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Karnataka State Syllabus Class 7 Science Chapter 2 Nutrition in Animals
Class 7 Science Nutrition in Animals NCERT Textbook Questions and Answers
1. Fill in the blanks:
- The main steps of digestion in humans are ingestion, digestion, absorption, assimilation, and egestion.
- The largest gland in the human body is the liver.
- The stomach releases hydrochloric acid and digestive juices which act on the food.
- The inner wall of the small intestine has many finger-like outgrowths called villi.
- Amoeba digests its food in the food vacuole.
2. Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) Digestion of starch starts in the stomach. (T/F)
(b) The tongue helps in mixing food with saliva. (T/F)
(c) The gall bladder temporarily stores bile. (T/F)
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F)
Tick (✓) mark the correct answer in each of the following:
(a) Fat is completely digested in the
(iii) small intestine ✓
(iv) large intestine
(iii) small intestine
(b) Water from the undigested food is absorbed mainly in the
(ii) food pipe
(iii) small intestine
(iv) large intestine ✓
(iv) large intestine
Match the items of Column I with those given in Column II:
|Column I||Column II|
|Food components||Product(s) of digestion|
|1. Carbohydrates||a. Fatty acids and glycerol|
|2. Proteins||b. Sugar|
|3. Fats||c. Amino acids|
1 – b,
2 – c,
3 – a
What are villi? What are their location and function?
The inner wall of the small intestine has thousands of finger-like outgrowths. These are called villi.
villi are located in the small intestine. The villi increase the surface area for absorption of the digested food. Each villus has a network of thin and small blood vessels close to its surface. The surface of the villi absorbs the digested food materials.
Where is the bile produced? Which component of the food does it digest?
The liver secretes the bile juice which is stored in the gall bladder, bile plays an important role in the digestion of fats. It breaks down the larger fat globules to smaller fat globules (emulsification) and thus helps in enzymatic action on the fats.
Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.
Cellulose (Ca type of carbohydrate) can be digested by ruminants but not by humans because ruminants have a large sac-like structure called rumen between the oesophagus and the small intestine. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans.
Why do we get instant energy from glucose?
Glucose is a simple sugar. Carbohydrates, when consumed, get digested into glucose. As glucose can be easily absorbed in the blood, it provides instant energy to the body. Hence, when glucose is taken directly, it does not have to be digested and thus acts as an instant source of energy.
Which part of the digestive canal is involved in:
(i) absorption of food Small intestine
(ii) chewing of food Buccal cavity.
(iii) the killing of bacteria Stomach.
(iv) complete digestion of food Small intestine.
(v) formation of feces Large intestine
Write one similarity and one difference between nutrition in amoeba and human beings.
The basic process of digestion of food and release of energy is the same in amoeba as well as in human beings in amoeba, Digestive juices are secreted into the food vacuole. They act on the food and break it down into simpler substances. Gradually the digested food is absorbed. Similarly, in human beings various digestive juices (mouth, stomach, intestine, etc.) act on food and break it down to simpler substances.
The digestion process in amoeba is simple while in human beings it is a complex process. The process of ingestion and egestion is quite different. Amoeba engulfs its food by surrounding the food particle with its pseudopodia. The undigested food which is largely carbon dioxide gas is expelled outside by the vacuole. While in human beings, the food (which is a complex substance) is taken inside the mouth and undergoes a complex process of digestion and absorption. Finally, the undigested food is expelled in the form of faeces.
Match the items of Column 1 with suitable items in Column II
|Column I||Column II|
|(a) Salivary gland||(i) Bile juice secretion|
|(b) Stomach||(ii) Storage of undigested food|
|(c) Liver||(iii) Saliva secretion|
|(d) Rectum||(iv) Acid release|
|(e) Small intestine||(v) Digestion is completed|
|(f) Large intestine||(vi) Absorption of water|
|(vii) Release of faeces|
a – iii,
b – iv,
c – i,
d – vii,
e – v,
f – vi
Label Fig. 2.11 of the digestive system.
Can we survive only on raw, leafy vegetables/grass? Discuss.
Raw leafy vegetables and grass are rich in cellulose, a type of carbohydrate. Many animals, including humans, cannot digest cellulose, because they do not have enzymes and a certain type of bacteria which can digest cellulose. We cannot survive by taking vegetables in raw form. That’s why we boil or cook vegetables which breaks down cellulose into simple carbohydrates which helps to digest easily.
Class 7 Science Nutrition in Animals Additional Important Questions and Answers
Define Animal Nutrition.
Animal Nutrition includes nutrient requirement, mode of intake of food and its utlization in the body.
What is digestion?
The components of food are complex substances such as carbohydrates, proteins, fats etc., These complex substances cannot be utilized directly, so they are broken down into simpler substances. The break down of complex components of food into simpler substances is called digestion.
What are the various (different) ways of taking food in animals?
Scraping, chewing, siphoning, capturing and swallowing, sponging, sucking etc., are the different ways of taking food in animals.
How starfish will take food?
It is one of the amazing facts. The starfish feeds on animals covered by hard shells of calcium carbonate. After opening the shell the starfish pops out its stomach through its mouth to eat the soft animal inside the shell. The stomach then goes back into the body and the food is slowly digested.
Write the neat diagram of human digestive system and label the parts.
Name the different types of teeth in Man?
The shapes and functions of our teeth are different. According to their function, the teeth are classified into three types.
- cutting and biting – incisor
- Piercing and tearing – canine
- Chewing and grinding – pre-molar and molar.
Define Milk Teeth and Permanent teeth.
The first seet of teeth grows during infancy are milk teeth. The second set that replaces milk teeth are permanent teeth.
What is tooth – decay?
The acids produced in our mouth due to leftover food or sweets. These acids gradually damage the teeth called Tooth decay.
What are ruminants?
The cows, buffaloes, and other grass-eating animals chewing continuously are called ruminants. They quickly swallow the grass and store it in a part of the stomach called the rumen. Here the food gets partially digested and it is called cud. Later the cud returns to the mouth in small lumps and the animal chews it. This process is called chewing the cud or rumination and these animals are called ruminants. The grass is rich in cellulose.
What is assimilation?
The absorbed food substances are transported through the blood vessels to different organs of the body where they are used to build complex substances such as proteins required by the body is called assimilation.
What is egestion?
The remaining waste passes into the rectum and remains there as semi-solid faeces. The faecal matter is removed through the anus from time – to – the time is called egestion.
Explain the digestion in the stomach.
The stomach is a thick-walled bag. Its shape is like a flattened ‘J’ and it is the widest part of the alimentary canal. It receives food from the food pipe at one end and opens into the small intestine at the other end. The inner lining of the stomach secretes mucous, hydrochloric and digestive Juices. The mucous protects the lining of the stomach. The acid kills many bacteria that enter along with the food and makes the acidic medium in the stomach which helps the digestive juices to act. Here the digestive Juices break down the proteins into simpler substances.
Write the neat diagram of Amoeba and label the parts.
Explain the feeding and digestion in Amoeba.
Amoeba feeds on some microscopic organisms. When it senses food, it pushes out pseudopodia around the food particle and engulfs it. The food becomes trapped in a food vacuole. Digestive juices are secreted into the food vacuole. They act on the food and break it down into simpler substances, gradually the digested food is absorbed.
Write the neat diagram of digestive system of ruminant.
Write the neat diagram of movement of the food in the oesophagus of the alimentary canal, label the parts and explain.
The swallowed food passes into the food pipe or oesophagus. The food pipe runs along the neck and the chest. Food is pushed down by the movement of the wall of the food pipe. Actually this movement takes place throughout the alimentary canal and pushes the food downwards. When the food is not accepted by our stomach, it is vomited out.
Explain the structure of large intestine and its function.
The large intestine is winder and shorter than small intestine. It is about 1.5 metre in length. Its function is to absorb water and some salts from the undigested food material.
Explain the structure and function of the small intestine.
The small intestine is highly coiled and is about 7.5 metres long. It receives the secretion from the liver and the pancreas. Its wall also secretes juices. The party digested food reaches the lower part of the small intestine where the intestinal juice completes the digestion of all components of the food. The carbohydrates get broken down into simple sugars such as gluscose, fats into fatty acids and glycerol and proteins into amino acids.
What is diarrhea?
Sometimes we have all experienced the need to pass watery stool frequently. This condition is known as diarrhea.
What is ORS?
ORS is an Oral Rehydration Solution. The boiled and cooled water with a pinch of salt and sugar dissolved in it. ORS solution should be given to diarrhea. Patients to prevent dehydration before consulting the doctor.
II. Fill in the blanks
- The breakdown of complex components of food into simpler substances is called digestion.
- Starfish feeds on animals covered by hard shells of calcium carbonate.
- The process of taking food into the body is called ingestion.
- The name of the piercing and tearing teeth is canine.
- The saliva breaks down the starch into sugars.
- The swallowed of damage the teeth by acids is food pipe or oesophagus.
- The process of damage the teeth by acids is tooth decay.
- If by chance the food particles enter the windpipe, we feel chaked get hiccups or cough.
- Bile Juice is stored in a sac called gall blader.
- The digestive juices break down the proteins into simpler substances.
- The finger-like outgrowths in the small intestine are called villi.
- The part of the stomach in ruminants is known as rumen.
- In Amoeba, the food becomes trappef in a food vacuole.
- Amoeba is a microscopic single-celled.
- The greass is rich in cellulose.