Chapter 2: Nutrition in Animals

Science • Class 7

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Chapter Analysis

Intermediate12 pages • English

Quick Summary

The chapter 'Nutrition in Animals' explains the different modes of nutrition in animals, detailing how animals obtain and digest food. It discusses the human digestive system and its various parts, such as the stomach, small and large intestines, and associated glands like the liver and pancreas. The chapter also covers digestion in simpler organisms like Amoeba, the process of rumination in ruminants, and the role of enzymes and digestive juices in breaking down food into nutrients.

Key Topics

  • Human digestive system
  • Digestion in ruminants
  • Digestion and absorption in small intestine
  • Role of digestive enzymes
  • Nutrient absorption
  • Amoeba feeding process
  • Bile and pancreatic juices
  • Nutrient assimilation

Learning Objectives

  • Understand the human digestive system and its components.
  • Explain the digestion process in ruminants.
  • Describe how nutrients are absorbed in the small intestine.
  • Identify the roles of different digestive enzymes.
  • Understand the feeding process of simpler organisms like Amoeba.
  • Explain the importance of saliva in the digestive process.

Questions in Chapter

Fill in the blanks: (a) The main steps of nutrition in humans are __________, __________, __________, _________ and __________. (b) The largest gland in the human body is __________. (c) The stomach releases hydrochloric acid and ___________ juices which act on food. (d) The inner wall of the small intestine has many finger-like outgrowths called _________. (e) Amoeba digests its food in the ____________.

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Mark ‘T’ if the statement is true and ‘F’ if it is false: (a) Digestion of starch starts in the stomach. (T/F) (b) The tongue helps in mixing food with saliva. (T/F) (c) The gall bladder temporarily stores bile. (T/F) (d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F)

Page 21

Tick (✓) mark the correct answer in each of the following: (a) Fat is completely digested in the (i) stomach (ii) mouth (iii) small intestine (iv) large intestine

Page 21

Match the items of Column I with those given in Column II: Column I: Carbohydrates, Proteins, Fats Column II: Fatty acids and glycerol, Sugar, Amino acids

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What are villi? What is their location and function?

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Where is the bile produced? Which component of the food does it help to digest?

Page 22

Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.

Page 22

Why do we get instant energy from glucose?

Page 22

Which part of the digestive canal is involved in: (i) absorption of food ________________. (ii) chewing of food ________________. (iii) killing of bacteria ________________. (iv) complete digestion of food ________________. (v) formation of faeces ________________.

Page 22

Additional Practice Questions

Explain the process of digestion in Amoeba and compare it with human digestion.

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Answer: Amoeba digests food by engulfing it with pseudopodia and forming a food vacuole where digestive enzymes act. In humans, digestion involves a complex system where food is mechanically and chemically broken down and absorbed as it passes through the digestive tract.

Why is cellulose not digested by humans, but by ruminants?

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Answer: Humans lack the specific enzymes to break down cellulose, whereas ruminants have specialized stomachs and symbiotic bacteria that enable them to digest cellulose.

What are the functions of the liver in the digestive process?

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Answer: The liver produces bile which emulsifies fats, making them easier to digest. It also processes nutrients absorbed from the gut.

Describe the role of enzymes in the human digestive system.

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Answer: Enzymes in the digestive system accelerate chemical reactions, breaking down complex food substances like proteins, carbohydrates, and fats into simpler molecules that the body can absorb.

Discuss how the small intestine is designed for absorption.

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Answer: The small intestine is lined with villi, which are small projections that increase its surface area for maximum absorption of nutrients into the bloodstream.

How does the stomach protect itself from self-digestion?

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Answer: The stomach lining secretes mucus that forms a protective barrier preventing the gastric acid from digesting the stomach tissue.

What could happen if there was an obstruction in the small intestine?

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Answer: An obstruction could prevent the passage of food, cause severe pain, and lead to nutrient deficiencies and potential life-threatening complications.

NCERT Exemplar

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Practice with NCERT Exemplar problems and solutions for this chapter. Exemplar problems are designed to help you master the concepts with advanced-level questions.

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