Q 1 – What is tooth decay?
Cavities are permanently damaged areas in the hard surface of your teeth that develop into tiny openings or holes. Cavities, also called tooth decay or caries, are caused by a combination of factors, including bacteria in your mouth, frequent snacking, sipping sugary drinks and not cleaning your teeth well.
Q 2 – Define: Absorption and Assimilation.
Absorption: The process in which the simple, soluble digested food substances are absorbed into the blood is called absorption.
Assimilation: The simple, soluble absorbed food substances are transported to the different parts of the body where they are utilised for energy, growth and repair. This process is called assimilation.
Q 3 – What is Salivary glands ?
The salivary glands produce saliva. The saliva contains an enzyme, called amylase that breaks down the starch present in the food into sugars. Saliva also makes the food wet and slimy so that it can be easily swallowed.
Q 4 – Why is the small intestine so long?
Small intestine performs a variety of functions. Food coming from stomach is continuously mixed with intestinal juices and is completely digested and absorbed. About 90% absorption of all nutrients occurs in small intestine, the other 10% occurs in stomach and large intestine. Villi present all along the length of small intestine, significantly increase the surface area. Increased length and increased surface area of small intestine makes it efficient to carry out various functions.
Q 5 – Why is the food needed to be digested?
Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair. Food and drink must be changed into smaller molecules of nutrients before the blood absorbs them and carries them to cells throughout the body.
Q 6 – (a) What are ruminants? Which of the following are ruminants?
Fish , Amoeba , Cow , Humans, Dogs , Sheep , Buffalo, deer , Goat, Giraffe
(b) Name the type of carbohydrate that can be digested by ruminants but not by umans. Give Reason also.
- Ruminants are the animals which contains cellulose digesting enzymes in their stomach.
- Ruminants can esaily digest carbohydrates present in grass.
- There stomach contains 4 compartments.
- Ruminants – cow , sheep , buffalo , deer , goat
Q 7 – How does Amoeba take in (ingest) the food ? From Which part of the body undigested food is egested in Amoeba?
Amoeba has no fixed place for egestion. The undigested food gets collected inside amoeba, then its cell membrane suddenly ruptures and the undigested food is thrown out of the body of amoeba.
Explanation:
Amoeba take in or ingest the food by forming pseudopodia(false legs) . … The food vacuole has many digestive enzymes in it which helps in digesting the prey. The undigested food or the waste material is egested or thrown out by the semi permeable membrane of Amoeba.
Q 8 – With the help of labelled diagram show the gradual decay of tooth.
Sweets and Tooth Decay The tooth is covered by white, hard outer covering of tooth called Enamel enamel below which dentine is present. It is similar to bone which Pulp cavity (with nerves and blood vessels) protects the pulp cavity having nerves and blood vessels. Bacteria are Gum 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 breakdown the sugars present from the leftover food and release acids. The acids gradually damage the tooth. This is called tooth decay.
Therefore, tooth decay is defined as the process of rotting of tooth and formation of cavity or holes in it which leads to the toothache.
When the holes or cavity reaches to the pulp cavity, it causes pain. If these cavities are not treated on time it causes severe toothache and may result in tooth loss.
Tooth decay can be prevented by adapting following measures.
(i) One should rinse and clean its teeth thoroughly after every Pulp cavity meal.
(ii) We should clean our teeth with the help of datun or brush Gradual decaying of human tooth and toothpaste, twice a day.
(iii) We should use dental floss which is a special strong thread. It is moved between two teeth to take out
trapped food particles.
(iv) Dirty fingers or unwashed objects must be avoided to put in the mouth.
(v) We should avoid the use of sweets, chocolates, toffees, ice-cream, etc. Much use of cold drink should also be avoided.”
Q 10 – Ruminants such as cows and buffaloes swallow their food hurriedly and then sit restfully and chew their food. Give reason.
Ruminants such as cows and buffaloes swallow their food hurriedly and store it in a part of the stomach called rumen. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans. Later, this partially digested food is returned to the buccal cavity of the animals in small lumps and animal chews it to complete the process of digestion. This process is called rumination.
Q 11 – Briefly describe the process of digestion in Amoeba with the help of labelled diagram
Amoeba is a microscopic single celled organism, which is found in pond water. It is a very simple animal and cannot be seen by naked eyes. Amoeba has a cell membrane, a rounded dense nucleus and many small bubble-like vacuoles in its cytoplasm. These vacuoles are of two types, i.e. food vacuole and contractile vacuole. Food vacuole contains food surrounded by water while contractile vacuole contains liquid or water and controls water regulation activity in Amoeba. Its shape is not fixed, i.e. it constantly changes its shape and position. The body of Amoeba has finger-like projections, called pseudopodia or false feet. It captures food and helps in locomotion of Amoeba.
Q 12 – Explain how the digestion of cellulose occurs in grass eating animals.
Digestion in Grass-Eating Animals
The herbivorous animals such as cow, buffaloes, etc eat grass. These animals quickly swallow the grass and store it in a part of stomach called rumen. The food is not chewed completely. Rumen possess cellulose digesting bacteria which breakdown the food by fermentation. This partially digested food or grass present in the rumen of cow is called cud.
This cud is brought back into the mouth of the cow from the rumen into small lumps and animal chews it again. This process is called rumination and animals are called ruminants.
When this cud is thoroughly chewed in the mouth of the cow, it is swallowed again. This time the chewed cud does not go back to rumen but enter into the other compartments of cow’s stomach and then into the small intestine for complete digestion and absorption of food. The cellulose digesting bacteria are not present in the body of human being, therefore human beings and other carnivore cannot digest cellulose present in plant food items.
Q 13 – What is oral rehydration solution ? How can you make the oral rehydration Solution at home when is it given to a person?
oral rehydration solution is a type of fluid replacement used to prevent and treat dehydration especially that due to diarrhoea .
we can make the oral rehydration solution at home by following this three points
six level teaspoons of sugar
* half (1/2) level teaspoon of salt
* one litre of clean drinking or boiled water and
then cooled -5 cupfuls (each cups about 200 ml
when the person got frequent loose motions and lack of water in the body then this ORS solution is given to a person.
Q 14 – Study the given experimental set-up. Test tube A contains boiled rice +3-4 ml water; test tube B contains boiled and chewed rice +3-4 ml water. What will you observe after pouring 2-3 drops of iodine solution in each test tube?
In test-tube A, the boiled rice contains starch. When we add 1-2 drops of iodine, the combination turns in the shade of blue-black. This indicates the presence of starch in the test tube A.
In test-tube B, the starch of rice converts into sugar on digestion. Thus, the colour of iodine will not change.
Q 15 – Fill in the Blanks:
(a) The main steps of nutrition in humans are ___________, ___________, ___________ , ___________ and ___________
(b) The largest gland in the human body is ___________.
(c) The stomach releases hydrochloric acid and ___________ juices which act on food.
(d) The inner wall of the small intestine has many finger-like outgrowths called ___________
(e) Amoeba digests its food in the ___________ .
(a) The main steps of nutrition in humans are ingestion, digestion, absorption, assimilation and egestion.
(b) The largest gland in the human body is the liver.
(c) The stomach releases hydrochloric acid and digestive juices which act on the food.
(d) The inner wall of the small intestine has many finger-like outgrowths called villi.
(e) Amoeba digests its food in the food vacuole.
Q 16 – Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) Digestion of starch starts in the stomach.
(b) The tongue helps in mixing food with saliva.
(c) The gall bladder temporarily stores bile.
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time.
(a) False
(b) true
(c) true
(d) true
Q 17 – Match the items of column I with those given in column II:
|
Column 1 |
Column 2 |
|
Food Components |
Product(s) of digestion |
|
Carbohydrates |
Fatty acids and glycerol |
|
Proteins |
sugar |
|
Fats |
Amino acids |
|
Column 1 |
Column 2 |
|
Food Components |
Product(s) of digestion |
|
Carbohydrates |
Product(s) of digestion |
|
Proteins |
Amino acids |
|
Fats |
Fatty acids and glycerol |
Q 18 – Which part of the digestive canal is involved in:
(i) Absorption of food ________ .
(ii) Chewing of food ________ .
(iii) Killing of bacteria ________ .
(iv) Complete digestion of food ________ .
(v) Formation of faeces ________ .
(i) small intestine
(ii) buccal cavity (Mouth).
(iii) stomach.
(iv) small intestine.
(v) large intestine.