Nutrition in Animals Class 7 Notes CBSE Science Chapter 2 (Free PDF Download)

Animal Nutrition:

This is a term that includes the nutrient requirement of the animal, its mode of food intake and the utilisation of the food in their bodies.

Classification of Animals Based on Feeding Habits:

It is of great importance that all organisms intake food in some way or the other for their growth and normal functioning of their body. Based on their feeding habits they can be classified as:

1. Herbivorous: This is the group of animals that feed only on plants or their products as the name suggests; ‘herbi’ meaning plant and ‘vore’ meaning eaters. Example: cow, sheep, deer, rabbit, camel, kangaroo, giraffe, etc.

2. Carnivorous: This is the group that feeds on the meat of other animals and the name suggests the same as, ‘carni’ means meat. Example: tiger, lion, bear, snake, eagle etc.

3. Omnivorous: This group of animals can feed on plants as well as the meat of other animals and the name ‘omni’ means all. Example: dog, human beings, etc.

4. Scavengers: This group of animals feed on dead and decaying meat left by other animals. Example: vulture, crows, jackal, etc.

Mode of Taking Food:

Although all organisms require food, the way they take it into their body differs from each other. All of them have special adaptations that help them for this. They could be as follows:

1. Chewing: This mode involves the biting and grinding of the food in the mouth by the teeth. Example - humans, dogs, etc.

2. Scraping: In this mode, the food is scraped off the surface by the jaw or an organ. Example - snails, ants etc.

3. Siphoning: In this mode, the food is sucked into the mouth. Example - bees, butterflies etc.

4. Capturing and swallowing: In this mode they usually capture the food and then swallow them. Example: lizard, etc.

5. Sucking: This mode involves the piercing of the food and then sucking the liquid out of it. Example: mosquitoes, etc.

6. Sponging: In this mode, the saliva is secreted over the food to dissolve it in order to draw it into the mouth. Example: houseflies etc.

Nutrition:

The process of taking in the food and converting it into necessary energy and nutrients for the growth and development of an organism is termed as nutrition. The process of nutrition is a complex one and includes some steps which are:

1. Ingestion: The process of intake of food into the body.

2. Digestion: The process of breaking down the ingested complex food molecules to simpler molecular form that can be absorbed by the body.

3. Absorption: The process by which the digested food is taken into the blood vessels.

4. Assimilation: The process of transporting the absorbed food to the various organs to build substances like proteins, etc.

5. Egestion: The process of eliminating the waste products from the body.

Digestion in Humans:

• In humans the food is taken in through the mouth and it passes through a continuous canal starting at the buccal cavity and ending at the anus. 

• All the components of this canal together are termed as the alimentary canal or digestive tract. 

• The digestive tract along with the associated digestive glands are termed as digestive system. 

• The different components of the digestive tract and their role in the process of digestion is as follows:

1. Buccal cavity: 

• The buccal cavity is the mouth which contains the teeth, tongue and the palate. This is the beginning of the alimentary canal and thus digestion. The food enters the mouth and is mechanically ground by the different sets of teeth, like the incisors, canines, premolars and the molars. 

• The salivary glands present here secrete the clear liquid, saliva, that helps in lubricating the food.

• The saliva is mixed with the food by the tongue, which has the taste buds for detecting the various tastes. 

• This turns the chewed food into a ball called a bolus, which travels down the alimentary canal for further digestion.

2. Oesophagus or the food pipe:

• The partly digested food moves along the oesophagus.

• The wall of the oesophagus propels the food forward and downwards towards the stomach. 

• Any food that is not accepted by our body is pushed back through the mouth and is known as vomiting.

3. Stomach:

• The food from the oesophagus is pushed into the stomach, which is a J-shaped thick-walled bag, being the widest part of the alimentary canal. 

• The inner wall of the stomach secretes mucus, which protects the stomach lining, hydrochloric acid, which destroys most of the bacteria in the food, helping the digestive juices to act upon the food. 

• The stomach also secretes digestive juices that break down the proteins to simple substances.

4. Small intestine:

• Now the partially digested food enters the small intestine, which is a coiled structure, about 7.5 metres in length. 

• It has secretions from liver, bile, that acts on the fats and secretions from pancreas, pancreatic juice that acts on carbohydrates, proteins. 

• At the end of the small intestine, intestinal juice completes the process of digestion of food, and carbohydrates are broken into glucose, fats into fatty acids and proteins into amino acids. 

• This digested food is then absorbed by the intestinal walls, by the finger-like projections called villi, present in them. These absorbed substances are then transported to the various organs of the body through blood vessels. 

• Once they are in the cell, the glucose is converted to carbon dioxide and water with the release of energy.

5. Large intestine: 

• The undigested food is passed onto the large intestine, which is shorter and wider in comparison to the small intestine, measuring around 1.5 metres. 

• The water and salts are absorbed here and the remaining solid waste is passed into the rectum as faeces for egestion from the anus.

Digestion in Grass-Eating Animals:

• Many animals that eat grass like cows, buffaloes etc eat the grass quickly and store it in a special part of their stomach which is called as rumen. 

• The food is partially digested here and that is known as cud. After some time this cud comes into the mouth, and this makes the animal chew it gradually. This process is known as rumination and these animals that exhibit this are known as ruminants. 

• These grass eating animals, like cattle the bacteria present in their rumen helps digest the cellulose of the grass. 

• Some animals like horse, rabbit etc, have a large sac-structure, Caecum, which is located between the oesophagus and small intestine for digesting the cellulose.

Feeding and Digestion in Amoeba:

• Amoeba is a single celled microscopic organism that keeps changing its shape constantly with the help of their finger-like projections, pseudopodia. 

• It captures the food with this and engulfs it and the food gets trapped in a food vacuole. 

• Digestive juices are secreted into this that break down the food to simple substances for absorption to help it grow and maintain itself.

Class 7 Science Chapter 2 Revision Notes PDF Download

The PDF form of Class 7 Science Nutrition in Animals notes can be accessed on any device, and you can use it offline. These notes explain the concepts very well and can be utilized by the students to score more. This pdf provided by Vedantu lays a great foundation of the topics covered in this chapter, which will help the students learn about Nutrition in Animals of Class 7. The PDF printable form of these notes can be served as the best resource for your exams. 

Class 7 Science Chapter 2 Revision Notes 

All the Plants can prepare their food by the method of photosynthesis, but on the other hand, animals cannot make their own. Animals eat plants directly or indirectly by eating animals that eat plants. Some animals eat both plants and animals.

2.1 Animals Are Classification Based on Eating Habits

(i) Herbivorous: The kind of animals that eat plants or plant products. Example: cow, goat, sheep, deer, kangaroo, giraffe, elephant, etc.

(ii) Carnivorous: The kind of animals that eat only the flesh of other animals. They never eat plants. Example: tiger, lizard, lion, etc.

(iii) Omnivorous: The kinds of animals that consume plants and other animals as their food. Example: bear, dog, human being, etc.

(iv) Parasites: The organisms that obtain their food from other animals either by outside (ectoparasites) or living inside (endoparasites) their body. Example: tapeworm and roundworm (inside body), tick and lice (outside body).

(v) Scavengers: Animals that feed on the remains of dead animals preyed by predators. Example: crows, jackal, vulture. etc. 

2.2. Digestion in Animals 

Animal nutrition includes the mode of intake of food and its utilization and the nutrient requirement in the body.

The human digestive system contains the alimentary canal and secretory glands. It includes:

• buccal cavity,

• oesophagus,

• stomach,

• small intestine,

• large intestine ending in the rectum

• anus

The Significant Digestive Glands which Secrete Digestive Juices Are

(i) the salivary glands,

(ii) the liver and

(iii) the pancreas.

The stomach wall and the wall of the small intestine also secrete digestive juices.

The modes of feeding vary in different organisms.

Nutrition is a Complex Process Involving:

(i) ingestion,

(ii) digestion,

(iii) absorption,

(a) assimilation and

(b) egestion

The wall of the small intestine and stomach secrete the digestive juices. Different organisms have different modes of feeding. Nutrition is a very complex process having ingestion, Digestion, absorption, assimilation, and egestion.

The taking of food through your mouth is the first step, which is called indigestion. Teeth can help in chewing the food and break it down, mechanically into small pieces. The tongue mixes saliva with the food during chewing and aids in swallowing food. Foodpipe will help the food to be pushdown. The stomach receives the food from the food pipe at one end, and it opens into the small intestine at the other. The Digestion of carbohydrates, like starch, starts in the buccal cavity and the Digestion of protein begins in the stomach. The liver secretes the bile. The pancreas secretes pancreatic juice. The digestive juice from the intestinal wall completes all the digestion procedures of all components of food in the small intestine. The food which is digested is absorbed in the blood vessels. 

The absorbed substances from the food are transported to different parts of the body. In the large intestine, water and some salts are absorbed from the undigested food. 

Anus helps to expel the undigested and unabsorbed residues. 

The grazing animals like buffaloes, cows, and deer are called ruminants. They ingest very fast, then swallow their leafy food and keep it in the rumen. After that, the food returns to the mouth, and the animal chews it peacefully.

The false feet or pseudopodia in amoeba ingests its food. After that, the food is digested in the food vacuole. It pushes out finger-like pseudopodia, which engulfs the prey.

Key Features of Class 7 Science Chapter 2 Nutrition in Animals

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Benefits of Studying Class 7 Science Chapter 2 Nutrition in Animals

• Our subject experts have prepared these notes on CBSE Class 7 Nutrition in Animals to provide a comprehensive understanding of the topics covered in this chapter.

• In this Revision Notes PDF, most topics and sub-topics are explained in a concise point-wise manner so that students can learn them easily before the exam.

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Chapter wise Revision Notes for Class 7 Science

• Chapter 1 - Nutrition in Plants Notes

• Chapter 3 - Fibre to Fabric Notes

• Chapter 4 - Heat Notes

• Chapter 5 - Acids, Bases and Salts Notes

• Chapter 6 - Physical and Chemical Changes Notes

• Chapter 7 - Weather, Climate and Adaptations of Animals to Climate Notes

• Chapter 8 - Winds, storms and cyclones Notes

• Chapter 9 - Soil Notes

• Chapter 10 - Respiration in Organisms Notes

• Chapter 11 - Transportation in Animals and Plants Notes

• Chapter 12 - Reproduction in Plants Notes

• Chapter 13 - Motion and Time Notes

• Chapter 14 - Electric Current and Its Effects Notes

• Chapter 15 - Light Notes

• Chapter 16 - Water: A Precious Resource Notes

• Chapter 17 - Forests: Our Lifeline Notes

• Chapter 18 - Wastewater Story Notes

Conclusion

CBSE Class 7 Chapter 2 Revision Notes on Nutrition in animals are prepared by our subject experts according to the updated CBSE Class 7 syllabus. Students can rely on these notes for their last-minute revisions as these notes cover all important topics and sub-topics of this chapter. In fact, the point-wise explanations of topics like digestion in humans, absorption, and assimilation of food, ingestion, and digestion in grass-eating animals and amoeba are highly beneficial when it comes to revising the chapter the day before the exam. So download and refer to the Nutrition in Animals Notes PDF from Vedantu and revise the chapter thoroughly in a short time span to ace your Science exam.