Practice Chapter 2 Nutrition in Animals Questions for Class 7 Science with Answers PDF
FAQs on Nutrition in Animals Worksheets for CBSE Class 7 Science (2025-26)
1. What are the most important questions from Chapter 2, Nutrition in Animals, for the Class 7 Science exam 2025-26?
For the CBSE Class 7 Science exam, some of the most important questions from Chapter 2, Nutrition in Animals, cover the human digestive system, digestion in ruminants, and nutrition in Amoeba. Key topics often tested include:
The functions of different organs in the alimentary canal (stomach, small intestine, liver).
The role of digestive juices like bile and pancreatic juice.
The structure and function of villi.
The process of rumination in grass-eating animals.
Comparison between human and Amoeba nutrition.
2. Describe the complete journey of food through the human alimentary canal. This is often a 5-mark question.
The journey of food through the alimentary canal is a fundamental process. For a high-scoring answer, detail the following steps:
Ingestion: Food is taken in through the mouth.
Digestion in Mouth: Teeth chew the food, and saliva from salivary glands begins carbohydrate digestion.
Oesophagus: The food pipe pushes food down to the stomach via peristalsis.
Stomach: Here, food is churned and mixed with gastric juices (HCl and enzymes) to digest proteins.
Small Intestine: Receives secretions from the liver (bile) and pancreas to break down carbohydrates, fats, and proteins completely.
Absorption: Nutrients are absorbed into the blood through villi in the small intestine.
Large Intestine: Absorbs water and salt from undigested food.
Egestion: The remaining waste (faeces) is removed through the anus.
3. What are villi? Explain their location and why their function is considered crucial for nutrition.
Villi are tiny, finger-like projections found on the inner walls of the small intestine. Their function is crucial for nutrition because they vastly increase the surface area available for the absorption of digested food. Each villus has a network of thin blood vessels close to its surface, which allows the digested nutrients to pass quickly from the intestine into the bloodstream and be transported to the rest of the body.
4. A cow can digest grass, but a human cannot. What is the key biological reason for this difference?
The key difference lies in their digestive systems. Cows are ruminants and possess a large, four-chambered stomach. One of these chambers, the rumen, contains specific bacteria and microorganisms that produce enzymes capable of breaking down cellulose, the main component of grass. Humans lack this specialised stomach chamber and the necessary cellulose-digesting bacteria, making it impossible for them to digest grass.
5. Why does the stomach secrete hydrochloric acid (HCl)? Mention its two most important functions in digestion.
The stomach secretes hydrochloric acid for two very important reasons. For exam purposes, remember these two functions:
Killing Pathogens: The acid creates a highly acidic environment that kills most of the harmful bacteria and other microorganisms that enter the body along with food.
Activating Enzymes: It provides the acidic medium (pH 1.5-3.5) necessary for the enzyme pepsin to function effectively and begin the digestion of proteins.
6. How does the mode of nutrition in an Amoeba differ from that of human beings, despite both being heterotrophs?
This is a classic comparison question. The primary difference is complexity. Humans have a complex, multi-organ digestive system (alimentary canal) where digestion occurs in different specialised parts. In contrast, Amoeba is a single-celled organism with a very simple mode of nutrition. It uses temporary finger-like projections called pseudopodia to engulf a food particle, forming a food vacuole. All digestive processes (digestion, absorption, assimilation) occur within this single vacuole inside the cell.
7. What is rumination? Briefly explain this important process in grass-eating animals.
Rumination is the process where grass-eating animals like cows and buffaloes quickly swallow their food, store it in a part of the stomach called the rumen, and later bring it back into the mouth to chew it thoroughly. This partially digested food is called cud. This adaptation allows them to consume a large amount of food quickly and then chew it later in a safe place. The chewed cud is then swallowed again for complete digestion.
8. What is the specific role of bile juice in digestion? Is it considered a digestive enzyme?
This is a common point of confusion. Bile juice, which is produced by the liver and stored in the gall bladder, is not an enzyme. Its most important function is the emulsification of fats. This means it breaks down large fat globules present in the food into smaller, more manageable droplets. This action dramatically increases the surface area of the fats, allowing the fat-digesting enzyme, lipase, to act more efficiently.
9. Name the four types of teeth in an adult human and state the primary function of each for exams.
For the CBSE 2025-26 exam, you should know the four types of teeth and their specific roles:
Incisors: The front teeth used for cutting and biting food.
Canines: The sharp, pointed teeth next to the incisors, used for piercing and tearing food.
Premolars: Located behind the canines, used for chewing and grinding food.
Molars: The large teeth at the back of the mouth, used for fine grinding and crushing of food before swallowing.
