NCERT Solutions for Class 7 Science Chapter 2
NCERT Solutions for Class 7 Science Chapter 2 - Nutrition in Animals
This chapter covers the following topics:
- Different ways of taking food
- Digestion in Humans
- Digestion of grass-eating animals
- Feeding and digestion in Amoeba
Nutrition is a process of interaction of nutrients and other substances which helps in maintenance, growth, and metabolism in organisms. Our body requires nutrients in a specific quantity. The nutrients we consume can be broadly classified as follows:
- Micro-nutrients - these are nutrients that are required in our body in small or micro quantities. Example: vitamin and trace elements
- Macro-nutrients - these are the nutrients required by our body in large or macro quantities. Examples: carbohydrates, protein, fats.
Not all nutrients provide energy. But they are still important for our bodies like water.
Why do we need nutrients?
As we have studied in earlier Classes, Less quantity of these nutrients will result in the deficiency of nutrients like deficiency of vitamin A causes night blindness, deficiency of vitamin C causes scurvy (bleeding of gums). Moreover excess of these nutrients also harms the body. Example: Nausea, diarrhea, and stomach cramps.
Therefore nutrients are vital for organisms. And their detailed study is as important to avoid such conditions.
Nutrition in animals gives a detailed discussion about nutrient requirements, mode of intake for food taken and its usage in the body.
The food we eat is made up of complex substances like carbohydrates. These complex substances cannot be used in our bodies directly. Therefore they are broken down into simpler substances. This process of breaking down complex substances into simpler substances is known as digestion. The components helping indigestion are made up of a system called the digestive system which is formed of some crucial organs of the organism’s body.
Why do we need to study Nutrition in animals?
Nutrition in animals is important to study as it helps in knowing the different processes involved in their respective digestion. It also gives us a better understanding of the digestive system and its part involved. The kind of food they eat and through which medium is also included in this Chapter.
Contents which are covered in Chapter 2- Nutrition in animals :
We are going to study nutrition in animals based on the following points.
2.1 Different ways of taking food-- in this topic, we will gain knowledge about the different ways by which an organism takes its food.
2.2 Digestion in humans-- here, we will discuss in detail the digestive system in humans, the parts of the digestive system, its function and the whole process of Digestion.
2.3 Digestion in grass-eating animals-- in this part, we are going to learn about the digestive process of grass-eating animals like cows and buffaloes. How the process actually occurs is discussed in detail.
2.4 Feeding and Digestion in Amoeba
In this, we are going to study the process of Digestion in a microscopic organism like amoeba. The parts of its digestive system are also discussed in detail.
Let's study these contents in detail one by one as discussed in Class 7 Science:
DIFFERENT WAYS OF TAKING FOOD :
Different organisms make food differently.
This is known as the node of taking. It may be Swallowing, Chewing, Sucking, gulping, etc. Different organisms have different modes of taking food. Therefore the digestive system differs for all organisms. Though the process remains the same, the organs involved will be different according to the physical structure of the organism.
Plants prepare their own food through photosynthesis. Other organisms are not able to use this process. Hence they rely on plants or other organisms for their food. Look at this table below to understand, which organism feeds on what substances and also their mode of intake
DIGESTION IN HUMANS :
The human body is of a complex nature. It is made up of organs that work together to form a system. This system then performs processes that are required for the growth and maintenance of the body. Digestion is one of the very important processes in humans. It takes place through the digestive system. The main function of this system is Digestion and absorption. The digestive system carries out its function in the following parts.
- Ingestion - the process by which food is taken in our mouth
- Secretion of juices- it is done by glands present in our body
- Movement of food- food is pushed from the mouth to the stomach. It is a downwards movement.
- Digestion - it is the process of breaking down of complex substances into simpler ones
- Absorption - the required nutrients are absorbed into the blood in this process
- Excretion - the nutrients which are not required or harmful to the body are removed by this process.
Now, we will analyze this process in detail.
In humans, whatever food we eat, passes through our mouth followed by a continuous canal that starts in the buccal cavity and ends in the anus.
This canal consists of:
- A buccal cavity
- Oesophagus i. e the food pipe
- Small intestine
- Large intestine which ends in the rectum
These parts together are called the alimentary canal or the digestive tract. Apart from these, the salivary glands, liver, pancreas also helps indigestion. This whole system is now called the digestive system.
What exactly happens in the digestive system?
The study of the digestive system is of extreme importance. This gives us a clear idea of what happens in our body as soon as we eat. Why does some food gets Digested easily and for some, they are being thrown or vomited outside? To get all these answers, let's have a look at what exactly happens in our body.
The process of food being taken from the mouth is called ingestion. We chew the food and mechanically break it down into simpler and smaller pieces with the help of our teeth. The saliva present in our mouth helps in the Swallowing of the food. The swallowed food now passes through the Oesophagus of the food pipe. This food is now pushed downwards by the movement of the wall in the food pipe. On some occasions, the movement of food downwards is not accepted by the food pipe. Hence it is thrown outside through our mouth. This is vomiting.
The stomach which looks like a flattened J is the biggest part of the alimentary canal. It receives the food through the food pipe and ends in the small intestine.
The small intestine receives juices from the pancreas.
The digested or broken down food when is taken into the blood vessels is known as absorption.
The absorbed food is transferred to the different parts of the body according to their usage. This is known as assimilation.
The large intestine absorbs water and salts from unwanted digested food. The remaining waste is now let into the rectum as semi-solid feces.
The time to time removal of fecal matters from the anus is called egestion.
DIGESTION OF GRASS EATING ANIMALS :
Grass eating animals like cows and buffaloes quickly swallow grass and Store it in the rumen, which is a part of their stomach.
This food is partially digested in their stomach to form cud. This could then return to the mouth in small lumps. And the animals chew this. This process is called rumination. For this, you might have seen these animals, Chewing throughout the day.
These animals are called ruminants.
FEEDING AND DIGESTION IN AMOEBA :
AMOEBA is a microscopic organism that is found in pond water. Its mode of food is other microscopic organisms. As soon as it senses food, it pushes its pseudopodia which are the false feet and traps the food in the food vacuole. Its digestive system breaks down the food into simpler materials. The undigested food is released through the vacuole.
The process of digestion follows the same rule in all organisms only the path differs from organism to organism depending on the structure of their body.
The Vedantu NCERT Solutions for Class 7 Science Chapter 2 Nutrition in animals provides easy and elaborated solutions for all the 13 questions discussed at the end of the Chapter. The team at Vedantu solutions strives hard to provide a comprehensive and up-to-date solution for questions asked in NCERT Class 7 Science for Chapter 2. You can find suitable yet simple answers for Nutrition in animals. The content and solutions designed by expert and qualified professionals give an informative yet easy to understand solution keeping in mind the students of Class 7
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