Willer Academy
Nation Builders Through Education | Founded by Er. Rahul Kumar Dubey Sir
Chapter 2: Nutrition in Animals
Subject: Science (Biology)
Class: 7
Series: Base Builder for Moderate to Hard
Learning Objectives
By the end of this chapter, you, the future scientist and nation-builder, will be able to:
- Understand different modes of nutrition in animals
- Describe the human digestive system and its functions
- Explain the process of digestion from ingestion to egestion
- Compare digestion in different animals
- Solve numerical problems related to digestion and nutrition
- Apply knowledge to real-life health and dietary situations
2.1 Introduction: How Animals Get Their Food
Unlike plants that make their own food, animals need to consume ready-made food. This food gives them energy to perform their life activities. The process of taking in food and its utilization by the body is called Nutrition.
Quick Check
Think about your favorite meal. How does your body turn that food into energy? Let's explore the amazing journey of food through your body!
2.2 Modes of Nutrition in Animals
Animals have different ways of getting their food:
1. Herbivores: Animals that eat only plants
- Examples: Cow, Goat, Deer
- Adaptations: Flat teeth for grinding, longer digestive systems
2. Carnivores: Animals that eat other animals
- Examples: Lion, Tiger, Eagle
- Adaptations: Sharp teeth for tearing, strong jaws
3. Omnivores: Animals that eat both plants and animals
- Examples: Human, Bear, Crow
- Adaptations: Combination of sharp and flat teeth
Task 1
Observe the eating habits of animals around your home or neighborhood. Classify them into herbivores, carnivores, or omnivores. Create a chart with pictures or drawings of these animals.
2.3 The Human Digestive System
The human digestive system is a complex process that breaks down food into nutrients that our bodies can use.
The Journey of Food
Above: Diagram of the human digestive system showing the path food takes from mouth to anus
Steps of Digestion:
- Ingestion: Taking food into the mouth
- Digestion: Breaking down food into simpler substances
- Absorption: Absorbing nutrients into the blood
- Assimilation: Using nutrients for energy and growth
- Egestion: Removing undigested waste
Numerical & Application 1: Digestive Timeline
- Scenario: Food typically takes 24-72 hours to pass through your digestive system.
- Problem: If a meal spends 30 minutes in the mouth, 2 hours in the stomach, 4 hours in the small intestine, and 18 hours in the large intestine, what is the total digestion time? What percentage of time is spent in the small intestine?
- Solution:
- Total time = 0.5 + 2 + 4 + 18 = 24.5 hours
- Percentage in small intestine = (4 / 24.5) × 100 ≈ 16.33%
This shows how different parts of our digestive system work for different durations!
2.4 Digestive System Organs and Functions
| Organ | Function | Digestive Juice | Enzyme |
|---|---|---|---|
| Mouth | Breaks down food mechanically | Saliva | Salivary amylase |
| Stomach | Churns food and breaks it down chemically | Gastric juice | Pepsin |
| Small Intestine | Absorbs nutrients into bloodstream | Intestinal juice, Pancreatic juice | Trypsin, Lipase |
| Large Intestine | Absorbs water and forms feces | Mucus | None |
Task 2: Model Building
Create a 3D model of the digestive system using everyday materials. You can use different colored tubes for intestines, a plastic bag for the stomach, and a funnel for the mouth. Label all parts and explain their functions.
2.5 Digestion in Other Animals
Different animals have different digestive systems based on their diet:
Ruminants (like cows):
- Have a four-chambered stomach
- Regurgitate food to chew it as "cud"
- Host bacteria that help digest cellulose
Birds:
- Have a crop for storing food
- Have a gizzard that uses stones to grind food
Amoeba:
- Uses pseudopodia to capture food
- Forms food vacuoles for digestion
Numerical & Application 2: Ruminant Digestion
- Scenario: A cow spends 8 hours per day eating grass and 6 hours chewing cud.
- Problem: If the cow is awake for 16 hours a day, what percentage of its waking time is spent on eating and ruminating? If the cow eats 15 kg of grass daily, how much does it eat per hour?
- Solution:
- Total time spent = 8 + 6 = 14 hours
- Percentage = (14 / 16) × 100 = 87.5%
- Eating rate = 15 kg / 8 hours = 1.875 kg/hour
This shows how much effort ruminants put into digesting their food!
Section B: MCQ Challenge (20 Questions)
Test your knowledge and find where you need to improve!
1. Which organ produces bile juice?
a) Stomach
b) Pancreas
c) Liver
d) Small intestine
2. The enzyme present in saliva breaks down:
a) Proteins
b) Fats
c) Starch
d) Minerals
3. Which of these is not a part of the human digestive system?
a) Esophagus
b) Trachea
c) Stomach
d) Intestine
Answers: 1-c, 2-c, 3-b, 4-a, 5-d, 6-b, 7-c, 8-a, 9-d, 10-b, 11-c, 12-a, 13-b, 14-d, 15-c, 16-a, 17-b, 18-c, 19-d, 20-a
Section C: Answer in Detail (For Answer Writing Practice)
Q1. Describe the process of digestion in humans, starting from the mouth to the large intestine.
Hint: Explain the role of each organ and the enzymes involved.
Q2. Differentiate between herbivores, carnivores, and omnivores with examples of each.
Hint: Focus on dietary habits, dental structure, and digestive adaptations.
Q3. Explain how digestion takes place in amoeba with the help of a diagram.
Hint: Describe the process of phagocytosis and formation of food vacuoles.
Section D: Tackle These! (Higher Order Thinking Skills - HOTS)
Q1. If humans had a digestive system like ruminants, how would our eating habits change? What would be the advantages and disadvantages?
Think about: Types of food we could digest, time spent eating, social implications.
Q2. Design a balanced meal for a day that includes all necessary nutrients. Explain your choices and how each food item would be digested.
Think about: Carbohydrates, proteins, fats, vitamins, and minerals required.
Q3. Some animals like snakes can swallow prey much larger than their head. How is this possible? What adaptations would the human digestive system need to do this?
Think about: Jaw structure, digestive enzymes, and stomach elasticity.
Section B: MCQ Challenge (20 Questions)
Test your knowledge and find where you need to improve!
1. Which organ produces bile juice?
a) Stomach
b) Pancreas
c) Liver
d) Small intestine
2. The enzyme present in saliva breaks down:
a) Proteins
b) Fats
c) Starch
d) Minerals
3. Which of these is not a part of the human digestive system?
a) Esophagus
b) Trachea
c) Stomach
d) Intestine
4. Which organ is called the food pipe?
a) Esophagus
b) Trachea
c) Small intestine
d) Large intestine
5. Which part of the digestive system absorbs most nutrients?
a) Mouth
b) Stomach
c) Small intestine
d) Large intestine
6. What is the role of hydrochloric acid (HCl) in the stomach?
a) To digest carbohydrates
b) To kill bacteria and activate enzymes
c) To absorb proteins
d) To neutralize acids
7. Which organ stores bile before releasing it into the small intestine?
a) Liver
b) Gall bladder
c) Pancreas
d) Large intestine
8. The finger-like projections in the small intestine that increase surface area are called:
a) Villi
b) Alveoli
c) Nephrons
d) Papillae
9. Which of the following is a ruminant animal?
a) Dog
b) Cat
c) Cow
d) Tiger
10. Which part of the digestive system mainly absorbs water?
a) Mouth
b) Large intestine
c) Small intestine
d) Stomach
11. Which enzyme helps in the digestion of proteins in the stomach?
a) Amylase
b) Lipase
c) Pepsin
d) Maltase
12. Which of the following animals has a gizzard for grinding food?
a) Cow
b) Human
c) Bird
d) Lion
13. In amoeba, food is digested inside the:
a) Nucleus
b) Food vacuole
c) Cytoplasm
d) Cell membrane
14. Which process is called 'egestion'?
a) Taking in food
b) Absorption of food
c) Chewing of food
d) Removal of undigested waste
15. Which organ secretes pancreatic juice?
a) Liver
b) Stomach
c) Pancreas
d) Small intestine
16. Which of these animals uses pseudopodia to engulf food?
a) Amoeba
b) Earthworm
c) Bird
d) Cow
17. In humans, most chemical digestion takes place in the:
a) Stomach
b) Small intestine
c) Mouth
d) Large intestine
18. Which part of the digestive system is also called the 'food factory'?
a) Mouth
b) Stomach
c) Small intestine
d) Large intestine
19. Which of the following pairs is correct?
a) Mouth – Lipase
b) Stomach – Amylase
c) Small intestine – Trypsin
d) Large intestine – Pepsin
20. What is assimilation?
a) Intake of food
b) Digestion of food
c) Absorption of food into blood
d) Utilization of absorbed nutrients in cells
Answers:
1-c, 2-c, 3-b, 4-a, 5-c, 6-b, 7-b, 8-a, 9-c, 10-b,
11-c, 12-c, 13-b, 14-d, 15-c, 16-a, 17-b, 18-c, 19-c, 20-d
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