5- Teeth and mucrobesTime to Answer
Rewrite the following statements by correcting the underlined word.
1. Permanent are the first set of teeth.
Ans. Temporary
2. A child has thirty two temporary teeth
Ans. Twenty
3. The first tooth appears during the first two months.
Ans. Six or seven
4. Permanent teeth are also known as milk teeth.
Ans. Temporary
Fill in the blanks.
1. The four front teeth in both upper and lower jaws are called incisor.
2. Canines help in tearing tough food.
3. Incisors are also known as cutting teeth.
4. Premolars are eight in number.
5. Molar are also known as grinding teeth.
1. The main cause of teeth decay bacterial infection.
2. The sticky coating formed on teeth plaque.
3.The hole formed in tooth due to tooth decay cavity.
Put a tick (√) mark on the DOs and cross mark DON'T s regarding tips to keep the teeth and gums healthy.
1. One should not wash their mouth after every meal. (X)
2. One should avoid sugary food. (√)
3.Flossing helps to improve the colour of teeth. (X)
4.potassium keeps the teeth healthy. (x)
1. Multiple choice questions (MCQs)
a. Shreya is 13 years old. How many teeth is she likely to have?
Ans. 28
b. Which is the innermost layer of a tooth?
Ans. Pulp
c. Which of the following holds our teeth in place?
Ans. Root
a. Pulp provides nourishment to the tooth.
b. The total number of incisor teeth in each jaw is 4.
c.The part of the tooth which we can see when we smile is called crown.
d. The pulp of tooth is made up of herves and bloodvessels.
3. Read the following two statements and choose the correct option
Statement 1. The outer portion of the tooth above the gum is called crown.
Statement 2. In a tooth, blood vessels and nerves are present in the root.
Ans . Both statements 1 & 2 are correct.
Q4. Short answer type questions.
a. What is enamel? Write two lines about it.
Ans. Enamel is the outer layer that is visible enamel is made of a very hard mineral that is perfect for breaking down the food which we eat. It is the hardest substance in the human body. But once it is warm out of chipped, it cannot be naturally repaired.
b. Name four main kinds of microbes.
Ans. Bacteria, viruses, ptotozoa and fungi.
c. Write few tips to keep teethand gums healthy.
Ans. 1. We should always rinse our mouth after eating or drinking any thing.
2. We should floss our teeth regularly flossing help to remove the food particles stuck between the teeth.
d. Name four different kinds of teeth.
Ans. Incisor, cainines, premolars and molars.
a. What type of food must one eat to keep the teeth healthy and what type of food must one avoid to prevent tooth decay?
Ans. Calcium and vitamin-C rich food are essential for maintaining healthy teeth and gums ones should limit their snacks and meals to 5 or 6 times per day snaks that stick to the teeth and cause decay should not be consumed through out the day.
b. What is the difference between milk teeth and permanent teeth?
Ans. Milk teeth- milk teeth are the initial set of teeth that develop through out child hood and full out between the ages of 6 and 8 years.
Permanent teeth- the second set of teeth that follow the milk teeth typically persist into old age. A human adult has 32 permanent teeth equally divided into the upper lower jaws. These are called permanent teeth.
c. Write four uses of microbes.
Ans. Uses of microbes:-
1.some bacteria change milk into curd and some help in making cheese.
2.some microbes help in baking bread and making wines.
3.microbes help in the decay of dead plants and animals.
4.some bacteria help to digest food in animals.
5.some bacteria produce vitamins in our body.
d. Describe the different parts of a tooth.
Ans.types of teeth are Incisors, canines, premolars and molars.
Incisors:- the front teeth in both the upper and lower jaws are called incisors. There are 8 incisors in our mouth. These are broad and flat with narrow edge. They used for cutting and biting food.
Canines or tearing teeth:- these are four in number are present on either side of the incisors in each jaw. These are the most stable teeth in the mouth. They help in tearing tough food such as meat.
Premolars or cracking teeth:-
These are broad teeth located next to the canines. They are eight in number and four in each jaw. They help in cracking and chewing the food.
Molars or grinding teeth:- These are broader than the premolars and lie next to them in the interior of each jaw. There are six molars in each jaw. They help in chewing and grinding food.
e. How does tooth decay occur?
Ans. Bacterial infection is leading cause of tooth decay. Food particles stuck on teeth cause bacteria to grow if they are not brushed regularly and throughly. These bacteria produce acids that eat away the protective layer of teeth. They also produce plaque a sticky coating that damage the dentine and eventually the pulp resulting in cavities.
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