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CBSE Sample Paper Class 7 Science Nutrition in Animals
Chapter 2
Nutrition in animals
Multiple choice questions: (marks: 1×4)
1.) Stomach is:
A.) J shaped
B.) S shaped
C.) U shaped
Ans: J shaped.
2.) The small intestine is about:
A.) 6.5 metres long
B.) 7.5 metres long
C.) 8.5 metres long
Ans: 7.5 metres long.
3.) The largest gland of the body is:
A.) The stomach
B.) The large intestine
C.) The liver
Ans: The liver.
4.) Large intestine is:
A.) 1.5 metres long
B.) 2.5 metres long
C.) 0.5 metres long
Ans: 1.5 metres long.
Fill in the blanks: (marks:1×3)
1.) …………breaks down the starch into sugar.
Ans: Saliva.
2.) The tongue has ………that detect different tastes of food.
Ans: taste buds .
3.) The digestive juices break down the………into simpler substances.
Ans: proteins.
Answer the following questions: (marks: 1×7)
1.) What is called digestion?
Ans: The breakdown of complex components of food into simpler substances is called digestion.
2.) What is called digestion?
Ans: The digestive tract and the associated glands together constitute the digestive system.
3.) What are the associated glands of the digestive system?
Ans: salivary glands,the liver and the pancreas are the associated glands of the digestive system.
4.) What is called ingestion?
Ans: The process of taking food into the body is called ingestion.
5.) Which is the widest part of the alimentary canal?
Ans: The stomach is the widest part of the alimentary canal.
6.) Who discovered the working of the stomach?
Ans: In 1822 an American army doctor William Beaumont discovered the working of the stomach.
7.) What is ceacum?
Ans: Ceacum is a large sac-like structure between the oesophagus and the small intestine. Animals like horses, rabbits, etc. have ceacum.
Answer the following questions: (marks:2×3)
1.) What are the parts of the alimentary canal?
Ans: The alimentary canal can be divided into various compartments:
(A) the buccal cavity,
(B) food pipe or oesophagus,
(C) stomach,
(D) small intestine,
(E) large intestine ending in the rectum and
(F) the anus. These parts together form the alimentary canal or digestive tract.
2.) What is amoeba?
Ans: Amoeba is a microscopic single-celledorganism found in pond water. Amoeba has a cell membrane, a rounded, dense nucleus and many small bubble-like vacuoles in its cytoplasm. Amoeba constantly changes its shape and position. It pushes out one, or more finger-like projections, called pseudopodia or false feet for movement and capture of food.
3.) What is called rumination?
Ans: Cows quickly swallow the grass and store it in a part of the stomach called rumen. Here the food gets partially digested and is called cud. But later the cud returns to the mouth in small lumps and the animal chews it. This process is called rumination and the animals like cows are called ruminants.
Answer the following questions: (marks:3×5)
1.) Discuss briefly about the digestive system?
Ans: The food passes through a continuous canal which begins at the buccal cavity and ends at the anus. The canal can be divided into various compartments:
A.) the buccal cavity,
B.) food pipe or oesophagus,
C.) stomach,
D.) small intestine,
E.) large intestine ending in the rectum and
F.) the anus.
These parts together form the alimentary canal or digestive tract. The food components gradually get digested as food travels through the various compartments. A.) The mouth and buccal cavity:
Food is taken into the body through the mouth. The process of taking food intothe body is called ingestion. We chew the food with the teeth and break it down mechanically into small pieces. Each tooth is rooted in a separate socket in the gums. Our teeth vary in appearance and perform different functions. Accordingly they are given different names.The tongue is a fleshy muscular organ attached at the back to the floor of the buccal cavity. It is free at the front and can be moved in all directions. We use our tongue for talking. Besides, it mixes saliva with the food during chewing and helps in swallowing food. We also taste food with our tongue. It has taste buds that detect different tastes of food.
B.) The foodpipe or oesophagus:
The swallowed food passes into the foodpipe or oesophagus. The foodpipe runs along the neckand the chest. Food is pushed down by movement of the wall of the foodpipe. Actually this movement takes place throughout the alimentary canal and pushes the food downwards.
At times the food is not accepted by our stomach and is vomited out.
C.) 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. The inner lining of the stomach secretes mucous, hydrochloric acid 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 medium in the stomach acidic and helps the digestive juices to act. The digestive juices break down the proteins into simpler substances.
D.) The small intestine:
The small intestine is highly coiled and is about 7.5 metres long. It receives secretions from the liver and the pancreas. Besides, its wall also secretes juices.
E.) Large intestine:
The large intestine is wider 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. The remaining waste passes into the rectum and remains there as semi-solid faeces.
F.) The anus:
The faecal matter is removed through the anus from time-to-time. This is called egestion.
Associated glands:
Salivary glands:
Saliva is produced through the salivary glands. Saliva helps in digestion and keep mouth moist.
B.) Liver:
The liver is a reddish brown gland situated in the upper part of the abdomen on the right side. It is the largest gland in the body. It secretes bile juice that is stored in a sac called the gall bladder. The bile plays an important role in the digestion of fats.
C.) Pancreas:
The pancreas is a large cream coloured gland located just below the stomach. The pancreatic juice acts on carbohydrates, fats and proteins and changes them into simpler forms. The carbohydrates get broken into simple sugars such as glucose, fats into fatty acids and glycerol, and proteins into amino acids.
2.) What is tooth decay? What are the reasons of it? What measures should be taken to reduce tooth decay? (2+1+2)
Ans: Normally bacteria are present in our mouth but they are not harmful to us. However, if we do not clean our teeth and mouth after eating, many harmful bacteria also begin to live and grow in it. These bacteria break down the sugars present from the leftover food and release acids. The acids gradually damage the teeth. This is called tooth decay. If it is not treated in time, it causes severe toothache and in extreme cases results in tooth loss.
Causes:
The causes of tooth decay are:
- Chocolates, sweets, soft drinks and other sugar products are the major culprits of tooth decay.
- lack of cleanliness.
Measures:
- one should clean the teeth with a brush or datun and dental floss at least twice a day and rinse the mouth after every meal.
- one should not put dirty fingers or any unwashed object in the mouth.
3.) What is called as diarrhoea? What are the causes of diarrhoea? Write down the remedial measures of diarrhoea? (1+2+2)
Ans: Diarrhoea meanes frequency of passing watery loose stool.
Causes:
- Infection,
- Food poisoning or indigestion,
- Food allergy
- Reaction of medicine
- Any other intestinal disease.
Remedies:
- Cleanliness should be maintained. Wash hands properly before and after eating.
- Do not eat very oily and spicy foods.
- Wash and cook the vegetables property before cooking.
- Do not eat undercooked and overcooked food.
- Maintain the hydration.
Even before a doctor is consulted the patient should be given plenty of boiled and cooled water with a pinch of salt and sugar dissolved in it. This is called Oral Rehydration Solution (ORS).