Learn Science [Form 2]

Chapter 1 - Lesson 4

CHAPTER 1: THE WORLD THROUGH OUR SENSES

1.4 The Sense of Taste

1 The tongue is the sensory organ that gives us the sense of taste. It is sensitive to sweet, salty, sour and bitter tastes.

2 The upper surface of the tongue is rough. This because it is covered with taste buds.

3 Taste receptors can be found in the taste buds. They respond to various chemicals in food. Each type of taste receptor is sensitive a certain type of taste.

4 (a) The tongue has four types of taste receptors. (b) These are sweet receptors, sour receptors, salty receptors and bitter receptors.
(c) Each receptor is located in a particular area of the tongue. Thus, each area of the tongue is able to detect a certain type of taste.

5 Figure 1.7 shows the location of the various taste receptors.

Figure 1.7 The taste receptors - each loacated in a particular are of the tongue

6 How food is tasted

7 Food that cannot dissolve in the saliva cannot be detected by the taste receptors.

Sense of taste and smell

1 Both the senses of taste and smell are needed to detect the flavours of food accurately.

2 The nasal cavity and the mouth are connected.

3 Chemicals from food that stimulate the taste receptors also move into our nasal passages. These chemicals stimulate the sensory cells in the nose.

4 If a person has a cold or closes his nose, the air passages in the nose are blocked. This reduces the sensitivity of the smell receptors. Food becomes less tasty or different from its original taste. This is because the senses of taste and smell are closely related.

×××××

ACTIVITY 1.2 : Relating the sense of taste to the sense of smell

Procedure
1 A few slices of apple are prepared. Two slices are rubbed with some onions.
2 A student closed his eyes and pinched his nose tightly.
3 He is fed with the slices of apples first and then a few slices rubbed with onion.
4 He is asked to describe the taste of what he has eaten.
5 The procedure is repeated. This time, the student closed his eyes but did not pinch his nose.

Results
1 As long as his nose is pinched, the two types of apples will taste the same.
2 Only when his nose is nit pinched can he taste the difference between the two slices of apple that he has tasted.

Conclusion
The sense of taste is related to the sense of smell.

×××××

***

Okay. So let's take a recap!

1.4 The Sense of Taste

Tongue ➡ is the sensory organ that gives us the sense of taste.
                ➡ is sensitive to sweet, salty, sour and bitter tastes.

The upper surface of the tongue is rough because it is covered with taste buds.

Taste receptors can be found in the taste buds. They respond to various chemicals in food. Each type of taste receptor is sensitive a certain type of taste.

The tongue has four types of taste receptors. These are sweet receptors, sour receptors, salty receptors and bitter receptors. Each receptor is located in a particular area of the tongue. Thus, each area of the tongue is able to detect a certain type of taste.

How food is tasted?
1. Chemicals in food dissolve in saliva.
2. The chemicals stimulate taste receptors in the taste buds.
3. Impulses from the taste receptors are sent along the nerves to the brain.
4. The brain identifies the taste.

Food that cannot dissolve in the saliva cannot be detected by the taste receptors.

Sense of taste and smell

Both the senses of taste and smell are needed to detect the flavours of food accurately.

The nasal cavity and the mouth are connected.

Chemicals from food that stimulate the taste receptors also move into our nasal passages. These chemicals stimulate the sensory cells in the nose.

If a person has a cold or closes his nose, the air passages in the nose are blocked. This reduces the sensitivity of the smell receptors. Food becomes less tasty or different from its original taste. This is because the senses of taste and smell are closely related.

***

So, yeah. The activity are just for you to understand. This is all copied from the book so I am planning to put some additional explanations or something from what I understand so it could help you to understand it more clearly. What do you think? Is it a good idea?

Additional update. Just put some recap at the end with bold and underlined words for you to keep. Those are just to highlight the important words. 😊

~ CutieKittyMe