Class 7
SUBJECT – SCIENCE
Ch -2: Nutrition in Animals
Can you explain all the points given below.
Different Ways of Taking Food
Various modes of feeding in different Animals
Digestion in Humans
Various processes involved in utilization of food in humans
Human Digestive System
Milk Teeth and Permanent Teeth
Sweets and Tooth Decay
Digestion in Grass-Eating Animals
Digestion in Amoeba
Answers
Answer :-
● Different ways of taking food :-
Different organisms take their food through different ways. Some of those ways are sucking, scraping, chewing, brewing, capturing and swallowing.
● Various modes of feeding in different animals :-
- Suction feeding- The organism ingests its prey via the fluids surrounding it. Example- Bony fish.
- Filter Feeding- The organism gets its food from the particles suspended in the water. Example- small fishes.
- Deposit feeding- The organism feeds on the particles suspended in the soil. Example- Earthworms
- Fluid feeding- The organism feeds on the body fluids of other organisms. Example- mosquitos
- Bulk feeding- The organism feeds by eating the whole body of another organism. Example- Python.
● Digestion in humans :-
The process of digestion in humans starts as the food enters the mouth. The saliva in the mouth helps in breaking down the starch into sugar. Then the food passes through the food pipe into the stomach where it gets mixed with several digestive juices which help in breaking the food particles further into simpler forms. The complete digestion of food occurs in the Small intestine and then it passes into the large intestine. In the Large intestine, the left out water content of the undigested matter is absorbed and then the waste matter passes through the Rectum and gets thrown out through the anus.
● Processes involved in utilization of food :-
- Ingestion- The process of getting the food into the digestive tract.
- Digestion- The process of breaking down of complex food particles into simpler forms.
- Absorption- The process of absorption of nutrients.
- Assimilation- The process of utilization of the absorbed nutrients by the cells of the body.
● Human digestive system :-
These are the components of the digestive system of humans in the correct order-
- Mouth
- Food pipe / Oesophagus
- Stomach
- Small intestine
- Large intestine
- Rectum
- Anus
● Milk teeth and permanent teeth :-
- Milk teeth- This is the first set of teeth in a human. There are 20 teeth in total. This set isn't permanent and thus, falls of after a certain age.
- Permanent teeth- This is the second set of teeth. There are 32 teeth in total. This set is permanent and thus doesn't fall off.
● Sweets and tooth decay :-
First of all, why does tooth decay occur ?
It occurs when the saliva in the mouth isn't able to come in contact with a particular area of the teeth.
In most of the cases, some sweet paricles stick to the teeth because of which, the saliva doesn't come in contact with the surface of that part of the tooth/teeth. This results in the development of tooth decay. Anyway, this can be prevented by regular brushing.
● Digestion in grass eating animals :-
The grass enters the mouth and then passes into the four chambered stomach through the esophagus. The four chambers are named as rumen, reticulum, omasum, and abomasum. The process starts with the first 2 chambers. An enzyme named cellulase is present in the rumen which helps to digest the cellulose content. The nutrients are absorbed and sent into the animal's bloodstream. The coarse particles are sent into the third chamber where it gets converted into cud. This cud is then sent back to the animal's mouth for chewing. After chewing, the cud passes into the third chamber again and from there it is sent to the 4th chamber. The complete digestion of food occurs in the fourth chamber.
● Digestion in Amoeba :-
When amoeba encounters a food particle, it spreads its pseudopodia (false feet) around the food particle and engulfs it. After ingestion, a food vacuole is formed around the food particle. The food particle gets broken down inside the vacuole and the nutritional content is absorbed. After this, the waste matter is thrown out of the body. Check the diagram for a better concept.
Answer:
Answer :-
● Different ways of taking food :-
Different organisms take their food through different ways. Some of those ways are sucking, scraping, chewing, brewing, capturing and swallowing.
● Various modes of feeding in different animals :-
Suction feeding- The organism ingests its prey via the fluids surrounding it. Example- Bony fish.
Filter Feeding- The organism gets its food from the particles suspended in the water. Example- small fishes.
Deposit feeding- The organism feeds on the particles suspended in the soil. Example- Earthworms
Fluid feeding- The organism feeds on the body fluids of other organisms. Example- mosquitos
Bulk feeding- The organism feeds by eating the whole body of another organism. Example- Python.
● Digestion in humans :-
The process of digestion in humans starts as the food enters the mouth. The saliva in the mouth helps in breaking down the starch into sugar. Then the food passes through the food pipe into the stomach where it gets mixed with several digestive juices which help in breaking the food particles further into simpler forms. The complete digestion of food occurs in the Small intestine and then it passes into the large intestine. In the Large intestine, the left out water content of the undigested matter is absorbed and then the waste matter passes through the Rectum and gets thrown out through the anus.
● Processes involved in utilization of food :-
Ingestion- The process of getting the food into the digestive tract.
Digestion- The process of breaking down of complex food particles into simpler forms.
Absorption- The process of absorption of nutrients.
Assimilation- The process of utilization of the absorbed nutrients by the cells of the body.
● Human digestive system :-
These are the components of the digestive system of humans in the correct order-
Mouth
Food pipe / Oesophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
● Milk teeth and permanent teeth :-
Milk teeth- This is the first set of teeth in a human. There are 20 teeth in total. This set isn't permanent and thus, falls of after a certain age.
Permanent teeth- This is the second set of teeth. There are 32 teeth in total. This set is permanent and thus doesn't fall off.
● Sweets and tooth decay :-
First of all, why does tooth decay occur ?
It occurs when the saliva in the mouth isn't able to come in contact with a particular area of the teeth.
In most of the cases, some sweet paricles stick to the teeth because of which, the saliva doesn't come in contact with the surface of that part of the tooth/teeth. This results in the development of tooth decay. Anyway, this can be prevented by regular brushing.
● Digestion in grass eating animals :-
The grass enters the mouth and then passes into the four chambered stomach through the esophagus. The four chambers are named as rumen, reticulum, omasum, and abomasum. The process starts with the first 2 chambers. An enzyme named cellulase is present in the rumen which helps to digest the cellulose content. The nutrients are absorbed and sent into the animal's bloodstream. The coarse particles are sent into the third chamber where it gets converted into cud. This cud is then sent back to the animal's mouth for chewing. After chewing, the cud passes into the third chamber again and from there it is sent to the 4th chamber. The complete digestion of food occurs in the fourth chamber.
● Digestion in Amoeba :-
When amoeba encounters a food particle, it spreads its pseudopodia (false feet) around the food particle and engulfs it. After ingestion, a food vacuole is formed around the food particle. The food particle gets broken down inside the vacuole and the nutritional content is absorbed. After this, the waste matter is thrown out of the body. Check the diagram for a better concept.