylase, which acts on starch (a carbohydrate) and breaks it down into sugar.

    1 mark

  2. (b) Organs with sphincters at their exit:
    1. The stomach – the pyloric sphincter controls the release of food into the small intestine.
    2. The anus – the anal sphincter controls the removal of undigested waste.

    1 mark

  3. (c)(a)(i) No mucus from the gastric glands: Mucus protects the inner lining of the stomach. Without it, the lining would be exposed to hydrochloric acid and pepsin. The acid would damage the lining and cause acidity and ulcers.

    1 mark

  4. (c)(a)(ii) No villi in the small intestine: Villi greatly increase the surface area for absorption. Without them, absorption of digested food would be greatly reduced. Most of the food would pass out unabsorbed, and the body would lack nutrients.

    1 mark

  5. (c)(b) OR alternative (marked instead of (c)(a) if chosen) – Emulsification: Bile salts break large fat globules into tiny droplets. This increases the surface area for lipase from pancreatic juice to act on. [1 mark]

  6. (c)(b) Making the medium alkaline: Food coming from the stomach is acidic. Bile neutralises it and makes the medium alkaline, which pancreatic enzymes need in order to work. So bile has no enzyme but is still important for digestion. [1 mark]

Answer: (a) Salivary glands; act on starch. (b) Stomach and anus. (c)(a) (i) Acid would damage the stomach lining (ulcers); (ii) absorption of digested food would be greatly reduced. (c)(b) Bile emulsifies fats and makes the acidic food alkaline for pancreatic enzymes to act

Where the marks are

  • Salivary glands; starch / carbohydrate (½ + ½ marks)
  • Stomach and anus (½ + ½ marks)
  • (c)(i) Stomach lining not protected from acid (1 mark)
  • (c)(ii) Digested food not absorbed / absorption area reduced (1 mark)
  • OR (c) Emulsification of fats (1 mark); makes the medium alkaline for pancreatic enzymes (1 mark)

Revise the chapter

  • Chapter: Life Processes (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Life Processes, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 31/3/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.