Why People Wear Glasses?

1.  A person with normal vision sees distant and close objects clearly.

2. The thickness of the eye lens is changed when looking at near or distant objects.

3.  This process is known as accommodation 

   A person who has defective vision needs spectacles to help him see clearly.

 - Two defects are:

       a)  Long-sightedness 

Light from a near object is focused behind the retina.

         b)  Short-sightedness 

Light from a far object is focused infront the retina.

As we have learnt in previous class, light can be reflected and refracted (bend). Which theory should we apply to correct this defect?

YES! REFRACTION!!!

a)  Long-sightedness 

The convex lens converges the light rays.

The converging light rays is focused onto the retina by the eye lens to form a sharp image.

    b)  Short-sightedness 

A concave lens diverges light rays before they enter the eye.

The diverging light rays is focused onto the retina 

by the eye lens to form a sharp image.

Now, let's watch this animation

As

* The Sense Of Taste *

1.A tongue is a taste organ

2.A tongue is sensitive to taste

      a. sweet 

      b. salty 

      c. sour 

      d. bitter

3. The tongue have 4 types of taste receptor:

      a. sweet receptor (cake)

      b. salt receptor    (table salt)

      c. sour receptor   (tomato)

      d. bitter receptor  (coffee)

Detection of taste by taste receptors: 

Food/drink dissolve in saliva

Chemical stimulates taste receptor (taste buds)

Taste receptor send message to brain through nerve

Exercise:

1.How do we taste food and drink?

2. Name the 4 basic senses that the tongue can detect?

3. Why can’t you taste dry food?

4. Why does food seem less tasty when you pinches

   your nose while eating?

DIGESTIVE SYSTEM

Let's discover where the food goes! 

What is digestion??


     - The digestive process involves breakdown of food from complex to simple form in the alimentary canal.


New terms: 

The digestion process involves:
       
a) Physical digestion: Mechanical process, breaking down food into smaller particles, by using the teeth.


b) Chemical digestion: Action of various enzymes.The end  products are simpler molecules which are soluble.

So, can you guess what happen to the food?

   1) Digestion of carbohydrates starts in the mouth

   2) Digestion of proteins starts in the stomach

   3) Digestion of fats starts in the small intestine

   4) Digestion of carbohydrates, proteins and fats ends in the 

       small intestine

Very FUN game !!!

How Stability Works?

1) The centre of gravity affect stability.


Definition: Stability refers to an object’s ability to remain in its original position


All object have an equilibrium points : The equilibrium point is the point at which the weight of an object is considered to act.




2) An object’s is unstable equilibrium if it continues to move further from it original position after being displaced and then released.

3) An object’s is neutral equilibrium if it remains in its displaced position.

4) An object’s is said stable equilibrium if it returns to its original position when slightly displaced and then released.

More example to make you understand..

The factors that affect the stability of an object:

a.The position of the centre gravity

b.The base area

c.The weight of an area.

~Knowing Mr. Photosynthesis~

Learning Biology is FUN! Photosynthesis doesn’t need to be hard~

1) Definition: Process by which plants and some single-celled organism produce sugars from sunlight and carbon dioxide.

Then the sugars become food for cellular respiration.

2) The process occurs in chloroplast. 

3) It involves - light reactions and the Calvin cycle.

       Converting light energy to chemical energy.

LIGHT REACTION

Occurs in presence of light

Occurs in grana

(Photolysis of water)

DARK REACTION

Occurs in light & dark

Occurs in stroma

(Formation of glucose)

4) Light reactions convert sunlight to ATP and NADPH.

5) The Calvin cycle uses ATP and NADPH to convert CO2 to sugar.

At the end of the process:

6 water molecules + 6 CO2 = 1 sugar + 6 oxygen molecules