Class 7 Science Ch 02: Nutrition in Animals

    I. Multiple Choice Questions (MCQs).
    Q.1. A snail contains many tiny teeth arranged in rows on a ribbon like tongue called
    a) Proboscis
    b) cnidocytes
    c) radula
    d) rumen
    Answer: c) radula
    Q.2. In humans, the teeth present in front and help to bite the food, are called
    a) canines
    b) incisors
    c) molars
    d) premolars
    Answer: b) incisors
    Q.3. The undigested food that remains in the small intestine passes into the _________.
    a) rumen
    b) large intestine
    c) stomach
    d) rectum
    Answer: b) large intestine
    Q.4. The largest gland present in the upper part of the abdomen is called ____________.

    a) liver
    b) pancreas
    c) kidney
    d) bile
    Answer a) liver
    Q.5. A soft appendage present in hydra that helps to procure the food is
    a) rumen
    b) proboscis
    c) tentacle
    d) vacuole
    Answer: c) tentacle

    II. Fill in the blanks by selecting appropriate words from the given list :
    List : abomasum, buds, pancreas, amylase, enamel
    Q.1. The formation of acid in the mouth, damages the ______________, causing tooth decay.
    Q.2. Tongue contains taste ______________ that help to determine bitter, sour, sweet and salty tastes.
    Q.3. Saliva contains an enzyme called ______________ that break down starch into sugar.
    Q.4. In ______________ the enzymes convert the complex nutrients of food into simpler ones to complete the digestion in ruminants.

    Q.5. Liver and ______________ secrete their juices in small intestine.
    Answer: 1- enamel
    2- buds,
    3- amylase
    4- abomasum
    5- pancreas

    III. Match the items of Column A with those of Column B.

    Column A                                                                           

             Column B  

    1. A unicellular organism.   
                                 

    (a) Alimentary canal 

    2. The organ by
    which lizard, frog and chameleon catch their prey. 

    (b) Sting cells

    3. The organ by which hydra paralyses its prey.   

     (c) Amoeba 

    4. The utilisation of food materials for the process of growth,
    reproduction or repair by the living organisms. 

     (d) Tongue

    5. The tubular passage from mouth to the anus.                                                                                                

    (e)
    Assimilation

    Answer: 1-c, 2-d 3-b 4-e 5- a
    Write ‘T’ for the true and ‘F’ for the false statements.
    Q.1. All the five steps of nutrition in an Amoeba occur within a cell.
    Q.2. Leaf cutting ants bite off pieces of leaves and carry them to huge underground nest.
    Q.3. In humans, the first set of teeth is called permanent teeth.
    Q.4. Alimentary canal is a hollow tube that connects mouth to the stomach.
    Q.5. Liver secretes bile which get stored in a sac like structure called gall bladder.

    Answer: 1-T, 2-T, 3-F, 4-F, 5-T
    V. Very Short Answer Questions.
    Q.1. What type of nutrition is found in animals?
    Answer: Heterotrophic nutrition.
    Q.2. Name the wave-like movement that pushes the food downward in oesophagus.
    Answer: Peristalsis
    Q.3. How does hydra get its food?

    Answer: Hydra uses its specialised sting cells cnidocytes which secrete poison to paralyse its prey. Thereafter, tentacles put this paralysed prey into its body cavity.
    Q.4. List the kinds of digestion in animals.
    Answer: The four basic types of digestive systems in animals are monogastric, avian, ruminant, and pseudo-ruminant.
    Q.5. What is the role of mucous in our stomach?
    Answer: Mucous protects the lining of stomach from hydrochloric acid.

    VI. Short Answer Questions.
    Q.1. What are the functions of tongue in our mouth?
    Answer: Tongue performs the following functions:

    • It helps to mix saliva with food.
    • It helps to find out the taste of food.
    • It helps in swallowing the food.
    Q.2. What is the function of gastric glands present in the inner wall of the stomach?
    Answer: The gastric glands are present in the inner wall of stomach, which secretes gastric juices. These juices contain enzymes that help to digest the food.

    Q.3. What is the function of villi present in the inner wall of small intestine?
    Answer: The inner wall of small intestine has millions of finger like projections called villi. These villi increase the surface area so that maximum absorption of digested food takes place. This absorbed digested food reaches to blood.

    Q.4. List at least three modes of feeding habit. Explain with suitable examples.

    Answer: The different animals have different modes of feeding habits.
    (a) In Ameoba special feet called pseudopodia help to procure food.
    (b) Lizard, frog and chameleon have long, sticky tongue to catch their prey. (c) Birds of prey like eagle, have sharp claws and curved beaks to grip the prey and to shred them into pieces.

    Q.5. How does nutrition in Amoeba occur? Discuss briefly.
    Answer: At the time of ingestion false feet called pseudopodia, surrounds the food to form a structure called food vacuole. In food vacuole digestive juices are released which convert the complex substances present in food into simpler, soluble substances. Digested food is absorbed and assimilated to get energy and maintain the life processes.

    Q.6. Name the different kinds of teeth in humans and their functions briefly.
    Answer: Four types of teeth present in our mouth are-
    (i) Incisors – These teeth are present in front and help to bite the food. Eight incisors are present in the mouth, four in each jaw.
    (ii) Canines – One canine tooth is present on either side of incisor in each jaw. Thus, four canines are present in mouth, two in each jaw. These teeth help in tearing the food.

    (iii) Premolars – Next two teeth on each side of jaw are premolars. They are eight in number. They help in grinding the food.
    (iv) Molars – These are situated at the innermost area of both the jaws. They are twelve in number, six in each jaw and help to chew and grind the food.

    VII. Long Answer Questions.
    Q.1. Write the functions of the following organs of our digestive system.
    (a) Salivary glands (b) Oesophagus (c) Stomach
    Answer: (a) Salivary glands secrete a digestive juice called saliva. Saliva contains an enzyme called amylase that break down starch into sugar.

    (b) The primary function of the esophagus is to transport food from the mouth to the stomach. Here, food is pushed downward by the contraction of the wall. Then this wall relaxes and next part of the oesophagus contracts.

    (c) The main function of stomach to receives food from the oesophagus at one end, and opens into a small intestine at the other end. The gastric glands are present in the inner wall of stomach, which secretes gastric juices. These juices contain enzymes that help to digest the food. Stomach also secretes mucous and hydrochloric acid. Hydrochloric acid kills the bacteria present in the food. Mucous protects the lining of stomach from hydrochloric acid.

    Q.2. Write about the structure and functions of following organs of our digestive system. (a) Small intestine (b) Large intestine
    Answer: (a) Small intestine is the Longest part(about 7.5 m) of the alimentary canal. It is also the site of complete digestion. Here, carbohydrates completely break down into glucose, fats into fatty acid and glycerol and protein into amino acid. Two glands liver and pancreas secrete their juices in small intestine. Liver secretes bile which get stored in a sac like structure called gall bladder. Bile helps to digest fat. Pancreas secretes pancreatic juice that also helps in digestion. The inner wall of small intestine has millions of finger like projections called villi. These villi increase the surface area so that maximum absorption of digested food takes place. This absorbed digested food reaches to blood.

    (b ) The undigested food that remains in the small intestine passes into the Large intestine. Here some amount of water is absorbed by the walls of Large intestine. Remaining waste is passed to rectum and then expelled from the body through the anus. The Length of Large intestine is 1.5 metres.

    Q.3. How does nutrition in ruminants occur? Explain briefly.

    Answer: Digestion of cellulose requires a special type of digestive system in which stomach is divided into four chambers – rumen, reticulum, omasum and abomasum.
    In grass eating animals, half chewed plant material reaches to first chamber of stomach called rumen where bacteria act upon cellulose. The partially digested food enters in the second chamber. From here, partially digested food which is back to mouth is called cud. Cud is further chewed by the animal. This process is called rumination and the animal that does it is called ruminant. The ruminated food is swallowed again and reaches directly to the third chamber of stomach. Here ruminated food is broken down into smaller pieces. Finally it reaches to fourth chamber where enzymes convert the complex nutrients into simpler ones to complete the digestion.

    Q.4. Draw a labelled diagram of human digestive system.
    Answer:

                      

    Q.5. Explain the nutrition in Amoeba with the help of a well-labelled diagram.
    Answer: Nutrition in Amoeba

                   

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